Study On Pretreatment Of Highly Concentrated Polyethylene Glycol Wastewater By Fenton/fenton-like

Polyethylene glycols(PEGs)are used as silicon cutting suspension in the photovoltaic industry,in which the wastewater emissions are considerable with high COD and poor biodegradability.In this paper,three kinds of advanced oxidation processes(Fenton,Fenton/C and Fenton/oxalic acid/UV)were used to pretreat the PEGs wastewater in order to improve the biodegradability.The ratio of Fe2+ with H2O2,pH,the dosage of H2O2,and reaction time were investigated in each process.The results showed that:(1)the optimal operation parameters in Fenton process were that pH,the ratio of Fe2+ with H2O2,the dosage of H2O2,and reaction time were 2.4,0.13,1mL/L and 8min,respectively.Under these conditions,the PEG400 and COD removal efficiency were 64.4%and 3.4%,respectively,the BOD5/COD increased from 0.19 to 0.36.(2)the optimal operation parameters in Fenton/C process were that pH,the ratio of Fe2+ with H2O2,the dosage of H2O2 and active carbon,and reaction time were 2.4,0.11,1mL/L,0.2mg/L and 4min,respectively.Under these conditions,the PEG400 and COD removal efficiency were 72.4%and 9.7%,respectively,the BOD5/COD increased to 0.46.(3)the optimal operation parameters in Fenton/oxalic acid/UV process were that pH,the ratio of Fe2+ with H2O2,the dosage of H2O2 and oxalic acid,and reaction time were 2.4,0.13,lmL/L,0.16mg/L and 4min,respectively.Under these conditions,the PEG400 and COD removal efficiency were 69%and 6.7%,respectively,the BOD5/COD increased to 0.43.Comparing three ways mentioned above,the processing of Fenton/C was adopted as pretreatment process,then treatment PEG400 wastewater using Fenton/C+ASBR process was investigated.The ASBR was operated at 40h HRT and 35±1? with MLSS of 12000mg/L.When the influent concentration of PEG400 and COD were about 2600 and 5100mg/L respectively,the effluent PEG400 and COD were 694 and 4550mg/L after Fenton/C process,and 0 andl225mg/L after ASBR.Thus the PEG400 and COD removal efficiency can reach 100%and 75.5%,respectively.The results suggested that Fenton/C+ASBR process can be an effective solution for the high concentration of PEGs wastewater.