Introduction of Alkali Recovery Technology for Inorganic Ceramic Membrane Wastewater

In daily life, a large amount of waste alkaline water comes from industries such as pulp and paper, petrochemical, textile printing and dyeing, washing and degreasing, and reclaimed wastewater. According to incomplete statistics, only four areas including black liquor treatment in the paper industry, viscose fiber wastewater, beer bottle washing wastewater, and ionized resin elution wastewater have treated 404 million tons of alkali-containing wastewater annually. Alkali recovery refers to the process of recovering the chemicals used from the waste liquor of alkaline pulping and cooking. The inorganic ceramic membrane system independently developed and produced by Jiuwu Hi-Tech can treat desizing wastewater and viscose fiber wastewater, etc., and realize the reuse of resources by recycling lye.

1. Application of inorganic membrane ceramic membrane wastewater alkali recovery technology

Desizing wastewater: The printing and dyeing industry is an important part of the textile industry and the main source of wastewater in the textile industry. A large number of pollutants in the wastewater come from the slurry used in the sizing process, mainly polyvinyl alcohol (PVA) slurry. The wastewater becomes alkaline with the pH of about 12. Based on the characteristics of high caustic soda concentration and high COD in the desizing wastewater, Jiuwu Hi-Tech adopts the "rough filtration + membrane concentration" process for the overall process. The coarse filter mainly intercepts large particles in the incoming water. The membrane concentration system uses inorganic membrane ceramic membranes to concentrate desizing wastewater. Ceramic membranes can retain most of the PVA slurry, and most of the caustic soda and some additives can pass through the inorganic membrane together with the clear liquid. The clear liquid of the inorganic membrane ceramic membrane system is stored in the clear liquid storage tank, and is used for processes such as volume reduction through an external pump to form alkali recovery. The concentrated water of the inorganic membrane containing PVA slurry only accounts for 10% of the total influent water, which facilitates centralized processing and reduces the difficulty of subsequent processing. The reuse rate of water and caustic soda in this process system exceeds 90%, reducing the impact of desizing wastewater on the wastewater treatment process of printing and dyeing enterprises.

Viscose fiber waste water: during the production process of viscose, waste lye containing semi-fiber is produced in the pressing section. The semi-fiber content is about 35g/L and the alkali content is about 200g/L. The waste lye is treated by the "inorganic membrane ceramic membrane + alkali-resistant organic membrane" process, which can realize the reuse of lye and effectively reduce the production cost of the enterprise. This lye is pretreated by the ceramic membrane of the small pore size inorganic membrane of Jiuwu High-tech. This reduces the fiber content in the waste lye, effectively reduces the processing load of the organic membrane, and can effectively extend the life of the organic membrane. Inorganic membrane ceramic membrane clear liquid is further filtered by alkali-resistant organic membrane. And the final filtrate half fiber content of the system is less than 5g/L. By recycling lye, resources are reused.

2. Description of inorganic membrane ceramic membrane wastewater alkali recovery process

1) The wastewater can achieve a reuse rate of more than 90%, and the reuse rate of caustic soda is higher than 90%.

2) The ceramic membrane system realizes PLC control, which can realize automatic operation without manual intervention.

3) Membrane clear liquid has stable quality and can be returned to the front-end printing and dyeing process to form alkali recovery.

4) The adopted process route has been verified by long-term operation, and the system has high reliability.