Removal Of Organic Pollutants In Reverse Osmosis Concentrate Using A Combination Technique Of Advanced Oxidation With Bioaugmentation

As a new sewage treatment technique,reverse osmosis(RO)technology is widely used in many areas of sewage disposal.In the RO process,70%~80% of the sewage is converted into clean water.And the remaining part of the sewage,which contains high salinity and bio-refractory organic pollutants,is the RO concentrate water.The concentration of polluant in ROC is 3 to 4 times as much as the raw water.Because of this,the ROC should be properly disposed before discharge.In this study,the AOP was combined with biological process for the treatment of refining reverse osmosis water.The wastewater samples were obtained from the RO concentrated drainage of Qilu petrochemical refinery petrochemical wastewater treatment plant located in Shandong.In the advanced oxidation unit,the single factor and response surface experiments were carried out and different impact factors associated with the COD removal were investigated.In the biological activated carbon(BAC)unit,the effects of influent modes,empty bed contact time and BAC height on COD and ammonia nitrogen removal were investigated.According to the effect of advanced oxidation combine with BAC process and the cost estimation,the feasibility of the combination process was discussed.The single factor experimental results showed that the optimal conditions of O3-Assisted UV-Fenton process were the initial p H of 3,H2O2 concentration of 680 mg/L,Fe2+ dosage of 400 mg/L,ultraviolet(UV)fluence of 540 mJ/cm2 and O3 consumption of 15 mg/L.Based on the results of single factor experiments,four factors(initial pH,H2O2 concentration,Fe2+ dosage and O3 dosage)were selected as the independent variables and optimized by the response surface approach.According to the response surface experiment results,the most significant interactive influence was observed between pH and O3 dosage.The maximum COD removal of 93.2% in the verifying test was obtained under the optimum conditions such as the pH of 2.5,H2O2 dosage of 824 mg/L,Fe2+ dosage of 300 mg/L,ozone dosage of 17 mg/L and UV fluence of 540 mJ/cm2.Model predicted values and the verification experiment value was close so the models had high fitting degree.The biodegradability of RO water increased after advanced oxidation process and can be treated by biotreatment.The biological activated carbon column was constructed,the film culture and salt-tolerant domestication of activated sludge was carried out.In the AOP combined with BAC experiment,the effect of influent modes,empty bed contact time(EBCT)and BAC height on COD and ammonia nitrogen removal were investigated.The COD and ammonia nitrogen removal achieved 87.5% and 84.2% respectively in upward flow,EBCT of 60 min,BAC height of 60 cm,and the e ffluent can meet the class one wastewater-discharging standard.Under the condition the wastewater treatment cost is about 2.657 yuan per ton.The treatment technology is feasible.