Abstract—The performance and stability of a domestic sewage treatment system consisting of an upflow anaerobic sludge blanket (UASB) reactor were assessed. This was to come up with a technical evaluation of using such a system to treat directly such wastewater containing high amounts of suspended solids (SS) in developing countries like Lesotho. Through time, the evolution of the sludge bed was monitored closely, in terms of accumulation of particulate matter and its general quality. The average total chemical oxygen demand (CODt) of the wastewater was 522 mgL-1, and the system could remove 80 % of the organic matter. The sludge production in the reactor system was high (up to 70 % of influent chemical oxygen demand found as suspended solid), necessitating repeated sludge discharges from the reactor, on average every 100 days. Considering the delicate balance of the methanogens in anaerobic reactors, perturbations of the microbiota arose following the sludge extractions, and these promoted reactor imbalance. This further brought about a decrease in reactor performance and hence of the general sustainability of the UASB process when treating domestic sewage directly. In addition, the system could not remove the macronutrients nitrogen and phosphorus. Additional treatment steps would be necessary to remove the suspended solids and nutrients, and thus to effectively treat such a wastewater.
Index Terms—Domestic wastewater, Nutrient removal, Physical entrapment, Rapid sludge build up, UASB.
aLaboratory of Microbial Ecology and Technology (LabMET), Ghent University, Coupure Links 653, B-9000 Ghent, Belgium.
bDept of Environmental Health, National University of Lesotho, P. O. Roma 180, Lesotho.
cResearch Program for Basic Sanitation (PROSAB), Sanitary Engineering Group, Department of Civil Engineering, Federal University of Campina Grande - R Aprígio Veloso 882, 58. 109-970 Campina Grande, Brazil.
dMinistry of Health & Social Welfare, Maseru, Lesotho
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Cite: Sunny Aiyuk, Philip Odonkor, Nkoebe Theko, Adrianus van Haandel and Willy Verstraete, "Technical Problems Ensuing From UASB Reactor Application in Domestic Wastewater Treatment without Pre-Treatment," International Journal of Environmental Science and Development vol. 1, no. 5, pp. 392-398, 2010.