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CN-122010363-A - Method and system for synchronously treating high-salinity high-ammonia-nitrogen high-COD wastewater based on acid fractionation

CN122010363ACN 122010363 ACN122010363 ACN 122010363ACN-122010363-A

Abstract

The invention discloses a method and a system for synchronously treating high-salinity high-ammonia-nitrogen high-COD wastewater based on acid fractionation. Aiming at wastewater with COD not less than 3500mg/L, TDS not less than 5000mg/L and ammonia nitrogen not less than 150mg/L, adding an acid regulator to adjust the pH value to 1.0-6.5 so as to convert ammonia nitrogen into ammonium salt, then carrying out fractional distillation to keep the ammonium salt and salt in a base solution, and finally condensing a gas phase fraction and separating a primary fraction to obtain clear water of a main fraction. The COD value of the main fraction clear water is lower than 30% of the COD value of the raw water, the ammonia nitrogen value is lower than 15% of the ammonia nitrogen value of the raw water, and the TDS removal rate is more than 50%. The method synchronously reduces three pollutants by one-step distillation, can be suitable for industrial waste acid such as waste sulfuric acid, waste hydrochloric acid and the like to realize waste treatment by waste, has simplified process and low cost, and is suitable for three-high waste water treatment in the industries of landfill leachate, chemical industry, pharmacy, printing and dyeing, food processing, coal chemical industry and the like.

Inventors

  • Request for anonymity

Assignees

  • 山东常青源环保科技有限公司

Dates

Publication Date
20260512
Application Date
20260410

Claims (8)

  1. 1. The method for synchronously treating the high-salt high-ammonia-nitrogen high-COD wastewater based on acid fractionation is wastewater with Chemical Oxygen Demand (COD) of more than or equal to 3500mg/L, total Dissolved Solids (TDS) of more than or equal to 5000mg/L and ammonia nitrogen (NH 3 -N) of more than or equal to 150mg/L, and is characterized by comprising the following steps of: (1) Acid regulation, namely adding an acid regulator into the wastewater, and regulating the wastewater to an acid environment with the pH value of 1.0-6.5 so as to convert ammonia nitrogen in the wastewater into ammonium salt; (2) Fractionating and distilling, namely introducing the acidified wastewater in the step (1) into acid corrosion resistant fractionating and distilling equipment to perform fractional distillation to obtain gas phase fraction and distillation bottom solution; (3) And (3) COD directional separation, namely condensing the gas phase fraction obtained in the step (2), and separating out a primary fraction with the volume ratio of 1% -25% to obtain clear water of a main fraction.
  2. 2. The method according to claim 1, wherein in the step (3), the COD value of the main fraction clear water is lower than 30% of the COD value of raw water, the ammonia nitrogen value is lower than 15% of the ammonia nitrogen value of raw water, and the TDS removal rate is more than 50%.
  3. 3. The method according to claim 1, wherein in the step (2), the process parameters of the fractional distillation are that the absolute pressure of the distillation is 0.005-0.1 MPa and the distillation temperature is 33-102 ℃.
  4. 4. The method according to claim 1, wherein in the step (3), the separation ratio is automatically adjusted within a range of 1% -25% according to the COD index requirement of the main fraction clear water.
  5. 5. The method according to claim 1, wherein in the step (1), the acid regulator is at least one of an inorganic acid, an organic acid and a corresponding waste acid, but does not include nitric acid, perchloric acid, hydrofluoric acid and a waste acid containing the above components, the mass concentration of the acid regulator is 0.5% -100%, and the mass concentration of the acid regulator is 0.5% -105% of sulfuric acid or waste sulfuric acid.
  6. 6. The method of claim 1, further comprising one or more post-processing steps: (a) Waste gas treatment, namely, waste gas generated by distillation is discharged after being sprayed and absorbed by alkali liquor; (b) The distilled water treatment, namely detecting clear water of the main fraction, and if the indexes of COD, ammonia nitrogen and TDS of the clear water do not meet the preset recycling or discharge standards, refluxing the clear water to the fractionating and distilling equipment for secondary treatment; (c) And (3) residue disposal, namely, regulating the pH value of the primary fraction and the distillation bottom solution separated in the step (3) to 6.0-9.0, identifying according to dangerous waste identification standards, and classifying and disposing according to identification results.
  7. 7. A high-salt high-ammonia-nitrogen high-COD wastewater synchronous treatment system for realizing the method of claim 1, wherein the high-salt high-ammonia-nitrogen high-COD wastewater is wastewater with Chemical Oxygen Demand (COD) not less than 3500mg/L, total Dissolved Solids (TDS) not less than 5000mg/L, and ammonia nitrogen (NH 3 -N) not less than 150mg/L, and the system is characterized by comprising: The acid regulating unit comprises an acid-resistant stirring tank, an acid storage tank, a metering dosing pump and an online pH monitor, wherein the metering dosing pump and the online pH monitor are controlled in a linkage manner and used for adding an acid regulator into the wastewater to regulate the wastewater to an acid environment with pH of 1.0-6.5; The fractionating and distilling unit is fractionating and distilling equipment which is resistant to acid corrosion corresponding to the pH value of the treated wastewater, is connected with the discharge end of the acid regulating unit and is used for fractionating and distilling the acid wastewater; The COD directional separation unit is connected with a gas phase outlet of the fractional distillation unit and comprises a phase separation tank, a primary fraction collection tank, a main fraction collection tank, a COD monitor and a proportion regulating valve, and is used for condensing the gas phase fraction and separating the primary fraction to obtain main fraction clean water; and the control unit is respectively connected with the acid adjusting unit, the fractional distillation unit and the COD directional separation unit in a signal way and is used for controlling the adding amount of the acid regulator, the pH value of the wastewater, the distillation temperature, the absolute pressure and the fraction separation proportion in a linkage way.
  8. 8. The system of claim 7, further comprising one or more of a pretreatment unit, an exhaust gas treatment unit, a distilled water treatment unit, and a residue treatment unit, wherein each of the matched units is in signal connection with the control unit to realize full-flow linkage control, and the pretreatment unit is used for coagulation filtration pretreatment of high-turbidity wastewater.

Description

Method and system for synchronously treating high-salinity high-ammonia-nitrogen high-COD wastewater based on acid fractionation Technical Field The invention belongs to the technical field of industrial wastewater treatment, and particularly relates to a method and a system for synchronously treating high-salt high-ammonia-nitrogen high-COD wastewater based on acid fractionation, which are particularly suitable for integrated treatment of nondegradable three-high wastewater with COD more than or equal to 3500mg/L, TDS more than or equal to 5000mg/L and ammonia nitrogen more than or equal to 150mg/L, and can be widely suitable for wastewater treatment scenes in multiple industries such as landfill leachate, chemical industry, pharmacy, printing and dyeing, food processing, coal chemical industry and the like. Background The high-salinity high-ammonia-nitrogen high-COD wastewater is the wastewater which is accepted by the environmental protection industry and is difficult to treat due to the strong inhibition of high salinity to microorganisms, high ammonia-nitrogen biotoxicity and high COD degradation resistance, and is widely generated in multiple industries such as landfill, chemical industry, pharmacy and the like. The prior art has four core defects, which are not fundamentally solved for a long time: 1. the neutral/alkaline distillation has the long-standing and unresolved technical problem of ammonia nitrogen-TDS coupling exceeding standard. The main stream neutral/alkaline distillation process is derived from the long-standing technical prejudice in the field, namely that the acid distillation can severely corrode equipment, volatile organic matters are easy to escape to cause secondary pollution, and the distillation operation is carried out in a neutral/alkaline environment. However, under neutral/alkaline conditions, ammonium ions are easy to hydrolyze to generate free ammonia, ammonia nitrogen in the distillate is seriously out of standard along with evaporation of water vapor, meanwhile, the free ammonia has a 'carrying effect' on salt, so that TDS of the distillate is synchronously out of standard, and a vicious circle of 'ammonia nitrogen-TDS coupling out of standard' is formed, which is a long-term trouble for the industry, and a fundamental solution is not found all the time. 2. Acid full-cut distillation cannot solve the problem of COD exceeding the standard pain point. In the acid distillation technology which occurs in recent years, ammonia nitrogen is fixed to ammonium salt through acid conditions, so that the problem of exceeding ammonia nitrogen volatilization is solved, but the dissociation degree of volatile organic acids (acetic acid, propionic acid and the like) in wastewater in an acid environment is reduced, and the volatile organic acids are easily volatilized along with water vapor in a large quantity, so that the COD of distillate is seriously exceeded, and the standard emission cannot be realized. The core mechanism of the acid distillation COD exceeding the standard is not revealed in the industry all the time, an effective solution is not proposed, and the technical barrier that the acid distillation ammonia nitrogen reaches the standard but the COD does not reach the standard and the alkaline distillation COD reaches the standard but the ammonia nitrogen/TDS does not reach the standard is formed. 3. Three indexes cannot be synchronously and greatly reduced, and the process redundancy cost is high. The prior art generally adopts a step-by-step treatment route, the typical process is evaporation desalination, alkaline blowing/biochemical ammonia removal, fenton/advanced oxidation COD removal, the process flow is long, the equipment is matched more, the occupied area is large, the operation management difficulty is high, the medicament and the energy consumption cost are superposed, the ton water treatment cost is high, the cooperative control of three indexes cannot be realized by the step-by-step treatment, the problem of insufficient reduction of one index is easily caused, and a set of integrated technical scheme capable of realizing synchronous and large-scale reduction of the three indexes cannot be provided in the industry. 4. The waste acid is not fully utilized, and a dangerous waste reduction cooperative scheme is not formed. The prior art does not form a synergistic scheme of waste acid reclamation and hazardous waste reduction aiming at the working condition that distillation residues are hazardous wastes, and cannot realize waste treatment by waste, thereby further exacerbating the environmental protection disposal cost and compliance pressure of enterprises. 5. The waste acid treatment has structural contradiction of more acid and less alkali, and the low-concentration waste acid is not fully utilized. The production amount of the industrial waste acid in China is large, and the production amount of the waste alkali is relatively insufficient, so that a market s