Optimization of the mode of sludge removal from secondary settling tanks

Summary

In the process of upgrading the Moscow Novokur’ianovskie wastewater treatment facilities the scraper mechanism for activated sludge collection in 54 m diameter secondary settling tanks was replaced by SO-54 sludge sucker. Since it was the first experience of using sludge suckers at the Kur’ianovskie wastewater treatment facilities it was decided to carry out experimental tests of the operation of the secondary settling tanks equipped with sludge suckers as well as to develop and approbate the method of efficient activated sludge collection and removal from the bottom of the settling tanks. The operation of SO-54 sludge sucker in different modes was analyzed. It was shown that the design of the settling tank provided for the operation control by switching off and on the suction pipes of the upper level of the sludge suckers, i. e. eliminating the use of complicated instruments. Regulating the operation of the suction pipes of the upper level of the sludge suckers with a time switch provides for maintaining the optimal height of the activated sludge layer. Switching off the suction pipes of the upper level of the sludge suckers results in the increased concentration of recycle sludge. As a result of changing SO-54 sludge pump operation the dosage of recycle sludge was increased from 4.6 to 7.1 g/l eliminating the effluent quality in relation to suspended solids. This allowed reducing the recycle sludge volume subject to pumping to the aeration tanks, and reducing the number of operating pumps, and power saving.

Key words

treatment facilities , sludge disposal truck , secondary settling tank , activated sludge , power saving