Comparison of the Efficiency of Municipal and Industrial Activated Sludge for Hospital Wastewater Treatment

The absence of efficient sewage treatment plant in many cities of Iran and national discharge standards for hospital wastewater makes the hospital wastewater treatment a necessity. Hospital wastewater is loaded with microorganism، heavy metals، toxic chemicals and radioactive elements. It can be hypothesized that the efficiency of activated sludge from industrial wastewater treatment plant can be different from municipal wastewater plant. In this study، the efficiency of activated sludge from dairy industry has been compared with that of municipal activated sludge for hospital wastewater treatment. To assess the efficiency of activated sludge، 1day، 3day and 5day aeration methods have been used. Before and after each aeration step، BOD، COD and MLSS of wastewater and sludge were determined. The most efficient method was found to be 5day aeration and the efficiencies of municipal activated sludge and dairy industry activated sludge were respectively 93. 9%، 93. 3% and 97. 4%، 97. 3% for COD and BOD. Nonparametric tests and paired t-test show that there is no significant difference between municipal and industrial activated sludge efficiencies for hospital wastewater treatment but a significant difference between time lengths of aeration (1day، 3dayes and 5days) was observed. Both the dairy industry and municipal activated sludge could have high efficiency for hospital wastewater treatment.