5000吨每天啤酒生产废水处理工程设计【含CAD图纸+文档】
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目 录1 引言22 材料与方法321 反应器系统322 分析方法33 结果与讨论531 无过滤啤酒废水组成5 32 UASB反应器的性能64 结论101. Introduction122. Materials and methods142.1. The reactor system used142.2. Analytical methods143. Results and discussion163.1. Opaque beer brewery effluent composition163.2. Performance of the UASB clarigester174. Conclusion22References2324热带气候下UASB反应器处理无过滤啤酒废水的研究W. Parawiraa, I. Kuditab, M. G. Nyandorohb and R. Zvauyaa摘要对生产性UASB反应器处理无过滤啤酒废水的研究已进行了两年。该反应器体积为500m3, 水停留时间约为24h。研究目的是根据处理效率评估UASB处理无过滤啤酒废水的性能。未经处理的无过滤啤酒废水中悬浮物较多、有机物浓度较高,在排入城市污水处理厂之前必须进行预处理。UASB反应器COD平均去除率为57 ,总固体和可沉降固体的去除率分别为50 和90。由于UASB反应器能积累氮、磷营养物,因而出水的氮、磷含量高于进水。研究结果表明,室温下采用UASB反应器处理无过滤啤酒废水,出水能达到污水排放标准。关键词: 厌氧消化,UASB ,无过滤啤酒废水,COD(化学需氧量)1 引言啤酒废水常用好氧法和厌氧法来处理。Zvauya等人采用中温好氧处理工艺处理无过滤啤酒废水。由于啤酒废水属于中高浓度有机废水,需要大量曝气。同时,好氧法也会产生大量的剩余污泥,需要另外处置,这就相应增加了污水处理的成本。Auster-mann-Haun和Seyfried采用UASB系统处理啤酒废水,结果比好氧处理系统更加环保和高效。厌氧法具有以下几个显著优点:无需曝气,能耗较低;部分有机物转化为甲烷,可作为能源;剩余污泥产量较少,处置费用较低。有机污染物在大量厌氧微生物菌群共同作用下降解,其过程分为四个阶段:水解、酸化、产乙酸和产甲烷阶段。这些厌氧微生物,包括酸化菌、产乙酸菌和甲烷菌组成互养关系。近年来,由于啤酒废水的特性适合厌氧法,因此广泛应用于啤酒废水处理中。然而,厌氧法也存在着一些问题:厌氧反应器初次启动过程缓慢; 因为厌氧过程是由大量不同类属的、相互制约的微生物菌群共同作用,厌氧处理过程不太稳定,难于控制。啤酒废水水质复杂、波动较大,而厌氧处理对水质波动尤为敏感。与生活污水相比,许多低pH、高有机负荷的工业废水采用厌氧法尚有疑问。但只要操作正确、监控得当,UASB反应器运行仍比较可靠。UASB污水处理系统运行的可靠性依赖于设计人员提供可靠的控制程序和操作人员的全面监控,尽量避免系统过负荷。虽然非洲国家大多数无过滤啤酒企业都属于大型企业,但很少有几家企业愿意处理其废水。本研究采用哈拉雷市最大的无过滤啤酒厂Zimbabwe新安装的UASB反应器,来评估其处理效果。2 材料与方法21 反应器系统该反应器材质为混凝土,体积为500m3,平均有机负荷为6kgCOD(m3d)。该厂污水处理系统包括集水池、筛滤(孔径05mm)、均衡池和UASB反应器。筛滤除去废水中大的悬浮物。均衡池用于均匀有机负荷、pH和啤酒间歇生产造成的水质波动,同时也稀释酿造过程中产生的有毒和抑制性化合物的浓度。在均衡池内投加尿素和正磷酸盐,以补充氮和磷等营养元素,保持废水中COD:N:P的比例为100:5:1。若废水呈酸性(pH=3363),则加碱调节进水DH值至中性。均衡池出水进入UASB反应器的底部,然后与气体一起从反应器顶部流出。在372 的温度范围内,UASB反应器采用活性污泥接种。污泥的培养驯化期为3个月,其间采用间歇进水,系统水力停留时间约为24h,但随进水情况变化而略有所差异。采用COD和PV评估UASB系统的性能。22 分析方法每月均对进水和出水采样,两天后出分析报告。采样方式为采集均样,24h为一个采样周期,每小时采样一次。测试所有水质指标以分析该日系统进出水的水质情况。(表2.1)是具体检测程序,本文所采用的数据均为月平均值。pH、COD、高锰酸盐指数、总固体TS、总悬浮物TSS、可沉降固体、总溶解性固体SS等指标的分析采用标准方法。磷酸根和总氮采用德国Merck公司的Nova 60分光光度计测试,其检测方法遵照使用说明。表2.1 检测程序监控项目样品类型分析频率啤酒废水(原废水,集水池)24h均样COD,PV,总硝基氮,磷酸盐,pH,总固体,沉淀物。每周三次UASB进水(平衡器出水)瞬时样/24h均样COD,PV,总固体,沉淀物,氮,磷酸盐每周三次UASB出水瞬时样/24h均样COD,PV,pH ,总固体,沉淀物,氮,磷酸盐每周三次3 结果与讨论31 无过滤啤酒废水组成未经处理的无过滤啤酒废水(原水)主要成分见(表2)。由于原水氮、磷含量较低,不足以提供厌氧菌生存所需的营养,因而按COD:N:P:100:5:1的比例向原水添加尿素和磷酸钾。据Ochieng等人报道:氮、磷含量丰富的啤酒废水比一般啤酒废水的COD去除率高。因原水呈酸性,故添加纯碱调节其pH为中性。当地政府允许的废水排放浓度见(表2)由(表3.1)可以看出,未经处理的无过滤啤酒废水的水质指标不能达标,其有机物和悬浮物浓度较高,而营养物含量较低,适于用厌氧法处理。此类废水类似于一般啤酒废水,都是有机污染物含量较高,而营养物含量较低。啤酒间歇生产特性造成了废水水质波动较大,因而COD浓度变化较大,很难有一个叵定的有机负荷,这就需要采用适宜的污水处理系统。本套UASB反应器采用活性污泥接种,取代了常用的絮状污泥或消化污泥,这主要是因为其内含有大量的甲烷菌,很容易繁殖。更为重要的是其生物活性强于消化污泥。表3.1 处理前无过滤啤酒废水水质参数数值范围平均浓度标准偏差(30个样品)哈拉雷市允许排放浓度pH3.306.304.50.66.89.0COD(mg/l)8240200001253542783000总悬浮物(mg/l)290130002841175600总固体(mg/l)5100875072011606总溶解性固体(mg/l)2020-5940452019272000沉淀物(mg/l)90-40027426810总氮(mg/l)0.01960.03360.0230.007400总磷酸盐(mg/l)16124595210高锰酸盐指数(mg/l)28790062723230温度()25352838032 UASB反应器的性能在这两年内,无过滤啤酒废水的UASB系统的性能见(图1)。该污泥处理系统的最终出水pH为6573。前三个月,UASB反应器出水的COD仍然较高,这可能是由于进水含有大量腐败啤酒是原因之一。第四个月起,由于在集水池去除了大部分的悬浮物,UASB反应器的性能明显改善。第5月、第6月和第11月,腐败啤酒造成反应器出水COD浓度偏高;此外,泵出现机械故障也严重影响了整套污水处理系统。从第l2月开始,COD去除率明显提高,这主要是第11月增加了一套孔径为05mm的细筛,减少了进入厌氧反应器的总固体量。第一道筛滤孔径为10mm。在这两年内,该套UASB系统COD平均去除率为57。Aysten-nann-Haun和Seyfried利用UASB反应器处理过滤啤酒废水的中试研究表明,其COD去除率可达80。室温下UASB反应器的一项小试实验表明,其COD去除率高达89,也就是说,UASB反应器的性能一般都能改善。进水COD 口出水CODCOD允许排放浓度(3gL) , COD去除率有机负荷可用PV(高锰酸盐指数)表示见(图2)。当地政府采用高锰酸盐方法测试有机负荷,但采用重铬酸盐回流滴定的方法优于高锰酸盐方法,因此可用这两种方法测试COD。研究期间,PV去除率为3070 ,平均为62。从第14个月开始,反应器出水的PV基本降至允许排放浓度80mgL。第17个月起,反应器处理效率有了明显改善,其COD和PV各见(图1)和(图2)。反应器进水减少是其原因之一。此外,反应器内接种污泥驯化、逐步适应来水水质也可能是一个原因。(图3)说明了UASB反应器总氮浓度的变化情况。一般来说,无过滤啤酒废水的氮含量较低,必须补充氮源来满足厌氧菌的生长需要。出水的总氮并不超标(400mgL),但由于总氮会造成下游水体的富营养化,并对甲烷菌具有一定毒性,因此必须监控该项指标。UASB反应器出水中总磷含量较高,高于当地政府的允许排放浓度(见图4),这主要是由于在均衡池内添加了三价磷酸盐补充营养。据文献报道,由于UASB系统不能产生大量的污泥,因而对氮和磷的去除率较低。氮是厌氧菌生长必须的营养元素,在生物反应器内如果没有积累有机物,进水和出水的总氮应该持平。氮和磷是水体的营养元素,其富营养化将引起藻类植物的过度繁殖。在后12个月,总磷相对较低。总固体和可沉降固体的减少情况分别见(图5)和(图6)。UASB反应器的总固体平均去除率为50。在起初的10个月内,总固体去除率低于40 ,而从第11个月开始,其去除率有了明显的改善,提升到60 8o。这主要是由于在第11月安装了一套孔径为05mm的细筛。可沉降固体去除率为87 9r7 ,平均为90。可沉降固体是啤酒废水的一个难题,需要在处理过程中监控。由于COD和总固体的平均去除率分别为57和50 ,因而必须改善UASB反应器的性能。碱的不断添加,不仅增加了处理成本,而且也让生物系统极易失衡或者崩溃。这就需要寻找一个低廉的替代品来改善系统的缓冲能力。这套500m3处理系统产生的沼气并没有收集和检测,而是未经燃烧直接排放到大气中。为更好地发展啤酒废水处理工艺,沼气的回收利用有着广阔的发展空间。4 结论本研究中,UASB反应器可将啤酒废水的有机负荷降低到允许排放浓度以下。对啤酒厂而言,更大收益在于厌氧过程产生的甲烷气,它既可作为蒸汽锅炉的燃料,也可通过发电机转化为电能。由此可以断定,啤酒厂内设置一套厌氧污水处理系统有其经济上的吸引力,同时,在这个能源缺乏、价格高昂的年代,这必将成为符合环保高要求的最佳选择。A study of industrial anaerobic treatment of opaque beer brewery wastewater in a tropical climate using a full-scale UASB reactor seeded with activated sludge W. Parawiraa, I. Kuditab, M. G. Nyandorohb and R. Zvauyaaa Department of Biochemistry, University of Zimbabwe, P.O. Box MP 167, Mount Pleasant, Harare, Zimbabweb Chibuku Breweries, P.O. Box 3304, Southerton, Harare, Zimbabwe Received 1 August 2003; accepted 17 January 2004. Available online 11 June 2004. AbstractA full-scale upflow anaerobic sludge blanket (UASB) reactor treating traditional opaque beer brewery wastewater recently installed at an opaque beer factory was studied for 2 years. The total volume of the reactor was 500m3 and the hydraulic retention time was approximately 24h. The aim of the study was to evaluate the performance of the UASB reactor during anaerobic digestion of opaque beer brewery wastewater in terms of treatment efficiency. The untreated opaque beer wastewater has high solids content and high organic matter, which need pretreatment before it is discharged into municipal sewage treatment works. The UASB reactor enables the brewery to meet the requirements of the wastewater discharged into municipal sewerage system of Harare. The average percentage reduction in Chemical Oxygen Demand (COD) was 57%. The total and settleable solids were also reduced by 50 and 90%, respectively. The effluent from the UASB reactor contained higher orthophosphates and nitrogen levels than the influent leading to the accumulation of these nutrients in the system. These results indicated that the UASB plant was effective for treating opaque beer brewery wastewater at ambient temperature to meet the quality of effluent that can be discharged into public water works. Author Keywords: Anaerobic digestion; UASB; Opaque beer brewery wastewater; Chemical Oxygen Demand 1. IntroductionThe opaque beer brewery industry uses large volumes of water and discharges large volumes of effluent throughout the year, which are highly polluting. In Zimbabwe, there are 20 opaque beer breweries that produce over 420 million litres of opaque beer each year. The opaque beer brewing involves the blending of sorghum malt, and maize grits, followed by its subsequent fermentation with yeast. Essentially the process involves lactic acid fermentation as well as alcoholic fermentation. The beer is marketed and consumed whilst still actively fermenting. The brewing process employs a number of batch-type operations in processing raw materials to the final beer product. In the process large quantities of water are used for the production of beer itself, as well as for general washing of floors, and cleaning the brewhouse, cellars, packaging and cleaning in place, after each batch is completed. Due to the opaque beer brewerys effluent characteristic high organic content and acidic nature, it has the potential to cause considerable environmental problems 1. Such industrial effluents may result in reduction of the efficiency of the municipal treatment works 2. The brewery effluents may affect water quality in many ways, including organic matter increase, and resultant increase in Biological Oxygen Demand (BOD5) and COD. The high organic loads in the wastewater arises from dissolved carbohydrates, the alcohol from beer wastes, and a high content of suspended solids, e.g. spent maize, malt, and yeast. In order to control pollution and protect the environment, brewery effluent containing high concentrations of organic matter cannot be discharged to sewers and watercourses. The municipal authority in Harare is placing severe restrictions on the quality of effluent which industry can discharge into their municipal system, which makes on-site pretreatment necessary for some types of effluent. The brewery effluent is composed of wastewaters from cleaning tanks, fermentation tanks, floors etc. 3. A highly polluted effluent will reduce the capacity of the municipal wastewater treatment plant considerably and even overload such a plant. The implementation of low-cost, efficient, simple mitigation measures is required to enable the traditional opaque beer brewery industry to contribute to water conservation. For the breweries, there are aerobic and anaerobic biological treatment options. Zvauya et al. 1 reported the possibility of using thermophilic aerobic treatment of traditional opaque beer brewery wastewater. However, brewery effluent is categorised as medium-to-high-strength organic wastewater and requires an intensive amount of energy for aeration. Another mitigating factor is the large amount of waste sludge generated from these aerobic treatment processes, which also needs to be handled and disposed of and this increases the cost of operation of the treatment system. Austermann-Haun and Seyfried 4 reported that UASB plant at a brewery proved to be environmentally safer and more efficient than a high rate aerobic pretreatment plant. On the other hand, anaerobic digestion is a simple and reliable option with several advantages. The advantages of the process include the fact that less energy is required because no aeration is needed, the organic matter in the influent is partly converted to methane, which can be used for energy production, and less excess biomass and sludge are formed and therefore less disposal cost 5 and 6. During anaerobic digestion organic pollutants are degraded by a consortia of microbial populations through multiple degradation steps such as hydrolysis/fermentation, acetogenesis and methanogenesis 7. These anaerobic microbes, including fermentative bacteria, acetogenic bacteria and methanogens usually form a syntrophic relation 8. Anaerobic digestion enables industry to comply with the stricter pollution control regulations, and also to satisfy the search for greater efficiency, better economy and the use of natural energy sources 9. In recent years, there has been an increasing interest in the application of anaerobic digestion to brewery wastewater since the nature and strengths of the brewery wastewater often provides ideal conditions for the digester operations. However, there are problems associated with the start-up and operation of anaerobic treatment process due to the complexity of the process that is carried out by a consortium of unidentified and interdependent microorganisms, which makes the process unstable and difficult to monitor. Given the particularly complex and fluctuating nature of the brewery wastewater, it is clear that anaerobic digestion could be a sensitive to the changes in wastewater composition. Also the anaerobic treatment of many industrial effluents with low pH and high organic load has always been problematic as compared to other wastes of different origin, e.g. municipal wastes 10. UASB reactors need not be unreliable if properly operated, monitored and controlled. The UASB wastewater (pre-) treatment systems represent proven sustainable technology for a wide range of very different industrial effluents 11, 12, 13 and 14. The onus, therefore, rests both on the designer to provide reliable control arrangements and on the operator to devise overall monitoring and control strategies to minimise an overload risk. Despite the fact that the opaque beer brewing industry is big business in most African countries, there are very few breweries that are attempting to treat their waste. Brewery effluent treatment work has been largely on clear beer wastewater 5. There are no published scientific reports of anaerobic digestion of opaque beer brewery wastewater using the anaerobic digestion technology to the best of our knowledge. The aim of this study was to evaluate the anaerobic digestion of opaque beer brewery wastewater from the largest opaque beer brewery in Harare, Zimbabwe using a recently installed UASB reactor. 2. Materials and methods2.1. The reactor system used The industrial full-scale UASB reactor or clarigester at an opaque beer brewery in Harare was used in the study. The UASB reactor was constructed of concrete. The volume of the UASB reactor was 500m3 based on the average organic loading rate of 6kg COD/m3 per day. The effluent treatment plant consisted of a receiving tank, screens (0.5mm mesh), balancing tank and the UASB reactor. The screens were used to remove heavy suspended solids. The balancing or buffering tank was used to balance the variations in organic loads, pH and flow resulting from batch operation of the brewing process as well as the dilution of toxic and inhibiting compounds from the processing plant. The nitrogen and phosphate nutrients supplements were added into the balancing tank in the form of urea and triple super phosphate. The nutrients were added to obtain a COD:N:P ratio of 100:5:1. The wastewater was acidic (pH 3.36.3) and thus soda ash was also added to adjust the influent pH to neutral. The wastewater emanating from the balancing tank was then fed into the bottom of the UASB reactor and the effluent discharged from the top together with the gas. The digester was originally seeded using a mixture of active municipal sludge, which was maintained at a temperature of approximately 372C for 3 months with intermittent feeding with brewery wastewater to acclimatise the bacteria to the feed substrate. The retention time was approximately 24h although it varied with influent flow. The performance of the UASB system was monitored by measurement of the COD, and permanganate value (PV) in the influent and the effluent over a period of 2 years. 2.2. Analytical methods Chemical analyses were conducted on both the influent and effluent composite samples collected after two days throughout every month after commissioning of the plant. Samples were collected every hour over a 24-h period and the measurement of the parameters was done to determine the overall parameter profile of the total brewery effluent for that day. The monitoring and reporting programme followed in this study was as shown below (Table 1). The mean value and the range for the month were reported in the monthly report of operation. The results presented here are monthly averages. Table 1. Monitoring programme employed in this study The following parameters were monitored and analysed according to standard methods: pH, COD, permanganate value, total solids (TS), total suspended solids, settleable solids, total dissolved solids 15. The amounts of orthophosphates and total nitrogen were measured with the test kits according to manufacturers instruction (Merck, Germany) using a Spectroquant Nova 60 photometer (Merck, Germany). 3. Results and discussion3.1. Opaque beer brewery effluent composition The average composition of opaque beer brewery wastewater from the opaque beer brewery before treatment is given in Table 2. The wastewater required nutritive and pH conditioning before it entered the reactor. As the raw wastewater was unable to provide sufficient nutrients for anaerobic microorganisms, urea and potassium phosphate were added to give a COD:N:P of 100:5:1. Ochieng et al. 16 reported a higher COD reduction with nitrates and phosphates enriched brewery wastewater compared with wastewater without nutrient enrichment. The effluent was acidic, thus, soda ash was also added to adjust the influent pH to neutral pH. The permissible limits of components in effluent discharged into public water are also shown in Table 2. As can be seen the levels of water quality parameters do not meet the effluent standards of the local authority. The results indicate that the untreated opaque beer brewery wastewater has high organic matter and suspended solids and low concentrations of nutrients. They is the type of wastewater for which anaerobic digestion would be an acceptable treatment method 17. The characteristic high concentrations of organic pollutants and low nutrient content characterised by large variations in these parameters is consistent with wastewater from clear beer breweries 3 and 11. The fluctuations in the wastewater characteristics are due to changes in what is happening in the plant during each period and discontinuous discharges of the brewerys departments. Owing to the large fluctuations in the strength of the brewery wastewater, the influent COD concentration showed large variations, making it difficult to use a constant organic loading rate. There is need for on-site treatment of the wastewater to protect the environment and reduce costs as heavy penalties are imposed for discharging substandard effluent into the urban treatment works. Table 2. Opaque beer brewery wastewater characteristics before treatment Activated sludge was chosen to seed the UASB reactor instead of pre-granulated bacterial flocs or digested sewage sludge because a considerable amount of methanogenic bacteria is found in activated sludge and it is easy to obtain large amounts. More importantly activated sludge contains little sand or soil and is composed mostly of biomass unlike digested sewage sludge 11. 3.2. Performance of the UASB clarigester The performance of the UASB plant at the opaque beer brewery was studied over a period of 2 years (Fig. 1). The final effluent from the wastewater treatment plant had a pH between 6.5 and 7.3. For first 3 months of the study, the effluent from the digester had high levels of COD remaining after treatment. This may have been probably due to the presence of suspended solids in the influent. There was a lot of bad beer destruction in these months as well. The total solids in the influent to the anaerobic digester were reduced as from the fourth month by removing solids from the bottom of the receiving tank, and the performance of the reactor improved. In the 5th, 6th and 11th month the effluent from the reactor had high COD because of beer destruction. The brewery was discharging spoilt beer into the effluent plant during these months. Furthermore the whole wastewater treatment plant also suffered heavily from pump mechanical breakdowns in these months. During pump breakdowns the influent was discharged directly into the municipal sewers. The average COD removal efficiency was 57% for the period of this study. The COD removal efficiency improved from the 12th month to the end of the study period. This was due to installation of a screen with a smaller mesh size (0.5mm) in the 11th month, which reduced the quantity of total solids entering the digester. The first screen had a mesh size of 1.0mm. The COD removal efficiency achieved in this study is comparable to an average of 60% obtained in a comparative laboratory-scale study of the effects of dairy and clear beer brewery effluents on the treatability of domestic sewage by Kilani 2. However, Stadlbauer et al. 18 reported COD removal efficiencies of 85 to 90% from a study of anaerobic purification of lager beer brewery wastewater in laboratory scale biofilm reactors with and without a methanation cascade. Austermann-Haun and Seyfried 4 also reported 80% COD removal efficiency from a pilot-scale UASB reactor treating clear bee
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