Evaluation of Sludge Management in Sewage Treatment Plant in Hamadan Province

Background and Currently, there is only one sewage treatment plant in Sercan City in Hamadan province. Extended aeration activated sludge is the main process of the plant and untreated effluent and disposal sludge are used for agricultural activities. The main objective of this research is to evaluate the stabilization degree and reuse potential of disposal sludge from the plant. This study was undertaken over a 12 months period from March 2001 to March 2002. In this project some indexes of sludge stabilization and reuse including VS/TS ratio, pH, SOUR, floatation, color, odor, coliform and fecal coliform were determined. The annual average ratio of VS/TS and SOUR in disposal sludge from this plant were 0.73 and 3.37 mg02/gr.vs.h, respectively. The average pH was about 7. The disposal sludge was septic and had dark brown color and floated after a short time. Also the annual average of fecal coliform density in disposal sludge was 8.97 ´ 107 MPN/g.ds. The disposal sludge was raw and destabilized. The microbial quality of disposal sludge was lower than the class B of USEPA regulation. Therefore, this sludge can not be discharged to environment or reused.