Volume reduction of spend acid from electrode foil industry

The purpose of this project is reducing the amount of spend acid produced in the process of aluminum foil production by CSRE membrane distillation system in an electronic enterprise in Jiangsu province. 

There is a large amount of spend acid in the electrode foil industry, including hydrochloric acid, sulfuric acid, nitric acid, etc. The spend acid contains a large amount of heavy metals, which cannot be directly discharged. The main way to solve the spend acid problem in such enterprises is to reduce the concentration and outsourcing. The traditional solution is to neutralize and return it to the sewage treatment station. With the gradual promotion of national environmental protection requirements, strict control on the total salt and other indicators, especially the heavy metal content is implemented. The disadvantages of dosing neutralization are gradually reflected. Firstly, a large amount of sludge is generated in the dosing-neutralization process, and the sludge containing heavy metals is defined as hazardous waste. Therefore, the treatment cost of hazardous waste has become an important expenditure of enterprises every year. Secondly, the supernatant after neutralization also contains a large amount of heavy metals, which will cause a serious impact on the sewage treatment system. 

Spend acid in this project is sulfuric acid system, mainly containing aluminum, copper, nickel and other heavy metals. CSRE membrane distillation system processes 192 tons of spend acid per day and concentrates spend acid to >40% before sending it to the hazardous waste treatment center to solve environmental problems of spend acid treatment in enterprises. CSRE membrane distillation system uses steam as a heat source with 0.23 ton steam consumption and electricity consumption of 4.8kwh per ton of distilled water. The system footprint is 64 square meters.