Ceramic membrane escort for pulping wastewater treatment

At present, physical coagulation and sedimentation is one of the mainstream methods to treat pulping wastewater in papermaking industry. Inject a certain amount of coagulant into the wastewater make the colloidal pollutants and some fine suspended solids, which is difficult to precipitate naturally form flocs of a certain size through the reaction processes of instability, coagulation and bridging, and then precipitate and separate them in the subsequent sedimentation tank to separate the colloidal pollutants from the wastewater.

Alkali recovery method and acid precipitation method can also be used. Alkali recovery treatment is an effective method to solve the problem of black liquor at present. Through the four main links of black liquor extraction, evaporation, combustion and causticization, the suspended solids, COD and BOD can be completely removed in black liquor, and alkali can be recovered to produce secondary steam. Acid precipitation method is to separate lignin from alkaline black liquor by acid precipitation, and then mix the wastewater with intermediate stage water for aerobic and anaerobic biochemical treatment.

The composite membrane system is used to deeply improve the original process, eliminate backward treatment policies, and make full use of the characteristics of the membrane for optimization treatment. The composite membrane system adopts ceramic membrane + ultrafiltration membrane + reverse osmosis membrane system. Due to its stable working characteristics and highly tolerant operating conditions, it has great advantages over the traditional wastewater treatment process.

In the whole process, a large number of impurities are removed, including macromolecular impurities such as lignin, cellulose and sugar, as well as small molecular impurities of inorganic salts. The removal accuracy is higher and the water production is easier to reach the index. The general temperature of pulping wastewater is 50-60 ℃, and the operating temperature of ceramic membrane can be used under the temperature, so there is no need for additional cooling. At the same time, the ceramic membrane is acid-base resistant. The preliminary treatment of wastewater can effectively protect the stable operation of subsequent membrane system after pretreatment and escort the pulping wastewater treatment.