Gas field wastewater treatment process based on special membrane

Abstract

The invention discloses a gas-field wastewater treatment technology based on a special membrane. The gas-field wastewater treatment technology comprises three main working processes, namely a first stage for removing oil and suspensions, a second stage for oxidizing and breaking gel by Fenton and a third stage for removing salt and COD by a core Super RO system. Oil removal and suspension removal are carried out by a dissolved air horizontal-flow type combined air floating technology with higher efficiency is adopted, and sewage and wastes are materialized by a Fenton fluidized bed with highest oxidization capacity, so that the mass transfer efficiency among all the substances is improved, the reaction time is shortened, and the consumption of medicines is reduced; therefore wastewater can directly enter a membrane system by only simpler pretreatment, the operation stability and the service life of the system are guaranteed, and the environment-friendly construction cost and the sewage treatment operation cost are greatly reduced.

Description

Technical field [0001] The present invention relates to the technical field of sewage treatment, in particular, to a gas field wastewater treatment process based on a special membrane. Background technique [0002] Gas field wastewater usually includes formation produced water, fracturing flowback fluid, drilling wastewater, purification plant wastewater, and mining rainwater. They usually have the following characteristics: ①The content of petroleum substances is high, and the oil content is generally about 100-500mg / L. Petroleum substances mainly exist in suspended state, some are emulsified, and the emulsified oil is stable and difficult to separate; ②High SS content, The suspended particles are small, the particle size is generally 1-100μm, and the total SS of wastewater is 300-5000mg / l; ③The organic matter content is high, and the COD of general gas field wastewater is basically 800-3000 mg / l (the drilling may be as high as tens of thousands). There may be a certain amount ...

AI Technical Summary

Problems solved by technology

However, the reinjection process has the following disadvantages: 1) High one-time engineering investment; 2) Unable to realize the utilization of sewage resources; 3) It has a direct impact on surrounding oil fields; 4) It has a direct impact on surrounding oil reservoirs

The existing problems are ① the operating cost is too high, depending on the water quality, the general operating cost is as high as 100 yuan / ton of water; ② the salt is not removed, and the local environmental protection requirements cannot be truly met; ③ a large number of new chemical agents are introduced, resulting in secondary secondary pollution

The existing problems are ① introducing evaporation can solve the salt problem, but direct evaporation investment and operating costs are too high; ② evaporative condensate may not meet the COD standard; ③ introducing a large number of new chemicals will cause secondary pollution

However, with membrane desalination, membrane fouling is the bottleneck of industrial application

According to investigations and analysis from the field test of produced water treated by roll-type reverse osmosis, although reverse osmosis can obtain clean water with very low salinity, it requires strict chemical or biological pretreatment (SDI<5, and other harsh conditions such as COD Requirements); the cost of the membrane itself is high, the flux of the membrane decreases significantly after pollution, and it is difficult to restore the flux even after cleaning. At the same time, chemical cleaning will produce chemical cleaning waste liquid, making it difficult to break through in the engineering application of gas field sewage recycling

Images