Flocculation-fiber Filtration Process With Low Energy Comsumption For High Stardard Phosphrus Removal From Municipal Wasterwater

In recent years, the standard of sewage treatment plant effluent keeps improving, thus advanced wastewater treatment becomes more and more important. The cost of some advanced phosphorus removal technology is not acceptable. In this study, flocculation in combination with backwashing fiber filter technology is used in advanced treatment of SS and TP. The device was optimi zed for two type of water. The pilot trail demonstrated the engineering feasibility and low-cost of the technology.Optimization of the device aimed to improve the effluent quality to meet the standards, where the concentration of TP and SS effluent was b elow 0.3 mg/Land 2 mg/L respectively. The device was divided into two parts. The first segment was the main filter section, in which the best pore ratio was 91%, and the best height was 1.3m. Unpowered backwashing was the cleaning method, and the washing intensity should be greater than 60 L/(m2?s). The second segment was the upper compact segment, where the best pore ratio was 88%, the set height was 0.3 m. Cleaning method is air and water anti–washout, air wash intensity was 10.8 L/(m2?s), water washing intensity was 7.36L/(m2?s).The pretreatment segment should be set for the high SS effluent. The pretreatment segment was made of fixed fiber, the best pore ratio was 97%, the best filtration rate was 10m/h, the best backwashing time is 6~8 hours. Average S S of influent was 40mg/L, average removal ratio of SS was 65%.The experiment proved medium scale device was stable. Average SS of influent was 19 mg/L, average SS of effluent was 1.3 nmg/L, average removal rate was 94.8%. Average TP of influent was 1.32 mg/L, average TP of effluent was 0.2mg/L, and average removal rate was 85.1%. Average COD of influent was 44.8mg/L, average COD of effluent was 23.3 mg/L, and average removal rate was 48.0%. Process has no function on removing NH3-N and NO3-N. After the backwash, the filtration kept high efficiency. The periodic quantity of pollutants was 5.73 kg. The water consumption rate of backwash was 0.3%, and the average of head loss was 119 mm. The sludge recycled from backwashing can be used on sludge dewatering to reduce the running costs. For the test water, chemical savings rate was 50%.For X sewage plant, which can treat 10000 t sewage daily, construction cost of raise standard transformation is 105,000 ￥, operating costs were 119,700 ￥/year. The treatment fee of water is 0.0328 ￥/d.