Health risk assessment of professional operating personnel in methanol wastewater reinjection stratigraphic process

Based on the high concentration of methanol wastewater in the process of natural gas exploitation in Shan Bei gas field, considering the blank of no methanol concentration controlling in our industrial wastewater reinjection stratigraphic standard, is conducted investigation on the concentration of methanol wastewater reinjection stratigraphic in Shan Bei gas field. According to the sampling analysis of the locale methanol wastewater, the methanol concentration in the air of reinjection operating room is determined by GC-MS method as 420mg/m³, the methanol concentration of wastewater is 51670 mg/L. Using the risk assessment principle, adopting the probability statistical method and Monte-Carlo stimulation method, health risk assessment is conducted for operators, aiming at the process of methanol wastewater reinjection formation of this concentration, then the result shows that the methanol wastewater of this concentration will cause unacceptable health risk for operating personnel, the life time health risk is 1.93E-04, the average annual health risk is 2.75E-06. Considering methanol dose on both exposure and reference basis for humans, combining the corresponding risk representation models, and the permissible discharging concentration of methanol wastewater which dose not cause health risk for operating personnel during reinjection stratigraphic process is proposed, this concentration can be determined as the limit value for methanol wastewater reinjection stratigraphic to provide a reference for methanol wastewater discharge standards domestically as well.