Application fields of membrane bioreactors

Membrane bioreactor application fields:

1 Municipal wastewater treatment and building water reuse

       1967 Year of first adoption MBR The first wastewater treatment plant using the process was built by a US company in Dorr-Oliver The plant treated 14m³/d wastewater. 1977 In a year, a wastewater reuse system was put into practical use in a high-rise building in Japan. 1980 Year, Japan built two treatment plants with capacities of 10m³/d and 50m³/d 的 MBR treatment plants.

       90 In the mid- 39 There were such plants in operation in Japan, with a maximum treatment capacity of 500m³/d and 100 many high-rise buildings used MBR treated wastewater for reuse in secondary water systems. 1997 Year, the UK Wessex company established in the UK Porlock what was then the world's largest MBR system, with a daily processing capacity of 2000m³ ，1999 In the year, another one was built in Dorset 的 Swanage with a capacity of 13000m³/d 的 MBR plant.

2 Industrial wastewater treatment

        90 Since the MBR the range of treatment objects has been continuously expanding. In addition to reclaimed water reuse and fecal wastewater treatment, MBR its application in industrial wastewater treatment has also received widespread attention, such as the treatment of food industry wastewater, aquatic product processing wastewater, aquaculture wastewater, cosmetics production wastewater, dye wastewater, and petrochemical wastewater, all of which have achieved good treatment effects.

       90 In the early Ohio built a system for treating industrial wastewater from an automobile manufacturing plant in MBR system, with a treatment scale of 151m³/d The organic load of the system reached 6.3kgCOD/m³˙d ， COD removal rate was 94% Most of the oil and grease were degraded. In the Netherlands, a traditional oxidation ditch wastewater treatment technology was used in a fat extraction processing plant to treat its production wastewater. Due to the expansion of production scale, sludge expansion and sludge separation difficulties occurred. Finally, Zenon membrane modules were used to replace the sedimentation tank, and the operation results were good.

3 Slightly polluted drinking water purification

        With the widespread use of nitrogen fertilizers and pesticides in agriculture, drinking water has been polluted to varying degrees. LyonnaisedesEaux company developed in the mid- 90 a process with simultaneous biological denitrification, pesticide adsorption, and turbidity removal functions in MBR In the year, the company built a drinking water production plant in France with a daily output of 1995年该公司在法国的 Douchy 建成了日产饮用水 400m³ The nitrogen concentration in the effluent was below 0.1mgNO2/L the pesticide concentration was below 0.02μg/L 。

4 Fecal wastewater treatment

        Fecal wastewater has a very high organic matter content. Traditional denitrification treatment methods require a very high sludge concentration, and the solid-liquid separation is unstable, affecting the tertiary treatment effect. MBR The emergence of has solved this problem well and made it possible to treat fecal wastewater directly without dilution.

NS Each group of flat membranes in the system has approximately 0.4m2 dozens of groups installed in parallel, forming an automatically openable frame device that can be automatically cleaned. The membrane material is a polysulfone ultrafiltration membrane with a cut-off molecular weight of 20000 The sludge concentration in the reactor is maintained within the range of 15000~18000mg/L 范围内。

5 Landfills / Treatment of leachate from composting

        Landfills / Compost leachate contains high concentrations of pollutants, and its water quality and quantity vary with climatic conditions and operating conditions. MBR technology was used by many wastewater treatment plants before the year for the treatment of this type of wastewater. Through 1994年前就被多家污水处理厂用于该种污水的处理。通过 MBR and RO technology combination, not only can remove SS and organic matter and nitrogen, and can effectively remove salts and heavy metals.

        United States Envirogen company developed a MBR used for the treatment of landfill leachate, and built a plant in New Jersey with a daily processing capacity of 40 ten thousand gallons (approximately 1500m³/d ), in 2000 put into operation at the end of the year. This MBR uses a naturally occurring mixed bacteria to decompose hydrocarbons and chlorinated compounds in the leachate, and its pollutant treatment concentration is 50 ~ 100 times that of conventional wastewater treatment plants. The reason for this treatment effect is that, MBR can retain highly efficient bacteria and make the bacterial concentration reach 50000g/ 。 COD hundreds to 40000mg/L ， 90% above.

6 Key areas and directions of application

      （ 1 ）Upgrades of existing urban wastewater treatment plants, especially plants where the effluent water quality is difficult to meet standards or where the treatment capacity has increased dramatically but the land area cannot be expanded.

      （ 2 ）Residential areas without drainage pipe networks, such as residential areas, tourist resorts, scenic areas, etc.

      （ 3 ）Areas or places with wastewater reuse needs, such as hotels, car washes, aircraft, mobile toilets, etc., giving full play to MBR small land area, compact equipment, automatic control, flexible and convenient features.

      （ 4 ）Treatment of high-concentration, toxic, and refractory industrial wastewater. For example, the papermaking, sugar, alcohol, leather, and synthetic fatty acid industries are a common point source of pollution. MBR It can effectively treat wastewater that cannot meet the standards of conventional treatment processes and achieve reuse.

      （ 5 ）Treatment and reuse of landfill leachate.

      （ 6 ）Application in small-scale wastewater treatment plants (stations). The characteristics of membrane technology are very suitable for treating small-scale wastewater.

7 Future research priorities

      （ 1 ）Mechanism and prevention of membrane fouling.

      （ 2 ）Optimization of process flow and operating conditions.

      （ 3 ）Relationship between sludge yield and operating conditions to reasonably reduce sludge yield and reduce sludge treatment costs.

      （ 4 ）Metabolic characteristics of microorganisms in the reactor and their effects on effluent water quality, sludge activity, etc., to determine suitable microbial growth and metabolic conditions.

      （ 5 ）Economic study of the process. Under the current level of economic development in China, the supply status of membrane products, and the requirements of standardized design, MBR Determination of the maximum economic flow rate for wastewater treatment.

      （ 6 ）Develop new membrane bioreactors with the goals of energy saving, treatment of special water quality objects, nitrogen and phosphorus removal, simple operation and maintenance, and long-term stable operation.