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Shady wahba 23:10, 8 September 2007 (UTC) Shady Wahba, University of Brighton, Uk'''. Civil Engineering Department.''' ICE Member

Phosphorous and nitrogen removal from municipal wastewater
Shady Wahba, University of Brighton'''

In the past decade, concern about the water quality of natural systems directly receiving sewage discharge has increased. The focus has been directed to all of the steps to control municipal Phosphorous and Nitrogen rate level. Phosphorus and nitrogen are the two major nutrients contributing to eutrophication, in most cases, these nutrients are growth limiting, algae can no longer grow if these nutrient pools are depleted, Therefore, environmental engineers consider the removal of Phosphorous and nitrogen from point sources, such as sewage treatment plant, a cost-effective and appropriate method for controlling the level and extent to which eutrophication occurs by either biological or chemical treatments.

Biological
''Biological process is more commonly used to treat domestic or combined domestic and industrial wastewater from a municipality. Engineers use basically the same processes that would occur naturally in the receiving water, but give them a place to happen under controlled conditions, so that the cleansing reactions are completed before the water is discharged into the environment''.(Used widely in US and most of Europe).

Chemical
chemical process is more often used to treat industrial wastewaters directly, because they often contain pollutants which cannot be removed efficiently by micro organisms, where Biological process is relatively low-cost means of removing nitrogen and phosphorous from wastewater compared to the chemical process.(Used widely in the Uk).

Summary
Wastewater treatment can be summarized as the sort of treatment needed to remove suspended and dissolved substances. These substances may be organic matter or suspended solids or may range from relatively simple inorganic, to an ever increasing number of highly complex synthetic organic compounds. In recent years, the effects of many of these substances on the environment have become understood more clearly, where many researches on potential toxic substance are continuing to determine their environmental effects and how these substances can be removed by both conventional and advanced wastewater treatment process .As a result, wastewater treatment requirements are becoming more stringent both in terms of limiting concentrations for many of these substances and their ability of treating plants concerned with establishing whole effluent toxicity limits.

Various treatment methods to remove Phosphorous and Nitrogen from wastewater by either Biological or chemical methods and this removal process is done through controlling the amount and form of nutrients discharged by the treatment system

The process of selecting a nutrient control strategy is important as it assesses and estimates three important things: firstly, the characteristics of the untreated wastewater, secondly the type of existing wastewater facility (in case of update) and thirdly the level of nutrient control required.

The need for seasonal versus year round nutrient removal must also be considered. The relatively simple wastewater treatment technologies can be designed to provide low cost sanitation and environmental protection while providing additional benefits as opposed to the reuse of water.

The processes have considerable appeal to designers and operators because nowadays the use of chemicals has been either eliminated or reduced substantially. For example, Phosphorus now is recognized as one of the major nutrients contributing to the increased eutrophication of lakes and other natural waters. This has led to many water quality problems including increased purification costs, interference with the recreational and conservation value of impoundments, loss of livestock and the possible effects of algal toxins on humans using eutrophic water supplies for drinking.The greatest tool that can be perpetrated in comparing costs for nutrient removal is to use generalized information, where each individual case must be considered on its merits, taking into account the local conditions, local cost, the particular characteristics of the sewage, the general mean temperatures, the influx of groundwater, the nature of groundwater, the cost of alternative methods, the proposed nature of sludge treatment.

Finally, although there is still a need for optimization of different methods for phosphorus and nitrogen removal, but it seems that it is more important to evaluate the phosphorus and nitrogen cycles in urban areas and its interactions with rural areas. Such an analysis should include technical, environmental, hygienic, economical and sociological aspects in order to secure a sustainable wastewater handling system.

Article Details
Shady Wahba, University of Brighton''' , ICE Member

BEng Civil Enginnering ,part from Dissertation, 2006.'''

Contact Email: Shady_wahba@hotmail.com For full dissertation