CN106966550A - The method of the high nitrate nitrogen desorption liquid processing of high salt - Google Patents

Abstract

The method for treating high-salt and high-nitrate-nitrogen desorption liquid of the present invention relates to a multistage treatment method for waste water comprising at least one chemical treatment step. Its purpose is to provide a method for treating high-salt and high-nitrate-nitrogen desorption liquid with stable treatment effect, no secondary pollution, and material resource utilization. The method for treating the high-salt and high-nitrate-nitrogen desorption liquid of the present invention comprises the following steps: firstly, high-salt and high-nitrate-nitrogen wastewater enters an oxidation tower containing a high-efficiency ozone catalyst for reaction to improve biodegradability and degrade COD, and the effluent enters a low-temperature crystallization evaporation device Circular reaction, the obtained salt crystals are used again as a regenerant, and the obtained residual liquid enters the EGSB reaction device containing efficient denitrification bacteria, and then a certain amount of external carbon source is added to the reactor to realize the conversion of nitrate nitrogen into nitrogen. The invention provides an effective process for resin desorption liquid treatment, effectively removes nitrate nitrogen in the desorption liquid, realizes the recovery and utilization of salt at the same time, and realizes material resource utilization. The invention belongs to the field of chemical wastewater treatment.

Description

Treatment method of high salt and high nitrate nitrogen desorption liquid

technical field

The invention relates to a multistage treatment method for waste water comprising at least one chemical treatment step, in particular to a treatment method for high-salt and high-nitrate-nitrogen desorption liquid.

Background technique

At present, as the eutrophication of water bodies becomes more and more serious, the state has issued relevant policies to propose the discharge standard requirements for total nitrogen in sewage, especially for the Taihu Lake Basin, which has proposed a discharge requirement of TN≤10mg/L. Therefore, it is necessary to carry out advanced treatment of biochemical tail water to make the total nitrogen discharge up to the standard. Resin adsorption technology is the most widely used tail water advanced treatment technology in recent years. It has the advantages of large adsorption capacity, good treatment effect, and reusability. Desorption liquid) is quite complex in composition, with a salt content as high as 8-15%, and a high concentration of organic pollutants, all at 2000-3000mg/L, with high salinity, high organic content, high nitrate nitrogen concentration, deep color, and poor biodegradability Features. The dope is difficult to handle, which greatly limits the further popularization and application of the resin. Therefore, it is urgent to find an efficient and economical desorption solution treatment method.

The main method of wastewater desalination is evaporation and crystallization, but the evaporation system has limitations on the concentration of organic matter in the influent. Once the concentration of organic pollutants is high, it will greatly affect the evaporation efficiency and the quality of crystallized salt. Therefore, ozone catalytic oxidation technology is used to degrade organic pollutants. On the one hand, the ozone catalytic oxidation effect is remarkable, and the removal efficiency of COD is 30% higher than that of ozone oxidation alone, and the dosage of ozone is 30% of the traditional one; on the other hand, the ozone catalytic oxidation technology does not bring in other magazine ions, and will not affect the follow-up Crystalline salt composition.

The conventional evaporation and crystallization system consumes a lot of energy, the equipment is prone to corrosion and scaling, and has high requirements on the quality of the influent water, resulting in high operating costs and low crystallization efficiency. The low-temperature evaporation and crystallization system uses 40-60°C boiler waste water or waste heat as energy, which can effectively save energy consumption. The equipment uses special plastic materials to avoid equipment corrosion and scaling.

The treatment of nitrate wastewater mainly adopts the method of biological denitrification. The denitrification reaction is when the dissolved oxygen concentration is lower than 0.5mg/L. The denitrification bacteria use the oxygen in the nitrate as the electron acceptor, and the organic matter as the carbon source and electron Donors provide energy and eventually nitrate or nitrite is reduced to _N2 or _N2O . Due to the lack of available carbon sources for wastewater itself, additional carbon sources are required to achieve denitrification, and easily biodegradable wastes are selected as carbon sources to reduce operating costs and achieve the purpose of "using waste to treat waste".

Contents of the invention

The present invention aims at the problems of complex composition, poor biodegradability, high total nitrogen, and high salt content of the concentrated liquid produced after wastewater is treated with resin, and provides a high-efficiency solution with stable treatment effect, no secondary pollution, and realization of material resource utilization. A method for the treatment of salt and high nitrate nitrogen desorption liquid, which uses ozone catalytic oxidation to degrade COD to reduce the pressure on the subsequent desalination system and biochemical system; uses a low-temperature evaporation crystallization system to reduce operating costs and achieve efficient recovery of salt in wastewater; biological desalination Nitrogen technology achieves the removal of NO3--N through the action of high-efficiency denitrification bacteria, and at the same time realizes "treating waste with waste".

The invention relates to a method for treating a high-salt and high-nitrate-nitrogen desorption liquid. The method comprises the following steps:

(1) Put the high-salt and high-nitrate desorption liquid in the ozone catalytic oxidation tower containing ozone catalyst for reaction, improve the biodegradability of the desorption liquid and degrade the COD of the desorption liquid, and the effluent of the ozone catalytic oxidation tower enters the lower one step operation;

(2) Transfer the effluent of the ozone catalytic oxidation tower to a low-temperature circulation evaporation crystallization device for crystallization to obtain salt crystals and residual liquid, and the obtained salt crystals are used again as regenerants, and the resulting residual liquid enters the next step of operation;

(3) Transfer the residual liquid into an anaerobic expanded granular bed reactor (Expanded Granular Sludge Bed, EGSB) containing highly efficient denitrification bacteria, and then add a certain amount of exogenous carbon to the reactor to provide the electrons required for denitrification The donor converts the nitrate nitrogen in the residual liquid into nitrogen gas, that is, completes the treatment of the high-salt and high nitrate-nitrogen desorption liquid of the present invention.

Preferably, the ozone catalyst in the step (1) is loaded with cadmium, nickel, tin, antimony, bismuth, manganese, zinc, copper, ruthenium, tin, Al ₃ O ₂ of one or more metals, the ozone concentration 60-100mg/L, contact oxidation time 1-3h, effluent COD removal rate 70-90%, biodegradability increased from 0.05-0.1 to 0.3-0.5.

Preferably, waste water or waste heat is used as a heat source in the crystallization process in the step (2), and the crystallization temperature is controlled at 30-60°C.

Preferably, the mass ratio of the salt crystals obtained in the step (2) to the residual liquid is 16-19:1-4.

Preferably, the concentration of microorganisms in the anaerobic expanded particle bed reactor is 5-10g/L, and the reflux system with an external reflux ratio of 40%-70% is installed; the hydraulic retention time is 24-36h, and the ascending flow rate is 1m/h -3.0m/h, the temperature is 15～35℃.

Preferably, the exogenous carbon in the step (3) is one or more of beer waste residue, cow dung fermented product, waste molasses and straw.

Preferably, the denitrification bacteria species in the step (2) is one or more of Nitrosomonas europaea, Bacillus megaterium, and Pseudomonas fluorescens .

Preferably, the removal rate of nitrate nitrogen in the effluent of the anaerobic expanded granular bed reactor is 80-90%.

The method for the treatment of the high-salt and high-nitrate-nitrogen desorption liquid of the present invention is different from the prior art in that:

The method for treating the high-salt and high-nitrate-nitrogen desorption liquid of the present invention has a stable treatment effect, no secondary pollution, and can realize resource utilization of materials.

In the method for treating high-salt and high-nitrate-nitrogen desorption liquid of the present invention, the front-end adopts an ozone catalytic oxidation tower, which can effectively reduce organic pollutants, do not introduce other impurity salts, and improve the efficiency of the subsequent evaporation system and the biodegradability of the denitrification system; The low-temperature evaporation crystallization system realizes the efficient recovery of sodium chloride, which can be used as a resin regeneration agent again to reduce operating costs; finally, the removal of nitrate nitrogen and the reuse of waste are realized by adding high-efficiency denitrification bacteria and external carbon sources , The removal rate of nitrate nitrogen can reach 80-90%.

Description of drawings

Fig. 1 is a process flow chart of the method for treating the high-salt and high-nitrate-nitrogen desorption liquid of the present invention.

detailed description

The method for treating the high-salt and high-nitrate-nitrogen desorption liquid of the present invention is further illustrated by the following examples.

Example 1

The method for the treatment of the high-salt and high-nitrate-nitrogen desorption liquid of the present embodiment is carried out in the following steps:

As shown in Figure 1, the resin adsorbs a chemical and biochemical tail water (wastewater) to produce a 30t/d concentrated liquid. The water quality CODcr is 2020mg/L, the total salt is 79600mg/L, and the concentration of nitrate nitrogen is 880mg/L.

The concentrated liquid (i.e. high-salt and high-nitrate-nitrogen desorption liquid) flows into the catalytic ozonation tower for 1.5 hours of contact reaction, then uses the ruthenium-tin composite alumina catalyst, the COD value drops to 400mg/L, and enters the 60°C evaporation crystallization system. Using waste heat as the reaction heat source, the system circulates the reaction until 90wt% of the salt crystals, the residual liquid flows into the EGSB reactor, and the quantitative denitrification bacteria and the front-end raw wastewater (that is, the high-salt and high-nitrate-nitrogen desorption liquid) are added. The bacteria species are Nitrosomonas, Bacillus megaterium and Pseudomonas fluorescens. After staying for 24 hours, the removal rate of COD is 70%, and the removal rate of NO ₃ ^- -N is 90%.

Example 2

The method for the treatment of the high-salt and high-nitrate-nitrogen desorption liquid of the present embodiment is carried out in the following steps:

The resin adsorbed a petrochemical biochemical tail water to produce 20t/d concentrated liquid, the water quality CODcr was 2550mg/L, the total salt was 88000mg/L, and the concentration of nitrate nitrogen was 1460mg/L.

After the concentrated liquid (i.e. high-salt and high-nitrate-nitrogen desorption liquid) flows into the catalytic ozonation tower for contact reaction for 2 hours, the COD value is reduced to 500 mg/L by using the antimony-manganese composite alumina catalyst, and then enters the evaporation crystallization system at 60°C. The waste heat is used as the heat source of the reaction, and the reaction is circulated in the system until the salt crystals reach 90wt%, the residual liquid flows into the EGSB reactor, and the quantitative denitrification bacteria and the front-end raw wastewater (that is, the high-salt and high-nitrate-nitrogen desorption liquid) are added. The strains were Nitrosomonas and Pseudomonas fluorescens. After adding exogenous carbon beer residue and staying for 30 hours, the removal rate of COD was 65%, and the removal rate of NO ₃ ^- -N was 86.6%.

Example 3

The method for the treatment of the high-salt and high-nitrate-nitrogen desorption liquid of the present embodiment is carried out in the following steps:

The resin adsorbs a lactic acid biochemical tail water to produce a 10t/d concentrated solution. The water quality CODcr is 3260mg/L, the total salt is 83800mg/L, and the nitrate nitrogen concentration is 2350mg/L.

After the concentrated liquid (i.e. high salt and high nitrate nitrogen desorption liquid) flows into the catalytic ozonation tower for contact reaction for 3 hours, the COD value drops to 550 mg/L, and the copper-nickel composite alumina catalyst is used to enter the evaporation crystallization system at 60 ° C. The waste heat is used as the heat source of the reaction, and the reaction is circulated in the system until the salt crystals reach 90wt%, the residual liquid flows into the EGSB reactor, and the quantitative denitrification bacteria and the front-end raw wastewater (that is, the high-salt and high-nitrate-nitrogen desorption liquid) are added. The strain is Nitrosomonas, adding exogenous carbon straw, and staying for 36 hours, the removal rate of COD is 78%, and the removal rate of NO ₃ ^- -N is 82.8%.

Example 4

The difference between the method of the high-salt and high-nitrate-nitrogen desorption liquid treatment of the present embodiment and embodiment 3 is:

The strains added were Pseudomonas fluorescens, and the exogenous carbon added was a mixture of cow dung fermentation and waste molasses; after staying for 20 hours, the removal rate of COD reached 85%, and the removal rate of NO ₃ ^- -N reached 91.4 %.

Example 5

The difference between the method of the high-salt and high-nitrate-nitrogen desorption liquid treatment of the present embodiment and embodiment 3 is:

The strains added were Pseudomonas fluorescens, and the exogenous carbon added was a mixture of beer residue, waste molasses, and straw; after staying for 18 hours, the removal rate of COD reached 79%, and the removal rate of NO ₃ ^- -N reached 88.5% %.

The above examples prove that the front end of the method for treating high-salt and high-nitrate-nitrogen desorption liquid of the present invention adopts an ozone catalytic oxidation tower, which can effectively reduce organic pollutants without introducing other impurity salts, and improve the efficiency of the subsequent evaporation system and the reliability of the denitrification system. Biochemical properties; then adopt low-temperature evaporation and crystallization system to achieve high-efficiency recovery of sodium chloride, which can be used as a resin regeneration agent again to reduce operating costs; finally, by adding high-efficiency denitrification bacteria and external carbon sources, the removal of nitrate nitrogen and Reuse of waste, the removal rate of nitrate nitrogen can reach 80-90%.

Although the specific embodiments of the present invention have been described above, those skilled in the art should understand that these are only examples, and the protection scope of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principle and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims (8)

1. a kind of method of the high nitrate nitrogen desorption liquid processing of high salt, it is characterised in that：It the described method comprises the following steps：

(1) the high nitrate nitrogen desorption liquid of high salt is placed in the catalytic ozonation tower containing ozone catalyst and reacted, improve de- The COD of the biodegradability of attached liquid and desorption liquid of degrading, the water outlet of catalytic ozonation tower is operated into next step；

(2) water outlet of catalytic ozonation tower is transferred into low-temperature circulating evaporated crystallization device to be crystallized, obtains salt crystallization and residual Liquid is stayed, gained Liquid Residue is operated into next step；

(3) Liquid Residue is transferred to the anaerobic expanded granular bed reactor of the strain containing denitrogenation, then external source carbon is added into reactor, is carried For the electron donor needed for denitrification, the nitrate nitrogen in Liquid Residue is converted into nitrogen, that is, the high nitrate nitrogen of high salt for completing the present invention takes off The processing of attached liquid.

2. the method for the high nitrate nitrogen desorption liquid processing of high salt according to claim 1, it is characterised in that：In the step (1) Ozone catalyst is the Al of carried noble metal₃O₂, ozone concentration is 60-100mg/L, and the catalytic oxidation time is 1-3h.

3. the method for the high nitrate nitrogen desorption liquid processing of high salt according to claim 1, it is characterised in that：In the step (2) Using waste water residual heat or used heat as thermal source in crystallization process, crystallization temperature is controlled at 30-60 DEG C

4. the method for the high nitrate nitrogen desorption liquid processing of high salt according to claim 1, it is characterised in that：In the step (2) Gained salt is crystallized and the mass ratio of Liquid Residue is 16~19:1~4.

5. the method for the high nitrate nitrogen desorption liquid processing of high salt according to claim 1, it is characterised in that：Described anaerobic expanded The concentration of microorganism is 5~10g/L, peripheral hardware reflux ratio 40%-70% return-flow system in grain bed reactor；Hydraulic detention time For 24~36h, upflow velocity is 1m/h-3.0m/h, and temperature is at 15~35 DEG C.

6. the method for the high nitrate nitrogen desorption liquid processing of high salt according to claim 1, it is characterised in that：In the step (3) External source carbon is the one or more in bear waste residue, cattle manure thing, blackstrap, stalk.

7. the method for the high nitrate nitrogen desorption liquid processing of high salt according to claim 1, it is characterised in that：In the step (2) Denitrogenation strain is the one or more in nitrosomonas, bacillus megaterium, fluorescent Pseudomonads.

8. the method for the high nitrate nitrogen desorption liquid processing of high salt according to any one claim in claim 1-7, it is special Levy and be：The nitrate nitrogen clearance of the anaerobic expanded granular bed reactor water outlet is 80-90%.