城市给水厂排泥水的减量化试验研究

Study on Reduction of Sludge Water in Urban Water Treatment Plants

为发展城市给水厂排泥水节水技术,在示范水厂开展了排泥水的减量化试验研究。通过对示范水厂排泥水水质的分析和排泥水的减量化生产性试验,提出了水厂各构筑物的节水排泥工况:折板絮凝池1#、2#排泥管的排泥时间为20s/次,3#、4#的为40s/次,5#～8#的为60s/次;平流沉淀池前20m的排泥周期为24h,采用双程排泥,后70m的排泥周期为48h,为单程排泥;V型砂滤池的反冲洗周期为48h,采用气冲(3min)/气水冲(3min)/水冲(5min)/全程表扫的反冲洗方式。运行表明,节水排泥工况对各构筑物的出水水质基本无影响,并可使絮凝池、沉淀池、砂滤池分别节水约25%、37.5%、39.7%,水厂的总排泥耗水率可从原来的3.07%降至1.9%。采用节水排泥工况后,水厂可减少排泥水量近43×104m3/a,同时节约生产成本约42万元/a,环境、经济效益可观。

The reduction of sludge water in urban water treatment plants was studied with a focus of developing water-saving technologies. By analyzing sludge water quality and conducting sludge reduc- tion tests in a demonstration water treatment plant, water-saving sludge discharge conditions of plant structures are brought up ： the sludge discharge time of folded plate flocculator is 20 seconds each time for pipes No. 1 and No. 2, 40 seconds each time for pipes No. 3 and No. 4, and 60 seconds each time for pipes No. 5 to No. 8 ; in the horizontal-flow sedimentation tank, the sludge discharge cycle for the first 20 meters is 24 hours, and the sludge discharge is two-pass at a time; the sludge discharge cycle for the backward 70 meters is 48 hours, and the sludge discharge is one-pass at a time; the backwash cycle of the V-shaped filter is 48 h, and the backwash procedure is air washing for 3 minutes, air-water washing for 3 minutes, water washing for 5 minutes and surface sweep washing for 11 minutes. The operation shows that the water-saving sludge discharge conditions do not affect the status of water quality and allow the flocculator, the sedimentation tank and the fiher to save water by 25% , 37.5% and 39.7% respec- tively. The total water consumption rate for sludge discharge is reduced from 3.07% to 1.9%. The water-saving sludge discharge conditions can reduce sludge water of nearly 430 000 m3/a and save produc- tion cost of 420 000 RMB annually. The environmental and economic benefits are all considerable.