According to the difference of alumina content and the addition of iron molecules, the color of water treatment materials polyaluminum chloride series will change from shallow to deep. The color change not only indicates the purity and quality of polyaluminum chloride, but also represents the different application scope. Although the higher the purity of polyaluminum chloride, the more expensive it is, the final quality of water purification is not only determined by the content of alumina.

In practical application, the raw water is affected by different industries, regions, seasons, temperatures and molecular contents. The pH value of raw water is the most important factor affecting the flocculation effect of polyaluminium chloride in wastewater treatment. Whether the flocculation and sedimentation function is fully played is closely related to the final effect of sewage treatment. If used properly, low content of polyaluminum chloride can also play a better effect than high content of polyaluminum chloride. How to make polyaluminum chloride play the most effective? No matter what type of sewage, the pH value of sewage can be reduced to about 7, which is the appropriate value for polyaluminum chloride to produce the maximum effect. After neutralizing the pH value of sewage, the best dosage can be determined through experiments. The steps to determine the dosage are as follows: 1. Dissolve polyaluminum chloride into 5% aqueous solution; 2. Take a 1000ml beaker and inject 1000ml water sample to be treated, add 0.2ml 5% PAC aqueous solution with a graduated dropper, stir evenly, stop stirring, and observe whether the supernatant is turbid after the clot is precipitated. If turbid, continue to add an appropriate amount of 5% PAC solution, observe again and repeat the above process until the supernatant is clear, record the total volume of PAC liquid consumed; 3. Calculate the dosage by formula: dosage = (total volume of consumed reagent * PAC solution concentration 5%) / water sample volume.

No matter which kind of polyaluminum chloride is used, the best flocculation effect and economic benefit can be achieved through the above methods.