碱-混凝剂法对制革废水中Cr^(3+)和COD去除效果研究

Effect of removal of Cr^(3+) and COD in tannery wastewater by the Alkali flocculation method

采用碱-混凝剂法研究制革废水处理过程.分别用MgO、CaO和MgO/CaO(质量比1∶4)三种碱剂调节pH到9.00,对废水中的Cr^(3+)和COD进行分析,确定最优碱剂.在此基础上,在废水中分别加入PAC、FeSO_4和Al_2(SO_4)_3三种混凝剂,取其上清液进行分析.试验结果表明,MgO/CaO调节pH到9.00,加入PAC混凝剂,且其投药量为4g/L时,Cr^(3+)和COD的去除率分别达到了99.96%和71%,同时出水中的Cr^(3+)浓度也完全符合国家标准.

The alkali flocculation method was selected to study the treatment process of tannery wastewater. The pH of tannery wastewater was adjusted to 9.00 with MgO, CaO and MgO/CaO（mass ratio is 1：4） respectively and then analysed Cr3＊ and COD in tannery wastewater to determine the best conditions. On this basis, PAC, FeSO4 and Al2（SO4）3 were added to the tannery wastewater and the supernatant was analysed. The removal rate of Cr3＋ and COD in wastewater reached 99.96% and 71% when the pH of tannery wastewater was adjusted to 9.00 with MgO/CaO, the coagulant was PAC and dosage was 4 g/L, besides, and the concentration of Cr3＋ in outgoing waste water met the state-speci- fied standards.