Effect of Shock Chromium(VI) Load on the Activated Sludge Process

Authors : Ülkü YETİŞ, Göksel DEMİRER, Hüseyin TEKİN

Pages : 445-454

View : 18 | Download : 9

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :The effects of shock doses of Crinsert ignore into journalissuearticles values(VI); on activated sludge process operating at a fixed dilution rate insert ignore into journalissuearticles values(0.12 h-1); without recycle has been investigated. Different levels of Crinsert ignore into journalissuearticles values(VI); insert ignore into journalissuearticles values(1.0, 2.0, 3.0, 5.0, 10.0, 25.0 and 50.0 mg/l); were suddenly dosed to activated sludge units, operating at steady state with a synthetic wastewater devoid of chromium and continued until a new steady state has been reached. The results have shown that Crinsert ignore into journalissuearticles values(VI); even at very low dosages of 1.0 and 2.0 mg/l was toxic to the activated sludge process when shock injection was applied. The process performances observed at these levels of Crinsert ignore into journalissuearticles values(VI); with acclimatised cultures in previous studies have never been reached. It has been observed that shock Crinsert ignore into journalissuearticles values(VI); doses at low levels have immediately influenced the reactor biomass concentration, but not the COD removal efficiency. However, higher levels of Crinsert ignore into journalissuearticles values(VI); insert ignore into journalissuearticles values(25.0 and 50.0 mg/l); caused immediate adverse effects, and dramatic reductions in COD removal efficiency have been observed. The time elapsed to reach a new steady state after the shock, has been observed to increase with increasing Crinsert ignore into journalissuearticles values(VI); dosages. However, the shock injection of 50.0 mg/l Crinsert ignore into journalissuearticles values(VI); caused complete destruction of microbial population and lead to oscillations in in effluent COD concentration without a new steady state taking place even after 1000 h insert ignore into journalissuearticles values(=120*hydraulic retention time);.
Keywords : Activated sludge, Cr VI, heavy metals, shock load