THE EFFECT OF BAFFLE INSTALLATION ON THE PERFORMANCE OF A SINGLE-CELLSTABILIZATION POND

The effect of baffles on the performance of an ineffective, single-cel led stabilization pond with theoretical retention time of 5-10 days, w as investigated. The efficiency of the pond was evaluated by comparing the microbiological and chemical quality of pond's influent and efflu ent, as well as by hydraulic tests. Removal of indicator microorganism (1 log) and BOD5 (55%) remained unchanged, regardless of the number o f baffles. Tracer study findings were characterized by the appearance of a peak of tracer within 15-20 hours after injection of the tracer, followed by a long ''tail'' of lower concentration. These findings, al ong with optical observations, indicated that the baffles succeeded in channeling influent flow to the planned routes (resulting in increase d traveling distance of the wastewater). However, the actual retention time of the influent, particularly a small but important fraction of it, remained short regardless of baffle installation. The lack of mixi ng caused by thermal stratification of the water column resulted in ra pid bottom flow in the cool hypolimnion. These findings may explain, i n part, the lack of success in improving treatment efficiency.