Due to its high sanitary efficiency, treatment of wastewater by Stabilization Ponds (SP) is proposed for sensitive coastal areas (proximity to bathing areas, shellfish farming lagoons). This process, suitable for small communities with high summer populations, requires a large surface area. The objective of this study is to compare High Rate Algal Pond (HRAP) purifying efficiency with that of SP. We have experimented with a HRAP process, which by generating algal growth reduces the required surface area; our studies suggest this to be by a factor of 5. This process is particularly interesting for nutrient removal, especially nitrogen, and could be useful in coastal areas susceptible to eutrophication. Its sanitary performance is comparable to that of SP. Environmental factors and pond depth play a more important role in HRAP efficiency than retention time of water in the basins.

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