Investigation on the treatment of organic pollutants in gas field water by advanced oxidation

Because of the large yield and complex water quality of gas field water, if it is directly discharging into the water body, it will cause serious damage to the environment and human health. Combining with the water quality characteristics of gas field water, the advanced oxidation treatment of gas field wastewater was carried out by using seperate O₃ oxidation technology and UV/H₂O₂ oxidation technology respectively. The effect of the influencing factors on the treatment of gas field wastewater under various oxidation conditions was investigated, and the characteristics of organic substances in the water after ozonation were also studied. Finally, the technology of O₃ + UV/H₂O₂ oxidation was put forward. The results showed that the organic species in gas field wastewater were complex and contain various kinds of non-degradable nitrogen-containing and sulfur-containing heterocyclic organic compounds. When ozone dosage was 7.5 g/h, pH=11, and oxidation time was 90 min, the mineralization degree of organic matter in gas field water was the highest of 20%. The characterization of organic matter after ozone showed that most of the substances were oxidized to be easily degraded ones, such as acids, alcohols, esters, etc.; the dosage of H₂O₂ in the process of UV/H₂O₂ oxidation was 6 720 mg/L, pH=3, reaction time was 90 min, reducing TOC from 87.27 mg/L to less than 10 mg/L; finally, when the two oxidation processes were combined, under 60 min reaction time at a pH of 3 with 4 880 mg/L H₂O₂ dosage, TOC can be reduced from 87.27 mg/L to less than 20 mg/L. If the time increased appropriately to 90 min, it can be reduced to 10 mg/L. Compared with the two processes, the dosage of hydrogen peroxide was reduced and the reaction time was shortened.