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1、英文文献： RECENT DEVEL OPMENTS IN BIOLOGICAL TREATMENT OF BREWERY EFFLUENTABSTRACTDuring the last two decades the brewing industry has shown increasing awareness for environmental protection and the need of sustainable production processes.Implementation of ISO 14001 certification and more stringent env
2、ironmental legislation have been important drivers for the brewing industry to invest in biological effluent treatment. The role of biological effluent treatment is discussed with special attention is given to combined anaerobic/aerobic treatment. Combining anaerobic pre-treatment with aerobic post-
3、treatment integrates the advantages of both processes amongst which reduced energy consumption (net energy production), reduced biological sludge production and limited space requirements, are of importance. The combination allows for significant savings on operational costs as compared to complete
4、aerobic treatment without compromising the required discharge standards.Descriptors: brewery effluent, biological treatment, anaerobic, aerobicINTRODUCTIONThe last 20 years environmental awareness of the brewing industry has grown significantly.leading to increased investments in environmental prote
5、ction measures. Important internal drivers for the brewing industry are implementation of environmental management systems (EMS) like ISO 14001 as well as the need for conducting of benchmark studies for brewery process optimalization. Knowledge about environmental emissions (e.g.effluent quality an
6、d quantity) can become management information, which may help to improve the efficiency of in-plant brewery processes (minimize product losses, spill of water and energy)6. Important external drivers for environmental investments are local legislation and environmental taxation systems (discharge le
7、vies). The overall result is a growing interest within the brewing industry in environmental pollution controls systems. This paper describes the most important (biological) technologies for purification of brewery effluent. Special attention is given to the role of anaerobic treatment in reducing w
8、aste and net production of energy rich biogas.Brewery effluent compositionThe quality and quantity of brewery effluent can fluctuate significantly as it depends on various different processes that take place within the brewery (raw material handling, wort preparation, fermentation, filtration, CIP,
9、packaging. etc). The amount of wastewater produced is related to the specific water consumption (expressed as hl water / hl beer brewed). A part of the water is disposed with the brewery by-products and a part is lost by evaporation. As a result the wastewater to beer ratio is often 1.2-2 hl/hl less
10、 than the water to beer ratio. Organic components in brewery effluent (expressed as COD) are generally easily biodegradable as these mainly consist of sugars, soluble starch, ethanol, volatile fatty acids, etc. This is illustrated by the relatively high BOD/COD ratio of 0.6-0.7. The brewery solids (
11、expressed as TSS) mainly consist of spent grains, kieselguhr, waste yeast and (hot)trub. Brewery effluent pH levels are mostly determined by the amount and type of chemicals used at the CIP units (e.g. caustic soda, phosphoric acid, nitric acid etc). Nitrogen and phosphorous levels are mainly depend
12、ing on the handling of raw material and the amount of spent yeast present in the effluent. Elevated phosphorous levels can also be the result of phosphorous containing chemicals used in the CIP unit. Table 1 summarizes some of the most relevant environmental parameters.Discharge requirementsThe effl
13、uent discharge limits a brewery has to comply with depends on local environmental legislation. It is obvious that in case of discharging to a municipal sewer discharge limits are less stringent than when the effluent is to be discharged into a sensitive receiving surface water body (river, lake sea,
14、 etc). Removal of organic compounds (COD chemical oxygen demand) from the wastewater is important to avoid anaerobic conditions in the receiving waters. Nutrients like nitrogen (N) and phosphorous (P) should be removed to avoid algae bloom disturbing the receiving waters ecosystem. Table 2 presents
15、some indicative discharge limits as are generally applied in the EU (EU Council Directive 1991) for receiving surface water bodies. Actual discharge limits might vary for each location, region and country.BIOLOGICAL EFFLUENT TREATMENT SYSTEMSAmong biological treatment systems one can distinguish bet
16、ween anaerobic (without oxygen)and aerobic (with air/oxygen supply) processes. Anaerobic treatment is characterized by biological conversion of organic compounds (COD) into biogas (mainly methane 70-85 vol% and carbon dioxide 15-30 vol% with traces of hydrogen sulphide). During aerobic treatment (air) oxygen is supplied to oxidize the COD into carbon dioxide and water. Both biological processes produce new biological biomass (biosolids). The overall basic reactions a
