In the production process of various catalysts, dyes and chemical intermediates, a large amount of acid-containing wastewater will be produced. Among all kinds of acid-containing wastewater, the treatment of mixed solutions containing organic acids and other organic substances is the most complicated. It can be considered to incinerate the organic acid waste liquid, but the cost of direct incineration of the organic acid waste liquid is higher, so the ceramic membrane is selected for concentration. The liquid is incinerated, and the COD of the clear liquid is reduced to a certain value for biochemical treatment.
Due to the high acid content of the material, the composition of the acidic substance is more complex, and due to the flocculation of the material, a large amount of suspended solids are produced. Directly passing through the organic membrane will cause irreversible damage to the organic membrane. Therefore, a ceramic membrane is used to remove suspended solids, and then concentrated by nanofiltration and multi-stage reverse osmosis. This research and development project is to concentrate the organic mixture through multi-stage membrane concentration.
First, the organic acid stock solution was directly processed by ceramic membrane to treat the flocs and then entered into the nanofiltration membrane, and then concentrated by the multi-stage reverse osmosis membrane, to investigate the changes in the COD value and pH value of the deacidified solution. After one-stage nanofiltration and multi-stage reverse osmosis membranes are treated, the COD value is significantly reduced, and as the number of reverse osmosis membranes increases, the single-stage reverse osmosis membrane has an obvious decrease in COD removal rate for organic acids, but it is still unable to meet the requirements of biochemical treatment.
Therefore, on the basis of the above experiments, the organic acid tertiary reverse osmosis membrane clear liquid was adjusted for pH value treatment. Add calcium oxide powder and ammonia water respectively to adjust the pH value. After calcium oxide is added, a large amount of solid precipitation is generated in the original solution, which is not conducive to the filtration and removal of impurities by the ceramic membrane. Although the addition of ammonia water will also cause a large amount of flocculation in the original solution, this flocculation is within the acceptable range of the ceramic membrane, so the solution of adding ammonia water to adjust the pH value is selected.
After adding ammonia water to the three-stage reverse osmosis clear liquid to adjust the pH=7, the ceramic membrane, nanofiltration membrane and multi-stage reverse osmosis membrane are concentrated. The experimental results show that, under the same operating conditions, the removal rate of COD is significantly higher than that when ammonia is not added. Therefore, experiments can be continued to explore the effect of adjusting the pH on the concentration of organic acid solutions according to this idea.
Jiangsu Jiuwu High-Tech Co., Ltd. is a specialized manufacturer of inorganic ceramic membrane elements and complete sets of equipment with the largest production scale, the largest variety of specifications, and the strongest R&D capabilities in China. Ceramic membrane has the characteristics of acid and alkali resistance, good chemical stability, and good thermal stability.