This proposal is designed for the treatment of anodizing wastewater generated by an aluminum alloy casting plant. The anodizing wastewater from the aluminum alloy casting plant amounts to 260 tons per day. Processing is conducted for 20 hours each day, equating to 7.5 tons per hour. During the anodizing process, there are rinsing steps. Based on the pollutants in the wastewater, anodizing production wastewater mainly falls into the following categories:

1. Pretreatment Wastewater

Pretreatment wastewater includes degreasing, alkaline washing, neutralization, anodizing, post-oxidation neutralization, and cleaning wastewater after dyeing processes. The main pollutants are pH, COD (Chemical Oxygen Demand), BOD (Biochemical Oxygen Demand), SS (Suspended Solids), and total aluminum.

2. Phosphorus-containing cleaning wastewater

Phosphorus-containing cleaning wastewater is produced in the chemical polishing process, and the main pollutants are pH, COD, SS, total phosphorus, and total aluminum.

3. Nickel-containing cleaning wastewater

In the sealing process, low-temperature or medium-temperature oxide film sealers are mainly used, which are nickel salt-type sealers. Therefore, the sealing process will produce nickel-containing cleaning wastewater, and the main pollutants are pH, COD, SS, and total nickel.

Aluminum alloy anodized dye has good water solubility, light resistance, heat resistance, and weather resistance, and is a kind of wastewater that is difficult to treat.

1. Reduce chromaticity

2. Water quality requires clarity

3. Low cost of use

4. Simple operation

Add 500 grams of decolorizer per ton of water, then add 0.4 kilograms of calcium hydroxide to adjust the pH, and finally add 3 kilograms of PAM diluted 1000 times to flocculate and precipitate clear water, reduce pollutants, and make it meet the emission standards.

After using the Beijingshi decolorizer in aluminum alloy anodized wastewater, the comparison results of pollutant content before and after:

Using highly efficient organic high-molecular-weight complex polymer decolorizing agents can effectively treat substances contained in wastewater. This process is suitable for a variety of aluminum anodizing dye types, with a wide pH range of operation and the characteristic of not producing secondary pollution. It is an efficient decolorization and precipitation process suitable for large-scale industrial applications. These processes do not affect biochemical systems. After separate pretreatment to remove color and some other pollutants, a combination of "inclined tube settling → biochemical system → secondary settling → sand carbon transition → security transition → ultrafiltration → ultrafiltration → reuse water tank" is used for deep processing, ensuring stable effluent meeting discharge standards.

The wastewater treatment results are satisfactory, with a satisfactory cost per ton of water treated and no impact on the biochemical system. After separate pretreatment to remove color and some other pollutants, the combination process of "inclined tube settling → biochemical system → secondary settling → sand carbon transition → security transition → ultrafiltration → ultrafiltration → reuse water tank" is used for thorough processing. The effluent is stable and meets discharge standards.