Characteristics and application of multiple membrane process in plating wastewater reutilization

摘要

A multiple membrane process aimed at reutilization of plating combined wastewater after physical and chemical pretreatment in mechanical industry was developed for selective separation to reduce cost and mitigated the increasing heavy metal pollution. The process was divided into three stages: firstly, microfiltration (MF) and ultrafiltration (UF) was used to separate the possible organic and suspended matters, secondly, electrodialysis (ED) was carried out for effective desalination, and thirdly, the concentrate from ED was treated by nanofiltration (NF) and reverse osmosis (RO) separately to increase the recovery rate of water. Results showed that filtration characteristics of UF membrane here was not so good as usually, even if compared with MF membrane. And RO performed better than NF in wastewater separation, especially in anti-compacting ability of membrane. Since the rejection rate of heavy metal ions and COD in ED/RO process is high, all the product water exceeded the related qualification and could be reused as cooling water in industry.