Assessment of seasonal variations on the performance of P-UASB/BAF for municipal wastewater treatment.

In this study, the effect of seasonal variations on the performance of combined anaerobic–aerobic system for wastewater treatment was investigated. The pilot plant system consists of packed bed anaerobic sludge blanket, followed by a biological aerated filter. The packing material in both units was a non-woven polyester fabric. The system was operated for more than two years at ambient temperature. The results indicated that the performance of the pilot plant was very satisfactory during the whole seasons. However, in summer, slightly better results were achieved for chemical oxygen demand, biological oxygen demand, total suspended solids and total Kjeldahl nitrogen due to the increase in temperature. Their corresponding average removal values were 90, 91, 97, and 54%, respectively, compared with 88, 90, 91, and 46% in winter. Nitrogen removal was related to nitrification/denitrification and bacterial assimilation, where its activity increased in the summer. The quality of the treated effluent during the whole seasons complies with the National Regulatory Standards for reuse in irrigation. [ABSTRACT FROM PUBLISHER]