Application of Air Floatation Machine in Water Treatment of Paper Industry

Application of Air Floatation Machine in Water Treatment of Paper Industry

Recently, the government has also made great efforts to control pollution in the paper industry. Here is a brief summary of the pollution control process in the paper industry:

Paper making sludge needs to be treated in a sludge concentration tank. The main sludge treatment process now is pre dewatering, combined with centrifugation or track dewatering. After the sludge concentration is increased, the utilization rate of flocculants will correspondingly increase. However, it should be avoided that the sludge concentration is too high, about 2%. If the concentration is too high, it will cause blockages in the pipeline for sludge transportation. If the concentration is too low, it will result in waste of flocculants.

Before entering the air flotation machine for dewatering, flocculants need to be added to the sludge pipeline to form the optimal floc. Different papermaking processes produce different types of sludge, and targeted addition of different types of flocculants is required. Generally, cationic amide polymerized iron sulfate is used for papermaking sludge. The commonly used polymer flocculants are mainly polyacrylamide. Before the reaction between sludge and amide, adding a little polyaluminum chloride as needed can shorten the coagulation time of sludge. When amide is used alone, due to the small flocs formed and low mechanical strength, the sludge will leak a large amount with the filtrate under the pressure of the filter belt, resulting in poor dewatering effect and low sludge recovery rate. Using cationic polyacrylamide alone can achieve good sludge dewatering effect, but the cost is relatively high. Therefore, if inorganic flocculants are combined with organic polymer flocculants, good results can be achieved and the cost of sludge dewatering can be reduced. The types and dosages of coagulants can be determined through experimental methods. After chemical conditioning, the sludge needs to be mechanically dehydrated. Due to the significant proportion of operating and post-treatment costs for sludge dewatering in the overall sewage treatment cost, it is crucial to choose energy-efficient and high-efficiency grid equipment. After multiple experiments, we recommend that the belt filter press dewatering machine has the advantages of low investment, automatic control and continuous operation, low energy consumption, high dewatering efficiency, easy management, low maintenance costs, low noise, and low chemical dosage. Therefore, it is recommended to use a hyperbolic mixer for dehydration equipment. The pressure filtration process of the belt filter oil machine is to first pass the sludge through the gravity dewatering zone, then to the pressure dewatering zone, and finally to the pressure dewatering zone. After three steps, a relatively dry sludge cake is produced. The concentration of dehydration is generally around 20%.