Studying the effects of the changes of the quantitative-qualitative pattern of the influent-increasing wastewater acceptance on flocks sedimentation in activated sludge

In every city, the produced wastewater has its special quantitative and qualitative pattern on the basis of culture, the manner of water distribution services, year’s seasons and temperature changes. The changes of this pattern, especially in the peak points, lead to great effects in the operation of wastewater's treatment plants which appears in activated sludge process as inappropriate sedimentation of sludge’s flocks. This phenomenon (sludge bulking) is one of the most important difficulties in operation of wastewater's treatment plants using activated sludge method that leads to the disturbance of the treatment plants’ steady state and undesired effects on the quality of the effluents. New established Treatment plants, got to their nominal capacity after several years, are encountered with an increasing amount in the capacity of the influent according to the expansion of covered population which intensifies the sludge bulking, but it should be mentioned that these effects are not the same as the effects of the changes in the quantitative-qualitative pattern. This research, which is the result of forty months of operation of Bojnourd's wastewater treatment plant by using activated sludge method, studies the non- sedimentation occurrence of activated sludge’s flocks which is produced by the effects of the quantitative-qualitative changes of the pattern of the annual influent and the increasing of the accepted capacity. In this study, which is on the base of the daily laboratorial tests done in the studying period, SVI and SDI parameters were assessed as qualitative sludge indicators and the amount of mass loading, resulted from the fluctuation of the producing wastewater pattern, was assessed as the target parameters. With respect to the fact that the wastewater treatment plant includes a biological selector, it had been never the factor of non-sedimentation of string bulking which can be indicated by the daily microscopic studies. According to the achievements of the planning and scheduling, the necessary operational maneuvers during the studying period of the effluents’ quality, was maintained on the level of the standard of the discharging to the acceptor waters.

کلیدواژه ها:

Municipal Wastewater ، Activated Sludge ، SVI ، SDI ، Sludge’s Bulking ، Operation