Heavy Oil Sewage Ecology In The Karamay Desert Area Utilize Evaluation Studies

Sewage outside the enterprise must be discharged to the environmental acceptance water body,the special environment in the desert oil field lacks the accepted surface water body,and there is no relevant standard for the comprehensive utilization of sewage in the petroleum and petrochemical industry.Therefore,based on the unique hydrogeological characteristics of desert soils and arid areas,the feasibility of ecological utilization of treated heavy oil sewage in the heavy oil area of Karamay was evaluated and studied.The main findings are as follows:(1)In this paper,the survey of artificial wetlands in the outflow plots of heavy oil sewage in Xinjiang Oilfield was carried out,and the pollutants in external drainage,soil and sediment were screened to confirm that salts and petroleum hydrocarbons were the main pollutants.The effects of external drainage on soil catalase activity and plant diversity in the area were studied,and the results showed that heavy oil sewage could enhance the activity of hydrogen peroxidase in the soil around the wetland,and there was no obvious impact on the diversity of plant species around the artificial wetland,but the plant growth status in the wetland was significantly different,which provided a basis for the ecological utilization of heavy oil sewage.(2)The effects of the main pollutants of heavy oil sewage on the activities of soil,medium-salt-tolerant plants and soil catalase were studied through potting test and germination test.Studies have found that oil concentrations below 30 mg/L do not affect the growth of alfalfa.When the total salt amount is above 3000 mg/L,the germination of seeds is significantly inhibited,and when the total salt amount is above7000 mg/L,watering has obvious inhibitory effect on the leaf area,plant height and chlorophyll content of Alfalfa.The higher the total salinity in the irrigation water,the more salt accumulates in the soil and the lower the peroxidase activity in the soil.The petroleum in the irrigation water mainly accumulates in the soil layer of 10 cm,and the higher the concentration of petroleum in the irrigation water,the more the accumulation in the soil layer of 10 cm,when the petroleum hydrocarbon content in the soil reaches a certain value,the soil catalase activity will be inhibited.(3)By HYDRUS-1D,the migration and accumulation of pollutants under long-term irrigation in desert soil was predicted,and the software predicted that the total salt content of 7105 mg/L heavy oil sewage under long-term irrigation was 6-14g/kg,and the salt accumulation was cyclical;the total salt content was 5000 mg/L irrigation,and the salt accumulation was 5-10g/kg.The petroleum hydrocarbon content in the soil is directly proportional to the irrigation time,the petroleum concentration is 30 mg/L irrigation,and the soil petroleum hydrocarbon content of 10-100 cm in the 28 th year is400-830 mg/kg.(4)Formulate a plan for the ecological utilization of sewage.Medium-salt-tolerant plants such as alfalfa are transplanted in desert areas.The ecological utilization standard of petroleum concentration in water can be relaxed to 30 mg/L.When the total salinity of sewage is controlled below 5000 mg/L,in addition to planting high-salt-tolerant plants,moderately salt-tolerant plants such as alfalfa can improve the soil environment and improve ecological quality.When the total salt content of sewage is controlled at about 7000 mg/L,it is necessary to plant more salt-tolerant plants such as reeds and sophora.When modifying the structure of plant communities,the proportion of shrubs(trees)with strong wind and sand fixation ability should be increased.