摘要
剩余污泥含水率高,体积庞大,需对其进行脱水处理以减小污泥体积,方便后续运输和处理处置。本论文研究了Fenton试剂调理城市污水处理厂剩余污泥,通过测定污泥毛细吸水时间(CST)、污泥比阻(SRF)和泥饼含水率来表征污泥脱水性能的变化,分别考察了污泥初始pH、H2O2投加量、H2O2/Fe2+、反应温度和反应时间对污泥调理效果的影响。综合考虑,确定Fenton调理污泥的最佳条件为：pH=3、抽滤脱水和离心脱水H2O2最佳投加量分别为3g/L和9g/L、H2O2/Fe2+(质量比)最佳范围为8～12、反应温度50℃、反应时间60min。对污泥离心上清液中胞外聚合物(EPS)含量的研究表明,Fenton调理后污泥上清液中蛋白质和多糖含量有大幅升高,说明Fenton试剂能有效氧化破解EPS,从而提高污泥的絮凝性,改善污泥的脱水性能。Fenton氧化后污泥颗粒粒径变小,比表面积增大。
研究了剩余污泥在中温厌氧消化条件下污泥脱水性能的变化及其作用机理。剩余污泥厌氧消化过程中,消化污泥比阻(SRF)相比于剩余污泥有一定的减小,消化污泥的过滤速度有一定的改善,但改善不明显。PAM、FeCl3和PAC三种絮凝剂调理实验显示,消化污泥的最佳投药量相对于剩余污泥均有所增加,说明消化污泥脱水性能变差。分析了2种污泥中胞外聚合物(EPS)含量及污泥颗粒特性的变化,表明消化过程导致EPS的降解并向液体中释放。随着EPS含量的减少,由EPS架桥形成的较大絮体解体成为较小的污泥颗粒,污泥中小颗粒的比例增加,污泥的脱水性能变差。
开展了板框压滤机污泥深度脱水试验,结果显示,Fenton试剂+铁盐调理和铁盐/石灰调理污泥脱水效果较好,压滤脱水后泥饼含水率低于60%。Fenton试剂+铁盐调理与铁盐/石灰调理相比,Fenton试剂+铁盐调理虽然进泥时间偏长,但是污泥稳定效果更好；加入的无机质较少,最终泥饼干固体量少；泥饼热值较高,泥饼pH值偏中性,有利于泥饼的资源化利用。
Sludge with high moisture content needed to be dewatered to reduce the sludge volume for facilitating transportation and subsequent disposal. The parameters for the condition of excess sludge by Fenton reagent were investigated, and the capillary suction time (CST), the specific resistance to filtration (SRF) and the water content of sludge cake were measured to examine sludge dewatering performance. The effects of initial pH of sludge, H2O2 dosage, H2O2/Fe2+ ratio, reaction time and temperature on sludge conditioning were investigated. The optimal condition parameters for sludge conditioning were determined as follows:pH=3, H2O2 dosages of filtration and centrifugal dehydration were 3g/L and 9g/L respectively, H2O2/Fe2+ ratio (mass ratio)=8-12, temperature T=50℃, and reaction time was 60min. The protein and polysaccharide contents in extracellular polymeric substances (EPS) increased after the excess sludge was conditioned by Fenton reagent, which demonstrated that Fenton oxidation could effectively break EPS structure and improve the flocculation and dewatering performance of sludge. After Fenton oxidation, sludge particle size became smaller and the surface area increased.
The change of dewatering performance of digested sludge was studied as well here. The result showed that SRF value of digested sludge was a little smaller than that of raw excess sludge, the filtration rate of digested sludge increased a little. PAM, FeCl3, and PAC were used in the sludge conditioning experiment, which revealed that the optimal dosages of digested sludge all increased compared to excess sludge and dewatering performance of digested sludge became worse. Through analyzing extracellular polymeric substances (EPS) content and the characteristics of sludge particle, it was found that digestion process led to the degradation of EPS and releasing into liquid. With the decreasing of EPS content in sludge, the larger floc formed by the bridging of EPS was disintegrated into smaller particles. The proportion of smaller particles in sludge increased and dewatering performance of digested sludge became worse.
Pilot scale experiment of sludge deeply dewatering with frame filter press had carried out, the result showed that the combination of Fenton reagent and ferric salt and the combination of ferric salt and lime had a good conditioning performance, the water content of sludge cake was below 60%. Compared with ferric and lime, the combination with Fenton reagent and ferric salt showed higher performance on sludge conditioning, such as more stability of sludge, less amount of sludge, higher caloric value and closer to neutral pH value of sludge cake even though it cost more time for sludge to get to the filter press.
引文
[1]李欣.阳离子调理剂与阳离子聚电解质联合作用于活性污泥脱水及机理研究[D].上海：上海交通大学,2009：1-5.
[2]李金红,何群彪.欧洲污泥处理处置概况[J].中国给水排水.2005,21(1)：101-103.
[3]徐强.污泥处理处置技术及装置[M].北京：化学工业出版社,2003.
[4]杨彦虎.浅析我国城镇污泥处理与处置方略[C].2010年中国城镇污泥处理处置技术与应用高级研讨会论文集.北京：高教出版社,2010,39-42.
[5]李笃中,何晶晶.污泥性质、胶羽结构与处置[J].科技导报.2004,(9)：26-28.
[6]彭晓峰,陶涛,陈剑波,等.国际污泥研究现状初探[J].自然杂志.2002,24(4)：191-194.
[7]唐小辉,赵力.污泥处置国内外进展[J].环境科学与管理.2005,30(3)：68-70.
[8]李金红,何群彪.欧洲污泥处理处置概况[J].中国给水排水.2005,21(1)：101-103.
[9]Midilli A, Dogru M, Akay G, et al. Hydrogen production from sewage sludge via a fixed bed gasifer product gas[J]. International Journal of Hydrogen Energy.2002, 27(10):1035-1041.
[10]罗刚,徐荣险.污泥处理处置技术的研究进展[J].广东化工.2007,12(34)：82-85.
[11]伊军,谭学军.污水污泥处理处置与资源化利用[M].北京：化学工业出版社,2004.
[12]尹军.城市污水的资源再生及热能回收利用[M].北京：化学工业出版社,2003.
[13]Chu, C. P., Lee, D. J., Peng, X. F., etc.The freeze of sludge[J]. Journal of the Chinese Institute of Chemical Engineers.2002,33(6):591-598.
[14]Allievi L, Colombi A, Calcaterra E, etc. Inactivation of fecal bacteria in sewage sludge by alkaline treatment. Bioresource Technology.1994,49(1):25-30.
[15]王治军,王伟,李芬芳.污泥热水解技术的发展及应用[J].中国给水排水.2003,19(10)：25-27.
[16]余林锋,汤兵,余国俊.超声波调理污泥的研究进展[J].化工环保.2007,27(5)：426-429.
[17]申迎华,王斌,王志忠.有机高分子絮凝剂在污泥脱水中的应用[J].高分子材料科学与工程.2004,20(5)：55-58.
[18]K. R. Tsang, P. A. Vesilind. Moisture distribution in sludge[J]. Water Science & Technology.1990,22(12):135-142.
[19]P. A. Vesilind. The role of water in sludge dewatering[J]. Water Environment Research.1994,66(1):135-142.
[20]Mikkelsen L H, Keiding K. Effects of solids concentration on activated sludge deflocculation, conditioning and dewatering[J]. Water Science and Technology. 2001,44(2-3):417-425.
[21]Karr P. R., Keinath T. M. Influence of particle size on sludge dewaterability[J]. Water Pollution Control Federation.1978,50(8):1911-1930.
[22]鹿雯.胞外聚合物EPS对污泥理化性质影响研究[J].环境科学与管理.2007,32(5)：27-30.
[23]Joseph L. Pavoni, Mark W. Tenney, Wayne F. Echelberger, Jr. Bacterial extracellular polymers and biological flocculation[J]. Water Pollution Control Federation.1972,44(3):414-424.
[24]王红武,李晓岩,赵庆祥.活性污泥的表面特性与其沉降脱水性能的关系[J].清华大学学报(自然科学版).2004,44(6)：766-769.
[25]Matthew J. Higgins, John T. Novak. Dewatering and settling of activated sludge: the case for using cation analysis[J]. Water Environment Research.1997,69(2): 225-232.
[26]陈银广,杨海真,吴桂标,顾国维.表面活性剂改进活性污泥脱水性能及其作用机理[J].环境科学.2000,21(5)：97-100.
[27]G.R Chang, J.C Liu, D.J Lee. Co-conditioning and dewatering of chemical sludge and waste activated sludge[J]. Water Research.2001,35(3):786-794.
[28]Choi Y G, Chung T H. Effects of humus soil on the setting and dewatering characteristics of activated sludge[J]. Water Science Technology.2000,42(9): 127-134.
[29]Neyens E, Baeyens J, Dewil R, et al. Advanced sludge treatment affects extracellular polymeric substances to improve activated sludge dewatering[J]. Journal of Hazardous Materials.2004,106(2～3):83-92.
[30]高智荣,宋玉容.污泥脱水机械的选择讨论[J].工业安全与环保.2002,28(6)：18-19.
[31]侯春香.污泥脱水设备选型[J].市政技术.2001,(3)：58-60.
[32]H. J. H. Fenton. Oxidation of tartaric acid in the presence of iron[J]. J. Chem. Soc., Trans.,1894, (65):899-910.
[33]D. F. Bishop, G. Stern, M. Fleischman, et al. Hydrogen peroxide catalytic oxidation of refractory organics in municipal wastewaters[J].I&EC Process Design and Development.1968,7(1):110-117.
[34]G. N. R. Tripathi. Electron-transfer component in hydroxyl radical reaction observed by time resolved resonance Raman spectroscopy[J].J.Am.Chem.Soc.1998, 120(17):4161-4166.
[35]雷乐成,何锋.均相Fenton氧化降解苯酚废水的反应机理探讨[J].化工学报.2003,54(11)：1592-1597.
[36]Cheves Walling, Andre Goosen. Mechanism of the Ferric Ion Catalyzed Decomposition of Hydrogen Peroxide. Effect of Organic Substrates[J]. J. Am. Chem. Soc.,1973,95(9):2987-2991.
[37]Namgoo Kang, Dong Soo Lee, Jeyong Yoon. Kinetic modeling of Fenton oxidation of phenol and monochlorophenols[J]. Chemosphere.2002,47(9):915-924.
[38]陈传好,谢波.Fenton试剂处理废水中各影响因子的作用机制[J].环境科学.2000,21(3)：93-96.
[39]Wink D A, Nis R W, Desrosiers M F, et al. A kinetic investigation of intermediates formed during the Fenton reagent mediated degradation of N-nitrosodimethylamine:evidence for all oxidative Pathway not involving hydroxyl radical[J]. Chem. Res. Toxicol,1991,4(5):51-12.
[40]M. L, Kremer. Complex visas'Free Radical'mechanism for the catalytic decomposition of H2O2 by Fe3+[J], Int. J. Chem. Kinet,1985,17(8):1299-1314。
[41]钟恒文,二宫加奈.生污泥的Fenton氧化处理.中国给水排水.2003,19(8)：46-47.
[42]Nurdan Buyukkamaci. Biological sludge conditioning by Fenton's reagent[J]. Process Biochemistry.2004,39(11):1503-1506.
[43]Lu M C, Lin C J, Liao C H, et al. Dewatering of activated sludge by Fenton's reagent[J]. Advances in Environment Research.2003,7(3):667-670.
[44]Tokumura M, Sekine M, Yoshinari M, et al. Photo-Fenton process for excess sludge disintegration. Process Biochemistry.2007,42(4):627-633.
[45]陈英文,刘明庆,惠祖刚,等.Fenton氧化破解剩余污泥的试验研究[J].环境工程学报.2011,5(2)：409-413.
[46]Novak J T, Park C. Chemical conditioning of sludge[J]. Water Science technology.2004,49(10):73-80.
[47]张自杰等.排水工程[M].北京：中国建筑工业出版社,2000.
[48]Hudson J A, Lowe P. Current technologies for sludge treatment and disposal [J]. Water and Environment Journal,1996,10(6):436-441.
[49]Bruss J H, Christensen J R, Rasmussen H. Anaerobic storage of activated sludge:effects on conditioning and dewatering performance [J]. Water Science and Technology.1993,28(1):109-116.
[50]Lawler D F, Chung Y J, Hwang S J, et al. Anaerobic digestion:effect on particle size and dewaterability[J]. Water Pollution Control Federation.1986,58(12): 1107-1117.
[51]Novak J T, Sadler M E, Murthy S N. Mechanisms of floc destruction during anaerobic and aerobic digestion and the effect on conditioning and dewatering of biosolids[J]. Water Research.2003,37(13):3136-3144.
[52]Miron Y, Zeeman G, Jules B, et al. The role of sludge retention time in the hydrolysis and acidification of lipids, carbohydrates and proteins during digestion of primary sludge in CSTR systems [J]. Water Research.2000,34(5):1705-1713.
[53]CJ/T221-2005.城市污水处理厂污泥检测方法[S].北京：中国标准出版社,2005.
[54]鹿雯,张登峰,胡开林,等.阳离子表面活性剂对污泥脱水性能的影响和作用机理[J].环境化学.2008,27(4)：444-448.
[55]谢敏,施周,李淑展.污泥脱水性能参数—比阻检测的若干问题研讨[J].环境科学与技术.2006,29(3)：15-16.
[56]GB11914-2002.水和废水监测分析方法[S].北京：中国环境科学出版社,2002.
[57]夏晨娇.剩余活性污泥脱水的高级处理方法研究[D].南京：南京理工大学,2009：21-22.
[58]李娟.Fenton氧化破解城市污泥及生物淋滤处理河道底泥[D].长沙：湖南大学,2008：28-29.
[59]何文远,杨海真,顾国维.酸处理对活性污泥脱水性能的影响及其作用机理[J].环境污染与防治.2006,28(9)：680-683.
[60]陈传好,谢波,任源,等.Fenton试剂处理废水中各影响因子的作用机制[J].环境科学.2000,21(3)：93-96.
[61]李欣.阳离子调理剂与阳离子聚电解质联合作用于活性污泥脱水及其作用机理[D].上海：上海交通大学,2009：38-40.
[62]高军林,台明青,陈杰瑢.剩余污泥与酒精糟液共厌氧消化性能研究[J].酿酒科技.2008,3(165)：123-126.
[63]Mikkelsen L H, Keiding K. Physico-chemical characteristics of full scale sewage sludges with implications to dewatering[J]. Water Research.2002,36(10): 2451-2462.
[64]鹿雯.胞外聚合物EPS对污泥理化性质影响研究[J].环境科学与管理.2007,32(5)：27-30.