Polyaluminium chloride is a process in which dispersed particles in water increase due to interaction and combination into aggregates. Its biggest use is as water treatment flocculant. Due to its outstanding advantages and wide application range, the dosage can be reduced by 1 / 3 ~ 1 / 2 compared with the traditional flocculant, and the cost can be saved by more than 40%. It has become an excellent water purification agent recognized at home and abroad.
Action principle of polyaluminium chloride in sewage treatment: polyaluminium chloride is a traditional method in water treatment, but it is also a widely used method with low cost and good effect. Coagulation is usually divided into two processes in research; Coagulation and flocculation.
Due to the addition of coagulant polyaluminium chloride, the electric double layer surrounding the colloidal particles is compressed to cause instability, and the process of forming small "micro flocs" through colloidal particle collision and aggregation is condensation; Flocculation refers to the process that micro flocs are further aggregated into large flocs visible to the naked eye through mechanical or hydraulic stirring.
In the actual operation of water treatment, these two stages occur almost synchronously. The purpose of coagulation treatment is to coagulate the pollutants into high-quality vitrification by adding coagulant polyaluminium chloride and using the functions of electrical neutralization, adsorption bridging, net capture and precipitation. These vitrification can be removed through the subsequent degree and filtration process.
The purpose of sedimentation and filtration is only to fully and completely separate the vitrification formed in the coagulation treatment from the treated water; The effect of disinfection treatment is also closely related to coagulation treatment. As the first production process of the traditional process, coagulation restricts the treatment effect of the subsequent process, which is called the key of water treatment.
We all know the professional application of polyaluminium chloride, but what problems should be paid attention to in the use of polyaluminum chloride, especially the harm of excessive use of polyaluminium chloride.
1. According to different conditions of raw water, a small test can be conducted before use to obtain the best dosage. For the convenience of calculation, the small-scale test solution shall be prepared according to the weight volume ratio (w / V), generally 2 ~ 5%. If 3% solution is prepared: weigh pac3g, put it into the cleaned 200ml measuring cylinder, add about 50ml of clean water, after dissolution, add water to dilute to 100ml scale, and shake well.
2. For production, mix and dissolve according to solid: clean water = about 1:5, and then add water to dilute to 2 ~ 3% (w / V). The solution below 1% is easy to hydrolyze, which will reduce the use effect, and the concentration is too high, which is easy to cause waste.
3. The dosage shall be added according to the best dosage obtained. Pay attention to observation and adjustment during operation. If there is less alum flower and large residual turbidity in the sedimentation tank, the dosage is too small. If there is large and upturned alum flower and high residual turbidity, the dosage is too large and should be adjusted appropriately.