A kitchen waste treatment method

Abstract

The present application relates to a kind of kitchen waste processing method, comprising the following steps: (1), to kitchen waste after slurry of sorting and crushing sandstone scum is removed;(2), slurry is hydrolyzed heating, then by oil extraction treatment, three-phase water is sent to anaerobic water tank and is stored and cooled;(3), wastewater is added to hydrolysis ammonification tank and is hydrolyzed ammonification, (4), wastewater is treated anaerobically, and sludge is removed from biogas liquid, and sludge removal clear liquid is sent to membrane bioreactor, and anaerobic sludge is sent to sludge tank and is stored, (5), anaerobic sludge is mixed with wastewater and added to hydrolysis ammonification tank and is secondary hydrolyzed ammonification, (6), water is separated from solid, and disc separation clear liquid is used as carbon source, (7), clear liquid and disc separation clear liquid are added to denitrification pool of membrane bioreactor and are biochemical reaction.The present application can ensure higher ammoniation rate without additional alkali intervention, ammoniated water can be used as carbon source of biochemical system, can greatly reduce processing cost, realize maximum economic resource utilization.

Description

TECHNICAL FIELD

[0001] The present application relates to a kitchen waste treatment method, belonging to the kitchen waste treatment technical field. BACKGROUND

[0002] Kitchen waste generally includes food waste, kitchen waste, market residue and other waste. Kitchen waste has high water content, high organic matter content and complex composition, and is difficult to handle. The kitchen waste treatment technology has aerobic composting, domestic waste incineration and direct landfill and other ways. The disadvantage of aerobic composting is that due to the high water content in kitchen waste and the high salt and oil content, the utilization of compost products is difficult. In addition, kitchen waste is rich in organic matter and other nutrients, and incineration and landfill treatment not only causes secondary pollution to the environment, but also causes resource waste.

[0003] The currently widely used centralized kitchen waste treatment method is to pretreat the kitchen waste by primary separation, fine separation, pulping and the like, then enter the oil extraction unit, the extracted biomass oil can be used as fuel, and the organic slurry after oil extraction enters anaerobic fermentation to produce biogas, and the produced biogas is used for power generation. As disclosed in CN111992566 A, a kitchen waste treatment method, the kitchen waste is separated to obtain slurry and mixed with diluent to make slurry, then impurities are removed to separate solid residue and slurry; the slurry after impurity removal is heated, then separated to obtain oil phase product, solid residue and slurry; the slurry after oil removal is subjected to acid fermentation, then subjected to alkaline fermentation to obtain biogas slurry and biogas; the obtained biogas slurry is subjected to solid-liquid separation to obtain solid residue and wastewater, the obtained wastewater is subjected to biochemical treatment and filtration, and the effluent is discharged to realize maximum utilization of resources in the kitchen waste treatment process.

[0004] Generally, kitchen wastewater is all used for anaerobic biogas production for power generation, except for self-use in the factory area, the remaining part is connected to the national power grid to obtain subsidies. Anaerobic biogas production is divided into four steps: hydrolysis, acidification / ammonification, hydrogen production and acetic acid production, and methane production. After anaerobic biogas production, 90% of COD is converted into methane, and 90% of organic nitrogen is converted into ammonia nitrogen, and then the wastewater is subjected to biochemical treatment. However, carbon source needs to be consumed during anaerobic treatment, which leads to imbalance of carbon and nitrogen ratio in the anaerobic effluent, and a large amount of externally purchased carbon source, such as methanol and sodium acetate, needs to be added in the subsequent biochemical treatment stage, which is actually a process of energy consumption and replenishment.

[0005] The three-phase wastewater after oil removal has excellent carbon-nitrogen ratio, and can be used as a carbon source. Meanwhile, the wastewater is taken from kitchen waste, and is stable and sufficient in source, without additional purchase cost. However, the kitchen waste mainly contains organic matters, and nitrogen mainly exists in the form of organic nitrogen. Directly entering the biochemical system will increase the organic load, and cannot be degraded into ammonia nitrogen within the designed residence time. Since the problem of accumulation of organic nitrogen cannot be solved, there is still a risk of high organic nitrogen after ultrafiltration and nanofiltration, so that the effluent cannot meet the standard, and therefore only a small part of the three-phase effluent can be added to replace a small part of the carbon source, instead of maximizing the resource utilization.

[0006] As the first two steps of the anaerobic reaction, the hydrolysis acidification will cause acidification and ammoniation reaction, and make the organic nitrogen change to ammonia nitrogen. Meanwhile, the system pH needs to be controlled to control the anaerobic reaction in the first two steps. The kitchen waste is acidic, and the separate hydrolysis acidification needs to continuously add an external alkali to adjust the pH, so as to ensure the forward reaction. However, the cost of the alkali agent is large, and the enterprise cannot afford it. Therefore, it is of great significance to solve the problems of difficult acidification and ammoniation of the kitchen waste, and to save energy and reduce emissions and resource utilization of waste. SUMMARY

[0007] The purpose of the present application is to provide a kitchen waste treatment method, which separately performs anaerobic treatment and hydrolysis ammoniation treatment,

[0008] Without external alkali intervention, the ammonia rate can be ensured to be high, the ammoniated effluent can be used as a carbon source for the biochemical system, the treatment cost can be greatly reduced, and the maximum economic resource utilization can be realized.

[0009] The technical scheme for achieving the above purpose is as follows: a kitchen waste treatment method, characterized by comprising the following steps:

[0010] 1. Pretreatment: the kitchen waste is poured into a stock bin, and then is sent to a large material sorting machine for crushing and sorting. The sorted coarse material liquid is sent to a fine sorting machine for further crushing and sorting. The sorted slurry has a particle size of less than or equal to 8 mm. The impurities sorted out by the large material sorting machine and the fine sorting machine are discharged. The sorted slurry and the stock bin leachate are sent to a sand and slag removal system to remove sand and slag;

[0011] 2. Oil extraction treatment: the slurry after sand removal is sent to a high-temperature heating tank for hydrolysis heating. The high-temperature hydrolysis temperature is between 80-90 DEG C, and the heating time is 1-2 h. The slurry is sterilized. The slurry after hydrolysis is sent to a three-phase centrifugal oil extractor for oil extraction treatment. The crude oil is discharged to a crude oil tank, and the three-phase effluent is sent to an anaerobic water tank for storage and cooling;

[0012] (4) Primary ammonification treatment: the wastewater in the anaerobic water inlet tank is added to the hydrolytic ammonification tank for hydrolytic ammonification, wherein the temperature during the hydrolytic ammonification is 37-42℃, the pH is 7.0±0.1, and the primary hydrolytic ammonification is completed in 10-12 days. During the primary hydrolytic ammonification, the hydrolytic ammonification tank does not have water inlet and water outlet;

[0013] (7) Anaerobic treatment: the wastewater in the anaerobic water inlet tank is sent to the anaerobic digestion tank for anaerobic treatment. The pH of the wastewater during the anaerobic treatment is 7.0-8.0. The biogas is generated for power generation after the anaerobic treatment of the wastewater. The sludge in the anaerobic digestion tank after being retained for 30-45 days is de-sludged. The clear liquid after the de-sludging is sent to the membrane bioreactor. The anaerobic sludge discharged is sent to the sludge tank for storage. Part of the anaerobic sludge is backflowed to the anaerobic digestion tank;

[0014] (8) Continuous ammonification treatment: the anaerobic sludge and the wastewater are mixed uniformly at a mass ratio of 1-1.5:10, and then added to the hydrolytic ammonification tank for secondary hydrolytic ammonification. The anaerobic sludge is used to provide alkalinity and microorganisms during the hydrolytic ammonification. The temperature during the secondary hydrolytic ammonification is controlled at 25-30℃, the pH is 5.5-6.0, and the SS is 40,000-50,000 mg / L. The volume ratio of the water inlet amount of the hydrolytic ammonification tank to the water inlet amount of the anaerobic digestion tank is 4-3:6-7;

[0015] (9) Ammonification wastewater solid-liquid separation treatment: the effluent after the secondary hydrolytic ammonification is sent to a disc separator for solid-liquid separation to remove the suspended solids in the secondary hydrolytic ammonification wastewater. The clear liquid of the disc separation is sent to the membrane bioreactor as a carbon source. The concentrated liquid of the disc separation is backflowed to the hydrolytic ammonification tank to supplement the sludge concentration. The removal rate of the suspended solids is >90%;

[0016] (10) Biochemical treatment: the clear liquid and the disc separation clear liquid are added to the denitrification tank of the membrane bioreactor. The wastewater is first subjected to continuous plug flow aeration for denitrification in the denitrification tank, and then flows into the nitrification tank by itself for nitrification reaction by air blowing. The wastewater after the nitrification reaction is lifted by a delivery pump to a membrane filtration assembly for sludge-water separation. The clear effluent after the separation is discharged up to the standard. The concentrated liquid is backflowed to the denitrification tank.

[0017] The kitchen waste treatment method adopts pretreatment, oil extraction treatment, primary ammoniation treatment, anaerobic treatment, continuous ammoniation treatment, and ammoniated wastewater solid-liquid separation treatment and biochemical treatment, the three-phase effluent after oil extraction is subjected to anaerobic treatment and ammoniation treatment, on the one hand, the wastewater is subjected to anaerobic treatment to realize biogas production and power generation, on the other hand, the wastewater after ammoniation treatment is used as a carbon source to replace purchased carbon sources such as methanol, the system ph is maintained, no additional alkali intervention is needed, and the reagent cost is greatly saved. Hydrolysis and ammoniation culture can be carried out as a carbon source to replace or even completely replace purchased carbon sources such as methanol, and the carbon source income of kitchen wastewater is much higher than the income brought by grid-connected power generation, so that the kitchen waste can be completely self-sufficient, the treatment cost is greatly reduced, and the most economic resource utilization is realized.

[0018] The anaerobic biogas production and power generation can realize resource utilization of most of the kitchen waste, and the kitchen three-phase wastewater is subjected to hydrolysis and ammoniation treatment, the kitchen three-phase wastewater and the anaerobic sludge are blended to realize co-ammoniation, the high ammoniation rate can be ensured without additional alkali intervention, and the COD is not lost in the biogas production stage, so the ammoniated effluent can be used as a carbon source for biochemical treatment of the anaerobic biogas.

[0019] The ammoniation treatment adopts primary ammoniation treatment and continuous ammoniation treatment, under the activity of ammonification bacteria, organic nitrogen is first converted into ammonia nitrogen through microbial decomposition and hydrolysis when the wastewater is subjected to hydrolysis and acidification in the primary ammoniation treatment, and the best ammoniation data of hydrolysis and acidification of the kitchen waste after oil removal is obtained, which provides reliable treatment parameters for the subsequent continuous ammoniation treatment, then in the continuous ammoniation treatment, the anaerobic sludge produced after anaerobic treatment is continuously blended and added to the wastewater to realize continuous hydrolysis and ammoniation, the suspended solids concentration and temperature of the wastewater in the hydrolysis and ammoniation tank are adjusted to a certain range by using the anaerobic sludge, the growth of methanogenic bacteria is inhibited, there is no risk of biogas production, the wastewater pH is easily controlled in 5.5-6.0, the activity of ammonification bacteria is ensured, the balance between ammoniation and acidification is achieved, and the ammoniation rate is improved.

[0020] The application adopts primary ammoniation treatment, continuous ammoniation treatment and solid-liquid separation treatment of ammoniated wastewater, and through the hydrolytic ammoniation of the primary ammoniation treatment, part of the organic nitrogen is converted into ammonia nitrogen, and then through the continuous ammoniation treatment, part of the organic nitrogen in the wastewater is further converted into ammonia nitrogen, so that the problem of slow degradation rate of organic nitrogen in the aerobic section is fundamentally solved, finally, through the disc separator for solid-liquid separation, the macromolecular organic nitrogen in the wastewater can be removed, since the wastewater after hydrolytic ammoniation has a high carbon-nitrogen ratio and the ammoniation rate is as high as 80%, the final effluent ensures the form of high COD, low organic nitrogen and high ammonia nitrogen, and is added to the biochemical treatment system, so that the problem of organic nitrogen accumulation caused by direct addition of three-phase wastewater is solved, ammonia nitrogen is easier to treat than organic nitrogen in biochemical treatment, and the sludge discharge capacity of the biochemical tank is not increased. The addition amount of the wastewater after hydrolytic ammoniation of the application is more than the direct addition amount of three-phase effluent, so the amount of replaceable methanol is also more, even completely replaced, the problem that three-phase effluent cannot be added too much is perfectly solved, the treatment cost is greatly reduced, the maximum economic resource utilization is realized, and the maximization of resources is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0021] The embodiments of the application will be further described in detail below with reference to the accompanying drawings.

[0022] Figure 1 is a flow chart of the kitchen waste treatment method of the application.

[0023] Figure 2 is a curve diagram of the change of ammonia nitrogen and total nitrogen after the primary ammoniation treatment of the application.

[0024] Figure 3 is a curve diagram of the change of pH, ammonia nitrogen and total nitrogen in the continuous ammoniation treatment of the application.

[0025] Figure 4 is a curve diagram of the change of COD and VFA in the continuous ammoniation treatment of the application. DETAILED DESCRIPTION

[0026] See Figure 1 The kitchen waste treatment method of the application, as shown in the figure, comprises the following steps:

[0027] 1. Pretreatment: pour the kitchen waste into the stock bin, then send it to the large material sorting machine for crushing and sorting, the coarse slurry after sorting is sent to the fine sorting machine for further crushing and sorting, the particle size of the slurry after sorting is ≤8mm, and the impurities sorted out by the large material sorting machine and the fine sorting machine are discharged. The present application adopts the existing large material sorting machine and fine sorting machine, such as the large material sorting machine and fine sorting machine of the company, the inert large impurities in the kitchen waste are scattered without crushing by the large material sorting machine, at the same time, the inert impurities are rubbed by the multiple stripping conveying knives, the oil-water mixture and part of the organic matter attached to the inert impurities are stripped and pushed to the outlet direction, the sorted slurry is filtered by the coarse steel screen plate and flows into the coarse slurry temporary storage bin below, and the inert impurities after sorting are landfilled or incinerated. The organic matter in the coarse slurry entering the fine sorting machine is cut and crushed, the crushed slurry flows into the fine slurry temporary storage bin below through the fine steel screen plate, and the light impurities sorted out are thrown out and can be incinerated or used as raw material for insect breeding.

[0028] The slurry after sorting and the dewatering of the stock bin are sent to the sand and slag removal system to remove sand and slag. The sand and slag removal system of the present application adopts a sand filter to intercept sand, colloid and suspended matter in the slurry, and the sand and slag are landfilled or incinerated.

[0029] 2. Oil extraction treatment: send the slurry after sand removal into a high-temperature heating tank for hydrolysis and heating. The slurry can be stirred by the electric stirring mechanism on the high-temperature heating tank, steam is introduced to make the slurry and steam mix quickly and heat uniformly. The high-temperature hydrolysis temperature of the present application is between 80-90℃, and the heating time is 1-2h. The slurry is sterilized to ensure complete hydrolysis and sterilization, to kill insect eggs without affecting anaerobic microorganisms. The slurry after hydrolysis is sent to a three-phase centrifugal oil extractor for oil extraction treatment. The crude oil is discharged to a crude oil tank, and the extracted oil can be further prepared into biodiesel or other chemical products according to demand, realizing resource utilization. The three-phase water is sent to an anaerobic water inlet tank for storage and cooling, and the three-phase solid slag is landfilled or used as raw material for insect breeding.

[0030] The water quality of the three-phase water after oil extraction treatment of the present application has pH of 3.5-4.0, COD of 110000-130000mg / L, ammonia nitrogen of 100-200mg / L, TN of 3000-3500mg / L, VFA of 8000-12000mg / L, and SS of 30000-40000mg / L.

[0031] (3) Initial ammoniation treatment: Add the wastewater in the anaerobic water inlet tank to the hydrolysis and ammoniation tank for hydrolysis and ammoniation. A sufficient amount of wastewater can be added to the hydrolysis and ammoniation tank for initial hydrolysis and ammoniation. The temperature during hydrolysis and ammoniation is 37-42°C, the pH is 7.0±0.1, and the initial hydrolysis and ammoniation is completed in 10-12 days. During the initial hydrolysis and ammoniation, the hydrolysis and ammoniation tank does not enter or discharge water. During the initial hydrolysis and ammoniation, the present invention adds sodium hydroxide 1-2 times a day to control the pH of the wastewater at 7.0±0.1. Under the active action of ammonifying bacteria, organic nitrogen is converted into ammonia nitrogen through microbial decomposition and hydrolysis, and the optimal ammoniation data of the hydrolysis and acidification process of the three-phase effluent is obtained. After subsequent continuous ammoniation treatment, the activity of methanogens can be effectively inhibited during the continuous hydrolysis and acidification process of the wastewater, thereby improving the ammoniation rate.

[0032] The water quality after the initial hydrolysis and ammoniaation of the present invention has a pH of 7.0±0.1, a COD of 110,000-130,000 mg / L, ammonia nitrogen of 1,200-1,500 mg / L, TN of 3,000-3,500 mg / L, VFA of 25,000-30,000 mg / L, and SS of 25,000-30,000 mg / L.

[0033] (4) Anaerobic treatment: The wastewater in the anaerobic water inlet tank is sent to the anaerobic digestion tank for anaerobic treatment. The present invention can anaerobically treat 60-70% of the wastewater every day, and the remaining 30-40% of the wastewater enters the hydrolysis and amination tank for hydrolysis and amination. During the anaerobic treatment of the present invention, the pH of the wastewater is 7.0-8.0, and the wastewater produces biogas and electricity after anaerobic digestion. Under anaerobic conditions in the wastewater in the anaerobic digestion tank, the organic matter in the wastewater is metabolized by microorganisms, accompanied by the production of methane and CO2. The conversion action of anaerobic microorganisms is used to decompose most of the biodegradable organic matter in the wastewater and convert it into biogas. The present invention desludges the biogas slurry after it has stayed in the anaerobic digester for 40 to 45 days, and can use a horizontal screw centrifuge to separate the solid and liquid of the biogas slurry. The clear liquid after desludge is sent to the membrane bioreactor, and the clear liquid after desludge does not increase the sludge discharge amount of the biochemical pool. The removed anaerobic sludge is sent to the sludge tank for storage, and part of the anaerobic sludge is returned to the anaerobic digester to maintain the anaerobic sludge concentration of the anaerobic digester.

[0034] After anaerobic treatment, the biogas slurry has a water quality of pH 7.0-8.0, COD 10,000-20,000 mg / L, ammonia nitrogen 2,800-3,000 mg / L, TN 3,000-3,500 mg / L, VFA 1,000-3,000 mg / L, and SS 18,000-23,000 mg / L.

[0035] (5) Continuous ammoniation treatment: Anaerobic sludge and wastewater are mixed uniformly in a mass ratio of 1 to 1.5:10 and then added to a hydrolysis and ammoniation tank for secondary hydrolysis and ammoniation. The anaerobic sludge is used to provide alkalinity and microorganisms during hydrolysis and ammoniation. The temperature during secondary hydrolysis and ammoniation is controlled at 25°C to 30°C, the pH is 5.5 to 6.0, and the SS is 40,000 to 50,000 mg / L. The suspended matter concentration and pH value in the hydrolysis and ammoniation tank are adjusted by anaerobic sludge, and the reaction temperature of the wastewater is controlled at the same time. The wastewater and anaerobic sludge are mixed to achieve co-ammoniation, thereby inhibiting the growth of methanogens while ensuring the activity of ammonifying bacteria, achieving a balance between ammoniation and acidification, and further converting organic nitrogen in the wastewater into ammonia nitrogen, thereby improving the ammoniation effect. The volume ratio of the water inlet of the hydrolysis and ammoniation tank to the water inlet of the anaerobic digestion tank of the present invention is between 4 to 3:6 to 7, which can use more ammoniated wastewater as a carbon source and maximize the economic benefits of waste resources. The anaerobic sludge in the sludge tank and the wastewater in the anaerobic water inlet tank are added to the ammonia inlet tank at a mass ratio of 1.1-1.4:10, stirred evenly in the ammonia inlet tank, and then pumped to the hydrolysis ammonia tank.

[0036] After the continuous ammoniation treatment of the present invention, the water quality of the secondary hydrolysis and ammoniation effluent is as follows: COD is 110,000-130,000 mg / L, ammonia nitrogen is 1,200-1,500 mg / L, TN is 3,000-3,500 mg / L, VFA is 25,000-30,000 / L, and SS is 40,000-50,000 mg / L. The ammoniated wastewater has a relatively high COD.

[0037] (6) Solid-liquid separation treatment of ammoniated wastewater: The effluent from the secondary hydrolysis and ammoniated wastewater is sent to a disc separator for solid-liquid separation to remove suspended solids in the secondary hydrolysis and ammoniated wastewater. The clear liquid from the disc is sent to the biochemical treatment system as a carbon source. Part of the clear liquid from the disc can also be stored and sold externally. The concentrated liquid from the disc is returned to the hydrolysis and ammoniated tank to replenish the sludge concentration, with a suspended solid removal rate of >90%. The present invention uses a disc separator to remove large molecular organic nitrogen from the wastewater, achieving a solid suspended solid (SS) removal rate of >90% in the ammoniated wastewater, and an ammoniated rate of over 80%. This method does not increase the amount of sludge discharged in subsequent biochemical treatment. The effluent from the ammoniated wastewater can form an excellent carbon source, significantly reducing treatment costs and the operating load of the biochemical treatment system. The disc separator of the present invention is a nozzle-type separator, which can process wastewater with high suspended matter. The concentrated liquid is returned to the hydrolysis and amination tank to adjust the sludge concentration. The disc separator regularly discharges sludge every 3 to 5 days and adds it to the anaerobic digestion tank, and the sludge is pumped into the anaerobic digestion tank to produce biogas.

[0038] The water quality of the water separated by the disc separator has pH of 5.5-6.0, COD of 80000-100000 mg / L, ammonia nitrogen of 1200-1500 mg / L, TN of 1400-1700 mg / L, VFA of 25000-30000 mg / L, and SS of 1000-2000 mg / L, so that the ammonia wastewater is greatly reduced in TN and high COD after the solid-liquid separation by the disc separator, and the ammonia wastewater can replace commercial carbon sources such as methanol, sodium acetate and glucose.

[0039] ⑺, biochemical treatment: the clear liquid and the disc-separated clear liquid are added into the denitrification tank of the membrane bioreactor to improve the C / N ratio in the wastewater, and the disc-separated clear liquid replaces the carbon source such as methanol. The membrane bioreactor of the present application is an integrated membrane bioreactor, the wastewater is subjected to continuous plug flow aeration for denitrification in the denitrification tank, and then flows into the nitrification tank by itself, and is subjected to nitrification reaction by air blowing aeration, the wastewater after the nitrification reaction is lifted by a delivery pump and is subjected to sludge-water separation in the membrane filtration unit, the filtered clear liquid is discharged, and the filtered concentrated liquid is returned to the denitrification tank. The sludge concentration in the denitrification tank and the sludge concentration in the nitrification tank are 15-30 g / L. The membrane filtration assembly of the present application can adopt an ultrafiltration assembly and a nanofiltration assembly, the wastewater after the nitrification reaction is subjected to sludge-water separation by the ultrafiltration membrane assembly, the treated ultrafiltration concentrated liquid is returned to the denitrification tank, and the clear liquid is sent to the nanofiltration assembly for filtration treatment, the clear liquid after the nanofiltration is discharged, the water quality of the nanofiltration clear liquid has pH of 6.0, COD < 230 mg / L, ammonia nitrogen < 0.4 mg / L, TN < 55 mg / L, and SS < 5 mg / L, the nanofiltration concentrated liquid is returned to the denitrification tank of the MBR membrane bioreactor, or can be discharged for treatment. When the wastewater is subjected to biochemical treatment, no additional carbon source is needed, and the treatment cost is greatly reduced. Embodiment

[0040] ⑴, the kitchen waste is poured into the stock bin, and then is sent to the large material sorting machine for crushing and sorting, the sorted coarse material liquid is sent to the fine sorting machine for further crushing and sorting, the particle size of the sorted slurry is ≤8 mm, the impurities sorted out by the large material sorting machine are discharged for landfill or incineration, the impurities sorted out by the fine sorting machine are discharged for incineration or insect breeding, and the sorted slurry and the leachate of the stock bin are sent to the sand filter to intercept sand, colloid and suspended solids in the slurry.

[0041] ⑵, the slurry after sand removal is sent to the high-temperature heating tank, steam is introduced into the high-temperature heating tank to heat the slurry, and the slurry is stirred to ensure that the sterilization of the slurry is completed, the specific treatment parameters are shown in Table 1, the hydrolyzed slurry is sent to the three-phase centrifugal oil extractor for oil extraction treatment, the crude oil is discharged to the crude oil tank for sale, the three-phase water is sent to the anaerobic water tank for storage and cooling, and the three-phase solid residue is incinerated or bred into insects, and the water quality of the three-phase water is shown in Table 2.

[0042] Table 1

[0043] Item Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Hydrolysis temperature (℃) 80 82 85 86 88 90 Heating time (t) 1 1.2 1.5 1.6 1.8 2

[0044] Table 2

[0045] Item Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 pH 3.5 3.6 3.7 3.8 3.9 4.0 COD (mg / L) 110000 115000 125000 120000 130000 130000 TN (mg / L) 3000 3100 3200 3300 3400 3500 Ammonia nitrogen (mg / L) 100 120 140 160 180 200 VFA (mg / L) 8000 9000 10000 11000 11500 12000 ss (mg / L) 40000 38000 36000 34000 32000 30000

[0046] (3) Add sufficient amount of wastewater in the anaerobic water inlet tank to the hydrolysis and amination tank for initial hydrolysis and amination, and add sodium hydroxide to control the pH of the hydrolysis and amination. The specific treatment parameters are shown in Table 3, and the water quality of the initial hydrolysis and amination is shown in Table 4. After the initial stage of amination reaction is completed, enter the continuous amination treatment. Figure 2 As shown in the figure, the changes in the indicators of ammonia nitrogen and total nitrogen with reaction time during the initial ammoniation treatment of the present invention show that in the initial hydrolysis and ammoniation process, organic nitrogen is gradually converted into ammonia nitrogen. At the same time, ammonia nitrogen is proportional to the residence time, gradually increasing from 100-200 mg / L to 1300-1400 mg / L and then tending to be flat, while total nitrogen does not change much.

[0047] Table 3

[0048] Item Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Hydrolysis and ammonification temperature (℃) 37 39 40 41 38 42 pH 6.9 7 7 7 7 7.1 Dosing frequency (times / d) 1 2 2 1 1 2 Hydrolysis and ammonification time (d) 12 11.5 11 10.5 11 10

[0049] Table 4

[0050] Item Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 pH 7.0 6.9 7.0 7.1 7.0 6.9 COD (mg / L) 110000 115000 125000 120000 130000 130000 TN (mg / L) 3000 3100 3200 3300 3400 3500 Ammonia nitrogen (mg / L) 1200 1250 1300 1350 1400 1500 VFA (mg / L) 25000 27000 26000 28000 29000 30000 ss (mg / L) 25000 26000 27000 28000 29000 30000

[0051] (4) The wastewater in the anaerobic inlet tank is fed into the anaerobic digester for anaerobic treatment. 60-70% of the wastewater is added to the anaerobic inlet tank daily to generate biogas and generate electricity. The specific anaerobic treatment parameters are shown in Table 5. After anaerobic digestion, the wastewater generates biogas and generates electricity. The biogas slurry, which has been in the anaerobic digester for 40-45 days, is desludged. The desludged clear liquid is fed to the membrane bioreactor. The removed anaerobic sludge is sent to the sludge tank for storage. Part of the anaerobic sludge is returned to the anaerobic digester. The biogas slurry water quality is shown in Table 6.

[0052] Table 5

[0053] Item Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Anaerobic influent amount (%) 70 68 65 64 62 60 pH 7.0 7.2 7.4 7.6 7.8 8.0 Biogas slurry residence time (d) 40 41 42 43 44 45

[0054] Table 6

[0055] Item Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 pH 7.0 7.2 7.4 7.6 7.8 8.0 COD (mg / L) 10000 12000 14000 16000 18000 20000 TN (mg / L) 3000 3300 3400 3300 3100 3500 Ammonia nitrogen (mg / L) 2800 2850 2900 2950 2950 3000 VFA (mg / L) 1000 2000 2500 2000 1500 3000 ss (mg / L) 18000 19000 20000 21000 22000 23000

[0056] ⑸. After the anaerobic sludge and wastewater are evenly mixed, add them to the hydrolysis and amination tank for secondary hydrolysis and amination. Every day, 30-40% of the wastewater and anaerobic sludge are fully mixed in the ammonia inlet tank according to the proportion, and then added to the hydrolysis and ammonia tank for continuous ammonia. The specific treatment parameters of the secondary hydrolysis and ammonia are shown in Table 7, and the water quality after the secondary hydrolysis and ammonia is shown in Table 8. Figure 3-4As shown, the indexes of the secondary hydrolysis ammoniation of the present application and the index change of the reaction time, in the continuous in-out process of the secondary ammoniation, the organic nitrogen part in the newly added wastewater can stably realize continuous ammoniation, the ammonia nitrogen can be maintained at 1200-1500 mg / L, the VFA is at 25000 mg / L-30000 mg / L, the pH range is at 5.5-6.0, and the COD is at 110000-130000 mg / L.

[0057] Table 7

[0058] Item Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Secondary hydrolysis and ammonification influent amount (%) 30 32 35 36 38 40 Anaerobic sludge to wastewater mass ratio 1:10 1.1:10 1.2:10 1.3：10 1.4：10 1.5：10 pH 5.5 5.6 5.7 5.8 5.9 6.0 Ammonification temperature (℃) 25 26 27 29 28 30 Hydrolysis and ammonification time 12 11.5 11 10.5 11 10 ss (mg / L) 40000 42000 44000 46000 48000 50000

[0059] Table 8

[0060] Item Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 pH 5.5 5.6 5.7 5.8 5.9 6.0 COD (mg / L) 110000 115000 125000 120000 130000 130000 TN (mg / L) 3000 3100 3200 3300 3400 3500 Ammonia nitrogen (mg / L) 1200 1300 1400 1400 1450 1500 VFA (mg / L) 25000 26000 27000 28000 29000 30000 ss (mg / L) 40000 42000 44000 46000 48000 50000

[0061] ⑹, the effluent after secondary hydrolysis ammoniation is sent to a disc separator for solid-liquid separation, and the suspended solids in the secondary hydrolysis ammoniation wastewater are removed, the disc separation clear liquid is sent to a biochemical treatment system as a carbon source, and the disc separation concentrated liquid is returned to the hydrolysis ammoniation tank for supplementing sludge concentration, and the sludge is discharged into an anaerobic tank for biogas production and power generation at regular intervals, and the water quality of the disc separation clear liquid is shown in Table 9.

[0062] Table 9

[0063] Item Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 pH 5.5 5.6 5.7 5.8 5.9 6.0 COD (mg / L) 80000 85000 90000 95000 98000 100000 TN (mg / L) 1400 1450 1500 1550 1650 1700 Ammonia nitrogen (mg / L) 1200 1300 1400 1400 1450 1500 VFA (mg / L) 25000 26000 27000 28000 29000 30000 ss (mg / L) 1000 1200 1400 1600 1800 2000

[0064] ⑺, biochemical treatment: the clear liquid and the disc separation clear liquid are added to the denitrification tank of the membrane bioreactor, and the insufficient part is replaced by a commercial carbon source, the nutrient ratio in the wastewater can be adjusted, the nitrate nitrogen in the activated sludge is converted into nitrogen gas, the wastewater is first subjected to continuous push flow aeration for denitrification in the denitrification tank, then the wastewater is self-flowed into the nitrification tank, and subjected to nitrification reaction by air blowing aeration, the wastewater after nitrification is discharged after reaching the standard after ultrafiltration and nanofiltration, the ultrafiltration concentrated liquid is returned to the denitrification tank, and the nanofiltration concentrated liquid can be returned to the denitrification tank or treated externally, and the water quality of the external discharge water is shown in Table 10.

[0065] Table 10

[0066] Item Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 pH 6.5 6.5 6.5 6.5 6.5 6.5 COD (mg / L) 200 190 140 230 210 190 TN (mg / L) 50 52 46 34 52 48 Ammonia nitrogen (mg / L) 0 0.1 0.4 0 0.2 0.4 ss (mg / L) 0 0 0 0 0 0

[0067] The income of each embodiment of the kitchen waste treatment method of the present application is shown in Table 11. Comparative Example 1 is to directly add 10% of the three-phase effluent as a carbon source into the membrane bioreactor, and 90% of the three-phase effluent is used for biogas production and power generation; Comparative Example 2 is to use the treatment method of the present application, 90% of the three-phase effluent is used for anaerobic treatment for biogas production and power generation, and 10% of the three-phase effluent is mixed with anaerobic sludge and then enters the continuous ammoniation treatment and is used as a carbon source into the membrane bioreactor for biochemical treatment of the kitchen wastewater. The specific cost data of the treatment is shown in Table 11. It can be seen that when the hydrolysis and ammoniation influent amount of the continuous ammoniation treatment is 35%, the total income is the highest, which is 8400 yuan / day, and the methanol is fully replaced. Increasing the hydrolysis and ammoniation influent amount will not only reduce the total income, but also increase the risk of exceeding the standard of COD after biochemical treatment. The income obtained by the treatment method of the present application is more than twice the income of Comparative Examples 1 and 2, and the kitchen waste treatment effect and economic income are balanced, which has important significance for energy saving and emission reduction and waste resource utilization.

[0068] Table 11

[0069] Item Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Anaerobic cost (yuan / day) 3000 2920 2800 2760 2680 2600 3782 3800 Carbon source cost (yuan / day) 1200 670 0 0 0 0 5400 5400 Power generation income (yuan / day) 11400 11310 11200 11130 11040 10950 12100 12200 Total income (yuan / day) 7200 7720 8400 8370 8360 8350 2920 3000

Claims

1. A method for treating kitchen waste, characterized in that: The following steps are involved: ⑴. Pretreatment: Pour the kitchen waste into the silo, and then send it to the coarse material sorter for crushing and sorting. The coarse material liquid after sorting is sent to the fine sorter for further crushing and sorting. The particle size of the slurry after sorting is ≤8mm. The debris sorted by the coarse material sorter and the fine sorter is discharged. The sorted slurry and the drain water from the silo are sent to the sand and slag removal system to remove sand, gravel and scum; (2) Oil extraction treatment: The slurry after sand removal is sent to a high-temperature heating tank for hydrolysis and heating. The high-temperature hydrolysis temperature is between 80 and 90 ° C, and the heating time is 1 to 2 hours. The slurry is sterilized and the hydrolyzed slurry is sent to a three-phase centrifugal oil extractor for oil extraction treatment. The crude oil is discharged to the crude oil tank, and the three-phase effluent is sent to the anaerobic water inlet tank for storage and cooling. (3) Initial ammoniation treatment: Add the wastewater in the anaerobic water inlet tank to the hydrolysis and ammoniation tank for hydrolysis and ammoniation. The temperature during the hydrolysis and ammoniation is 37-42°C, the pH is 7.0±0.1, and the initial hydrolysis and ammoniation is completed in 10-12 days. During the initial hydrolysis and ammoniation, no water enters or exits the hydrolysis and ammoniation tank. (4) Anaerobic treatment: The wastewater in the anaerobic water inlet tank is sent to the anaerobic digester for anaerobic treatment. The pH of the wastewater during anaerobic treatment is 7.0-8.

0. After anaerobic digestion, the wastewater produces biogas and generates electricity. The biogas slurry that has been in the anaerobic digester for 30-45 days is desludged. The clear liquid after desludge is sent to the membrane bioreactor. The anaerobic sludge removed is sent to the sludge tank for storage, and part of the anaerobic sludge is returned to the anaerobic digester; (5) Continuous ammoniation treatment: the anaerobic sludge and the wastewater in the anaerobic water inlet tank are mixed uniformly in a mass ratio of 1 to 1.5:10, and then added to the hydrolysis and ammoniation tank for secondary hydrolysis and ammoniation. The anaerobic sludge is used to provide alkalinity and microorganisms during hydrolysis and ammoniation. The temperature during the secondary hydrolysis and ammoniation is controlled at 25°C to 30°C, the pH is 5.5 to 6.0, and the SS is 40,000 to 50,000 mg / L. The volume ratio of the water inlet of the hydrolysis and ammoniation tank to the water inlet of the anaerobic digestion tank is between 4 and 3:6 and 7. (6) Solid-liquid separation treatment of ammoniated wastewater: The effluent from the secondary hydrolysis and ammoniated process is sent to a disc separator for solid-liquid separation to remove suspended solids from the secondary hydrolysis and ammoniated wastewater. The clear liquid from the disc is sent to the membrane bioreactor as a carbon source, and the concentrated liquid from the disc is returned to the hydrolysis and ammoniated tank to replenish the sludge concentration. The suspended solids removal rate is >90%; ⑺. Biochemical treatment: The clear liquid and the disc clear liquid are added to the denitrification tank of the membrane bioreactor. The wastewater is first subjected to continuous push flow aeration in the denitrification tank for denitrification, and then the wastewater is gravity-flowed into the nitrification tank for nitrification reaction through blower aeration. The wastewater after nitrification reaction is lifted by a delivery pump and transported to the membrane filter assembly for mud-water separation. The separated clear liquid effluent meets the discharge standards, and the concentrated liquid is returned to the denitrification tank.

2. A method for treating kitchen waste according to claim 1, characterized in that: In the second step, the water quality of the three-phase effluent is as follows: pH 3.5-4.0, COD 110,000-130,000 mg / L, ammonia nitrogen 100-200 mg / L, TN 3,000-3,500 mg / L, VFA 8,000-12,000 mg / L, and SS 30,000-40,000 mg / L.

3. The method for treating kitchen waste according to claim 1, wherein: In the third step, sodium hydroxide is added 1 to 2 times a day to control the pH of the wastewater at 7.0 ± 0.

1.

4. The method for treating kitchen waste according to claim 1, wherein: In the third step, the water quality after the initial hydrolysis and ammoniaation is as follows: pH 7.0±0.1, COD 110,000-130,000 mg / L, ammonia nitrogen 1,200-1,500 mg / L, TN 3,000-3,500 mg / L, VFA 25,000-30,000 mg / L, and SS 25,000-30,000 mg / L.

5. The method for treating food waste according to claim 1, wherein: In the fourth step, the water quality of the clear liquid after desludging is 7-8 in pH, 10,000-20,000 mg / L in COD, 2,800-3,000 mg / L in ammonia nitrogen, 3,000-3,500 mg / L in TN, 1,000-3,000 mg / L in VFA, and 18,000-23,000 mg / L in SS.

6. The method for treating kitchen waste according to claim 1, wherein: In the fifth step, the anaerobic sludge in the sludge tank and the wastewater in the anaerobic water inlet tank are added to the ammonia inlet tank at a mass ratio of 1.1 to 1.4:10, and are stirred evenly in the ammonia inlet tank to form mixed wastewater, which is then pumped into the hydrolysis and ammonia tank.

7. The method for treating kitchen waste according to claim 1, wherein: In the fifth step, the water quality of the secondary hydrolysis and ammonia effluent is 5.5-6.0 in pH, 110,000-130,000 mg / L in COD, 1,200-1,500 mg / L in ammonia nitrogen, 3,000-3,500 mg / L in TN, 25,000-30,000 mg / L in VFA, and 40,000-50,000 mg / L in SS.

8. The method for treating food waste according to claim 1, wherein: In the sixth step, the disc separator is a nozzle-type separator, and the disc separator regularly discharges mud every 3 to 5 days and adds the mud into the anaerobic digestion tank.

9. The method for treating food waste according to claim 1, wherein: In the sixth step, the pH of the effluent is 5.5-6.0, COD is 80,000-100,000 mg / L, ammonia nitrogen is 1,200-1,500 mg / L, TN is 1,400-1,700 mg / L, VFA is 25,000-30,000 mg / L, and SS is 1,000-2,000 mg / L.

10. The method for treating food waste according to claim 1, wherein: In the sixth step, the membrane bioreactor is an MBR integrated membrane bioreactor processor.

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