Technology for recovering water resources and salt from coking wastewater in coal chemical industry

Abstract

A technology for recovering water resources and salt from coking wastewater in the coal chemical industry comprises the following steps: the wastewater is subjected to defluorination chemical treatment and subjected to sodium carbonate softening and precipitating treatment simultaneously, an advanced oxidation process is used for TOC (total organic carbon) degradation, a multi-medium and activated carbon filter is used for filtering separation, ultrafiltration is performed, nanofiltration membrane separation is performed, calcium and magnesium ions are separated, the calcium and magnesium ions in water produced through nanofiltration are lower than 2 mg / L, CaF2 crystallization scaling is hard to form, and nanofiltration passing liquid and nanofiltration strong brine are obtained; the nanofiltration passing liquid and the nanofiltration strong brine are treated respectively. Fluoride ions, hardness and organic carbon in the wastewater are removed, separation of multivalent salt and monovalent salt as well as concentration and evaporative crystallization of the salt is realized, more than 98% of the water resources is recovered, more than 95% of the salt resources are recovered, secondary hazardous waste is not produced, the system operation cost is reduced, and the problem about resource recovery and the environmental problem are solved finally.

Description

technical field [0001] The invention relates to the technical field of environmental engineering, in particular to a coal chemical coking wastewater water resource and salt recovery process. Background technique [0002] On April 21, 2014, the Ministry of Environmental Protection issued the "Notice on Strengthening Environmental Protection Management in the Process of Resolving Serious Overcapacity Conflicts", which clearly requires that "coking wastewater should be pretreated (gravity degreasing method, coagulation sedimentation method, air flotation degreasing method) ) + nitrification and denitrification biochemical treatment technology, the treated phenol cyanide wastewater is reused and must not be discharged outside.” Coal chemical coking wastewater biochemical effluent zero discharge is very difficult and is a world-class technical problem. The main difficulty is that the biochemical effluent of coking wastewater has high TOC content, high salt content, high hardness,...

AI Technical Summary

Problems solved by technology

Typical domestic cases adopt the process of lime softening + filtration + membrane concentration + evaporation for biochemical effluent. The bottom liquid of the evaporation bottom in the final process contains TOC, calcium, magnesium, fluoride ions and a large amount of sulfate ions. The bottom liquid of the evaporation bottom cannot crystallize and forms viscous With concentrated brine slurry, it can only be treated as hazardous waste in the end

The recovery rate of water is about 92%-95%, and the salt cannot be recovered

Therefore, the current domestic mainstream technology cannot achieve zero emission and resource recovery in a full sense