Talk:Sewage

Merging Blackwater (waste) into Sewage
If we accept the definition of Sewage given in the article, then it's basically anything -- Blackwater (waste), Greywater, whatever -- that goes into a sewage system. Thus, sewage is not necessarily blackwater. Blackwater, on the other hand, is any water with fecal matter and/or urine in it, including that which does not go into a sewage system. Thus, blackwater is not necessarily sewage. The two categories are distinct. 70.245.108.95 (talk) 02:13, 6 January 2008 (UTC)

Blackwater (waste) into Sewage may be slightly more specific than Sewage but I think they're close enough to be best covered in the same article. Should the blackwater section develop, it could always be split later. --Chriswaterguy talk 10:01, 15 October 2007 (UTC)

Yes, it could be merged into a broader category page called "Poop". —Preceding unsigned comment added by 72.211.131.123 (talk) 23:03, 29 December 2007 (UTC)

i agree we shuld merge them together even though sewage isn't really black water

(it saves space) —Preceding unsigned comment added by Gigikun (talk • contribs) 14:16, 27 January 2008 (UTC)


 * Thinking about it more carefully, I see that as Gigikun and 70.245.108.95 point out, the terms are related but distinct (sewage can also include greywater and industrial waste). So I withdraw my suggestion and remove the merge notices. --Chriswaterguy talk 03:29, 14 August 2008 (UTC)

Sewage tunnels
Perhaps it could be mentioned that sewage tunnels can be converted and used for building out the subway systems. This, as trough the use of composting toilets/composting toilet collection system, sewage tunnels are no longer required. Sewage requires allot of water, so it would safe that resource too. —Preceding unsigned comment added by 81.245.64.190 (talk) 11:33, 8 July 2009 (UTC)

Good article from Scientific American
Could be used to expand the article: http://www.scientificamerican.com/article.cfm?id=treating-sewage

Merge with the article on "wastewater" ?
I have just been doing some work on the page on wastewater and on this page. But more and more I reach the conclusion that the two pages should be merged. OK, sewage can be equated to municipal wastewater, not so much to industrial wastewater. I checked in the important textbook Metcalf & Eddy (I added that reference) and the only time "sewage" is mentioned is in the listing of terms where it says simply "older term, see wastewater". So there is a lot of overlap between the pages of "sewage" and "wastewater". EvM-Susana (talk) 22:11, 12 April 2015 (UTC)


 * I have streamlined the content of this article. If we don't merge it with wastewater then at least it should be very focussed on municipal wastewater only and not on sewage sludge treatment. I see it as an overview article from where people can find the important links to other articles to go in depth on this topic.EvM-Susana (talk) 20:50, 8 June 2015 (UTC)


 * Coming back to my own comments six years later, I still see a lot of overlap with wastewater which I find problematic. We should decide which content should go where and not duplicate the same in two articles. Comments, User:Velella? EMsmile (talk) 03:12, 22 April 2021 (UTC)

Gold in poo
Perhaps imbibing Goldschläger has something to do with this. 7&amp;6=thirteen (☎) 15:23, 4 May 2015 (UTC)

Merge to sewage treatment?
I am wondering if this article is better off merged into sewage treatment? As it stands it is just a high level article that talks about collection, treatment and reuse, but all the content is pretty much available elsewhere, so it just links to the other locations. I think it's better to move this to sewage treatment, and whatever doesn't fit there could be moved to wastewater. What do you all think, e.g. User:Velella? EMsmile (talk) 03:25, 22 April 2021 (UTC)
 * I've just re-arranged some content under a heading called "management" which I feel a bit better about. If we want to focus the article more as an "overview" article, explaining the issues of collection, then perhaps it is better off not merged with "sewage treatment". But I think it would be really important to revisit wastewater and sewage and to make sure they don't overlap too much. Currently, I see a lot of talk about sewage in the wastewater article. The two terms are colloquially used interchangeably, so we have to be really clear what we mean in which article. EMsmile (talk) 04:25, 22 April 2021 (UTC)
 * I still think a merger of sewage into sewage treatment makes sense and deserves further discussion., your thoughts? EMsmile (talk) 00:42, 15 July 2021 (UTC)
 * The existing sewage treatment article is already too large to be easily navigated, and adding the content of the sewage article would make the situation worse. A preferable information structure might be to move some information from the sewage treatment article into linked subordinate articles describing alternative treatment schemes or process sequences. Alternatives like evaporation, dilution, groundwater recharge, or sewage farming may be inappropriately minimized by grouping the subject of sewage with the present conventional treatment scheme. Thewellman (talk) 04:49, 15 July 2021 (UTC)
 * I don't think that the existing sewage treatment article is too large but this seems to be a "personal preference" thing, where you seem to favour shorter articles over medium sized ones. Would be great to get a third opinion on this but currently it seems to be only you and me interested in these topics. :-) But I don't understand: which parts of "sewage treatment" do you want to move to sub-articles? Once they are moved, would it make the article small enough so that sewage (which is a rather short article) could be merged into it? Where do you want to include topics such as dilution and groundwater recharge? I don't see them as very important but they could easily be mentioned here (in the "alternative options" section in sewage treatment). By the way, a separate article on sewage farm already exists and is linked from "sewage treatment". The dilution aspect is already included under "disposal". EMsmile (talk) 06:01, 15 July 2021 (UTC)
 * I consider the present sewage article to be of appropriate size in a useful format. I suggest a similarly useful sewage treatment article might be limited to the present sections Pretreatment (including Grit removal but without a separate heading), Primary treatment, Secondary treatment, and Disinfection with an appropriate lead section, See also list, Tertiary treatment section emphasizing links to subordinate articles in either list or text format, and Ponds section explaining correlation with mechanized primary and secondary treatment. Linked subordinate articles would cover most of the the material presently found in the Flow equalization, Fat and grease removal, Filtration, Biological nutrient removal, Nitrogen removal, Phosphorus removal, Sludge treatment and disposal, Odor control, and Fourth treatment stage sections. Dilution and groundwater recharge might be listed (with sewage farm) in the sewage article as alternatives to sewage treatment. Thewellman (talk) 23:20, 15 July 2021 (UTC)
 * Are those sub-articles that you mentioned all in existence already? I had a quick look and most of them are still in red (unless they exist under different names and I haven't found them yet); Flow equalization, Fat and grease removal, Filtration, Biological nutrient removal, Nitrogen removal, Phosphorus removal, Sludge treatment and disposal, Odor control, and Fourth treatment stage. If they exist already then it's easy to re-arrange the content. If they still have to be created it's more time consuming (and personally I am not a big fan of creating new small sub-sub-articles that will linger with low view rates; so I would not be volunteering my time for it but if someone else wants to do it, go ahead). I think the alternatives to treatment fit well into the article on sewage treatment, rather than in the article on sewage. The article on sewage should just be on the material itself. What to do with it belongs under "sewage treatment" (even "sewage farm" (and outdated term by the way) is a form of treatment). An alternative would be to rename the article to "Sewage management".'' EMsmile (talk) 00:22, 16 July 2021 (UTC)
 * I'll have a go at creating some focused links. I prefer small, focused articles allowing a reader to quickly find the information being sought. Comprehensive technical articles with high view rates simply indicate most users needed to wade through a long discussion of peripherally related material to find the information they really wanted. Many of the tertiary or 4th treatment technologies, like filtration, are specialized applications of more widely used chemical engineering operations or processes. Fat and grease removal is an example of froth floatation. Nitrogen removal can be covered by a link to the Use in wastewater treatment section of the denitrification article. Odor control could be similarly linked to an example section of the scrubber article. Fourth treatment phase is covered by the Fate of pharmaceuticals in sewage treatment plants section of the Environmental impact of pharmaceuticals and personal care products article. Thewellman (talk) 02:33, 16 July 2021 (UTC)
 * What's your evidence for this kind of statement?: "Comprehensive technical articles with high view rates simply indicate most users needed to wade through a long discussion of peripherally related material to find the information they really wanted." It might also be that people find it an important topic, search for it on Google (or directly on Wikipedia) and then enjoy reading up about it and come back to it for more. They might actually enjoy finding the information all in one place, not fragmented in lots of sub-articles. Having links to sub-articles for more details is good but to shrink articles right down to the bare bones and basically just making them like a page of links would not be right. For example: do you find the article on climate change also too long? Or the articles on Earth or menstrual cycle? All three are featured articles, quite long, quite detailed and comprehensive. - Note that had plans to get the "sewage treatment" article to GA status (see here), although I am not sure if they are still actively pursuing that goal currently. EMsmile (talk) 10:44, 16 July 2021 (UTC)
 * Although I realize sewage treatment may release greenhouse gases, most sewage treatment occurs on earth, and menstrual products are sometimes found in sewage, I am similarly opposed to merging the content of the climate change, earth, and menstrual cycle articles into the sewage treatment article. These articles are fundamentally dissimilar to the technology aspects of sewage treatment. A more reasonable comparison is the electrical engineering article which has lost its featured article status as it swelled to the size you are suggesting. The articles on paper and papermaking are better examples of a material and technologies related to that material. Both articles stand alone within the size limits I am suggesting. There is no need for merging, despite the overlap. Reviewers of these articles focus on absence of source citations rather than mentioning deficient breadth of coverage. Thewellman (talk) 00:20, 17 July 2021 (UTC)
 * I don't understand what you meant with: I am similarly opposed to merging the content of the climate change, earth, and menstrual cycle articles into the sewage treatment article.! I am getting more and more confused with your statements. The point I tried to make is that the articles climate change, Earth and menstrual cycle do a good job in each explaining the "full content" of their topic in ONE article (and being fairly lengthy), rather than being just a list of links to sub-articles, which is how I fear you want to convert sewage treatment into. Unless you were joking when you said: I am similarly opposed to merging the content of the climate change, earth, and menstrual cycle articles into the sewage treatment article.. I really don't get what you tried to say with that statement. Anyway, perhaps just go ahead and make those changes to the "sewage treatment" article that you have in mind. Maybe then I'll understand what your plans are with it. - And where exactly does it say that the main (and only?) reason that electrical engineering got demoted was that it's too long? I've never heard of length being the Number 1 criterion! EMsmile (talk) 12:07, 18 July 2021 (UTC)
 * You have correctly interpreted the tongue-in-cheek nature of merging the featured articles you mentioned, but the problem of defining the scope of the sewage treatment article is a significant issue. A problem with the electrical engineering article arose from editors adding unsourced material in potentially inappropriate locations because the article subject is so broad. The editors who compiled the featured article were unable or unwilling to devote the required time and effort keep such a large article organized.
 * As you suggest, some subjects like history, are better adapted to a single chronological article. I doubt sewage and the treatment thereof is amenable to such coverage, as there are numerous alternative source, treatment, and disposal forks which will be difficult to assemble into a universally agreeable format for individuals seeking information about just one of those forks. For a fixed amount of text, we might consider the choice between a Wikipedia of six-million articles or a Wikipedia of six-hundred-thousand articles. I suggest the limited time available to many qualified editors of emerging sewage treatment technologies will produce higher quality short articles than might be obtained by expecting those editors to determine where their information might best fit within a comprehensive article, and those editors may be less able to watch the larger article to keep duplicative material out of other locations.
 * I am disinclined to purge the sewage treatment article, because I don't want to discourage the editors who have compiled that information. I simply suggest there is no need to compound the complexity of this article by adding all the information in the sewage article. I think a more productive discussion might be how to reduce the duplication in those two articles, with a longer-range goal of conceptualizing a data structure for the less common treatment technologies and disposal options utilized for only a small fraction of sewage. Thewellman (talk) 03:13, 19 July 2021 (UTC)

Problems with recent edits (July 2021)
Hi, I find some of the changes you made recently not ideal (and I am missing an overview on the talk page about your reasoning for the major re-write). Here are the things that I find problematic: EMsmile (talk) 07:37, 23 July 2021 (UTC)
 * (1) You have changed the referencing style from the long citation method to the short citation method, and have now created a mixture of citation styles. Let's just stick with the long citation style, like it was before.
 * (2) You have now used two very old books on many occasions. I really don't see why a book from 1959 and one from 1975 need to be cited many times in an article that is edited in 2021 (that's 60 years later!). I think the Metcalf & Eddy book is far more suitable as it's continually being updated.
 * (3) There are statements that you have taken from those old books which clearly show that it's outdated information or perhaps specific to the United States (?). Do you have an agenda to push for sewage to NOT be treated at sewage treatment plants? I don't mind that you want to show alternatives to treatment but you are writing it as if treatment is the least important option, whereas it's actually the most important option, see examples below.
 * (4) In the "treatment" section you have this sentence which doesn't talk about treatment of sewage: Examples of treatment processes used for stormwater include retention basins, wetlands, buried vaults with various kinds of media filters, and vortex separators (to remove coarse solids)..
 * (5) Here again you put treatment last: Management of sewage may include collection for release to surface water, infiltration to groundwater, or reuse, with or without sewage treatment.
 * (6) Here in this sentence you left out treatment altogether: Sewage may be collected and transported in a sanitary sewer or in a combined sewer that conveys stormwater runoff, sewage and industrial wastewater to an evaporation or infiltration basin, or to a stream, lake, or ocean..
 * (7) What is this supposed to mean (with a citation from 1959 in the sentence that follows)? and perceptions of individuals generating the sewage may differ from other segments of the population.?
 * (8) This one is also wrong: Sewage used for another purpose like irrigation or groundwater recharge may be called reclaimed water.. It should be "treated sewage".
 * (9) Why is this now under "sources" and not under "pollutants"?: Sewage contains pathogens of four types.
 * (10) Why are you using the term "domestic sewage" now? It should be either "sewage" or "domestic wastewater".
 * (11) This section is not needed in my opinion as the same can be found in wastewater; but useful to differentiate domestic sewage from the following terms.
 * (12) There is content in the lead that is not in the main body; this is no good because the lead is supposed to be a summary of the article (this was probably already like this before your recent round of edits but needs addressing).
 * (13) You removed this content (it was unsourced but perhaps sources could be found for it? The words "sewage" and "sewer" came from Old French essouier "to drain", which came from Latin exaquāre. Their formal Latin antecedents are exaquāticum and exaquārium.[citation needed] Both words are descended from Old French assewer, derived from the Latin exaquare, "to drain out (water)".[citation needed]
 * (14) Unser Pollution, can we put the SI units first and then the American units? Even better, I think we should quote mg/l ranges, i.e. concentrations.
 * (15) This is wrong as it relates to the United States but makes it sound like it's universal: The volume of domestic sewage produced per person varies with the availability of water and cost of water, and is typically within the range of 50–100 US gal (190–380 l; 42–83 imp gal) per capita per day. The amount of sewage produced is MUCH lower in other parts of the world. In fact, all the figures that you quote in the section on pollutants need to be either clearly stated as being for the United States, and secondly values for other types of countries should also be provided, e.g. for developing countries.
 * (16) You've deleted this entire section (it was probably too detailed but was there nothing that could have been salvaged?): The following chemical or physical pollutants can occur in sewage due to household activities or due to industrial wastewater mixing:
 * Just to say some of the other edits you made I agree with, especially if the aim was to reduce overlap with other articles. Probably it's a matter of "the shorter the better" for this article. EMsmile (talk) 07:56, 23 July 2021 (UTC)
 * I've taken the liberty of placing numerals by your bulleted comments for reference to my responses below:
 * (1) Good point, but possibly a lower priority than other issues you mention.
 * (2) My library reflects the time of my professional work in this field. While treatment technologies have improved, and synthetic organic chemicals and plastics have become more common, the major elements of sewage remain relatively unchanged in much of the world. I would encourage use of later sources if you can find them with the same specificity to sewage as opposed to sewage mixed with industrial waste, and/or diluted with stormwater. Industrial wastewater and its treatment is appropriately addressed in a separate article which emphasizes the importance of pre-treatment. The inclusion of industrial wastewater with community sewage is unique to the industrialized world and should not be implied as a part of domestic sewage. Stormwater is similarly addressed in separate articles.
 * (3),(5),(6)&(8) Do you have an agenda to push that sewage MUST be treated at sewage treatment plants? Such an agenda might seem a non-neutral position in view of the numerous populations who find other priorities for their limited resources. Perhaps the sewage treatment article will discuss the trade-offs of treatment vs source control or dilution.
 * (4) I agree this should be moved to an article dealing specifically with stormwater.
 * (7) I hope to keep this article neutral by recognizing individual differences in perception of acceptable waste disposal practices. Aside from differences between populations, or individuals within a given population, the same individual may accept different water quality standards downstream in comparison to upstream.
 * (9) Pathogens are the essential difference between sewage and other wastewaters. Our disgust at the odor of sewage has been an evolutionary advantage encouraging us to avoid the disease risks of human excrement. The odor of decomposing excrement has been a major factor in the history of sewers giving sewage its name.
 * (10) I found the term in the cited source which focused on sewage in the era before industrial wastes and stormwater were widely recognized as sources of pollution. It is valuable in that context as discussed under (11).
 * (11) I strongly disagree. Wastewater is a broad term which tends to obscure the differences between sewage, industrial wastes, and dilution sources like infiltration and surface runoff.
 * (12) I agree the lead needs work in accordance with our merger discussion of segregating sewage from sewage treatment.
 * (13) I have no objection to including this information if you can find a source for it.
 * (14) I have no objection to putting SI units first, but I have reservations about substituting concentrations for mass when describing sources. Concentrations may be entirely appropriate when discussing treatment options (in the treatment article) or disposal options (in either article.)
 * (15) The cited sources did not specify those were United States figures. I encourage you to include alternative figures from sources clearly differentiating sewage from more broadly defined wastewaters including industrial wastes, and combined sewer flows.
 * (16) I am concerned about the probable contributions of industrial wastewater rather than sewage in those unsourced lists. I have attempted to mention these pollutants within the text where I could find sources.
 * Thewellman (talk) 16:04, 23 July 2021 (UTC)
 * Thanks for your replies. I currently don't have time to delve into this article further. I feel that your changes have made some improvements but also made some things worse. Many statements are specific to the US now, which is why I am going to add the "globalize" tag. When I have more time, I will utilise Metcalf & Eddy as well as publications by EAWAG and Marcos Von Sperling for more current information and for information from around the world. In my opinion, this is a far better book to use than books from the 1970s but even better would probably be publications that are available open source and online, so that we don't have to use textbooks only which are behind paywalls and which make it difficult for other Wikipedia editors to contribute. And regarding having an agenda for treatment, I am just going by what the latest literature says. There is a focus nowadays on management, i.e. treatment and often reuse (where the treatment options are matched with the reuse intentions). Certainly, the approach of "dilution" is no longer a current one. But again, this kind of discussion needs to be more at sewage treatment than here. This article should just describe what sewage is. What to do with it should be in an article called "sewage management" (which is the current sewage treatment article) EMsmile (talk) 03:17, 26 July 2021 (UTC)
 * I am planning to come back to this article in the next few days. I am currently working on water pollution which required a lot of work. I've started to work with the book by Marcos Von Sperling and am loving it. Clear, easy language, and the pdf file is available online for free. So my plan is to replace all the old citations (e.g. Metcalf & Eddy 1971) in this article with citations from this book, or if I can't find them then the Metcalf & Eddy 4th edition from 2003 which I happen to have on my desk (but which is not available for free, so not quite ideal). EMsmile (talk) 02:26, 5 August 2021 (UTC)

Treatment versus disposal
I have been puzzled about why knowledgeable editors are reverting mention of solid waste in sewage and disposal options with minimal treatment. Perhaps these editors have very limited experience attempting to implement modern treatment technologies to small rural communities. I spent my professional career assessing the ability of small rural communities to comply with first-world disposal regulations after central government had funded construction of sewer systems and treatment plants designed by engineers experienced in building treatment works for larger communities. A major problem was the inability to scale labor required to operate these rural systems. Communities of several hundred residents could typically afford to pay a single, part-time individual with very limited training or experience. While that individual might be required to respond to emergencies 24/7, their pay was based on spending a few hours each day checking and cleaning the treatment plant and pump stations. There were seldom any backup employees on the payroll, so unexpected problems required finding private contractors with significantly higher overhead costs unaffordable to the community. Most of the significant violations involved large solid waste in the sewage. Smaller sewer lines entirely adequate for the liquid flows involved were easily blocked, and raw sewage overflows typically went unobserved until the operator arrived for his morning checks and then remained uncorrected until central government authorities were convinced to muster appropriate repair personnel with equipment to correct the problem. Cleanup and repair of damaged equipment fell to small communities who never had the financial resources to purchase that equipment. Keeping the treatment system operational required the central government to fund replacement of equipment which had not met its expected design life because of inadequate maintenance.

This article will be of greater use to the relatively uneducated people considering options for sewage treatment and disposal than to the trained consultants who will help them choose appropriate options. It would be a disservice to the less informed readers to limit affordable choices for smaller communities with less affluent populations, but some of the present text sounds like advertising of unaffordable or unsustainable options. I am planning to come back to this article in the next few days. Thewellman (talk) 20:43, 24 August 2021 (UTC)


 * I think we have several issues here. Once we have them sorted out, the rest might flow quite naturally.


 * 1) Firstly, if we had merged sewage and sewage treatment (my original proposal) then we wouldn't now have the problem to decide where the non-treatment options should be covered. I don't think they should be in both articles. Currently I am thinking the non-treatment options should be explained at sewage but one could also argue they should be at sewage treatment. But not in both articles.
 * 2) With regards to treatment, there are different options, the more high tech ones and then the low tech ones, like ponds. This should come out clearly at sewage treatment and I plan to work on this, mainly using the book by Marcos von Sperling as a reference.
 * 3) There are some options for dealing with sewage which I think in your mind constitute "treatment" whereas in my mind they are "disposal", for example marine outfalls. This might be a philosophical question. However, we have an authoritative publication on this which is the EAWAG compendium. This publication is well respected in the field of water and sanitation, it has a global view and gets updated regularly. They group all the technologies into functional groups of user interface, transport, treatment, disposal or reuse. If you look at page 138 here you can see what they call disposal or reuse options (not treatment): D.1 Fill and Cover/Arborloo D.2 Application of Stored Urine D.3 Application of Dehydrated Faeces D.4 Application of Pit Humus and Compost D.5 Application of Sludge D.6 Irrigation D.7 Soak Pit D.8 Leach Field D.9 Fish Pond D.10 Floating Plant Pond D.11 Water Disposal/Groundwater Recharge D.12 Surface Disposal and Storage D.13 Biogas Combustion.
 * 4) Overall with this article, I think it is very important to give it a global perspective and to not give the data from one particular country (United States) more weight than necessary. I've left some of the US data for comparison but I really didn't like how before my edits there were "per capita flowrates" given without saying for which country they were. Sewage flowrates per person are much higher in the US than elsewhere. Using the book by Marcos von Sperling has the big advantage that it's more encompassing, up to date and available as a free pdf file so any reader or editor can check up for themselves. - If you want to add more information that is specific to the US, I propose you consider this article: Water supply and sanitation in the United States.
 * 5) Regarding solid waste, we have a section called "Solid and liquid wastes" so I am not sure what you are referring to when you said "reverting mention of solid waste". I might have cut down a bit the excessive detail of children throwing toys into the toilet, or people flushing down pregnancy test kits but only because we need to use summary and encyclopedic style with due weight for the different topics, it's not a "how to" guide. Also, the content had no reference.
 * 6) Where does the present text read like advertising? EMsmile (talk) 00:06, 25 August 2021 (UTC)
 * P.S. I am today reworking the sewage treatment article to include more information on different types of treatment, i.e. also the lower cost options. I think you'll agree with me on that one and will find that a useful set up changes (I hope). So far, that article was geared mainly towards activated sludge treatment plants or other high tech systems. Again, it should be more of an overview article, not zooming too much (we have sub-articles for that).EMsmile (talk) 01:08, 25 August 2021 (UTC)
 * P.P.S. I have now added in both articles the sentence that land application can be regarded as both, disposal or treatment. I found a suitable reference for it in the von Sperling book. Again, we just need to be careful that the same content about land application is not in both articles or that they don't overlap too much on that point. If the focus is on treatment it should be at sewage treatment. EMsmile (talk) 04:40, 25 August 2021 (UTC)


 * I'm puzzled as to why you would label my comments as Treatment versus disposal as I think our differences are broader than that. I shall attempt to reply to your comments by the numbers:
 * (1) Disposal options are certainly fundamental to treatment decisions, but they are equally important to decisions about separation versus combination of blackwater, greywater, stormwater, and industrial wastewater. Differing foci would complicate the location of this information in a single article, so I remain unconvinced of the merit of a combined article.
 * (2) I agree about the value of von Sperling's work as a source, but it is inappropriate to eliminate other sourced information.
 * (3) Feces, urine, and bathing have been part earth's biome for as long as apes have existed on the planet. We can either compartmentalize their catabolism or allow it to occur within our larger ecosystem. In reality, most treatment will catabolize only a fraction of the total. The more modern chemicals we mix with our sewage raises the issue of whether they should be mixed. The EAWAG compendium is valuable, but less than comprehensive.
 * (4) I agree with the advantages of providing a worldwide perspective. First world practices have been, and will be, more exhaustively evaluated in published work. There may be disagreement about assumed accuracy of per capita weighting of their observations on a national, first world, or global scale.
 * (5) Solid waste is a more significant component of sewage than might be suggested by its volume. Solid waste is as aesthetically displeasing as odor because it can be visibly detected without the analyses required for many other components of concern. Treatment options which fail to anticipate solid waste may fail to remove solid waste or have their treatment functions disabled by solid waste. The flexibility and tensile strength of cloth makes it a particularly challenging problem for treatment machinery, yet the sourced listing of clothing was eliminated. Challenging the presence of children's toys in sewage illustrates how many readers without childcare experience may be surprised by children's fascination with flush toilets. I intend to restore both.
 * (6) Mixing industrial waste with sewage reduces concentrations of blackwater pollutants and pollutants unique to industrial waste without removing either from the waste stream. Dilution of sewage increases capital costs of treatment and reduces the fraction of organic waste removed by secondary treatment. I am concerned this text may encourage unreasonable expectations of treatment and inappropriately reduced concern about mixing of industrial wastewater. The following statements imply a treatment plant is a integral part of the sewer system, while treatment or disposal might be a more neutral destination: These can range from decentralized systems (including on-site treatment systems) to large centralized systems involving a network of pipes and pump stations (called sewerage) which convey the sewage to a treatment plant. For cities that have a combined sewer, the sewers will also carry urban runoff (stormwater) to the sewage treatment plant.
 * Most treatment options will merely reduce, rather than eliminate, some pollutant concentrations; some will generate new waste streams; and other pollutants will remain unchanged in treated sewage. The bold adjective inappropriately implies treatment will eliminate pollution: Sewage can cause water pollution when discharged untreated to the environment.
 * Regulations vary widely regarding land disposal, and residual concentrations of pollutants reaching groundwater will depend upon overlying soil conditions and relative volumes of sewage and groundwater. The bold text seems inconsistent with this variation: Groundwater recharge is a method of treated sewage disposal to reduce saltwater intrusion, or replenish aquifers used for agricultural irrigation. Treatment is usually required to sustain percolation capacity of infiltration basins, and more extensive treatment is required for aquifers used as drinking water supplies.
 * Addition of industrial wastewater to sewage may significantly change the efficiency of treatment. The Addition of other flows section fails to consider industrial wastewater.
 * The following statements imply industrial wastewater is an integral part of sewage: Sanitary sewers serving industrial areas also carry industrial wastewater. Sewage also contains micro-pollutants, municipal solid waste and pollutants from industrial wastewater.
 * The following statement implies pre-treatment: For most cities, the sewer system will also carry a proportion of industrial effluent to the sewage treatment plant that has usually received pre-treatment at the factories to reduce the pollutant load.
 * Thewellman (talk) 22:02, 29 August 2021 (UTC)


 * I am finding it very tedious to work on this article because you and I don't agree on my things and what we really need is a third or fourth editor to get involved. What a pity that so few Wikipedia editors are interested in this topic. At this stage, I just want to react to two of your comments. About Point (2). Yes, it is appropriate to replace an old, inaccessible textbook from 1959 with a newer, accessible textbook from 2015 if the new book contains information about the same topic. Why do you insist on using a textbook from New York (dealing with the situation in the United States only) from 1959 as a reference just because you happen to have that book on your bookshelf? I really don't think we need to have two sentences about the per capita load of BOD and suspended solids just after each other, one from 1959 and one from 2003. Therefore, I have deleted the sentence and reference from 1959. and about Point (5): the fascination of children with flush toilets can be added to flush toilet if you have suitable up to date references for that. Here for the sewage article, we already explain that there is solid waste in the sewage, we don't need to spell out every possible pathway how that solid waste might have entered the sewage. Also, only a minority of people worldwide even have flush toilets. So if you expand the content about flush toilets you are once more increasing the article's bias towards to the United States and Europe. Please have a think about that, whether the fact that children might throw toys into a flush toilets is really so important that it needs to be added to a global article on sewage. EMsmile (talk) 01:27, 9 September 2021 (UTC)


 * (2) I suggest the age of sources does not necessarily reflect improved accuracy or veracity. They may express different observations for reasons not evident in their descriptions. I suggest it is inappropriate to assume the last word is universally correct. The deleted earlier information was on a dry weight basis, while the later information was on a wet weight basis. This is a significant difference given the variability in urine quantity with fluid intake. The earlier source gave dry weight estimates for toilet paper, urine solids, and greywater solids missing from the later source. Dry weight is the essential measure of percent removal which may be inappropriately concealed by dilution when the focus is on waste concentration.
 * A publication from 1959 would be next to impossible for readers to access nowadays. If you didn't have it on your bookshelf you couldn't access it either. Therefore, if newer, more accessible (and reliable) sources exist, they should be used instead. See also WP:RS Especially if the old source is just about one country, rather than about the global situation. EMsmile (talk) 07:44, 9 September 2021 (UTC)
 * This response ignores the issue of dry weight quantities missing from the later source. Dry weight is essential to mass balances verifying removal of pollutants, while the ambiguity of volumes or wet weights is exacerbated by the fact sewage has a thousand times more water than pollutants. Compiling information from an international realm of sources exceeding what can be found in small libraries is a magnificent advantage of Wikipedia. Why should that possibility be ignored? Thewellman (talk) 05:07, 11 September 2021 (UTC)
 * (5) I suggest it is useful for readers to understand WHY sewage contains solid waste and the likely range of solid waste products found in sewage. Anthropologists have found water play a nearly universal fascination of children across virtually all cultures. In view of their contribution to sewage reaching treatment plants, emphasis on flush toilets is at least as appropriate as emphasis on treatment.
 * I don't have the data available but I would expect that most of the solid waste gets into sewage from the streets, not from the flushing. For starters, flush toilets wouldn't allow flushing of larger bits of solids waste anyhow. Anyhow, that information that you wanted in there about flush toilets is back in so I guess that satisfies your requirements. EMsmile (talk) 07:44, 9 September 2021 (UTC)
 * The substituted excerpt from sewage treatment is less useful than the focused summary it replaced, and offers nothing which cannot be found at the main article link for those interested. Thewellman (talk) 06:51, 9 September 2021 (UTC)
 * That's exactly the purpose of an excerpt: to give the reader a glimpse of what would be in the transcribed article. There is no point writing a new paragraph about sewage treatment, when the information about sewage treatment is available at sewage treatment. That information that you had added, was about a specific kind of sewage treatment which I find not helpful. If you think the first two paragraphs of sewage treatment are not good enough, then I suggest you change them there, not here. EMsmile (talk) 07:39, 9 September 2021 (UTC)
 * If the same paragraph contents and structure were equally useful describing more than one subject, excerpts would be more widely used in paper encyclopedia. Why should we think they are any more appropriate in Wikipedia? Thewellman (talk) 05:07, 11 September 2021 (UTC)

Entropy
I suggest consideration of dilution with respect to earlier discussions about the advantages of treatment, and an inclusive definition of wastewater. In a natural environment, the biological pollutants of blackwater might be diluted until dissolved oxygen depression was negligible and the probability of infection of another individual was acceptably low as a means of preventing overpopulation. Some type of treatment may help sustain present levels of overpopulation if waste isolation is not possible. Disinfection is the most important treatment from a health standpoint, but the commonly used chemical oxidation for disinfection has the significant disadvantage of converting organic compounds in wastewater to endocrine disruptors. Diluting blackwater with other wastewaters containing organic material prior to disinfection increases the volume of oxidizing chemicals required for disinfection and the probability of creating hazardous quantities of endocrine disruptors.

This is just one example of the disadvantages of mixing wastewaters prior to treatment, or in a larger sense, of blurring the differences between different types of wastewater. Dilution of sewage by mixing with stormwater or industrial wastewater may be an advantage where treatment objectives are specified in terms of concentrations rather than mass, but treatment chemical costs and energy costs of pumping will be increased by the greater volume of wastewater requiring treatment for a pollutant unique to a single type of wastewater. Where might be the best place to discuss the benefits of source control in comparison with possible economies of scale for end of pipe treatment? Thewellman (talk) 00:20, 28 July 2021 (UTC)
 * I think that kind of content would fit well at sewage treatment. Do you have suitable references at your fingertips? Ideally those that other people can access freely as well online, not old textbook from 30 years ago (not having a snipe here, just thinking practically). - I wonder if you have also seen this article: urine diversion. It explains the concept of keeping urine separately from the rest of the wastewater streams, and how to treat, manage and reuse the collected urine. - Overall, I don't see dilution as a promising thing nowadays, simply because most of our environmental problems occur due to population increase - more people living together in smaller spaces. Sure, in rural areas with lots of space you can easily dilute and not treat. Even a city like Sydney used to have long ocean outfalls rather than treatment because it was felt that the huge Pacific can deal with that little bit of wastewater from Sydney. As Sydney grew though, so did the need for treatment prior to dilution in the ocean. EMsmile (talk) 02:20, 5 August 2021 (UTC)
 * I think you will find the city of San Diego, California, with a population of about 1.4 million, still uses ocean outfall dilution of primary treated sewage as a substitute for secondary treatment: https://www.sandiegouniontribune.com/news/politics/story/2020-11-24/u-s-house-oks-bill-giving-san-diego-long-sought-relief-on-pt-loma-sewer-discharge-rules
 * https://www.pointloma-obmonthly.com/news/story/2021-01-22/san-diego-optimistic-about-federal-legislation-to-streamline-permit-for-point-loma-sewage-plant
 * Thewellman (talk) 05:47, 5 August 2021 (UTC)
 * I didn't say it's not happening. Of course it's still happening. In fact there are estimates that 50-90% of all wastewater is discharged untreated (worldwide); see here. You could call that dilution as well. But the more the population grows, the less likely it gets that this can be a sustainable approach. Of course we can mention it in the article but I feel that you are over-exaggerating its importance (we should follow WP:DUE in our articles). It's more of a disposal pathway than a treatment option... EMsmile (talk) 09:09, 5 August 2021 (UTC)
 * Merely mentioning dilution doesn't seem like an appropriately neutral weight for an option used for fifty to ninety percent of sewage. We must cover what is and what has been in addition to what could be or what should be. Thewellman (talk) 10:20, 5 August 2021 (UTC)
 * We can describe the current situation, namely that 50-90% of sewage is discharged untreated at a worldwide level, but not making it seem like it's a great new treatment option. It is merely a disposal option. See also discussion about persistent organic pollutants at water pollution - even small concentrations of toxins can be damaging to the environment. Dilution is not the solution. Either way, this kind of information (and discussion) should be at sewage treatment, not here. EMsmile (talk) 08:01, 6 August 2021 (UTC)

How much about collection systems do we want to include?
I have just added two excerpts about two sewer systems to the section on "Collection". However, I am wondering if we should shorten this further by replacing it with just one excpert that is transcluded from sewerage or from gravity sewer? That's how I have done it at sewage treatment which takes an excerpt from sewerage. I am undecided. Either way, I think the excerpts are a good solution here as it means the content only has to be improved/updated in one location and will automatically update in the other articles as well. EMsmile (talk) 14:29, 25 August 2021 (UTC)
 * It seems rather obvious to me that sewage would not be so named if it did not flow in sewers. Description of sewers therefore seems an essential part of the sewage article. The difference between sanitary and combined sewers may be useful background for flow equalization factors and variable pollutant concentrations important to sewage treatment decisions, but similar variation could be caused by holiday occupancy fluctuations or by industrial discharge quantities and concentrations changing with production changes. The focus on variation in sewage treatment design would be quite different from focus on sizing for dilution in the sewage article. I see no reason to think the same text would be satisfactory for both articles. Thewellman (talk) 04:05, 11 September 2021 (UTC)


 * Firstly, in other places/countries/settings, the same substance that you call "sewage" is called "domestic wastewater" and therefore, not all sewage/domestics wastewater flows into sewers. Think of houses connected to septic tanks. They produce domestic wastewater but may not be connected to sewers. Secondly, sewers can be mentioned in passing here but not in detail because that's what the separate Wikipedia articles on sewers are there for. We don't need to repeat the same content over and over in different articles. Short mention: yes. Details: no. That's my opinion. EMsmile (talk) 13:37, 13 September 2021 (UTC)

Collaborative editing not working well
, I am finding it really hard to collaboratively edit this Wikipedia article with you if you make a huge number of changes in one single edit like you have done here. In the edit summary you stated "restructured to improve utility of the table of contents". This makes it sound like a simple act of moving things around but in reality you have deleted a heap of content and re-inserted other text that I had earlier removed, plus new text. I find that rather uncooperative because it makes it really hard for the other person (me in this case) to follow your thought process and to review the edits to understand what was changed and why. If you look at the history page you'll see that when I edit, I save frequently and explain each individual step in the edit summary so that others can follow what I have done. I don't enjoy anymore working on this article when it's like that; it feels more like an edit war now. Probably best if I step away for a while. Hoping that another editor will show up at some stage who can bring in fresh eyes and perspective as well as recent and accessible references to use. EMsmile (talk) 02:02, 9 September 2021 (UTC)
 * A problem with the structure I replaced is the difficulty persons with a casual interest may have in finding useful summaries of subordinate topics. Many readers are simply unwilling to wade thru a long article. The format I changed prevented table of contents listing of significant topics because 4th level topics do not appear in the table of contents. Restructuring on a piecemeal approach leaves the article at a nonfunctional structure with each intermediate revision. The suggested inflexibility of organization is a serious impediment to useful informational access. While this structure may make sense to professionals in the field, it may be confusing to readers with less experience.
 * Management, for example, is widely perceived as personnel operating as administrators of a business.
 * General characteristics, for another, is a nonfunctional description of an accumulation of marginally related topics which might better be condensed into separately named topics.
 * Related types of flows gives no clue that the subject is blackwater and graywater rather than laminar, turbulent, convective, viscous, peak, average, wet weather, dry weather, fluid, metered, river, or tidal. Thewellman (talk) 06:06, 9 September 2021 (UTC)
 * We can discuss the different section titles but my complaint here was that in one sweeping change, you changed far more than just "restructured to improve utility of the table of contents" which made it all the more difficult for me to understand what all the changes were (you added and deleted a lot of content as well, e.g. the content about marine outfalls). Point taken about "management". I like to use generic section headings, and I think management is a generic section heading. And I added "related types of flows" because before it made it seem like "greywater" and "blackwater" equals sewage which is not true. My original section heading there was "sub-types" which you also disagreed with. EMsmile (talk) 07:46, 9 September 2021 (UTC)
 * In general, I think Level-1 headings should be relatively generic, things like "Characteristics", "types", "costs", "environmental issues", "society and culture". Also I think in most cases, Level 1 headings should include some Level-2 headings, as they can usually be grouped together in one Level-1 heading. That's why I don't think "Flowrates" should be a Level-1 heading on its own but so be it. (compare also with the structure of textbooks on this topic, e.g. the von Sperling book: https://iwaponline.com/ebooks/book/72/Wastewater-Characteristics-Treatment-and-Disposal) EMsmile (talk) 07:54, 9 September 2021 (UTC)


 * Wikipedia is not a textbook, and attempts to make Wikipedia articles like textbooks limit the unique possibilities of this project. As an engineer educated in the slide-rule era, I recall the cherished textbooks of classmates who painstakingly labeled the tabs carefully inserted on critical pages where important text was underlined or highlighted with differently colored markers. While those modifications might remain essential to those textbook owners well into their professional career, they were of little utility to fellow students in the same discipline, and an annoyingly useless distraction to readers with dissimilar backgrounds. The fact that any given organizational structure seems appropriate to one Wikipedia editor does not imply other editors will share that opinion.
 * Wikipedia replaces textbook table of contents and index with internal links which can immediately take readers to the specific area of interest. Large articles require a lengthy list of table of contents links with an organizational structure concealing the subject of interest hidden within ambiguously broad categories. Thewellman (talk) 04:49, 11 September 2021 (UTC)
 * I see you have already made all those changes now. I disagree with your way of using Level-1 and Level-2 headings. But I give up. EMsmile (talk) 14:15, 13 September 2021 (UTC)

Potential for conflict of interest
The recent pattern of edits to this article and related articles sewage treatment, wastewater, wastewater treatment, and industrial wastewater treatment has been to subordinate the various types of wastewater to their treatment, and to suggest these variations are less important than an encompassing definition of wastewater. Such simplification would conceal important environmental consequences of mixed wastewater.

Generators of industrial wastewater are plagued by public resistance to disposal of chemical wastes with defined hazardous concentrations. Alternatives include expensive removal of these chemicals from industrial wastewater, or dilution of the industrial wastewater with a greater volume of municipal sewage to drop the overall concentration of hazardous waste below the defined limit. Individuals with limited understanding of the wide variety of treatment options may be placated by the belief the industrial wastewater is being "treated" while treatment sequences intended for municipal sewage may have little effect on industrial wastewater, and industrial wastewater may diminish the effectiveness of municipal sewage treatment processes on sewage pollutants.

The present condition of our biosphere illustrates the consequences of focusing on concentrations of hazardous materials in waste streams rather than eliminating those materials from waste. Edits increasing the difficulty of differentiating wastewater types and treatment options limit the general public ability to understand the environmental consequences of waste disposal options. Who might benefit from such obfuscation? Thewellman (talk) 20:46, 13 September 2021 (UTC)


 * I didn't understand what you were getting at and whether this kind of comment is actually suitable for a talk page. A statement such as "Who might benefit from such obfuscation?" leaves me puzzled as to what you are getting at. Conspiracy theories? What kind of conflict of interest are you saying that I have, apparently? Like I just wrote in my comment below, I am working with the expert Marcos von Sperling to improve this article, as well as sewage treatment. It would be nice to know that other editors, including you, work on the assumption of good faith regarding my edits. We are all just doing the best we can. EMsmile (talk) 04:22, 14 October 2021 (UTC)


 * I am simply taking the issue of our disagreements up on this article talk page as suggested by your Wikipedia user profile. That user profile indicates you are being paid to edit Wikipedia, and the above comment indicates you have chosen to rely heavily upon the opinions of a single individual with unknown business interests. I do not question that your edits may be in good faith, but WP:CoI emphasizes Any external relationship can trigger a conflict of interest. That someone has a conflict of interest is a description of a situation, not a judgement about that person's opinions, integrity, or good faith. Thewellman (talk) 19:37, 14 October 2021 (UTC)


 * I still don't get what you are getting it? I have declared my potential WP:CoI on my user page, what else do you want me to do? What do you mean with "the opinions of a single individual with unknown business interests", what are you getting it? Are you referring to Marcos Von Sperling, a well known academic in Brazil who has written numerous textbooks published by IWAP and made open access so that anyone can read up on them? What kind of business interests are you referring to? It would be nice if we could stick to the actual Wikipedia article and not push conspiracy theories. Please tell me which of my recent edits to the article you disagree with and if you have recent, reliable references (that are accessible) to underline your points/opinions? I think all the comments that Marcos made, and which I incorporated last week, were very well founded and also provided a balanced global view (not centered on the US anymore, how the article used to be). I explained in the edit summaries exactly what was changed and why. We should be grateful that an academic has taken the time to review this article rather than complaining about "the opinions of a single individual with unknown business interests". Are content experts not welcome in Wikipedia anymore? EMsmile (talk) 13:20, 18 October 2021 (UTC)


 * P.S. if you want to approach and invite another content expert to review this article and help improve it further, that's fine by me. I am happy to do it, just suggest names and I can send them the same invitation e-mail that I had sent to Marcos. The more the merrier. It's not easy to find someone who's willing to volunteer his or her time but it's worth trying.  EMsmile (talk) 13:43, 18 October 2021 (UTC)

There are none so blind as those who will not see. (attributed variously to John Heywood in 1546, ‘Works of Thomas Chalkley’ in 1713, and Jonathan Swift's ‘Polite Conversation’ in 1738) Thewellman (talk) 19:31, 18 October 2021 (UTC)

Mixing is dilution
I am reverting a recent edit separating industrial wastewater from the other diluents alleging doesn't make sense to have industrial wastewater under a heading of "dilution". It is not diluting the sewage because it usually adds more organic load etc. Yet, of the sixteen industrial wastewaters listed in that article, only the food industry adds an organic load likely to be catabolized by the same microorganisms acclimated to domestic sewage. Only one other, the paper industry, has a heavy loading of organic waste similar to toilet paper, but with a nitrogen deficiency in comparison to domestic sewage which may require a different catabolizing microbial population. The other fourteen are primarily associated with inorganic pollutants unlikely to be catabolized by secondary treatment. Some of those inorganic pollutants may suppress one or more of the microbial species catabolizing sewage wastes. While a fraction of these inorganic wastes may be removed to accumulate in sewage treatment sludge, such accumulation may reduce potential re-use of those biosolids. Thewellman (talk) 22:13, 14 September 2021 (UTC)
 * When the industrial wastewater has a high organic matter or nutrient concentration than the sewage then mixing the two streams together does not constitute dilution. See for example wastewater from the food processing industry, breweries, slaughterhouses... Therefore, I find it misleading to speak of mixing = diluting. I am going to take another look and see if this can be improved. EMsmile (talk) 04:17, 14 October 2021 (UTC)
 * Organic matter encompasses a very broad range of compounds. The ability of secondary treatment bioreactors to catabolize any given compound depends upon organisms with enzymes specific to that compound. Food processing wastes with a high probability of sewage bioreactor species with suitable enzymes comprise a narrow subset of industrial wastewaters. Mixing does nothing to reduce the mass of pollutants to be treated, but the volume of sewage lowers the concentration of pollutants unique to industrial wastewater, and the volume of industrial wastewater lowers the concentration of pollutants unique to sewage. Lower concentrations of pollutants reduces the rate at which those pollutants will be destroyed by treatment processes, and slower treatment reactions require larger treatment plants. Bioreactors are typically unable to reduce pollutants below a minimum food concentration necessary to sustain the catabolizing organisms, and larger volumes at that minimum concentration result in larger remaining quantities of pollutants in the treatment plant discharge. I propose to preserve language describing the disadvantages of mixing wastewaters. Thewellman (talk) 20:23, 14 October 2021 (UTC)
 * Which sentence(s) in the existing text are we discussing right now? Yes, for sure, mixing of wastewaters has disadvantages and this should come out in the article if it's not clear yet. I thought the description about dilution and assimilative capacity is pretty good now. Although perhaps that part should be moved to its own section so that we are not lumping two concepts into one section. Dilution in the receiving water body might be a different concept to dilution with stormwater in the sewer. But if you prefer to keep it all together in the existing heading called "dilution" that's also fine by me. EMsmile (talk) 00:07, 15 October 2021 (UTC)
 * I'm not sure the issue can be restricted to a single sentence. It depends upon the overall article organization and emphasis. Thewellman (talk) 20:22, 18 October 2021 (UTC)

Reviewer's comments (October 2021)
I am working with an external content expert (Marcos Von Sperling) to review this article, as well as sewage treatment. This is part of this project. I will save after each small change and explain in the edit summary what was done. Happy to engage in further discussions on those changes. He has also sent me some images, some of which I have now included in sewage treatment. EMsmile (talk) 04:18, 14 October 2021 (UTC)

Comments about concentrations and ranges of pollutants in sewage
These were comments from the reviewer (in brackets some of my comments how I have addressed them or not):
 * 1) What about not stating typical single values, but rather ranges of values? Also, not mention only developing countries, but make them more universal? (reply: I have included ranges and tried to find more info about Europe but have not yet achieved much)
 * 2) There many books presenting this type of information, but I guess most of them will not be freely available. I thought about this book, which is really international, and includes people from Delft: HENZE, M., VAN LOOSDRECHT, M.C.M., EKAMA, G.A., BRDJANOVIC, D. (2008). Biological wastewater treatment. Principles, modelling and design. IWA Publishing, London, 2008. 511 p. In pages 35-36 of the English edition there are useful tables presenting per capita loads and flows (typical values, in g/cap.d and m3/cap.d) and another table showing country values (note that they are in kg/cap.yr). There is this Spanish version of the book, which is freely available: LÓPEZ VÁZQUEZ, C.M., BUITRÓN MÉNDEZ, G., GARCÍA, H.A., CERVANTES CARRILLO, F.J. (2017). Tratamiento biológico de aguas residuales: Principios, modelación y diseño. IWA Publishing, London. 576 p. Disponível para download em: http://wio.iwaponline.com/content/16/9781780409146. In this Spanish version, the tables are in pages 37-38. Since the authors, and the book itself, are well known, this should be a good international reference. (reply: I have now utilised information from this book).
 * 3) Combine the ranges from my Table 2.24 with the values from Tables 3.14 and 3.15 from Metcalf& Eddy 4th edition (or Table 3.18, Metcalf, 5th edition, which has slightly different values). The idea could be to produce typical ranges, emphasizing that the values vary from location to location, and are likely to be at the upper values in more developed regions. Also, in urban areas they are usually higher than in rural areas (Metcalf, p. 183) (reply: I haven't don't this yet; the question is how much depth do we go into, given that we are not writing a textbook here; maybe it's enough how we have it now.)
 * 4) Another source, that may be representative for European countries, is the German Standard ATV-DVWK-A 198:2003. (reply: I haven't looked into it yet)
 * 5) I see that in different places, the values of per capita pollutants contributions, and also concentrations, appear in this article. Besides some repetition, the values are different. What about creating a subsection such as “Typical sewage composition”, and present all values in this section? Ideally, the values should be presented after the constituents have been described. (reply: I have now implemented that) EMsmile (talk) 09:32, 15 October 2021 (UTC)
 * I would support using ranges where more than one estimate is provided for similar situations using a format like BOD per capita: (low number) -(high number) It would be important not to mix dissimilar circumstances in such ranges. When the differing values have differing explanations, it would preferable to list multiple values with an explanation of the circumstance where that value was measured or estimated. BOD per capita: from (low lumber) for Brazilian cities with combined sewers through (intermediate number) for rural United States residences in the 1970s to (high number) for 21st century European municipalities with industrial waste

or possibly in tabular format where estimates from multiple differing circumstances are available. Thewellman (talk) 03:30, 16 October 2021 (UTC)

Additional references on standards

 * 1) Additionally, there are many publications on standards, and one could search those from US (USEPA), Canada, Australia etc, and they would hopefully be open-access. The European standards for the discharge of urban wastewater are: Official Journal of the European Communities No. L 135/40 (Council of the European Communities, 1991). I think it is still applicable. The following book covers standards, in general: SCHMIDT, M., GLASSON, J., EMMELIN, L., HELBRON, H. (eds) (2008). Standards and thresholds for impact assessment. Vol. 3. Environmental Protection in the European Union (Series). Springer-Verlag. pp. 125-132. ISBN: 978-3-540-31140-9. (reply: I haven't looked into these publications yet and probably won't have time to do so in the near future. If future editors can look into this, that would be great.) EMsmile (talk) 09:32, 15 October 2021 (UTC)

Comments about reuse of raw sewage
This is the sentence that Marcos had proposed: "An alternative to discharge into the environment is to use the treated effluent in a productive way, for agricultural, urban or industrial uses. In this case, the quality of the treated sewage must also comply with the requirements for each specific use." You (Thewellman) changed that to "An alternative to discharge into the environment is to use the raw sewage or treated effluent in a productive way, for agricultural, urban or industrial uses. In this case, the quality of the sewage must also comply with the requirements for each specific use." - I don't think this is a correct/useful statement for this Wikipedia article, at least not in its current wording. But let's see if we can find a recent, reliable reference for either of the statements to see which one is true, i.e. please not one from the 1950s in the US which would probably state that raw sewage can just be spread on farms. We have learned since then that this is too risky. At the very least there would have to be some preliminary treatment such as screening. You don't want toilet paper on the farm land, would you. So I can see very few cases where anyone would recommend to use raw sewage for productive ways; it would be very risky to do so in agriculture. We should probably refer to the WHO guidelines which propose the system of multiple barriers, where treatment is one of them. And which urban or industrial uses could there possibly be for raw sewage? EMsmile (talk) 13:31, 18 October 2021 (UTC)
 * "risky"? What risks are you talking about? On one hand we have the risk that some people might get sick, and perhaps die, reducing energy requirements of earth's human population. On the other hand we have the risk that energy requirements for pumping and treating sewage generated by the earth's present and projected future human population will cause global warming making populated parts of earth uninhabitable. Our species has survived a long history of agricultural use of untreated sewage, sometimes euphemistically termed night soil. Toilet paper is readily compostable in soil. Rejection of earlier publications on this subject implies willful ignorance. There may be justification for regulations encouraging agricultural use of raw sewage similar to agricultural use of domestic animal manure. Thewellman (talk) 20:08, 18 October 2021 (UTC)
 * I have no problem with reuse of excreta in agriculture. I did a lot of work on the relevant Wikipedia article here: reuse of human excreta (you might enjoy that article). But it has to be done safely, and there are various ways of doing so (applying raw sewage without any accompanying measures is not recommended; applying several barriers, one of them can be treatment (doesn't have to be), is recommended). This is described in the WHO guidelines that I mentioned above. Yes, with risks I mean public health risks, and I find your statement of "some people might get sick, and perhaps die, reducing energy requirements of earth's human population" extremely cynical. No need to talk about that further if you take that position. - Please provide a reliable recent publication that can be used as a source to underpin your statement that raw sewage, completely untreated, including all its plastic waste etc, is fine to use for agricultural reuse; and also for your statement that raw sewage can be used for urban or industrial uses? Which ones? Please provide a suitable publication, and not one from the 1950s from the US. If those are the only ones that you can find to underpin your statements, doesn't that tell you something? Knowledge can change after 5 decades, you know (I have provided suitable & recent references for all my main statements) But overall I am getting so tired of discussing all this with just you. I plan to encourage some other Wikipedians to take a look at this page. What is the best way to draw their attention to this? Ping some people that we have worked with on other pages? Write on WikiProject pages? Start a "request for comment" WP:RfC process? EMsmile (talk) 13:33, 19 October 2021 (UTC)
 * Update: I have changed that sentence in question to this sentence which I think is probably a good compromise (it says neither raw sewage nor treated sewage but just sewage): An alternative to discharge into the environment is to reuse the sewage in a productive way (for agricultural, urban or industrial uses), in compliance with local regulations and requirements for each specific reuse application. Public health risks of sewage reuse in agriculture can be minimized by following a "multiple barrier approach" according to guidelines by the World Health Organization.

Content in the section on reuse and reclamation
Hi User:OAnick, I see that you have added some information about reuse that was taken from a recent policy brief (https://www.leeds.ac.uk/policy-leeds/doc/expanding-agriculture-sanitation-circular-economy). This is good content and worth mentioning but since the policy brief refers to sewage treatment & reuse I think the bulk of it fits better in the other Wikipedia articles that talk specifically about reuse of wastewater. This will be these ones: sewage treatment, reclaimed water, reuse of excreta. I am mindful that we should not duplicate too much content across different articles but rather make the reader aware of the issue, then point them across. Your policy brief states that "Technologies are available for rapid scaleup to recover carbon (C), nitrogen (N), phosphorus (P), water and energy, addressing multiple UN policy objectives." so from that I infer that you are not talking about raw sewage reuse directly but to recover those ingredients (using technology) and then reusing that. Let me know if I understood it correctly. EMsmile (talk) 15:13, 19 October 2021 (UTC)

Proposal to change or delete the section on "sewage treatment"
I am proposing to either delete or modify the section on "sewage treatment". At the moment, it reads like this: Sewage treatment is beneficial in reducing environmental pollution. Bar screens can remove large solid debris from sewage, and primary treatment can remove floating and settleable matter. The remaining liquid usually contains less than half of the original solids content and approximately two-thirds of the BOD in the form of colloids and dissolved organic compounds. Secondary treatment can reduce the BOD of organic waste in undiluted sewage, but is less effective for dilute sewage. Water disinfection may be attempted to kill pathogens prior to disposal, and is increasingly effective after more elements of the foregoing treatment sequence have been completed. I find this problematic because it gives some "arbitrary" facts about certain aspects of some types of sewage treatment rather than providing a broad overview. It talks about bar screens and primary treatment but not all forms of sewage treatment plants use bar screens or primary treatment. Hence, I think we would be better off moving this content to sewage treatment and using an excerpt from sewage treatment instead, such as the first two paragraphs from the lead. Alternatively, I propose to delete this section altogether. After all, the word "sewage treatment" is already mentioned about 15 times in the article so people will know that they have to click through if they want to learn more about sewage treatment. This article is about "sewage", not about "sewage treatment". Advice by Marcos about this was (referring to the sentence starting with "the remaining liquid": "Ok, I think you can remove this, because the sentence is not very clear, and especially because it covers primary treatment, which is not being dealt with in this article (it is covered in the Sewage Treatment article). The current article is about sewage, before it is treated." EMsmile (talk) 04:25, 27 October 2021 (UTC)
 * I have revised the present text to address the perceived ambiguities mentioned above. I suggest it would be no more appropriate to delete this content than it would be to delete the sewage section of the sewage treatment article. The present language is a condensed description of the most commonly applied treatment sequence, rather than the rambling paragraphs of duplicative information suggested as excerpts, while the broader overview is available through the main article link for readers wishing to explore those alternatives. Thewellman (talk) 05:59, 27 October 2021 (UTC)
 * The revision is better but not sufficient, in my personal opinion. There is no "sewage" section at sewage treatment, only one that refers specifically to sewage characteristics and uses an excerpt for it. What you call "the most commonly applied treatment sequence" might be valid for the situation in the United States but not necessarily at a global level because sewage treatment can take so many different forms. This is what the first paragraph of the lead of sewage treatment tries to explain (why do you call this "rambling"?): Sewage treatment (or domestic wastewater treatment, municipal wastewater treatment) is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is suitable for discharge to the surrounding environment or an intended reuse application, thereby preventing water pollution from raw sewage discharges. Sewage contains wastewater from households and businesses and possibly pre-treated industrial wastewater. There are a high number of sewage treatment processes to choose from. These can range from decentralized systems (including on-site treatment systems) to large centralized systems involving a network of pipes and pump stations (called sewerage) which convey the sewage to a treatment plant. For cities that have a combined sewer, the sewers will also carry urban runoff (stormwater) to the sewage treatment plant. Sewage treatment often involves two main stages, called primary and secondary treatment, while advanced treatment also incorporates a tertiary treatment stage with polishing processes and nutrient removal. Secondary treatment can reduce organic matter (measured as biological oxygen demand) from sewage,  using aerobic or anaerobic biological processes.. I think taking that as an excerpt would be fine. EMsmile (talk) 12:57, 28 October 2021 (UTC)
 * My problem with the excerpt (like the sewage treatment article) is that broad description of options fails to quantify the pollutant reduction expected from those treatment options. The present text, by comparison, informs readers that bar screens remove solid waste, primary treatment removes suspended solids and floating material, and disinfection kills pathogens. Quantification of BOD removal by secondary treatment would be a valuable improvement. After explaining what is in sewage and why it may be harmful, I would hope to give readers incentive to explore treatment options. Taxpayers understandably question why public resources should be invested in building and operating sewage treatment facilities. The popularity of sewage treatment plant tours among the general population provides a good estimate of the appeal of reading about how to differentiate one type of treatment from another without knowing why it matters. Thewellman (talk) 19:17, 28 October 2021 (UTC)
 * Quantification of removal rates is too much information for one paragraph that is meant to summarise sewage treatment. There are a myriad of treatment options and a myriad of countries with different sewage characteristics. Trying to come up with some "magic figures" that apply to all this is not actually possibly. It can even be misleading. Most likely, the figures you have given apply to a particular type of sewage treatment process in a particular country and makes the reader think it is so easy and it's the same everywhere. Which it isn't. Like I said above not all sewage treatment plants use primary treatment, therefore there is no need to single that out and give the impression that the sequence is always bar screens, primary treatment, secondary treatment etc. I think the first paragraph at sewage treatment does a good job to give an overall impression what sewage treatment may entail, and that there are many different options. I would prefer to use it as an excerpt (of course it can be improved further) - because then any future modifications have to be made only in one article, not in two. EMsmile (talk) 13:07, 22 November 2021 (UTC)

The information about colloidal solids
I've been discussing with Marcus how the information about colloidal solids could be presented better and here is his proposal: "To accommodate your points about colloidal solids, and also Thewellman, I suggest the following editing, and the insertion of a subtitle called “Solids”, before the subtitle “Organic matter”: Solids “Sewage consists primarily of water and usually contains less than one part of solid matter per thousand parts of water. In other words, one can say that sewage is composed of around 99.9% pure water, and the remaining 0.1% are solids, which can be in dissolved, colloidal or suspended form. A practical physical characterization of solids is based on their size, using a simple filtration technique in the laboratory. The results are expressed as: (a) suspended solids (solids that are larger than approximately 1 μm, or 1/1000 mm, and are thus retained in the filter) and (b) dissolved solids (those that are smaller than around 1 μm, and thus pass through the filter). Colloidal solids are not usually determined separately, and are mostly incorporated into the results of the fraction of dissolved solids. The two main fractions of suspended and dissolved solids can also be characterized in terms of their organic and inorganic fractions. In typical sewage, approximately half of the solids are organic and half are inorganic. As a matter of fact, all sewage constituents can be associated to this practical characterization by size (suspended or dissolved), since size is an influential factor in the way the pollutants act and also how they are removed in wastewater treatment plants.” *** References for the paragraph: my book p.35, Metcalf 2014 p. 73-77, Henze in English p. 35-36. Organic matter
 * The next paragraph is fine but I think that it would be better to remove the percentage values related to proteins, carbohydrates, oil and grease etc. They are in my book, but are based on an old reference. Since not much use will be made of those numbers, I think it is better to remove the %. *** " EMsmile (talk) 12:59, 28 October 2021 (UTC)
 * I am dismayed by, and can only wonder about the reasons for (as mentioned in the above conflict of interest section) repeated efforts to remove quantification from this article. I have observed sewage treatment plants, constructed at considerable expense, which fail to make any measurable reduction of BOD. Some actually increase BOD and NFR concentrations by providing a habitat for algal growth or possibly by detoxifying waste. Understanding the reasons for these disappointments will require definition of the wastes being treated and the organisms catabolizing those wastes. The organisms or inorganic mechanisms might be addressed in the sewage treatment article, or in subordinate articles on specific treatment processes, if sewage is defined here; but potentially interested readers will find little reward in wading through lengthy descriptive prose which fails to quantify expected water quality improvements. Thewellman (talk) 20:02, 28 October 2021 (UTC)
 * I see no reason to assume not much use will be made of those numbers. They may be old numbers, but they may be all we have. Pi is an old number, but we keep using it until we find a source for a better number. Thewellman (talk) 21:45, 28 October 2021 (UTC)
 * It is not an assumption, it's a fact that when designing a sewage treatment plant, percentage values related to proteins and carbohydrates are NOT used in design. What is used are values on BOD removal and suspended solids etc. Of course we can bombard the readers with all sorts of figures but does that really improve the quality of the article, or does it rather lead to confusion. Furthermore, you keep insisting on data from the 1950s from the US, whereas we do have more current numbers from a range of countries in those books that I have mentioned above which are actually accessible to readers, unlike those books from the 1950s in the US who are only accessible to those who have them on their book shelves because they worked in that country at that time. So I would rather use the newer, more global, more accessible figures than old figures from one particular country that are not accessible to readers. I am finding this all very tedious to be honest. Thanks to the inputs by Marcos, the new article is much better than the version from a few months ago (same goes for sewage treatment). I am going to make those last changes about colloidals that he suggested when I have time. I think there is not much point discussing this further as we simply don't see eye to eye on this one. So let's just agree to disagree and move on. EMsmile (talk) 13:01, 22 November 2021 (UTC)
 * I don't dispute what is presently used for wastewater treatment plant design. I suggest that may be a contributing factor for the inability of some treatment plants to produce desired waste reduction, and why dilution may be similarly effective as treatment in reducing those waste concentrations. Perhaps focus on the chemical nature of human wastes would improve the success of biological treatment.
 * I have no objection to more recent figures where they are available for similar wastes. My objection is to removal of older figures without replacement or with replacement by figures for different wastes. While the type and amounts of industrial wastewater mixed with sewage may vary widely from one part of the world to another, wastes generated by the human body in those locations remain very similar. Obsession with widely available references ignores the unique value of Wikipedia to individuals with NO access to other references. I hope I haven't given the impression that I don't find it equally tedious to respond to continuing efforts to minimize the differences between sewage and industrial wastewater. Thewellman (talk) 23:39, 22 November 2021 (UTC)
 * I have stayed away from this topic and Wikipedia itself for several months  just to enjoy some clear air and reduced stress. I am slowly dabbling my toes in the water again, but it does feel like coming in halfway through a conversation, so apologies if I seem to be going over old ground. However, just to comment on this specific thread, and the statement suggested above "In other words, one can say that sewage is composed of around 99.9% pure water, and the remaining 0.1% are solids, which can be in dissolved, colloidal or suspended form. A practical physical characterization of solids is based on their size, using a simple filtration technique in the laboratory.". This is correct gravimetrically but wrong operationally. Most of the suspended solids are complex mixtures with considerable quantities of water entrained in them. They may dry out to 0.1% (typically in the UK) but as sewage solids separated out as primary sludge, the proportion is very much greater.  So the question that concerns me is what is this section on solids supposed to represent? An academic analytical view of sewage composition, or an operational view of sewage composition that might say that the particulate solids fraction is some 3 to 4 times the mass as determined by analysis.  Velella  Velella Talk  17:55, 22 November 2021 (UTC)
 * I have attempted to address this ambiguity, but I would value suggested improvements. Perhaps someone has a newer source than the older reference I selected for its more compact description of the sources of variation. Thewellman (talk) 23:03, 22 November 2021 (UTC)
 * Hi Velella, welcome back! I've missed you for this article and also the one on sewage treatment. It's been a "turbulent process" in the last few weeks and months, so to speak. and I value getting more eyes and brains for both of these articles. So I hope you're going to dip in more than your toes if you have time and energy. :-) EMsmile (talk) 20:09, 5 December 2021 (UTC)