Industrial enterprises are mainly distributed in the electronics, plastics, electroplating, hardware, printing, food, printing and dyeing industries. From the perspective of the amount of wastewater discharged and the degree of harm to the environment, electroplating, circuit boards, surface treatment and other inorganic pollutants mainly contain inorganic pollutants and food, printing and dyeing, printing, and domestic sewage and other organic pollutants. Wastewater is the focus of treatment. Wastewater polluted by acids and alkalis is irritating and corrosive, while organic oxygen-containing compounds such as aldehydes, ketones, ethers, etc. are reductive, which can consume dissolved oxygen in the water and make the water deoxygenated and cause the death of aquatic organisms. Industrial wastewater contains a large amount of nutrients such as nitrogen, phosphorus, and potassium, which can promote the growth of algae and consume dissolved oxygen in the water, resulting in eutrophication pollution of the water body. The content of suspended solids in industrial wastewater is very high, up to 3000mg/L, which is 10 times that of domestic wastewater.
In wastewater treatment, micro- and ultra-filtration membranes are used for the separation of the activated sludge (biomass) from the treated water. This offers the advantages of a complete removal of solids and bacteria, as well as most of the viruses, namely those attached to the suspended solids. Compared to the conventional activated sludge process (CAS) this technology allows a much higher biomass concentration (MLSS) whereby the reactor volume and the footprint decreases. More than 100 industrial wastewater treatment membrane bioreactors (MBR) are in operation in Europe. Data of three case studies for a sewage sludge dewatering plant in UK (12,000 m3/d), a plant for the treatment of pharmaceutical wastewater in Germany (3600 m3/d), as well for revamping of an chemical WWTP >2000 m3/d in Italy, are given. MBRs will be used in future wherever high quality effluent is required, because of a sensitive receiving water body or due to the fact of water reuse as process water. MBRs are a perfect pre-treatment in industrial applications when further treatment with nanofiltration or reverse osmosis is considered. The technique is advanced and can be applied both in municipal and industrial wastewater treatment. Higher operational costs must be balanced by superior effluent quality.