Modification and Optimization Operation of Intermediate High-density Sedimentation Tank

In view of unstable operation,high chemical dosage and high effluent turbidity of the intermediate high-density sedimentation tank in a waterworks,the original sludge scraper was changed into airlift device,the sludge storage tank was added outside of the high-density sedimentation tank,and the sludge was returned by pump. The flow meter and E + H throw-in type sludge concentration meter was used to test return sludge,and the single main pipe was replaced by two DN100 sub-pipes at the sludge return point. Sludge flow meters and valves were installed on the sub-pipes to control the operation of intermediate high-density sedimentation tank. The commissioning and optimization results showed that the effluent turbidity could be effectively reduced by increasing the concentration of return sludge and SS of flocculation zone. The effluent turbidity of high-density sedimentation tank was below 1 NTU by controlling SS of flocculation zone in the range of 400 mg / L to 500 mg / L,and the maximum flow rate of 3 700 m3/ h and more than 20% of the design load could be achieved.