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Process for separating nitrates, COD salts and sulfates by evaporating wastewater containing nitrates, COD salts and sulfates

A technology of nitrate and salt nitrate, which is applied in the field of evaporation and separation of nitrate COD salt nitrate wastewater containing nitrate COD salt nitrate, can solve the complex process flow of the wastewater pretreatment system, the large consumption of refrigeration equipment and cold energy, and the energy consumption of refrigeration Dashi water Glauber's salt and other problems, to achieve the effect of strong adaptability of raw materials, low TOC, high yield of salt salt

Inactive Publication Date: 2020-02-14
CHINA LIGHT IND INT ENG CO LTD
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AI Technical Summary

Problems solved by technology

[0006] Among the above-mentioned processes, process 1) has problems such as complex process flow of wastewater pretreatment system, adding chemicals, and large amount of miscellaneous salts; process 2) has complex process process of wastewater pretreatment system, adding chemicals, large refrigeration energy consumption, Glauber's salt decahydrate needs re-evaporation and denitrification, and the amount of miscellaneous salts is large; process 3) there is a complex process flow in the wastewater pretreatment system, adding chemicals, refrigeration equipment and cold energy consumption, and the COD of the frozen mother liquor corresponds to reducing substances and calcium It is difficult to remove the enrichment of magnesium ions in circulation, and the amount of miscellaneous salts is large, etc.

Method used

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  • Process for separating nitrates, COD salts and sulfates by evaporating wastewater containing nitrates, COD salts and sulfates

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] Embodiment 1 (nitrate type brine): get 200m 3 Salt salt wastewater (NaCl 5.29g / l, NaCl 2 SO 4 39.91g / l, CaSO 4 0.007g / l, MgSO 4 0.006g / l, COD corresponding to reducing substances 0.058g / l, NaNO 3 0.20g / l) as raw material, the 200m 3 Salt salt wastewater is evaporated (evaporation temperature 100°C) and concentrated to obtain fresh water and 25.46m 3 Concentrate (NaCl 46.5g / l, Na 2 SO 4 313.5g / l, CaSO 4 0.055g / l, MgSO 4 0.047g / l, COD corresponding to reducing substances 0.458g / l, NaNO 3 1.579g / l); the 25.46m 3 Concentrate (NaCl 46.5g / l, Na 2 SO 4 313.5g / l, CaSO 4 0.055g / l, MgSO 4 0.047g / l, COD corresponding to reducing substances 0.458g / l, NaNO 3 1.579g / l) and 16.81m 3 Salt circulating mother liquor (NaCl290.5g / l, Na 2 SO 4 64.5g / l, CaSO 4 0.11g / l, MgSO 4 0.094g / l, COD corresponding to reducing substances 3.03g / l, NaNO 3 10.452g / l) mixed evaporation (evaporation temperature 100°C) to obtain 7.879 tons of nitrate, fresh water and 23.57m ...

Embodiment 2

[0035] Embodiment 2 (nitrate type brine): get 200m 3 Salt salt wastewater (NaCl 20.55g / l, NaCl 2 SO 4 20.80g / l, COD corresponding to reducing substances 0.206g / l) as raw materials, the 200m 3 Salt salt wastewater is evaporated (evaporation temperature 100°C) and concentrated to obtain fresh water and 22.91m 3 Concentrate (NaCl 179.40g / l, NaCl 2 SO 4 181.58g / l, COD corresponds to reducing substances 1.799g / l); the 22.91m 3 Concentrate (NaCl 179.40g / l, NaCl 2 SO 4 181.58g / l, COD corresponds to reducing substances 1.799g / l) and 56.67m 3 Salt circulating mother liquor (NaCl 290.5g / l, NaCl 2 SO 4 64.5g / l, COD corresponds to reducing substances 3.175g / l) mixed evaporation (evaporation temperature 100°C) to obtain 4.145 tons of nitrate, fresh water and 79.47m 3 Saturated salt solution (NaCl 308g / l, NaCl 2 SO 4 55g / l, COD corresponds to reducing substances 3.175g / l); the 79.47m 3 Saturated salt solution (NaCl 308g / l, NaCl 2 SO 4 55g / l, COD corresponds to 13.01m in ...

Embodiment 3

[0036] Embodiment 3 (salt salt type brine): get 200m 3 Salt salt wastewater (NaCl 39.91g / l, NaCl 2 SO 4 5.92g / l, CaSO 4 0.007g / l, MgSO 4 0.006g / l, COD corresponding to reducing substances 0.058g / l, NaNO 3 0.20g / l) as raw material, the 200m 3 Salt salt wastewater is evaporated (evaporation temperature 100°C) and concentrated to obtain fresh water and 25.46m 3 Concentrate (NaCl 313.5g / l, Na 2 SO 4 46.5g / l, CaSO 4 0.055g / l, MgSO 4 0.047g / l, COD corresponding to reducing substances 0.458g / l, NaNO 3 1.579g / l); the 25.46m 3 Concentrate (NaCl 313.5g / l, Na 2 SO 4 46.5g / l, CaSO 4 0.055g / l, MgSO 4 0.047g / l, COD corresponding to reducing substances 0.458g / l, NaNO 3 1.579g / l) and 93.78m 3 Nitrate circulating mother liquor (NaCl305g / l, Na 2 SO 4 55g / l, CaSO 4 0.11g / l, MgSO 4 0.094g / l, COD corresponding to reducing substances 3.03g / l, NaNO 3 10.452g / l) mixed evaporation (evaporation temperature 55°C) to obtain 7.815 tons of salt, fresh water and 119.99m 3 S...

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Abstract

A process for separating nitrates, COD, salts and sulfates by evaporating wastewater containing nitrates, COD salts and sulfates is provided. The process includes A) performing evaporation concentration on wastewater containing salts and sulfates and adopted as a raw material to obtain fresh water and a concentrated solution; B) evaporating the concentrated solution to obtain salts or sulfates, fresh water and a salt-sulfate saturated solution; C) evaporating the salt-sulfate saturated solution to obtain a salt-sulfate mixture and a mixed salt mother liquor, drying the mixed salt mother liquorto obtain mixed salts containing nitrates, reductive compounds corresponding to CODs, salts and sulfates; D) dissolving the salt-sulfate mixture with the wastewater to obtain a mixed salt solution; E) evaporating the mixed salt solution at 40-140 DEG C and crystallizing to obtain sulfates or salts, and a circulating mother liquor for sulfate or salt preparation; F) allowing the circulating motherliquor for sulfate or salt preparation to participate in evaporation in the next cyclic process step B at an evaporation temperature of 40-140 DEG C to evaporate, crystallize and precipitate salts orsulfate and to obtain a circulating mother liquor for salt or sulfate preparation, with the circulating mother liquor for salt or sulfate preparation participating in evaporation in the step E of thenext cyclic process.

Description

technical field [0001] The invention belongs to the technical field of inorganic chemical industry, in particular to a process for evaporating and separating nitrate-COD salt-nitrate wastewater containing nitrate-COD salt-nitrate. Background technique [0002] COD is chemical oxygen demand. It is the amount of oxidant consumed when a certain strong oxidant is used to treat water samples under certain conditions. It is an indicator of the amount of reducing substances in water. Reducing substances in water include various organic matter, nitrite, sulfide, ferrous salt, etc. Therefore, chemical oxygen demand (COD) is often used as an indicator to measure the content of reducing substances in water. Known processes for separating COD salt nitrate from COD salt nitrate wastewater include: [0003] 1) After complex pretreatment, the wastewater is concentrated by membrane method (reverse osmosis, electrodialysis, etc.), and the concentrated solution is separated by nanofiltratio...

Claims

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Application Information

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IPC IPC(8): C02F1/04C01D3/04C01D3/14C01D5/16C02F101/10C02F101/16
CPCC01D3/04C01D3/14C01D5/16C02F1/04C02F2101/10C02F2101/101C02F2101/163
Inventor 彭赛军
Owner CHINA LIGHT IND INT ENG CO LTD
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