水电工程砂石系统生产废水处理工艺优化研究

针对目前水电工程砂石加工系统生产废水主流工艺存在的问题,现场采集了白鹤滩水电站和乌东德水电站两处废水原样,利用数值模拟、现场及室内实验等多种方法对废水处理工艺主要流程进行了优化。研究表明:模拟预测两级石粉回收预处理总回收率可达60%左右,较单级回收率提高约50%;投加合适的药剂可大大改善废水絮凝沉降性能,当固体颗粒粒径较小时联合投加聚丙烯酰胺(PAM)和氧化钙(Ca O),静水沉速可提高约11倍。泥渣脱水调理剂在药剂类型和药量方面均与前端絮凝沉淀流程中所投加药剂具有一致性,而且"前端一次加药"工艺是可行的。将"隔膜压榨+进气穿流"工艺引入压滤脱水工艺中,单机工作循环时间减少67%的同时,泥饼含水率可降低至15%左右。

Study on optimization of treatment process of waste water originated from sand and gravel system of hydropower projects

Aiming at the poor effect of waste water treatment process in sand and gravel system, field wastewater of 2 process-ing systems for sand and stone in Baihetan Hydropower Project and Wudongde Hydropower Project was sampled. And then the numerical simulation, field and laboratory experiments were conducted to optimize the main wastewater treatment process. Experi-ment results show that total recovery rate by two-step stone-powder recycling can reach to about 60%, an improvement to sin-gle-step recycling by 50%;sedimentation performance can be significantly improved by adding suitable flocculant, if the parti-cle size of suspended solids was small, the co-conditioning technology with PAM and CaO should be applied, and the hydrostat-ic settling velocity is improved by 11 times. The agent used in wastewater sedimentation and slurry dewatering have much consis-tency in type and dosage of front-end sedimentation process, so the technology of only adding flocculant in front-end sedimen-tation process is feasible. The technique of diaphragm pressing and high pressure air flow were introduced into filter press, then dewatering time has been decreased by 67%, and moisture content of the powder cake has been reduced to 15%.