Performance Evaluation of a Waste Stabilization Pond in a Rural Area in Egypt

Abstract

The performance evaluation of the waste stabilization pond (WSP) as a model of domestic wastewater treatment unit in rural area was carried out. The unit comprised of anaerobic, facultative and maturation ponds in two series. The effluents of WSP which are discharged in the drain had the BOD reduced to 109-245 mg L^-1 (Mean = 145.3 mg L^-1, 50.65% removal), while the COD was reduced to 221-400 mg L^-1 (Mean = 289 mg L^-1, 48.95% removal) and the total suspended solids (TSS) were reduced to 118-190 mg L^-1 (Mean = 157.8 mg L^-1, 44.3% removal). The reduction percentages of total coliform (TC), faecal coliform (FC), E.coli, faecal streptococci (FS), salmonellae and Listeria were 98.8, 95.6, 79.4, 96.8, 97.9 and 89.5% respectively. Also, the removal percentages of coliphage and infectious rotaviruses were 49.03 and 99.66% respectively. Identical sequences of rotaviruses VP-6 detected in the final effluent of the pond and the drain were observed. Euglena variables and Chlamydomonas reinhardt were predominant in anaerobic, facultative and maturation effluents. It has been noticed that pollution affected species diversity of zooplankton; the number of species in facultative pond was 8 species because of high pollution level, whereas in maturation pond increased to 21 species. Also, pollution in anaerobic pond increased density of ciliates (Protozoa) which are known to be bio-indicators of organic pollution. The percent removal of ciliates in the maturation pond was 70%. It is recommended to make some modifications in the design to increase the efficiency of WSP.