High-salinity and high-hardness wastewater treatment method

Abstract

The invention discloses a high-salt and high-hardness wastewater treatment method which comprises the following steps: detecting COD (Chemical Oxygen Demand) and total nitrogen in fly ash, and storing different fly ashes in a classified manner; s2, feeding the fly ash with different COD and total nitrogen contents in the S1 into a slurry tank after compatibility, uniformly mixing, and cleaning to obtain fly ash washing water; the method comprises the following steps: adding sludge into a biochemical pool, carrying out stuffy aeration, carrying out microbial acclimatization, enabling microorganisms to gradually adapt to an environment from low salt to high salt, and controlling the range of salinity and hardness, so that halotolerant bacteria are gradually acclimatized in a manner of gradually transitioning from low salt to high salt, and the halotolerant bacteria are rapidly propagated; a large number of halotolerant bacteria gradually adapt to a high-salt environment, the content of COD and total nitrogen in sewage needing to be treated is further increased by preparing fly ash water, the requirements of strains for nutrient substances are met, the halotolerant bacteria rapidly and massively breed in the final sedimentation tank, and internal microorganisms breed at the highest speed at the most efficient rate.

Description

Technical Field

[0001] The invention relates to the field of water treatment, in particular to a method for treating high-salt and high-hardness wastewater. Background Art

[0002] Biological treatment is one of the most commonly used methods for wastewater treatment. Biological treatment has the characteristics of wide application range, strong adaptability and low operating cost. However, the fly ash generated by hazardous waste incineration disposal enterprises and waste incineration power plants, and the ash washing wastewater generated in the further harmless disposal process, not only has high salt content, but also high hardness. The fly ash washing wastewater brings certain difficulties to biological treatment. This type of wastewater has complex components, no recycling value, high salt content, serious pollution, and must be treated before discharge. The cost of using other treatment methods is high. Therefore, biological treatment is still the preferred method. In the treatment process of this type of wastewater, the types and number of microorganisms in the biological treatment system are small, and the operation of the system is often impacted by the influent water quality load, and problems occur frequently. After the development of this type of wastewater treatment in recent years, the technology has been basically mature, but the operation stability is poor, and the treatment effect can meet the emission standards of the country or related industries. However, it also has many major disadvantages: First, unstable operation, resulting in higher pollutants in the wastewater, causing certain damage to the environment; second, unstable operation, increasing the cost of wastewater treatment; third, unstable operation, curbing the improvement of enterprise production capacity.

[0003] To this end, we proposed a high-salt and high-hardness wastewater treatment method to solve the above problems. Summary of the invention

[0004] The purpose of the present invention is to provide a method for treating high-salt and high-hardness wastewater to solve the problems raised in the above-mentioned background technology. The technical solution of the present invention provides a solution that is significantly different from the prior art to the technical problem that the prior art solution is too single.

[0005] To achieve the above object, the present invention provides the following technical solutions: A method for treating high-salt and high-hardness wastewater comprises the following steps: S1. Detect COD and total nitrogen of fly ash, and classify and store different fly ashes; S2, the fly ash with different COD and total nitrogen contents in S1 is sent into a slurry tank for stirring and mixing, and then washed to obtain fly ash washing water; S3. After adding sludge into the biochemical pool, it is exposed to the atmosphere to acclimate the microorganisms, allowing them to gradually adapt to the low-salt to high-salt environment and control the range of salinity and hardness; S4. After the salt-tolerant bacteria are obtained after the domestication, the fly ash water and activated carbon prepared in S2 are added to finally complete the entire wastewater treatment.

[0006] In a further embodiment, the amount of sludge added to S3 is 5%-10% of the volume of the biochemical pool, and salt-containing sludge is used.

[0007] In a further embodiment, the fly ash storage in S1 is divided into high COD fly ash, high total nitrogen fly ash and low total nitrogen fly ash.

[0008] In a further embodiment, high COD fly ash, high total nitrogen fly ash and low total nitrogen fly ash are divided into three bins, namely, bin A, bin B and bin C.

[0009] In a further embodiment, the salt content of the sludge in S2 is controlled at 20 g / L-30 g / L, and the hardness of the sludge is maintained at 10 g / L-20 g / L.

[0010] In a further embodiment, the exposure time in S3 is controlled to be 40 hours to 50 hours.

[0011] In a further embodiment, sodium acetate is added during the aeration in S3 to remove nitrates, and potassium dihydroxy phosphate is added as a microbial nutrient.

[0012] In a further embodiment, the sign of completion of acclimation in S4 is that the contents of nitrite and nitrate are both less than 3 mg / L.

[0013] In a further embodiment, the fly ash washing in S2 is water washing and filter pressing.

[0014] In a further embodiment, the ratio of water to ash during fly ash washing is 3:1, the COD in the fly ash washing water is less than 200 mg / L, and the total nitrogen content is less than 200 mg / L.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention gradually domesticates the salt-tolerant bacteria by gradually transitioning from low salt to high salt, and allows the salt-tolerant bacteria to multiply rapidly, allowing a large number of salt-tolerant bacteria to gradually adapt to the high-salt environment, and further increases the COD and total nitrogen contents in the sewage to be treated by configuring fly ash water to meet the needs of the bacteria for nutrients, allowing the salt-tolerant bacteria to multiply rapidly and in large quantities in the final sedimentation tank, allowing the internal microorganisms to grow at the fastest speed at the most efficient rate, and at the same time, by remixing the fly ash water and washing it with the ratio of water to ash being 3:1, the COD and total nitrogen in the prepared fly ash washing water are controlled below 200 mg / L to prevent the death of the microorganisms, thereby using an absolute number of microorganisms to remove a large amount of harmful substances such as COD and total nitrogen in the sewage in the shortest time, and the domesticated microorganisms can grow rapidly in a high-salt environment, can adapt to a complex sewage environment, and achieve the effect of quickly removing pollutants in the sewage. DETAILED DESCRIPTION

[0016] Example 1: Please refer to Tables 1-3, in the embodiments of the present invention, a method for treating high-salt and high-hardness wastewater is: The fly ash was tested for COD and total nitrogen, and high COD fly ash, high total nitrogen fly ash and low total nitrogen fly ash were divided into three bins, namely bin A, bin B and bin C. The COD content in bin A was 340ppm, the total nitrogen content was 153ppm, and the ammonia nitrogen content was 4.1ppm. The COD content in warehouse B was 151ppm, the total nitrogen content was 26.3ppm, and the ammonia nitrogen content was 6.6ppm; The COD content in bin C was 181ppm, the total nitrogen content was 317ppm, and the ammonia nitrogen content was 2.8ppm; As shown in Table 2, the fly ash from the three bins A, B, and C are sent to the slurry tank at a mass ratio of 17:62:21 for mixing. A little water is added during mixing to promote full mixing. The COD content of the fly ash dry basis in the slurry tank is 190ppm, the total nitrogen content is 108ppm, and the ammonia nitrogen content is 5.38ppm. The fly ash dry basis in the slurry tank is further subjected to three-stage countercurrent water washing and filter pressing. After filter pressing, the concentrations of COD and total nitrogen in the fly ash washing water are detected to ensure that the water-ash mass ratio is 3:1. The COD in the fly ash washing water prepared after washing is <200mg / L, and the total nitrogen content is <200mg / L. After confirmation, the configuration of the fly ash washing water is completed; Add sludge that accounts for 10% of the total volume of the biochemical pool, and use salty sludge. After adding it, expose it to the sun for 48 hours to acclimate the microorganisms, so that the microorganisms can gradually adapt to the low-salt to high-salt environment. The salt content of the sludge is controlled to be maintained at 30g / L, the hardness of the sludge is maintained at 20g / L, and the daily fluctuation of salinity is controlled within 15%; During aeration, sodium acetate is added as a carbon source to eliminate nitrate. If the nitrate is too low, potassium dihydroxy phosphate is added as a nutrient for microorganisms, and nitrite and nitrate are tested. When both nitrite and nitrate are less than 3 mg / L, the microbial acclimation is completed.

[0017] After obtaining a stable salt-tolerant strain, we began to add fly ash washing water, and at the same time added activated carbon to control the COD index within a reasonable range, and finally discharged it to complete the wastewater treatment; If you want to make salt-tolerant bacteria proliferate in large numbers, you need to slowly increase the salt concentration. Rapid changes in salinity or too short an acclimation time will reduce the activity of microorganisms and prevent salt-tolerant bacteria from proliferating in large numbers.

[0018] When treating the configured fly ash water, a small amount of water should be taken in according to the total nitrogen and COD indicators of the discharged water. In the initial stage of acclimatization, the COD of the biochemical effluent is relatively high. Therefore, activated carbon is added to the final sedimentation tank of the biochemical effluent to control the COD index within the qualified range before discharging it, thus completing a wastewater treatment cycle.

[0019] After 130 to 150 days, the contents in the warehouse are as follows: The COD content in warehouse A was 135ppm, the total nitrogen content was 147ppm, and the ammonia nitrogen content was 12ppm; The COD content in warehouse B was 120ppm, the total nitrogen content was 26.3ppm, and the ammonia nitrogen content was 8.0ppm; The COD content in bin C was 200ppm, the total nitrogen content was 280ppm, and the ammonia nitrogen content was 28ppm; As shown in Table 3, the fly ashes from the three bins A, B, and C were sent to the slurry tank at a mass ratio of 13:50:38 for mixing. A little water was added during mixing to promote full mixing. The COD content of the fly ash dry basis in the slurry tank was 152ppm, the total nitrogen content was 137ppm, and the ammonia nitrogen content was 16ppm. The fly ash dry basis in the slurry tank was further subjected to three-stage countercurrent water washing and filter pressing. After filter pressing, the concentrations of COD and total nitrogen in the fly ash washing water were tested to ensure that the COD in the fly ash washing water was less than 200mg / L and the total nitrogen content was less than 200mg / L. After confirmation, the configuration of the fly ash washing water was completed; The fly ash water is treated again by combining the salt-tolerant bacteria that have been cultivated in the fly ash water. After the treatment is completed, the fly ash water is discharged.

[0020] Example 2: Please refer to Table 1-3. The difference from Example 1 is: The fly ash from bins A, B and C is sent into the slurry tank in a mass ratio of 15:60:25 for mixing. A little water is added during mixing to promote full mixing.

[0021] The sludge put into the biochemical pool accounts for 5% of the total capacity of the entire biochemical pool, and the sludge used is low-salt sludge, and the exposure time is 40 hours.

[0022] The salt content of the sludge is controlled at 25g / L, the hardness of the sludge is maintained at 15g / L, and the daily fluctuation of salinity is controlled within 20% during aeration.

[0023] Example 3: Please refer to Table 1-3. The difference from Example 1 is: The fly ash from bins A, B and C is sent into the slurry tank for mixing in a mass ratio of 16:65:23. A little water is added during mixing to promote full mixing.

[0024] The sludge put into the biochemical pool accounts for 7% of the total capacity of the entire biochemical pool, and sludge with low salt content is preferred, and the exposure time is 50 hours.

[0025] The salt content of the sludge is controlled at 20g / L, the hardness of the sludge is maintained at 10g / L, and the daily fluctuation of salinity is controlled within 10% during aeration.

[0026] Comparative Example 1: The COD content in warehouse A was 340 ppm, the total nitrogen content was 153 ppm, and the ammonia nitrogen content was 4.1 ppm; The fly ash from bin A is sent to the slurry tank for mixing. The COD content of the fly ash dry basis in the slurry tank is 340ppm, the total nitrogen content is 153ppm, and the ammonia nitrogen content is 4.1ppm. The fly ash dry basis in the slurry tank is further washed and filtered to complete the configuration of fly ash washing water; The same microorganism acclimation as in Example 1 was carried out to obtain microorganisms with the same effects.

[0027] After obtaining a stable salt-tolerant bacterial strain, fly ash washing water was added. At this time, due to the high COD content in the fly ash washing water and the lack of total nitrogen content, the content of microorganisms would increase rapidly in the early short period of time. However, due to the lack of nutrients required by the microorganisms, the number of microorganisms would begin to decline rapidly, resulting in a large amount of untreated COD still in the sewage.

[0028] Comparative Example 2: The COD content in bin C was 181 ppm, the total nitrogen content was 317 ppm, and the ammonia nitrogen content was 2.8 ppm; The fly ash in bin C is sent to the slurry tank for mixing. The COD content of the fly ash dry basis in the slurry tank is 181ppm, the total nitrogen content is 317ppm, and the ammonia nitrogen content is 2.8ppm. The fly ash dry basis in the slurry tank is further washed and filtered to complete the configuration of fly ash washing water; The same microorganism acclimation as in Example 1 was carried out to obtain microorganisms with the same effects.

[0029] After obtaining a stable salt-tolerant bacterial strain, fly ash washing water was added. At this time, due to the high total nitrogen content in the fly ash washing water and the lack of COD content, the content of microorganisms would increase rapidly in the early short period of time, but then the number of microorganisms would begin to decline rapidly due to the lack of nutrients required by the microorganisms, resulting in a large amount of untreated total nitrogen still in the sewage.

[0030] Analysis shows that both Comparative Examples 1 and 2 are unable to maintain a large microbial community due to the difference in COD and total nitrogen content. Although the microorganisms can still treat a certain amount of sewage in the early stage, they are weak in the later stage of treatment.

[0031] Comparative Example 3: The same fly ash washing water was prepared as in Example 1, and untamed microorganisms were directly added to the fly ash washing water to be treated; Due to the high salt content of fly ash wash water, microorganisms do not reproduce in large quantities, but decay rapidly and eventually die. Only a very small number of microorganisms survive and slowly treat the fly ash water, resulting in incomplete sewage treatment; Analysis shows that in Comparative Example 3, since the microorganisms were not domesticated in a high-salt environment, they could not adapt to the high-salt fly ash water environment, so the microorganisms could not reproduce or survive at all.

[0032] Table 1 shows the residual amount of COD and total nitrogen in each wastewater after the wastewater is treated in each embodiment.

[0033] Analysis of Table 1: From the perspective of COD residual, Example 1 has the best removal effect, followed by Example 2, and Example 3 has the worst effect. This is related to factors such as sludge dosage, exposure time, and salinity control.

[0034] Table 2 shows the COD, total nitrogen and ammonia nitrogen content of the three warehouses

[0035] Analysis in Table 2: COD and total nitrogen content in warehouse A are the highest, warehouse B has the lowest, and warehouse C has the highest total nitrogen content.

[0036] By mixing fly ash from different bins, the COD and total nitrogen content of the fly ash in the slurry tank can reach a more balanced level.

[0037] Table 3 shows the internal contents of each bin and the internal contents of the slurry tank after 130 days

[0038] Analysis of Table 3: After 130 days of treatment, the COD and total nitrogen contents of the fly ash in the three silos decreased, indicating that part of the COD and total nitrogen were removed during the fly ash washing process.

[0039] The ammonia nitrogen content in warehouse A and warehouse B increased, while the ammonia nitrogen content in warehouse C remained unchanged.

[0040] The COD and total nitrogen contents of the fly ash in the slurry tank also decreased, but the decrease was not as large as that in the individual bins, indicating that the fly ash washing process had limited effect on the removal of COD and total nitrogen.

[0041] From the perspective of the total nitrogen residual, the removal effects of the three embodiments are relatively ideal, and the total nitrogen content is less than 1ppm. Overall, the treatment effect of embodiment 1 is the best, and the COD and total nitrogen removal rates are the highest.

[0042] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0043] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for treating high-salt and high-hardness wastewater, characterized in that: The following steps are included: S1. Detect COD and total nitrogen of fly ash, and classify and store different fly ashes; S2, the fly ashes with different COD and total nitrogen contents in S1 are mixed into a slurry tank and then washed to obtain fly ash washing water; S3. After adding sludge into the biochemical pool, it is exposed to the atmosphere to acclimate the microorganisms, allowing them to gradually adapt to the low-salt to high-salt environment and control the range of salinity and hardness of the sludge; S4, after the salt-tolerant strains are obtained after the domestication, the fly ash washing water and activated carbon prepared in S2 are added to finally complete the entire wastewater treatment; The amount of sludge added to S3 is 5%-10% of the volume of the biochemical pool, and salt-containing sludge is used; the salt content of the sludge is controlled at 20g / L-30g / L, and the hardness is maintained at 10g / L-20g / L.

2. A method for treating high-salt and high-hardness wastewater according to claim 1, characterized in that: The fly ash storage in S1 is divided into high COD fly ash, high total nitrogen fly ash and low total nitrogen fly ash.

3. A method for treating high-salt and high-hardness wastewater according to claim 2, characterized in that: High COD fly ash, high total nitrogen fly ash and low total nitrogen fly ash are divided into three bins, namely bin A, bin B and bin C.

4. A method for treating high-salt and high-hardness wastewater according to claim 1, characterized in that: The exposure time in S3 is controlled between 40 hours and 50 hours.

5. A method for treating high-salt and high-hardness wastewater according to claim 4, characterized in that: During the aeration in S3, sodium acetate is added to remove nitrates, and potassium dihydroxy phosphate is added as a microbial nutrient.

6. A method for treating high-salt and high-hardness wastewater according to claim 5, characterized in that: The sign of completion of acclimatization in S4 is that the contents of nitrite and nitrate are both less than 3 mg / L.

7. A method for treating high-salt and high-hardness wastewater according to claim 1, characterized in that: The fly ash cleaning in S2 is water washing and filter pressing.

8. A method for treating high-salt and high-hardness wastewater according to claim 7, characterized in that: When the mass ratio of water to ash during fly ash washing is 3:1, the COD content of the obtained fly ash washing water is less than 200 mg / L and the total nitrogen content is less than 200 mg / L.

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