XXX小型电镀厂废水处理工程优秀毕业设计完整版.docVIP

小型电镀厂废水处理工程 第 PAGE 90 页 共 NUMPAGES 92 页 第 PAGE 3 页 共 NUMPAGES 92 页 摘 要：电镀是世界三大污染行业之一，随着我国乡镇电镀企业的迅速发展，我国的电镀污染问题日趋严重。本文首先阐述了我国电镀废水的污染现状以及对人类产生的危害，在对化学处理、离子交换、电解法、生物处理等电镀废水处理方法的分析和比较后，结合乡镇电镀企业要求工艺简单、成本低等特点，决定采用NaHSO4化学还原沉淀法处理该企业的含铬、锌废水。本工艺是在pH=2.5时用NaHSO4溶液将Cr6+还原为Cr3+，在用NaOH溶液调节pH=8后生成Cr(OH)3和Zn(OH)2沉淀，在添加絮凝剂PAC和PAM后生成的絮体在斜板沉淀池中沉淀，出水经砂滤器过滤后可回用于砂滤器反冲洗水及各种溶液的配制，或者达标排放，而污泥则统一交于专业的环保公司处理。在设计中采用了较为先进的ORP测定仪、在线pH计和液位计实现反应过程的自动控制。通过设计计算确定了各构筑物的尺寸以及设备的选型，并对设计和操作管理中的要求进行了说明，最后对电镀废水治理的前景进行了展望。 关键字：电镀废水；Cr；Zn；化学还原沉淀法 Abstract：With the speedy development of the electroplating enterprise in towns in our country, electroplating industry，as one of the biggest pollutions in the world ,causes the pollution more and more severely . In this paper, describes the present situation of the electroplating effluent water pollution and the great harm it makes to the human kind has been described. After the analyses and the comparison of different ways for treatment of electroplating effluent such as chemical treatment process、ion exchange process、electrolytic method and biological process, I decide to adopt the NaHSO4 reduction-precipitation to treat the waste water containing Cr and Zn for the corporations , considering the features of the town electroplating corporations’ demands of simple techniques, low costs, etc. This technology is to deoxidize Cr6+ into Cr3+ by NaHSO4 solution at the PH=2.5, then adjust the PH to 8 with NaOH solution to make Cr(OH)3 and Zn(OH)2 sediment. The flocculating constituent，formed after adding the flocculating agent PAC and PAM , can be deposited in the sloping plank settling tank. The water left after filtrating through a sank filter can be recycled as the backwash of sank filter and be used in confecting various solutions or be discharged an emission standard. and, the sludge can be solved by the professional environmental protecting companies. It adopts some relatively advanced equipment such as measuring element of ORP、pH meter and content g