Denitrification treatment method for kitchen anaerobic wastewater
Technical Field
The invention relates to the field of sewage treatment, in particular to a denitrification treatment method for kitchen anaerobic wastewater.
Background
The waste water after anaerobic fermentation and dehydration of the kitchen waste slurry and the waste water generated in other processes of kitchen waste treatment have complex components, high organic matter content, particularly high ratio of cellulose, protein, lipid and other organic matters difficult to biodegrade, so that the treatment difficulty is high; meanwhile, the wastewater contains high ammonia nitrogen, high salt content, high suspended matters and high total nitrogen and phosphorus, and is discharged after being untreated, so that most of surface water and part of shallow groundwater are directly polluted, and the economic sustainable development and water supply safety are affected. Meanwhile, due to the characteristic of low carbon nitrogen ratio of the kitchen wastewater, total nitrogen of the kitchen wastewater cannot be effectively removed, so that the kitchen wastewater treatment is a great challenge in the current day.
At present, the kitchen wastewater treatment mainly adopts a process route of combining several or more process units such as anaerobic biological treatment, aerobic biological treatment, membrane technology treatment and the like. For other treatment processes of wastewater like high ammonia nitrogen, such as landfill leachate, the problems of low total nitrogen and ammonia nitrogen removal efficiency and high operation cost generally exist.
Disclosure of Invention
In order to overcome the defects and shortcomings of the prior art, the invention aims to provide a denitrification treatment method for kitchen anaerobic wastewater, which can rapidly reduce total nitrogen, ammonia nitrogen and phosphorus in water, and obtain good denitrification efficiency and COD removal effect.
The aim of the invention is achieved by the following technical scheme:
a denitrification treatment method of kitchen anaerobic wastewater comprises the following steps:
(1) Filtering and degreasing the kitchen anaerobic wastewater to obtain degreasing wastewater;
(2) Pumping deoiling wastewater into an adjusting tank, mixing inlet water with nitrifying reflux liquid, and simultaneously adding kitchen waste acidified water wastewater hydrolysate to adjust the carbon-nitrogen ratio;
(3) Pumping the materials into a biological denitrification reactor from the bottom of the regulating tank, and simultaneously adding a denitrification bacterial agent for denitrification treatment;
the denitrifying bacteria agent comprises thiobacillus denitrificans, pseudomonas denitrificans, paracoccus denitrificans and rhodotorula mucilaginosa;
(4) The wastewater after denitrification treatment is discharged after passing through the first anoxic tank, the aerobic aeration tank, the second anoxic tank and the MBR membrane bioreactor in sequence.
Preferably, the denitrifying bacteria agent comprises the following components in parts by weight: 30-40 parts of thiobacillus denitrificans, 20-25 parts of pseudomonas denitrificans, 15-30 parts of paracoccus denitrificans and 25-30 parts of rhodotorula mucilaginosa.
Preferably, the temperature of the denitrification treatment in the step (3) is 36-38 ℃, the pH is 6.0-8.5, and the hydraulic retention time is 3-6 hours.
Preferably, the inlet water and the nitrifying reflux liquid in the step (2) are mixed in a volume ratio of 1 (2.5-3.5).
Preferably, in the step (2), the feeding speed is controlled to be 4L/h-6L/h; the pH value in the regulating tank is controlled to be maintained between 6.0 and 7.0.
Preferably, in the step (2), the ratio of the biochemical oxygen demand to the total nitrogen is controlled to be more than or equal to 3.
Preferably, the preparation steps of the kitchen waste acidified water wastewater hydrolysate in the step (2) are as follows:
(2-1) mechanically crushing the separated kitchen waste, controlling the grain diameter to be 5-50 mm, and then mixing the kitchen waste with water which is 1-5 times of the mass of the kitchen waste to obtain a fluid mixture with the solid content of 10-22%;
(2-2) feeding the fluid mixture obtained in the step (2-1) into a hydrolysis reactor, circularly and repeatedly stirring the kitchen waste, controlling the temperature in a hydrolysis tank to be 50-56 ℃ by adopting a high-temperature hydrolysis mode, carrying out hydrolysis acidification on the kitchen waste for 2-5 days, supplementing the consumption of water in the high-temperature acidification by adopting a spraying mode, and controlling the pH value of the acidification liquid to be 3-6.5.
Preferably, the degreasing treatment in the step (1) specifically includes:
adding a flocculating agent, and controlling the pH value of the oil pollution sedimentation tank to be 6.0-7.0 in the flocculation process; the stirring intensity is controlled to be 55-65 r/min.
Preferably, the flocculant comprises polyethylenimine, active silicic acid, soluble starch; wherein, the adding amount of active silicic acid in each liter of wastewater is 30-60 mg, the polyethyleneimine is 100-300 mg, and the soluble starch is 10-20 g.
Preferably, in the step (4), the temperature of the wastewater in the first anoxic tank is about 36-38 ℃, the pH value is 6.0-7.0, and the hydraulic retention time is 45-48 hours;
the temperature of the wastewater in the aerobic aeration tank is 32-34 ℃, the pH value is controlled to be neutral, and the hydraulic retention time is 4-5 days;
endogenous denitrification enhanced denitrification is carried out on the wastewater in a second anoxic tank, the temperature is 34-35 ℃, the dissolved oxygen is less than 0.2mg/L, the pH is controlled to 7-8, and the hydraulic retention time is 23-25 hours;
the hydraulic retention time of the wastewater in the MBR membrane bioreactor is 1-2 days.
The principle of the invention is as follows:
according to the invention, kitchen waste hydrolysis acidification liquid is used as a carbon source for denitrification, and meanwhile, thiobacillus denitrificans (T.Denitrification) Pseudomonas denitrificans (P.Denitrification), paracoccus denitrificans (P.Denitrification) and rhodotorula mucilaginosa (R.mucileginosa) are compounded to construct the high-efficiency denitrifying flora. Thiobacillus denitrificans (t.Denitrifics), which is a specialized inorganic autotrophic bacteria, obtains energy in the process of oxidizing sulfides, and generates nitrogen by taking nitrate as an electron acceptor, is a main functional microorganism in the synchronous desulfurization and denitrification treatment process of wastewater; pseudomonas denitrificans (P.Denitrifics) has the capability of heterotrophic nitrification and aerobic denitrification, and the strain can perform synchronous nitrification and denitrification to efficiently and thoroughly remove total nitrogen in sewage; paracoccus denitrificans (p.Denitrifics), which is a facultative nutrition type bacterium, grows by taking organic carbon and ammonia nitrogen in high ammonia nitrogen wastewater as carbon sources and nitrogen sources in heterotrophic conditions, and can utilize the ammonia nitrogen in wastewater to produce single cell proteins in heterotrophic and autotrophic conditions; rhodotorula mucilaginosa (R.mucileginosa) has wide nutrient range and can remove total nitrogen in sewage. In the complex environment of kitchen waste and wastewater, the expected purpose is difficult to achieve by adopting a single strain treatment mode, and organic wastes and inorganic ions in the kitchen waste are utilized to the greatest extent by adopting the combination of a plurality of strains which have different requirements on living conditions, substrates and the like and are not mutually antagonistic.
Compared with the prior art, the invention has the following advantages and beneficial effects:
(1) The invention adopts the kitchen waste hydrolysis acidification liquid as a carbon source, and the kitchen waste hydrolysis acidification liquid is a fermentation product generated in the anaerobic digestion stage of the kitchen waste, has the characteristics of high organic matter content, low price, no toxic or harmful effect, good biodegradability and the like, and can solve the problems of high toxicity, high cost and the like of exogenous carbon sources such as methanol and the like. The carbon-nitrogen ratio is the key of denitrification, and compared with carbon sources such as methanol, the kitchen waste hydrolysis acidification liquid has better denitrification performance.
(2) According to the invention, the kitchen waste acidizing fluid is used as a carbon source, and thiobacillus denitrificans (T.Denitrificans), pseudomonas denitrificans (P.Denitrificans), paracoccus denitrificans (P.Denitrificans) and rhodotorula mucilaginosa (R.mucileginosa) are compounded, so that the denitrification efficiency and the dephosphorization efficiency are improved, and the denitrification and dephosphorization time is shortened.
(3) The invention adopts the hydrolyzed and acidified raw water as the carbon source to adjust the carbon-nitrogen ratio, so that the method can meet the requirements of high-efficiency denitrification bacterial growth and the consumption of a denitrification reactor on the carbon source, and improves the denitrification efficiency.
Detailed Description
The present invention will be described in further detail with reference to examples, but embodiments of the present invention are not limited thereto.
Examples
The denitrification treatment method of the kitchen anaerobic wastewater of the embodiment comprises the following steps:
(1) Filtering and degreasing the kitchen anaerobic wastewater to obtain degreasing wastewater;
(2) Pumping deoiling wastewater into an adjusting tank, mixing inlet water with nitrifying reflux liquid, and simultaneously adding kitchen waste acidified water wastewater hydrolysate to adjust the carbon-nitrogen ratio;
(3) Pumping the materials into a biological denitrification reactor from the bottom of the regulating tank, and simultaneously adding a denitrification bacterial agent for denitrification treatment;
the denitrifying bacteria agent comprises thiobacillus denitrificans, pseudomonas denitrificans, paracoccus denitrificans and rhodotorula mucilaginosa;
(4) The wastewater after denitrification treatment is discharged after passing through the first anoxic tank, the aerobic aeration tank, the second anoxic tank and the MBR membrane bioreactor in sequence.
In this embodiment, the composition of the denitrifying bacteria agent is as follows: 30-40 parts of thiobacillus denitrificans, 20-25 parts of pseudomonas denitrificans, 15-30 parts of paracoccus denitrificans and 25-30 parts of rhodotorula mucilaginosa.
In this embodiment, in step (1), anaerobic kitchen waste water is filtered, specifically:
filtering the anaerobic kitchen wastewater through square fine meshes with the diameter of 1mm in the solid-liquid separation tank, and removing solid impurities.
In this embodiment, the degreasing treatment in step (1) specifically includes:
adding a flocculating agent, and controlling the pH value of the oil pollution sedimentation tank to be 6.5 in the flocculation process; the stirring strength was controlled to 60r/min.
Wherein the flocculant comprises polyethylenimine, active silicic acid and soluble starch; wherein, the adding amount of active silicic acid in each liter of wastewater can be 30-60 mg, polyethyleneimine is 100-300 mg, soluble starch is 10-20 g, and the preferable method is: the adding amount of active silicic acid in each liter of wastewater is 50mg, the polyethyleneimine is 200mg, and the soluble starch is 15g; the oil stain removal efficiency in the whole process is higher than 90%.
In this embodiment, the inlet water and the nitrified reflux liquid in the step (2) are mixed in a volume ratio of 1:3.
In the embodiment, the feeding speed is controlled to be 5L/h in the step (2); the pH value in the regulating tank is controlled to be maintained at 6.5.
In this embodiment, the ratio of the biochemical oxygen demand to the total nitrogen in the step (2) is controlled to be 3 or more.
In this embodiment, the preparation steps of the kitchen waste acidified water wastewater hydrolysate in step (2) are as follows:
(2-1) mechanically crushing the separated kitchen waste, controlling the grain diameter to be 5-50 mm, and then mixing the kitchen waste with water 3 times of the mass of the kitchen waste to obtain a fluid mixture with the solid content of 10-22%;
and (2-2) feeding the fluid mixture obtained in the step (2-1) into a hydrolysis reactor, circularly and repeatedly stirring the kitchen waste, controlling the temperature in a hydrolysis tank at 53 ℃ in a high-temperature hydrolysis mode, carrying out hydrolysis acidification on the kitchen waste for 3 days, supplementing the consumption of water in the high-temperature acidification by a spraying mode, and controlling the pH value of the acidification liquid at 5. The high-temperature hydrolysis can effectively shorten the hydrolysis time and improve the hydrolysis efficiency; the hydrolysis reaction stage adopts batch processing mode.
In this example, the denitrification treatment in step (3) was carried out at 37℃and pH 7, and the hydraulic retention time was 4 hours.
In the embodiment, in the step (4), the temperature of the wastewater in the first anoxic tank is about 37 ℃, the pH value is 6.5, and the hydraulic retention time is 48 hours;
in the embodiment, the temperature of the wastewater in an aerobic aeration tank is about 33 ℃, the pH value is controlled to be neutral, and the hydraulic retention time is 4-5 days;
in the embodiment, the wastewater is subjected to endogenous denitrification enhanced denitrification in a second anoxic tank, the temperature is 34-35 ℃, the dissolved oxygen is less than 0.2mg/L, the pH is controlled to be 7-8, and the hydraulic retention time is 23-25 hours;
the hydraulic retention time of the wastewater in the MBR membrane bioreactor is 1-2 days.
Test 1:
identifying the components of the kitchen waste acidified water wastewater hydrolysate sample prepared in the embodiment: the components and the concentrations (g/L) of the kitchen waste hydrolysate after high-temperature acidification and hydrolysis are determined as follows: ethanol 1.7, propionic acid 14.2, butyric acid 12.8, isovaleric acid 0.3, valeric acid 1.5 and acetic acid 16.8. The index concentration of the hydrolysis acidification liquid is as follows: chemical oxygen demand COD 92.5g/L, ammonia nitrogen 1.32g/L and total nitrogen 1.2g/L.
The kitchen waste acidified water wastewater hydrolysate prepared in the embodiment is compared with an exogenous carbon source effect. Anaerobic digestion of kitchen waste produces mixed volatile fatty acids such as propionic acid, butyric acid, isovaleric acid, valeric acid, acetic acid and the like, and exogenously added carbon sources such as methanol can be utilized by denitrifying bacteria only by being converted into Volatile Fatty Acids (VFAs), so that the kitchen waste acidizing fluid has better denitrification performance compared with the exogenously added carbon sources such as methanol and the like. The kitchen waste acidizing fluid is used as a preferential carbon source, and is supplemented with the efficient denitrification bacterial group, so that the denitrification and dephosphorization efficiency is improved and the denitrification and dephosphorization time is shortened through the construction of the efficient denitrification bacterial group.
Test 2:
preparing multiple groups of composite microbial agents by using high-efficiency denitrification bacterial groups with different proportions, comparing the microbial agents with exogenous carbon source methanol, measuring the change of water quality after treatment of each group of microbial agents, and comparing whether the acidolysis solution of kitchen waste is a carbon source or not. The specific compositions of the denitrifying bacteria in each group are shown in Table 1.
TABLE 1
And (3) respectively setting an activated sludge cuvette with methanol and acidolysis solution as carbon sources and two compound bacteria agents, performing denitrification circulation treatment twice a day, and measuring the water quality after 5 days. Wherein: methanol is used as a carbon source; group 2: methanol is used as a carbon source; group 3: methanol is used as a carbon source; group 4: acidolysis water is used as a carbon source; group 5: acidolysis water is used as a carbon source; group 6: acidolysis water was used as a carbon source, and the results are shown in Table 2. Compared with methanol, when the kitchen waste hydrolysis acidification liquid is used as a carbon source for denitrification, the denitrification rate is higher by using the kitchen waste hydrolysis acidification liquid as the carbon source, and ammonia nitrogen in water outlet can be basically controlled in a standard reaching range. In a comprehensive view, compared with traditional external carbon sources such as methanol, sodium acetate and the like, the kitchen waste hydrolysis acidification liquid has good denitrification performance and higher economical efficiency, and has a certain popularization and application prospect. Meanwhile, 30-40% of thiobacillus denitrificans, 20-25% of pseudomonas denitrificans (Staphylotherm), 15-30% of paracoccus denitrificans and 25-30% of rhodotorula mucilaginosa have remarkable denitrification effect.
TABLE 2
The embodiments described above are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the embodiments described above, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principles of the present invention should be made in the equivalent manner, and are included in the scope of the present invention.