2450MHz电磁波污泥脱水过程中的温度效应
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摘要
采用2450MHz电磁波进行污泥脱水,研究电磁波加载过程中污泥温度变化对于剩余污泥性质和溶出效应的影响.研究发现,经电磁波加载后,污泥的容积指数(SVI)随着温度的升高而降低,在温度为80℃时由原泥的130.73mL/g降至最低值95.25mL/g,污泥沉降性能得到改善;经电磁波加载后,污泥离心含水率也随着温度的升高持续降低,最低降到80℃时的93.52%;污泥的毛细吸水时间(CST)在60℃时由原泥的29.4s降至最低值23.2s,污泥比阻(SRF)始终高于初始值,说明电磁波的加载一定程度上可以改善剩余污泥的离心脱水和板框压滤脱水效果,但不利于剩余污泥的真空抽滤.在电磁波加载过程中,检测污泥胞外聚合物(EPS)及上清液中可溶性化学需氧量(SCOD)的含量,发现污泥温度升高有利于污泥胞内物质的溶出.在80℃时,污泥上清液中SCOD含量由初始的124.1mg/L增大到883.4mg/L;同时也发现,温度高于60℃后,污泥中微生物细胞破壁更明显,污泥EPS含量随之发生变化,对污泥脱水性能的影响更加显著.
In this paper,the influence of temperature on residual sludge properties and solubility was studied during the process of sludge dewatering with 2450 MHz electromagnetic wave.Results showed that sludge volume index(SVI) decreased from 130.73 mL/g to 95.25 mL/g at 80℃,which improved the sludge settlement performance.At the same time,the centrifugal water content of the sludge achieved the lowest of 93.52% at 80℃ and the capillary suction time(CST) of the sludge decreased to 23.2 s at 60℃.The value of the specific resistance to filtration(SRF),however,was always higher than the initial value of the raw sludge.Therefore,electromagnetic wave treatment of sludge could improve the dewaterability of centrifugal and plate frame filter press of residual sludge,while deteriorated the dewaterability of vacuum filtration.According to the analysis of the extracellular polymeric substances(EPS) and the soluble chemical oxygen demand(SCOD) in the supernatant,higher temperature was beneficial for the solubilization of sludge.The SCOD raised from the initial value of 124.1 mg/L to 883.4 mg/L at 80℃.The disruption of microbial cell in sludge was more obvious,when the sludge temperature was higher than 60℃.The EPS in the sludge was closely related to the change of dewaterability of the sludge.
In this paper,the influence of temperature on residual sludge properties and solubility was studied during the process of sludge dewatering with 2450 MHz electromagnetic wave.Results showed that sludge volume index(SVI) decreased from 130.73 mL/g to 95.25 mL/g at 80℃,which improved the sludge settlement performance.At the same time,the centrifugal water content of the sludge achieved the lowest of 93.52% at 80℃ and the capillary suction time(CST) of the sludge decreased to 23.2 s at 60℃.The value of the specific resistance to filtration(SRF),however,was always higher than the initial value of the raw sludge.Therefore,electromagnetic wave treatment of sludge could improve the dewaterability of centrifugal and plate frame filter press of residual sludge,while deteriorated the dewaterability of vacuum filtration.According to the analysis of the extracellular polymeric substances(EPS) and the soluble chemical oxygen demand(SCOD) in the supernatant,higher temperature was beneficial for the solubilization of sludge.The SCOD raised from the initial value of 124.1 mg/L to 883.4 mg/L at 80℃.The disruption of microbial cell in sludge was more obvious,when the sludge temperature was higher than 60℃.The EPS in the sludge was closely related to the change of dewaterability of the sludge.
引文
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[22]Wang Y W,Wei Y S,Liu J X.Effect of H2O2 dosing strategy on sludge pretreatment by microwave-H2O2 advanced oxidation process[J].Journal of Hazardous Materials,2009,169(1-3):680-684.
[23]Mickael R,Jean V,Jeremy O,et al.Compression dewatering of municipal activated sludge:Effects of salt and pH[J].Water Research,2012,46(14):4448-4456.
[24]Christopher F F.The rheological and physico-chemical characteristics of sewage sludges[J].Enzyme and Microbial Technology,2002,30(3):340-345.
[2]Chen Z,Zhang W J,Wang D S,et al.Enhancement of activated sludge dewatering performance by combined composite enzymatic lysis and chemical re-flocculation with inorganic coagulants:Kinetics of enzymatic reaction and re-flocculation morphology[J].Water Research,2015,83:367-376.
[3]Yu J,Guo M H,Xu X H,et al.The role of temperature and CaCl2 in activated sludge dewatering under hydrothermal treatment[J].Water Research,2014,50:10-17.
[4]董立文,汪诚文,张鹤清,等.电导率对城镇污泥电渗透脱水效果的影响[J].中国环境科学,2013,33(2):209-214.
[5]Li H,Jin Y Y,Rasool B M,et al.Effects of ultrasonic disintegration on sludge microbial activity and dewaterability[J].Journal of Hazardous Materials,2009,161(2/3):1421-1426.
[6]张浩,杨艳玲,李星,等.超声声能密度对净水厂污泥脱水性能的影响[J].中国环境科学,2017,37(3):1009:1015.
[7]Yu Q,Lei H Y,Li Z,et al.Physical and chemical properties of wasteactivated sludge after microwave treatment[J].Water Research,2010,44(9):2841-2849.
[8]Wang N N,Wang P.Study and application status of microwave in organic wastewater treatment-A review[J].Chemical Engineering Journal,2016,283:193-214.
[9]Li L,Yuan S H,Chen J,et al.Removal of ammonia nitrogen in wastewater by microwave radiation[J].Journal of Hazardous Materials,2009,161(2/3):1063-1068.
[10]乔俊莲,郑广宏,徐文倩,等.微波协同活性炭法处理甲基橙废水的研究[J].水处理技术,2008,34(9):23-25.
[11]Yu Q,Lei H Y,Yu G W,et al.Influence of microwave irradition on sludge dewaterability[J].Chemical Engineering Journal,2009,155(1/2):88-93.
[12]田禹,方琳,黄君礼.微波辐射预处理对污泥结构及脱水性能的影响[J].中国环境科学,2006,26(4):459-463.
[13]Liu J B,Wei Y S,Li K,et al.Microwave-acid pretreatment:Apotential process for enhancing sludge dewaterability[J].Water Research,2016,90:225-234.
[14]龚雅君.电磁波预处理对剩余污泥絮凝脱水效果的影响研究[D].武汉:武汉理工大学,2015.
[15]国家环保总局.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,2002:105-106.
[16]高磊,张诗文,叶蓉,等.生物裂解效应对污泥脱水减量的作用研究[J].中国环境科学,2016,36(12):3717-3723.
[17]于洁.热水解联合氯化钙改善污泥脱水性能[D].杭州:浙江大学,2013.
[18]刘欢,杨家宽,时亚非,等.不同调理方案下污泥脱水性能评价指标的相关性研究[J].环境科学,2011,32(11):3394-3399.
[19]牛中奇,侯建强,王海彬,等.电磁波的生物学窗效应[J].中国生物医学工程学报,2003,22(2):126-132.
[20]Claire B,Jean P D,Helene C.Effects of thermal treatments on five different waste activated sludge samples solubilisation,physical properties and anaerobic digestion[J].Chemical Engineering Journal,2008,139(2):236-244.
[21]Wang L P,Li A M.Hydrothermal treatment coupled with mechanical expression at increased temperature for excess sludge dewatering:The dewatering performance and characteristics of products[J].Water Research,2015,68:291-303.
[22]Wang Y W,Wei Y S,Liu J X.Effect of H2O2 dosing strategy on sludge pretreatment by microwave-H2O2 advanced oxidation process[J].Journal of Hazardous Materials,2009,169(1-3):680-684.
[23]Mickael R,Jean V,Jeremy O,et al.Compression dewatering of municipal activated sludge:Effects of salt and pH[J].Water Research,2012,46(14):4448-4456.
[24]Christopher F F.The rheological and physico-chemical characteristics of sewage sludges[J].Enzyme and Microbial Technology,2002,30(3):340-345.