BAFFLED POLISHING PONDS FOR THE TREATMENT OF ANAEROBICALLY TREATED SEWAGE: EFFECT OF DISPERSION NUMBER

Abstract

The stabilization of municipal wastewater by the combination of a high rate anaerobic reactor and tertiary treatment units in the form of polishing ponds is a low cost solution. In the course of the present study soluble synthetic wastewater was treated by a combination of bench-scale ABR reactor followed by two different polishing pond models having different configurations. The operation and performance of two bench-scale pond models over the three month were monitored. One model was operated with the classical longitudinal baffles arrangements, and the other one was operated with the additional transverse baffles along with the longitudinal ones, designated as R-2. Both the FPUs were operated to maintain a DT of one day. The performances of both the pond models were compared at the PSS with respect to be different polluting parameters. It was found that among the different polluting parameters. It was found that among the different polluting parameters mainly BOD removal was significant. The concentration of the BOD in the final effluent was reported as around 27 mg/L, which was below the permissible limit for discharged i.e. 30 mg/L. The pond systems were also compared with the six full scale FPU at the different places. It was observed that the performance of the first pond model (R-1) was of almost the same level as compared to those full scale FPUs, but with the new system a much better performance was achieved with respect to the different polluting parameters. To have the exact hydraulic flow pattern of the fluid in both the pond model a tracer study was performed by using LiCI as the tracer. Dead volume spaces were calculated as 41% in R-1 and 31% in R-2 by generating the retention time distribution (RTD) curves by using the Levnespiles model.