Application of membrane technology in wastewater treatment and recycling
< br /> Its advantage is almost complete removal of SS, general bacteria, viruses, such as e. coli, and decoloring, reduce produce chloroform ( THM) Precursors of effluent water quality is good, because membrane devices to take up the space is little, particularly suitable for old plant upgrade or factory space under the condition of limited use.
in urban sewage treatment and recycle, membrane process is often used in secondary treatment after deep processing, multiple in microfiltration ( MF) Ultrafiltration (, UF) Replace conventional deep processing of precipitation, filtration, adsorption, aseptic processing, such as by nanofiltration membrane ( NF) And reverse osmosis ( RO) Water softening and desalting. In the water reuse, currently the most used is the MF, UF and activated sludge membrane bioreactor.
of each are not identical, industrial wastewater reuse purpose is different, the application of membrane technology are also diverse. But no matter what kind of wastewater treatment, membrane technology has to cooperate with other technical reasonable can play its role. Because the composition of sewage is extremely complex, the retrieval and utilization of different purposes and requirements of water quality standards and process are different, every single water treatment technology is difficult to reach the water water quality requirements.
it is generally believed MF removal microorganism, bacteria in sewage, eggs, viruses, and UF can be removing the large molecules in sewage, such as the production of protein, humic acid and some THM precursors and dye. Sewage treated by MF and UF dissolved salt and most of the ion is still difficult to removal, must by the RO membrane to the component removal. Secondary effluent can be treated by RO meet drinking water standards, the desalination rate can reach more than 90%, water recovery more than 75%, the removal rate of COD and BOD of more than 85%. But RO need operation under high pressure, high cost, previously used in wastewater treatment is more MF and uf membrane. In recent years, the development of NF membrane can intercept molecular weight greater than 200 low molecular and bivalent ions and high, for monovalent ions intercept rate is very low, so can be operating under low pressure, transparent and water, low operating cost, can remove all viruses, bacteria in wastewater treatment, pesticide, surfactant and trichloromethane precursors, this kind of material with chlorine in water ( Such as sterilization chlorine) Reaction yield of carcinogens, such as THM because this kind of precursors for low molecule organic matter mostly, with conventional water treatment technology and MF, UF's good removal, and NF can remove more than 90% of the country's second out of the water dissolved carbon and THM precursors and two-thirds of 4/5 of salinity, hardness, water conforms to the United States in 1986 the provisions of the laws of pollutant of safe drinking water.
charged membrane electrodialysis is under the effect of electric field force of membrane process, and more used in industrial wastewater treatment and reuse, such as metal ions, such as charged ion in electroplating wastewater separation and recycling.
liquid membrane technology promote the mass transfer process, available for chemical reactions and mass transfer speed, high separation efficiency, already in the processing of waste water containing phenol and so on application research on pilot scale.
Membrane separation (
It is given priority to with MF, UF, NF) Combined with biological response of membrane bioreactor ( MBR) Used most frequently in sewage treatment of membrane separation activated sludge process, which replace the conventional activated sludge with membrane separation by gravity sedimentation in the separation of the second pond, has the advantages of compact device, water quality is good. / /