摘要
医院污水中含有大量细菌、病毒及其他有毒有害物质,如果不加处理直接排入环境水体中,将会对环境和人类健康产生巨大的危害,因此,需要研究对其进行有效处理的方法。随着"SARS"和“甲流”等公共卫生事件的爆发,社会对医院污水处理的关注越来越多。而且,随着对传统医院污水处理方式的缺点的逐渐认识,采用更先进的处理方式是医院污水处理的大势所趋。膜生物反应器(MBR),由于其占地面积小,自动化程度高,出水水质优异,消毒效率好,成为近年来用于废水处理的研究热点。
本实验结合MBR和传统活性污泥法中的生物铁法各自的优点,通过在MBR中投加氢氧化铁絮体来改善污泥性能,减缓膜污染,以获得更好的处理效果。对该系统用于医院废水处理的有机物去除效果、污泥特性和膜污染情况进行了研究,在优化工艺的运行条件和参数、污泥浓度以及充分认识微生物特性的基础上对其机理进行了初步探讨,主要的研究结果如下:
(1)氢氧化铁投加量为污泥浓度的1.5%的实验条件下,研究在不同曝气时间下有机物的去除效果,得出如下结论:曝气时间7h以后系统对COD、氨氮等的去除趋于稳定,COD浓度可以降低到30mg/L以下,氨氮浓度可以降低到1mg/L以下,在综合考虑经济成本条件下,在之后的实验中选择曝气时间为7h。
(2)采用氢氧化铁-膜生物反应器处理医院废水,系统表现出良好的有机物去除效果以及长期的运行稳定性。在连续运行不排泥的条件下,其COD的降解率最高可达到92.1%,氨氮的降解率最高可以达到99.6%,对于有添加剂的医院废水,通过改进工艺条件后出水仍然能达到《医疗机构水污染物排放标准》(GB18466-2005)。
(3)生物铁-MBR工艺一定程度上提高了出水水质,本实验条件下,氢氧化铁最佳的投加量为混合液污泥浓度的3%,此时生物铁-MBR出水COD、总P、NH3-N比普通MBR平均分别高9.13%、18%和4.2%。生物铁-MBR中,由于其膜组件对细菌、病毒高效的截留效果,本实验装置对大肠杆菌的去除效率在98%以上。
(4)对于生物铁-MBR工艺,氢氧化铁投加量为污泥浓度的1.5%-3%的生物铁污泥具有更好的絮状结构,这样就降低了膜表面滤饼层阻力,缓解了膜孔堵塞对膜污染的影响。然而,当投加量增大到5%时,生物铁污泥解体为碎小的颗粒,就削弱了生物铁污泥对溶解性有机物的吸附,从而,有机物去除率降低。此外,较高的有机物消耗,还会滋生大量的丝状菌,由于丝状菌能释放更多的胞外聚合物,从而加剧了膜的污染,降低了膜通量。
(5)研究投加氢氧化铁对跨膜压差(TMP)和膜通量的影响时发现:在投加混凝剂的当天,TMP升高,膜通量突然降低。其原因可能是此时形成的含有铁盐的活性污泥絮体为微絮物,比较碎小,在初期容易形成膜孔的吸附及堵塞阻力Rf。
Hospital waste water, which contains a great deal of bacteria, virus and other toxic and harmful components, should be treated and disinfected properly before discharge. Otherwise, it will do great harm to human health and environment. After several public health incidents breaking out, such as the SARS and H1N1,more and more attentions have been attracted on the treatment of hospital sewage. However, it becomes a trend to develop new methods to treat hospital sewage, with the disadvantages of traditional methods being found. Membrane bioreactor(MBR), because of it's small footprint, high automation, excellent water quality, high disinfection efficiency, become the research focus for wastewater treatment in recent years.
This experiment combined MBR with bioferric of conventional activated sludge, which adds hydrogen ferric oxide flocs to MBR to improve the performance of the sludge reduce membrane fouling and obtain better treatment results. This paper makes a research on the organic matter removal rate, sludge characteristic and the membrane fouling of the system. Besides, the mechanism is studied on the analysis of process operating conditions and parameters, sludge concentration, and microbiological characteristics. The following conclusions can be obtained:
(1) On the dosage of ferric hydroxide sludge concentration of 1.5%,the removal rate of organic is studied under different aeration time. Following conclusions can be obtained:the removal rate of COD、NH3-N and so on, becomes stabilized after the aeration time of 6h-7h. In the comprehensive consideration of economic costs, the aeration time of 6h-7h is chosen.
(2) Under certain conditions, the system of iron hydroxide-MBR showed good organic removal and long-term operation stability for the treatment of hospital wastewater. In continuous operation without sludge discharge condition, the COD degradation rate can reach 92.1%,the degradation rate of ammonia can reach 99.6%.The output water of this improved system can meet the "standards for medical water pollutants"(GB18466-2005).
(3)Bioferric-MBR process has improved the quality of effluent to some extent. In this experiments, the iron hydroxide dosage of 3% of MLSS concentration is considered to be the best, on which condition, biological iron-MBR average effluent COD, total P, NH3-N were higher than the ordinary MBR by 9.13%,18%, and 4.2%.In this system, because of the membrane of MBR, the removal efficiency of E. coli is more than 98%.
(4) For the biological iron-MBR process, the sludge with hydrogen ferric oxide dosage of 1.5%-3% sludge concentration have good structure, which reduces the membrane surface cake layer resistance and ease membrane pore blockage on the membrane fouling. However, when the dosage was increased to 5% sludge concentration, bio-sludge disintegrates to small particles, which reduce the adsorption ability of biological iron sludge. Thus, the organic matter removal rate is reduced. In addition, the high consumption of organic matter will encourage the growth of filamentous bacteria, which can release much more EPS, thus increasing membrane fouling and reducing membrane flux.
(5) On the research of the effect of hydrogen ferric oxide dosage on the TMP and membrane flux, conclusions can got as follows:the first day of adding coagulant, TMP increased and flux suddenly decreased. The reason may be that activated sludge containing ferric floc is too small and adsorbed to the membrane pore to make a blocking resistance Rf.
引文
[1]国家环保总局.医院污水处理技术指南[S].2003,12-10.
[2]马世豪,凌波.医院污水污物处理[M].北京:化学工业出版社.2000,12-13.
[3]国家环保总局.GB 18466-2005.医疗机构水污染物排放标准[S].2005,06-10.
[4]陈志莉,张统.医院污水处理技术及工程实例[M].北京:化学工业出版社.2003,6.
[5]苏君,王新平,赵建平.乌鲁木齐市医院污水处理水平现状分析[J].新疆环境保护.1999,21(1):60.
[6]谷康定,熊光练,詹明胜,等.武汉市医院污水处理现状调查分析[J].中国给水排水.2005,21(6):28-30.
[7]黄厚建.上海仁济医院污水处理工艺及参数的确定[J].中国医院建筑与装备.2006,7(1):40-42.
[8]黄其明.综合医院的污水处理[J],给水排水.2001,27(5):68-70.
[9]常丽春,王凯军.我国医院污水处理现状分析及发展趋势探讨[J].环境与园林.2004,6(3):108-110.
[10]俞守业,贾秀芹.医院污水处理工程设计及运行[J].工业用水与废水.2005,36(6):77-81.
[11]印辉,王宇.CASS工艺在医院污水处理中的应用[J].江苏环境科技.2003,16(2):24-27.
[12]王凯军,常丽春.我国医院污水处理设施建设的研究与探讨[J].中国给水排水.2005,21(3):22-24.
[13]蔡广,李建.医院污水处理技术方案选择及经济指数比较[J].工业水处理.2003,23(6):71-73.
[14]顾建雯.CASS法和ClO_2消毒法在医院污水处理中的应用[J].实用全科医学.2005,3(6):562-563.
[15]吴克宏,邓正栋,谢思桃.医院污水处理技术综述[J].工业用水与废水.2002,32(1):40-42.
[16]郭小梅.因地制宜选择适宜的消毒方法[J].福建环境.2000,17(5):20.
[17]刘勇,郭伟,柏乃玉.氯化消毒处理综合型医院污水的技术探讨[J].铁道安全卫生与环保.2000,27(4):22-24.
[18]韦奇发,周伯雄.采用次氯酸钠法处理医院废水的效果评价[J].机电安全.2001(10):25-26.
[19]鲁晓晴,张超英.漂白粉杀灭嗜肺军团菌及其影响因素的实验研究[J].中国公共卫生.2001,17(8):711-712.
[20]冯建社.利用二氧化氯复合消毒剂处理医院污水[J].中国环境监测.1998,14(6):54-55.
[21]程太平,章家海.医院污水消毒方案分析[J].安徽化工.2000,5:30.
[22]黄君礼,唐玉兰,王丽等.ClO2和Cl_2混合消毒剂对氯仿形成的影响[J].环境科学.2003,24(2):102-107.
[23]杨春伟.医院污水氯化消毒处理的相关因素及探讨[J].云南环境科学.1997,16(3):47.
[24]谷康定,熊光练,詹明胜等.武汉市医院污水处理现状调查分析[J].中国给水排水.2005,21(6):28-30.
[25]杨立群,高泽宣,肖铁等.医院污水处理前后致突变性的研究[J].中国现代医学杂志.2002,12(10):107-112.
[26]高泽宣,杨立群,章满等.医院污水处理前后卤代烃的分析研究[J].中国公共卫生.1996,12(10):458-463.
[27]查锦富.医院污水排放管理的实践与思考[J].江苏卫生事业管理.1998,9(3):148
[28]Stephenson T, Judd S,Jefferson B, Brindle K. Membrane bio-reactors for wastewater treatment [J].Alliance House (London):IWA Publishing,2000.
[29]曹占平,张宏伟,张景丽.污泥龄对膜生物反应器污泥特性及膜污染的影响[J].中国环境科学.2009,29(4):386-390.
[30]李琳(译).膜技术基本原理[M].北京:清华大学出版社,1999:270-273.
[31]Cheng T W, Y.H.M.,Gau C T. Resistance analyses for ultra filtration in tubular membrane module [J].Separation Science and Technology.1997,32(16):2623-2640.
[32]杨琦,黄霞,尚海涛,文湘华.分置式膜-生物反应器凝胶层膜污染模型研究[J].环境科学.2006,27(11):2345-2349.
[33]赵宝杰.一体式膜生物反应器膜污染控制的研究[D].太原理工大学硕士研究生学位论文,2007.
[34]H.Reihanian, C.R.R.a.A.5.M.Mechanisms of Polarization and Fouling of Ultra-filtration Membranes by Proteins [J].Journal of Membrane Science,1983.16:237-258
[35]Davis W.J,Le M.S,Heath C.R. Intensified activated sludge process with submerged membrane micro filtration [J].Water Science and Technology,1998,38(4-5):421-428.
[36]唐受印,戴友芝.水处理工程师手册[M].北京:化学工业出版社,2000,299-304.
[37]许振良.污水处理膜分离技术的研究进展(二)[J].净水技术.2000,19(4):3-6.
[38]芮延年,郭旭红,刘文杰.超声振动强化膜分离过程机理的研究[J].环境污染治理技术与设备.2002,3(6):43-46.
[39]邢传红,文湘华,钱易.管式膜-生物反应器处理城市污水的工艺设计[J].中国给水排水.1999,15(1):1-4.
[40]许宁,李志富,冯文华.膜生物反应器处理医院污水的应用研究[J].泰山医学院学报.2003,24(3):216-219.
[41]丁杭军,文湘华,黄霞等.一体式膜—生物反应器处理医院污水[J].中国给水排水.2001,17(9):1-5.
[42]杨静,王锦等.生物铁膜生物反应器(SMBR)处理生活污水的实验研究[J].江苏环境科技.2008,21(2):26-28.
[43]赵玉华,据冉,傅金祥,由昆.混凝法控制膜生物反应器污泥膨胀的实验[J].沈阳建筑大学学报.2005,21(6):19-21.
[44]邹海燕,奚旦立.生物铁法-SMBR性能的研究[J].环境科学.2005,26(6):65-70.
[45]陈英文,张利民,夏明芳,沈树宝.高效混凝-膜生物反应器工艺处理印染废水的研究[J].2004,1(2):24-27.
[46]张永宝,姜佩华,冀世锋,奚旦立.投加氢氧化铁对SMBR中膜污染的防治[J].环境污染与防治.2004,26(6):444-446.
[47]布多,张颖,顾平.氯化铁絮凝法减轻膜污染[J].城市环境与城市生态.2003, 16(6):46-48.
[48]孙天华,林少宁等.生物铁法处理高浓度难降解印染废水的研究[J].中国环境科学.1991,11(2):138-142.
[49]肖羽堂等.铁屑强化传统工艺处理难降解印染废水实践[J].给水排水.1998,24(4):37-39.
[50]邓南圣等.铁氧化物对染料溶液的光化学脱色研究[J].上海环境科学.1998,17(8):1-38.
[51]张亚静等.铁碳内电解法处理印染废水环境污染与防治[J].2000,22(5):33-36.
[52]Lee J. C..Potential and limitation so falumorzeolite additon to improve the performance of a submerged membrane bioreactor [J].Water Science and Technology, 2001,43(11):59-60.
[53]李春杰等.SMSBR中PAC对膜污染的防治作用[J].中国给水排水.2002,18(6):5-9.
[54]李旭东,何小娟,邱江平等.间歇曝气MBR处理低碳高氮磷城市生活污水研究[J].环境科学.2008,29(6):1533-1537.
[55]国家环保局《水和废水监测方法》编委会.水和废水监测分析方法(第四版)[M].北京:中国环境科学出版社,2002,211-212,279-281,694-696,704-706.
[56]马青山,贾瑟,孙丽氓.絮凝化学和絮凝剂[M].北京:中国环境科学出版社,1988.
[57]汤鸿霄,钱易,文湘华.水体颗粒物和难降解有机物的特性与控制技术原理:上卷水体颗粒物,第一版,北京:中国环境科学出版社,2000,25-28.
[58]王东升,刘海龙,晏明全等.强化混凝与优化混凝:必要性、目标和发展方向[J].中国化学会第七届水处理化学会暨学术研讨会,山东大学.2004.9.13-9.15.
[59]严煦世,范瑾初.给水工程[M].北京:中国建筑工业出版社,1999.
[60]桥本奖,须藤隆一.新活性污泥法[M].北京:学术书刊出版社,1990.
[61]姚重华,顾国伟.混凝剂和絮凝剂[M].北京:中国环境科学出版社,1995,6-9.
[62]郑兴灿,李亚新.污水除磷脱氮技术[M].中国建筑工业出版社,1998.
[63]熊小京,申茜等.A/O MBR处理印染废水中进水pH值对降解性能的影响[J].厦门大学学报(自然科学版),2005,44:93-97.
[64]由昆,傅金祥,琚冉.间歇曝气对膜生物反应器影响的实验研究[J].工业安全与环保,2006,32(7):16-18.
[65]GUI Ping, HUANG Xia,et al.Influence of the operation parameters on membrane filtration[J].Environmental Science,1999,20(3):38-41.
[66]Lim B.S.,Choi B.C.,Yu S.W.,Lee C. G. Effects of operational parameters on aeration on/off time in an intermittent aeration membrane bioreactor [J].Desalination,2007, (202):77-82.
[67]S.Yasutoshi. Filtration Characteristics of Hollow Fiber Micro filtration Membranes Used in Membrane Bioreactor for Domestic Wastewater Treatment. Wat.Res.1996, 30(100):2385-2392.
[68]Tardier E., Grasmick V.Fouling Mechanisms in Membrane Bioreactors Applied to Wastewater Treatment. Budapest:Presented paper for 7th World Filtration Congress.1996:20-23.
[69]邹联沛.膜生物反应器处理污水的性能及其应用研究[D].哈尔滨工业大学博士学位论文.2001:127-129.
[70]杨宗政,顾平.膜生物反应器运行中的膜污染及其控制[J].膜科学与技术.2005,25(2):81-84.
[71]Choo K.H.,K.S.H.,YoonS.H.Approaches to membrane fouling control in anaerobic membrane bioreactors [J].Water Science and Technology,2000.41(10-11):363-371.
[72]Nakao,S.Determination of pore size and pore size distribution:Filtration membranes [J].Journal of Membrane Science,1994.96(1-2):131-165.
[73]Shimizu,Y.,Okuno.Filtration Characteristics of Hollow Fiber Micro-filtration Membranes Used in Membrane Bioreactor for Domestic Wastewater Treatment [J].Water Research,1996.30(10):2385-2392.
[74]Shoji, H.,Karube. Biochemical Features of Pseudo-membrane at the Bone-Cement Interface of Loosened Total HIP Prostheses [J].Journal of Biomedical Materials Research, 1983.17(4):669-678.
[75]Noor,M.J.M.M.,Ahmadun,F.R.,Mohamed,T.A.,Muyibi,5.A.,Peseod,M.B. Performance of flexible membrane using kaolin dynamic membrane in treating domestic Wastewater[J].Desalination,2002.147(1-3):263-268.
[76]董秉直,夏丽华,范瑾初等.混凝处理防止膜污染的作用与机理[J].环境科学学报.2005.25(4):530-534.
[77]Forster C F. Factors involved in the settlement of activated sludge-nutrients and surface polymers [J].Wat Res.1985,19(10):1259-1264.