1. Acid-base neutralization method: Alkaline wastewater is treated by adding acidic substances, which are neutralized and filtered to basically purify the alkaline wastewater. Neutralization treatment is considered as one of the minimum requirements for wastewater treatment. At the same time, it is also a necessary link for partial and complete clarification and recycling.

2. Flocculation method: Alkaline wastewater often contains a lot of suspended solids, which can be treated by adding flocculant. Magnesium salt coagulant used in printing and dyeing factory can effectively remove the chromaticity in alkaline printing and dyeing wastewater treatment, and at the same time obviously reduce the concentration of COD, PH value and sulfide, and its effect is better than that of basic aluminum chloride and ferrous sulfate. The self-made adjustable magnesium salt coagulant not only has good treatment effect, but also can greatly reduce the treatment cost, and has good environmental and economic benefits.

3. Chemical precipitation method: Chemical precipitation method is to add an appropriate precipitant to the wastewater to make the harmful substances in the wastewater become insoluble and remove them by precipitation.