Research On Technologies For Refining Reverse Osmosis Concentrate Treatment

With the double-membrane process(microfiltration/ultrafiltration-reverse osmosis)is widely used in refining sewage depth treatment and reuse,it causes a remarkable increase in reverse osmosis concentrate production.There is so low biodegradability for refining reverse osmosis concentrate that hardly meet the national discharge standard,which has been a bottleneck treatment that restricts the reuse of refining sewage.We study the refining reverse osmosis concentrate which produced from a petrochemical company in North China.Technologies of catalytic oxidation,Fenton reagent oxidation and electro-Fenton oxidation are used for preliminary experimental research,in order to decrease the concentration of organic pollutants,improve water biodegradability and provide strengthen conditions for the subsequent biological treatment.Results provide basic research and data support for dealing with refining reverse osmosis concentrate.Experimental results show that:(1)Under optimal reaction conditions that include ozone dosing time of 20 min,manganese sand and catalyst zeolite dosage of 1 g/L and 0.75 g/L,initial pH for ozone oxidation,manganese sand as well as zeolite catalytic oxidation of 8.45,11 and 9 respectively,the CODCr decreases from 174 mg/L to 127 mg/L and its removal rate reaches 27.43% of catalytic oxidation.(2)Under optimal reaction conditions that include hydrogen peroxide/ferrous ion(molar ratio)of 2:1,hydrogen peroxide dosage of 340 mg/L,initial pH of 3 to 4 and treatment time of 2 h,the CODCr decreases from 171 mg/L to 114 mg/L,its removal rate reaches 33.76% as well as the proportion of non-biodegradable organic contaminants declines from 89.47% to 84.12% of Fenton reagent oxidation.(3)Under optimal reaction conditions that include electrode material of pure iron plate,electrode distance of 3 cm,applied current of 0.3 A,hydrogen peroxide dosage of 170 mg/L,initial pH of 4 and treatment time of 21 min,the CODCr decreases from 167 mg/L to 102 mg/L,its removal rate reaches 39.64% as well as the proportion of non-biodegradable organic contaminants declines from 88.76% to 80.10% of electro-Fenton oxidation.After having been treated by electro-Fenton oxidation,reverse osmosis concentrate effluent was treated by BAF.Results show that the CODCr decreases from about 100 mg/L to 75 mg/L.However,it still does not achieve the target that CODCr below 60 mg/L.(4)Under suitable reaction conditions,the CODCr of reverse osmosis concentrate A and B decrease from 85.6 mg/L and 73.4 mg/L to 56.2 mg/L and 51.5 mg/L,respectively.The CODCr removal rate reach 31.8% and 29.84% by electro-Fenton oxidation.Results indicate that after electro-Fenton oxidation,reverse osmosis concentrate A and B achieve the target that CODCr below 60 mg/L.