Process method for combining physical-chemical treatment and biochemical treatment for reinjection water with oil-field produced water

Abstract

The invention discloses a process for combining physical-chemical treatment and biochemical treatment for reinjection water with oil-field produced water. In the process, the oil-field produced water is treated in an oil removal tank unit, and then the treated oil-field produced water enters an electrocoagulation unit for physical-chemical treatment, enters an MBR (membrane bioreactor) unit for biochemical treatment and then is treated through an ultraviolet disinfection unit. The requirement on water quality of the reinjection water treated with the oil-field produced water is met. The treated reinjeciton water can steadily meet the technical requirements that SS is less than or equal to 1 mg / 1, the particle size is equal to or smaller than 1 mum, and the oil content is equal to or lower than 1 mg / 1; no coagulant is required to be added, thereby saving the cost of chemical preparations; the produced mud amount is only one half of that in the conventional process, so that the mud treatment cost is saved, and further the process is simple to maintain and saves daily maintenance cost; and the provided process not only can steadily meet the requirement on the water quality of the reinjection water treated with the oil-field produced water for a long time, has low treatment cost, but also prevents the environmental pollution from adding the coagulant.

Description

technical field [0001] The invention belongs to a waste water treatment and reuse process method, in particular to a process method combining physicochemical and biochemical treatment of oilfield produced water for reinjection. Background technique [0002] At present, the water quality of oilfield produced water used for reinjection after treatment, the main water quality indicators are oil content and suspended solids. The stricter requirements are that the oil content does not exceed 1mg / l, the SS does not exceed 1mg / l, and the particle size does not exceed 1um. The main water treatment process currently used for oilfield produced water for reinjection is a combination of sedimentation separation (or air flotation treatment) and filtration treatment. Among them, sedimentation separation (or air flotation treatment) mainly includes gravity sedimentation method, coagulation sedimentation method, inclined plate sedimentation method, pressure sedimentation method, gas flotat...

AI Technical Summary

Problems solved by technology

However, the currently used water treatment process for reinjection of oilfield produced water has obvious defects: First, the treated effluent cannot meet the water quality requirements for reinjection water in a long-term and stable manner (oil content≤1mg / l, SS≤1mg / l, particle size ≤1um); Second, the treatment cost is relatively high, especially coagulation sedimentation or coagulation air flotation requires a large amount of chemicals, which is expensive; third, the large amount of sludge produced by coagulation sedimentation or coagulation air flotation is relatively serious to the environment , especially due to the addition of coagulant (chemical agent) to produce new chemical pollution; Fourth, it does not have the function of dealing with COD, ammonia nitrogen and disinfection

Images