Membrane separation technology refers to the process of separating, purifying and concentrating different components of feed liquid by selectivity of membrane. According to the different materials, the membranes can be divided into inorganic membranes and organic membranes. The inorganic membranes are mainly ceramic membranes and metal membranes, which have low filtration accuracy and low selectivity. Organic membranes are made of macromolecule materials. They are more widely used than inorganic membranes because of their low cost, wide pore size and various components.
Application of membrane technology in coking wastewater reuse technology:
1) Pretreatment + UF + NF process: Pretreatment + UF + NF process is used to treat the biochemical effluent from the coking plant wastewater treatment station under the company. The treated effluent quality reaches the standard except for the high chloride ion content. The effluent can be used as a supplementary water for recycling water. Compared with ultrafiltration membrane, nanofiltration membrane can improve water yield, but chloride ion in water can not be removed by nanofiltration membrane, so the equipment will be corroded when the effluent is reused.
2) Pretreatment + UF + RO process: Pretreatment + UF + RO process is used to treat biochemical effluent from coking plant wastewater treatment station, and the treated effluent is reused as supplementary water for circulating water. The effluent quality of this process is good, and it can be used as recycling water. The chloride ion content in effluent is low and the corrosion of equipment is small. However, the process has some shortcomings, such as large sludge, low water yield and rapid decline of water yield, which need to be improved urgently.
3) pretreatment + membrane bioreactor (MBR) + reverse osmosis membrane (RO) process: the coking wastewater is advanced treated by pretreatment + membrane bioreactor (MBR) + reverse osmosis membrane (RO) process, and the treated wastewater is reused as boiler supplementary water. The effluent quality of the process is good and the content of each component reaches the discharge standard. However, in the process of operation, the MBR is easily blocked by sludge, which leads to heavy cleaning work and low water yield.
4) Pretreatment + membrane bioreactor (MBR) + reverse osmosis membrane (RO) process: the coking wastewater was treated in depth by pretreatment + ultrafiltration membrane (UF) + nanofiltration membrane (NF) + reverse osmosis membrane (RO) process, and the effluent was reused as circulating water. The process increases the nanofiltration process before reverse osmosis, which greatly reduces the filtration load of reverse osmosis membrane, prolongs the working cycle and service life of reverse osmosis membrane, reduces the reverse washing frequency of membrane, and increases the water yield of the whole process. After the treatment of coking wastewater by reverse osmosis membrane, the lower chloride ion content in the effluent greatly reduces the corrosiveness of equipment, but the process 1 Secondary investment is higher.
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4th Phase Water Technologies LLC
