Physicochemical and biochemical combined treatment method of fracturing backflow liquid

Abstract

The invention provides a physicochemical and biochemical combined treatment method of fracturing backflow liquid. The physicochemical and biochemical combined treatment method comprises the following steps of: (1) introducing the fracturing backflow liquid into a regulating sedimentation tank, and controlling the pH value of the fracturing backflow liquid to 6-8, wherein the hydraulic retention time of the fracturing backflow liquid is 2-4 hours in the regulating sedimentation tank; (2) introducing a supernatant from the regulating sedimentation tank into a coagulation sedimentation tank, adding a polyaluminium chloride water solution and a polyacrylamide water solution to the coagulation sedimentation tank, depositing to remove suspended particles out of waste water inside the coagulation sedimentation tank, introducing the supernatant from the coagulation sedimentation tank into an intermediate tank, and regulating the CODconcentration of the waste water inside the intermediate tank to 800-1200mg / L; (3) treating the waste water from the intermediate tank into an aerobic fluidized bed membrane bioreactor in which biological membrane culture is completed, wherein the aerobic fluidized bed membrane bioreactor operates in a way of a continuous water feeding and continuous drainage under the condition of aeration, and the treated waste water is discharged after passing through the membrane assembly of the aerobic fluidized bed membrane bioreactor.

Description

technical field [0001] The invention belongs to the field of oil and gas field wastewater treatment, and particularly relates to a method for treating fracturing flowback fluid. Background technique [0002] Shale gas reservoirs have physical characteristics such as low porosity and low permeability, and the resistance to gas flow is greater than that of conventional natural gas. Therefore, fracturing treatment is required for the exploitation of shale gas. At present, the commonly used shale gas fracturing technologies include multi-stage fracturing, simultaneous fracturing and clear water fracturing. 3 / Well, the flowback ratio is about 40-60%, the flowback process is long, and the amount of flowback fluid is large. The commonly used types of fracturing fluids are hydraulic fracturing fluids, fiber fracturing fluids and clean fracturing fluids. The additives in the fracturing fluid mainly include acids, antibacterial agents, demulsifiers, corrosion inhibitors, surfactan...

AI Technical Summary

Problems solved by technology

Oxidation, electrolysis, adsorption, reverse osmosis and other operations used in the above process lead to very high investment and operating costs, and the process route of the above process is long and the operation is very cumbersome. In addition, due to the relatively harsh reaction conditions of the above process, the operation High parameter requirements lead to the problems of difficult operation and difficult control in the above-mentioned process

At present, there are also reports on the use of biochemical methods to treat fracturing flowback fluid, but the existing biochemical treatment methods are mainly static culture, and it takes about one month to meet the discharge standards. The treatment efficiency is very low, and engineering applications cannot be realized. Most of the pollutants contained in the fracturing flowback fluid are difficult to biodegrade. Using the existing conventional biochemical treatment methods to treat this type of wastewater, it is difficult to achieve the required pollutant removal effect in the effluent

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