Method and system for treating coal chemical wastewater in zero-discharge manner

Abstract

The invention relates to a method and a system for treating coal chemical wastewater in a zero-discharge manner, and belongs to the field of technologies for treating water in an environment-friendly manner. The method for treating the coal chemical wastewater in the zero-discharge manner includes carrying out anaerobic biological desulfurization on the coal chemical wastewater to convert sulfate in the wastewater into hydrogen sulfide; carrying out hydrolytic acidification to improve the biodegradability of the wastewater; carrying out secondary A / O (anoxic-oxic) biochemical treatment, ozone oxidation, aeration biochemical treatment, softening, ultra-filtration and secondary reverse osmosis; converting Ca2+ into Na+ by means of ion exchange; generating purified water by means of membrane concentration and generating sodium chloride which is crystal salt by means of evaporation and crystallization. The system for treating the coal chemical wastewater in the zero-discharge manner comprises a buffer pool, an anaerobic biological desulfurization unit, a hydrolytic acidification unit, a secondary A / O biochemical unit, an ozone oxidation unit, an intermediate water pool, an aeration biological filter, a softening unit, an ultra-filtration unit, a secondary reverse osmosis unit, an ion exchange unit, a membrane concentration unit and an evaporation and crystallization unit which are sequentially connected with one another. The method and the system have the advantages that the problems of mixed salt hazardous waste and difficulty in controlling operation can be fundamentally solved by the aid of the method and the system, and the crystal salt can be recycled.

Description

technical field [0001] The invention belongs to the technical field of environmental protection water treatment, and in particular relates to a zero-discharge treatment method and system for coal chemical industry wastewater. Background technique [0002] Coal chemical industry wastewater is a kind of industrial wastewater that is difficult to treat. Coal chemical industry mainly includes coal gasification, liquefaction, dry distillation, tar processing and calcium carbide acetylene chemical industry, etc. Among them, coal gasification wastewater is a type of wastewater with the most complex pollutant components, high concentration, and difficult to be biodegraded. Coal gasification includes medium-temperature gasification and high-temperature gasification. Medium-temperature Lurgi gasification wastewater contains a large amount of toxic and harmful substances such as phenol, ammonia, and tar. Organic pollutants include phenols, polycyclic aromatic compounds, and nitrogen, o...

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Problems solved by technology

[0008] The invention provides a zero-discharge treatment system for coal chemical wastewater. After anaerobic biological desulfurization treatment and ion exchange, the sulfate radicals in the wastewater are completely removed, and the effluent reaches the "Water Quality Standard for Regenerated Water for Circulating Cooling Water" (HG / T3923- 2007), the water reuse rate is >98%, which solves the problem of hazardous waste of mixed salt in existing processes and the difficulty of salt separation by evaporation, crystallization and salt separation of binary systems of sodium chloride and sodium sulfate, and realizes the resource utilization of crystalline salt

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