给水厂嗅味及溴化物复合微污染原水处理试验与工程应用

Experiment and Engineering Application of Treatment Methods for Micro-Polluted Raw Water with Taste and Odor in WTPs

随着农村城市化、农业工业化的推进,水环境受到了污染。针对水的浑浊度、菌类仅采用混凝、沉淀、过滤、消毒工艺的水厂不能大幅度降低水中溶解杂质,不可避免地引起了自来水水质变化。以山东省新泰市Q水厂为例,自2010年开始,水库水源水因网箱养鱼和支流河道污水汇入,导致藻类繁殖,高锰酸盐指数(COD_(Mn))、氨氮等污染物含量增加,水质恶化。藻类破裂释放的微囊藻毒素和放线菌代谢产生的土臭素(geosmin,GSM)、2-甲基异莰醇(2-methylisoborneol,2-MIB)严重影响了饮用水供水水质。根据微污染杂质的主要成分、变化规律及产生的环境因素、生物因素等,特对强化常规处理法、物理吸附法、化学氧化法、生物降解等微污染水源水处理方法进行比较分析。认为采用臭氧(O_(3))氧化还原能有效氧化藻致嗅化合物和微囊藻毒素。考虑到当地水源水中含有溴化物的特点,选用O_(3)氧化和生物活性炭(BAC)过滤联用较为合理。经对Q水厂出厂水试验,在水温为10℃左右、O_(3)投加量≤2.0 mg/L、BAC滤池空床接触时间为12 min,具有去除CODMn50%、氨氮40%以上、溴酸盐≤0.01 mg/L的效果。按此工艺实施Q水厂升级改造工程,实现了出厂水水质稳定达标。通过对O_(3)-BAC工艺的处理效能持续监测和低温条件下的强化处理运行管控研究发现:低温季节,气水冲洗活性炭滤层摩擦剧烈,生物膜脱落,增殖缓慢,降低生物氧化降解作用,除污染效果变差。调整冲洗方式后,改善了这一现象;选用水并联、O_(3)化氧气串联的完全混合连续式反应器(CSTR)溶解臭氧化气体,增大气、水接触面积和气体浓度差、加快液膜紊动更新,和通用的水串联、O_(3)化气体并联的鼓泡式反应器相比,极大提高了O_(3)化气体溶解度。理论计算,制水成本减少了44.63%。

With the advancement of rural urbanization and industrialization of agriculture,the water environment has been effectively remove the dissolved impurity in water,inevitably causing the change of tap water quality.Taking Q WTP in Xintai City,Shandong Province as an example,since 2010,the reservoir serving as the water source has been imported by cage fish culture and tributary river sewage,resulting in the deterioration of water quality with the increase of pollutants such as algal reproduction,permanganate index(COD_(Mn))and ammonia nitrogen.The microcystin released by algae and geosmin(GSM)and 2-methylisoborneol(2-MIB)produced by actinomycetes metabolism seriously affect the quality of drinking water.According to the main composition of micropollutants,their change,environmental affecting factors and biological factors,the methods of strengthening conventional treatment,physical adsorption,chemical oxidation and biodegradation of micro-polluted source water were compared and analyzed.Results show that ozone(Os)can effectively oxidize algal odor compounds and microcystin.Considering that the local source water contains bromide,the combination of ozone oxidation and biological activated carbon(BAC)filtration is more reasonable.The test results showed that when the water temperature is about 10℃,the dosage of O_(3)is less than 2.0 g/L,and the contact time of BAC filter empty bed is 12 min,the removal efficiency of COD_(Mn)and ammonia nitrogen was 50%and 40%respectively,and bromate is less than 0.01 mg/L.Q WTP was upgraded using O_(3)-BAC process,and the quality of effluent was stable and up to standard.Through continuous monitoring of treatment efficiency of O_(3)-BAC process and intensive treatment operation control under low temperature conditions,it was found that in low temperature season,the friction of activated carbon filter layer under gas-water washing was intense.The biofilm fell off,and the proliferation was slow.The biological oxidation degradation was reduced,and the pollution removal effectiveness became worse.The complete mixed continuous reactor(CSTR)with water in parallel and O_(3)in series was used to increase the contact area of gas with liquid and the gas concentration dfference,accompanying with the accelerating on the liquid film turbulence renewal.Compared with the common bubble reactor with water in series and O_(3)gas in parallel,CSTR greatly improved the solubility of O_(3)gas.By theoretical calculation,the cost of water production is reduced by 44.63%.