TCCA (trichloroisocyanuric acid) mother liquor wastewater treatment method

Abstract

The invention belongs to the technical field of wastewater treatment and discloses a TCCA (trichloroisocyanuric acid) mother liquor wastewater treatment method. The TCCA mother liquor wastewater treatment method is mainly technically characterized by comprising the following steps: wastewater is regulated by a regulation tank and then enters a chlorinolysis tank, hydrochloric acid is added to the chlorinolysis tank, hypochlorite is removed, treated water enters a dechlorination tank, produced chlorine enters a nitrogen removal tank in the step 3, and small amount of sodium bisulfite is added to the dechlorination tank to remove redundant hypochlorite; alkali is added to precipitate melamine cyanurate, the precipitated melamine cyanurate is recovered, chlorine is introduced into the nitrogen removal tank, ammonia and excessive chlorine react to produce nitrogen which is exhausted, then sodium sulfite is added to remove excessive hypochlorite, finally, evaporative crystallization is performed, coarse salt which is separated out is collected, and evaporated condensate is discharged up to standard. According to the TCCA mother liquor wastewater treatment method, cyanuric acid is recovered, the energy consumption for wastewater treatment is low, salt is purified and recovered completely, investment for recovery equipment is small, and the hazardous waste amount is reduced.

Description

technical field [0001] The invention belongs to the technical field of chemical wastewater treatment, and in particular relates to a method for treating trichloroisocyanuric acid mother liquor wastewater. Background technique [0002] The content of COD in trichloroisocyanuric acid mother liquor wastewater is as high as 6580mg / L, ammonia nitrogen is about 2000-4000mg / L, pH is about 3-4, TDS content is more than 100000-120000mg / L, and it also contains melamine, cyanuric acid, chlorine Sodium chloride, sodium hypochlorite, free chlorine, trichloroisocyanuric acid, dichloroisocyanuric acid, monochloroisocyanuric acid, etc. The concentration of pollutants is high, the concentration of salt content is high, and the composition is complex. It is the most complicated and difficult to treat in the sodium production chemical wastewater. [0003] At present, after conventional advanced oxidation processes such as iron-carbon micro-electrolysis, Fenton oxidation, and ozone oxidation a...

AI Technical Summary

Problems solved by technology

[0003] At present, after conventional advanced oxidation processes such as iron-carbon micro-electrolysis, Fenton oxidation, and ozone oxidation are used, the COD value is difficult to meet the discharge standard of "Water Quality Standards for Sewage Drainage to Urban Sewers" (CJ3082-1999)

Even after multi-stage advanced oxidation treatment, it can be reduced to below 500mg / L, but the operating cost and investment are huge, which is unacceptable to enterprises

In addition, the salt content is high, and the ordinary membrane method cannot be used. The disc reverse osmosis treatment is used, and the investment and operating costs are high. The multi-effect evaporation crystallization investment is moderate, but the operating cost is high. MVR evaporators and forced circulation evaporators are used. , the operating cost is reduced, but the investment is relatively high. At the same time, the sodium salt evaporated and crystallized by the above evaporator contains high impurities and cannot be reused.

[0004] To sum up, the main difficulty in the treatment of trichloroisocyanuric acid mother liquor wastewater is that the concentration of pollutants is high, the concentration of salt content is high, and the composition is complex, so conventional processes cannot be used. Therefore, how to remove COD, purify the available salt content, and recover salt, Reducing investment and operating costs is the focus and difficulty of this type of water treatment