| Petrochemical wastewater contains complex components and is difficult to degrade making it becomes the hotspot in the field of industrial wastewater treatment.These compounds like polycyclic aromatic hydrocarbons are hard treated so that conventional methods such as biological processes which could remove most biodegradable organic pollutants can only degrade little of them.In these cases,there is a need to combine biological processes with other pre-treatment technologies or advanced treatment technologies to achieve a further degradation of pollutants.As an important branch of advanced oxidation technology,Light-driven advanced oxidation process has been widely used because of its wide adaptability,mild reaction conditions and harmlessness without secondary pollution.Under the action of ultraviolet light,strong oxidant could produce photochemical reaction and accelerate the formation of hydroxyl radical to eliminate the pollutants unselectively and finally change the pollutants to low-toxic or nontoxic micro molecular compounds.The effect of typical light-driven AOPs technology UV/H2O2 process on petrochemical wastewater treatment was investigated by analyzing the initial pH,H2O2 dosage and UV intensity.The results showed that significant order of three factors were UV light intensity>H2O2 dosage>pH value.The optimum condition for degrading COD were obtained as followed:pH value of 6,H2O2 dosage of 6g/L and UV light intensity of 6mW/cm2.After reaction under the optimum condition,the COD removal（%）,DOC removal（%）,BOD removal（%）and UV254 removal（%）were 83.1%,85.4%,82.2%,90.5%,respectively.Meanwhile,the SUVA value changed from 3.719 to 2.400 and the biodegradability value changed from 0.524 to 0.467 which showed that pollutants with conjugated bond like polycyclic aromatic hydrocarbons could be treated effectively.Comparative study of UV,H2O2,UV/H2O2,UV/Fenton in treating petrochemical wastewater were investigated under the condition of initial p H of 4,H2O2 dosage of 6g/L and UV light intensity of 6mW/cm2.Methods sorted by COD removal was UV/Fenton>UV/H2O2>UV>H2O2UV/Fenton was the combination of Fe and UV/H2O2 and was used as the advanced treatment for petrochemical reverse osmosis concentrate.The study showed that the DOC removal of the group using Fe2+was higher than the group which using Fe3+under the same dosage.Analyzing the orthogonal experiment with DOC removal as an index,the significant order of four factors were Fe2+dosage>UV light intensity>H2O2 dosage>pH value.Under the condition of pH value of 4,H2O2 dosage of 20mmol/L,Fe2+dosage of 0.3mmol/L and UV light intensity of 6mW/cm2 the highest COD,DOC removal were 51.5%and 43.7%,respectively,reaching the second class of National Wastewater Discharge Standard（GB8978-1996）.At the same time the biodegradability value was marked increased from0.038 to 0.285.3D-EEM results showed that refractory organics were mainly composed by aromatic organics like tryptophan and soluble microbial by-products.The fluorescence intensity of 5 regions was decreased by 56.3%,67.5%,76.1%,68.3%,79.7%,respectively after treatment,achieving the purpose of converting the organic pollutants into nontoxic micro molecular. |
