Acid washing wastewater mainly comes from industrial processes such as metal surface treatment, electroplating, steel pipe acid washing, and stainless steel cleaning. It contains high concentrations of acidic substances (such as hydrochloric acid, sulfuric acid, nitric acid), heavy metal ions (such as iron, zinc, nickel, chromium), and suspended solids, and has strong corrosiveness and certain toxicity. With the increasingly strict environmental regulations and the deepening of the concept of resource recycling, effective treatment of acid washing wastewater and the recycling of water resources and acid solution have become key links in the green development of enterprises. This article will recommend a pickling wastewater treatment company - Suzhou Isbe Environmental Protection Equipment Technology Co., Ltd., and see how they treat pickling wastewater.

1、 Main characteristics of acid washing wastewater

Low pH value: Strong acidity, severe corrosion to equipment and pipelines;

High content of heavy metals, such as Fe ² ⁺/Fe ³ ⁺, Cr ³ ⁺, Ni ² ⁺, Zn ² ⁺, etc., pose significant environmental hazards;

High COD: containing a small amount of organic additives, affecting the effectiveness of biochemical treatment;

Large fluctuations in water quality: significantly affected by changes in production processes.

2、 Process flow of acid washing wastewater treatment and reuse

To achieve the standard discharge and resource utilization of acid washing wastewater, an integrated treatment route of "neutralization precipitation+heavy metal removal+membrane separation+reuse" is often adopted:

1. Neutralization and precipitation

Add lime or sodium hydroxide, adjust the pH to 8-9, and allow heavy metals to form hydroxide precipitates;

Assisted by PAC and PAM to enhance flocculation and sedimentation, removing most suspended solids and heavy metals.

2. Deep removal of heavy metals

Using ion exchange resin or chelating resin to adsorb residual heavy metal ions;

Or use sulfide precipitation method to further reduce the concentration of heavy metals.

3. Membrane separation and reuse

The pre treated effluent enters the ultrafiltration (UF)+reverse osmosis (RO) system;

RO produced water can be reused for cleaning, cooling, and other processes, achieving efficient water resource circulation;

Concentrate the concentrated water and recover the acid solution or dispose of it as hazardous waste.

4. Acid recovery technology

For high acid and high metal concentration wastewater, diffusion dialysis, electrodialysis and other technologies can be used to recover free acids;

Realize acid recycling and reduce chemical consumption.

The treatment and recycling of acid washing wastewater are important means to achieve clean production, energy conservation, and emission reduction. In the future, we should strengthen the application of new materials and intelligent control technology, promote the development of processing systems towards high efficiency, energy conservation, and resource utilization, and help achieve the green transformation and sustainable development goals of the manufacturing industry.