TREATMENT OF INTERMITTENTLY FLOWING WASTEWATERS

Conventional biological treatment of intermittently flowing wastewater s is one of the significant problems of regions having seasonal activi ties. A system consisting of an downflow aerated packed reactor (DAPR) followed by inclined tube settler (ITS) was tried to overcome the dif ficulties for the above mentioned wastes. The DAPR-ITS system can be r egarded as a combination of activated sludge and trickling filter proc ess followed by a high rate sedimentation unit (ITS). Three different no-feed periods ranging from 3 to 26 weeks were used to characterize t he off-season activities. After this no-feed period the system was sta rted using different now rates. The performance of the system was eval uated using chemical oxygen demand (COD), biochemical oxygen demand (B OD), nitrogen (N), phosphate (P) and total suspended solids (TSS) para meters. The results showed that DAPR-ITS achieved about 80 % COD remov al efficiency from the time of starting the system and reached steady state conditions within a few days. The removal efficiencies of other parameters had similar trends as GOD. Thus, DAPR-ITS system has been p roven to be a satisfactory method for intermittently flowing wastewate rs.