| With the rapid development of social economy and the swift growth of urban population,city water consumption and sewage production is increasing year by year,and a lot of waste sludge has been produced,which was the inevitable by-products of waterworks and municipal wastewater treatment plants with the characteristics of bad smell,huge productivity,complex composition(eg.heavy metal,refractory organics,pathogenic microorganisms and nutrient substance)and so on.Waste sludge was perishable and stinky,contaminate soil,influence environmental health status,destroy urban landscape and easily cause water(surface water andgroundwater)sedimentation;furthermore,the heavy metal and deleterious organics could migrate and enrich by food chain,and then engender long-term potential hazards to the ecological environment and human health.The traditional disposal methods of sludge such as incineration,sanitary landfill,dump in ocean,land use polluted soil and water(eg.lake,river,sea and so on)easily.The more serious is that the unreasonable disposal of toxic and harmful substances would lead to the expansion of the scope of its toxicity and bring negative effects on the ecological environment and human survival.The organic matter and nutrients contained in the sludge were not effectively used,which is a waste of disguised resources.In recent years,sludge reduction and resource utilization has become a research hotspot,so a new type of sludge based catalytic micro electrolysis filler(CMEF)was prepared by sludge using high temperature pyrolysis.Based on the determining of optimum preparation conditions,tetracycline was used as the target pollutant to study the degradation performance of organic compounds in wastewater and discuss the removal mechanism in this study systematically.Through the study,the main conclusions of this paper were as follows:(1)Made CMEF with sludge,clay and reductive Fe powder,and optimize the preparation conditions and raw material ratios by orthogonal test.The optimum preparation conditions of CMEF is sintering temperature of 950°C,and weights of sludge,clay,and reductive Fe powder were 20,20,and 10 g,respectively.That was,mass ratios of three raw materials were 2:2:1.Sludge-based carbon filler(SCF)was prepared with the same preparation conditions.(2)The morphologies and chemical characteristics(e.g.,surface area,function groups,surface and internal morphology features,and valence state of Fe)of CMEF and SCF were determined by BET,FTIR,SEM,TEM,XRD and XPS.The results show that: CMEF and SCF contained abundant surface functional groups,which has the potential to adsorb and oxidize organic pollutants.Surface area of CMEF was just half of control fille by the addition of reductive Fe powder.CMEF surface was rough,loose void with particle aggregation.Fe in CMEF show the valence states of 0,2 and 3.(3)Treating 100mg/L tetracycline(TC)water solution with CMEF and SCF by equal mass,results show TC removal rate of the two fillers were 99.9% and 83% with 2.5 h and 3.0 h,respectively,when the reaction reached balance.The removal rate of TC was obvious higher of CMEF than SCF.Adsorption was the main reason of TC removal by SCF,while other facters influenced removal of TC by CMEF except adsorption and chemisorption.(4)The analysis of degradation products,the product of TC treated by CMEF and SCF,could be further confirmed that removal of TC by SCF mainy depend on adsorption,because of the big specific surface area and abundant surface functional groups.Nevertheless,adsorption,microelectrolysis,catalysis were worked tegether in the removalof TC by CMEF,beceuse of the Fe/C battery made of carbon which formed from sludge roasting and reductive Fe powder..To sum up,CMEF prepared by sludge and reductive Fe powder had high removal efficiency for tetracycline in wastewater.It could confirm that the preparation of high efficiency water treatment materials by sludge was feasible,which was also a new way of sludge in resource utilization. |
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