Shale gas drilling wastewater treatment method

Abstract

The invention provides a shale gas drilling wastewater treatment method. The Shale gas drilling wastewater treatment method comprises the following steps that S1, the pH of drilling wastewater is adjusted to be 8-11, a coagulant and a coagulant aid are added, after uniform stirring, static settlement is conducted, and then solid-liquid separation is conducted; S2, the pH of clear liquid obtained through solid-liquid separation in the step S1 is adjusted to be 2-5, hydrogen peroxide and a Fe / C filler are added, and air is pumped in for reaction for 1.5-2 h; S3, the pH of the wastewater treatedin the step S2 is adjusted to be 9-11, a chemical precipitation agent is added, the temperature is controlled to be 80 DEG C, uniform stirring is conducted, reaction is conducted for 20-40 min, and then solid-liquid separation is conducted; S4, the pH of clear liquid obtained through solid-liquid separation in the step S3 is adjusted to be 7-9, an ammonia-nitrogen removing agent is added, and reaction is conducted for 20-30 min; and S5, the wastewater treated in the step S4 is treated through a low-temperature vacuum evaporation method, and thus condensed water and concentrated liquor are obtained. According to the shale gas drilling wastewater treatment method, the shale gas drilling wastewater is sequentially subjected to coagulating sedimentation, Fenton oxidation-microelectrolysis, chemical precipitation, ammonia-nitrogen removing and four-effect evaporation treatment, the conventional indexes in the treated drilling wastewater can reach the primary standard of the wastewater comprehensive discharging standard.

Description

technical field [0001] The invention belongs to the technical field of drilling wastewater treatment, and in particular relates to a treatment method for shale gas drilling wastewater. Background technique [0002] Shale gas drilling wastewater has a complex composition and contains various components in the mud. The main pollutants include: suspended solids mainly bentonite, petroleum, heavy metals, organic matter and chlorides, etc. The composition and concentration vary with the mud system, Drilling well depth and drilling formation change, it is a mixture of mud dilution and oil. In general, shale gas drilling wastewater has the following characteristics: [0003] ① Large chroma, high viscosity, complex chemical composition, generally dark brown or black viscous liquid, poor biochemical treatment; [0004] ② High water content, not easy to dehydrate, pH is generally greater than 7; [0005] ③ Contains more solid substances, such as clay, bentonite, rock debris, etc.; ...

AI Technical Summary

Problems solved by technology

[0003] ① Large chroma, high viscosity, complex chemical composition, generally dark brown or black viscous liquid, poor biochemical treatment;

[0004] ② High water content, not easy to dehydrate, pH is generally greater than 7;

[0006] ④ Due to the high oil content of certain special drilling fluids, the oil content in drilling wastewater is also high;

[0008] As an emerging industry in China, shale gas mining has a large difference in water quality between its drilling wastewater and conventional natural gas drilling wastewater. At present, there are various methods for treating various wastewater, including coagulation sedimentation, chemical oxidation, and physical adsorption. According to environmental protection requirements, different wastewater methods and their combinations can be used to obtain different treatment effects, but there are few technologies for targeted treatment of shale gas drilling wastewater. Therefore, it is necessary to seek economically feasible and technically feasible The treatment technology of drilling wastewater is imperative

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