Treatment method of thick oil sewage

Abstract

The invention provides a treatment method of thick oil sewage. According to the treatment method, thick oil sewage raw water is subjected to coagulation treatment, anaerobic biochemical treatment and biochemical treatment in sequence, and effluent reaches an emission standard. The method is used for treating thick oil wastewater in an oil field and can effectively improve the biodegradability of the thick oil wastewater and greatly reduce the CODCr content of the thick oil wastewater. A coagulating agent used during the coagulation treatment is high-temperature-resistant, the selective adsorption distribution of the coagulating agent on a thick oil-water interface is helpful for breaking and eliminating oil-water micro emulsion, and a synergistic effect principle is used for improving the emulsion breaking and oil removing performance of the coagulating agent and improving the purification performance by virtue of an effect of coagulating solid suspended particles and colloid particles; and after coagulation treatment, the CODCr of the effluent is reduced to 190-160mg / L, and the biodegradability of the sewage is improved from less than 0.2 to between 0.25 and 0.35.

Description

technical field [0001] The invention relates to a method for treating sewage, in particular to a method for treating heavy oil sewage containing a variety of refractory organic substances produced in the process of oil extraction in an oil field. Background technique [0002] At present, most of the oilfields are in the secondary and tertiary oil recovery stage, and large-scale production is usually realized by water flooding, steam flooding and polymer flooding. In the production of heavy oil oilfields, a large amount of waste water is produced along with heavy oil, which is called heavy oil sewage. [0003] The oil-water density difference of heavy oil sewage is small, and the colloid and asphaltene contained in it have natural emulsifying properties, and the biodegradability is extremely poor. The composition of oil recovery wastewater in heavy oil oilfields is complex. In addition to petroleum, it also contains a large number of chemical agents added during the extractio...

AI Technical Summary

Problems solved by technology

The composition of oil production wastewater in heavy oil oil fields is complex. In addition to petroleum, it also contains a large number of chemical agents added in the mining process, such as demulsifiers, viscosity reducers, oil displacement agents and other refractory substances. In addition to increasing the COD of the sewage itself, it also reduces the biodegradability of the sewage, and contains organic components that inhibit or poison the growth and reproduction of microorganisms. During the operation of biochemical treatment, the death or variation of biological strains will cause the sewage treatment effect. The problem of gradual decline

[0004] The analysis data shows that the petroleum in heavy oil wastewater is mainly composed of hydrocarbons, alcohols, and esters, plus various chemical additives with extremely poor biodegradability, resulting in the characteristics of high CODCr content and poor biodegradability in heavy oil wastewater , it is difficult to effectively treat with conventional methods, and with the increasingly stringent requirements of the national and local environmental protection departments for external sewage discharge, the difficulty and key of the heavy oil sewage treatment process is to adopt suitable and effective process methods to make it meet the discharge standards

[0005] Patent CN103601340A discloses a method for treating heavy oil sewage, which is to sequentially process the raw water of heavy oil sewage through catalytic oxidation treatment at normal temperature and pressure, anaerobic biochemical treatment, contact oxidation treatment and ozone activated carbon aerated biological filter treatment process, but heavy oil The temperature of sewage is usually 80-90°C. If catalytic treatment at normal temperature and pressure is used, it needs to be cooled first, which increases the cost of the process.

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