Resourceful treatment process for kitchen waste wastewater

Abstract

The invention discloses a kitchen waste wastewater resourceful treatment process, and belongs to the technical field of kitchen waste resourceful utilization. The treatment process provided by the invention comprises the following steps: adding a ferrate composite oxidant into the kitchen waste wastewater to carry out alkali adjustment and oxidation synchronous treatment, adding biological iron or chemical polyferric sulfate to react, and then adding denitrifying bacteria to carry out denitrification treatment. The treatment process provided by the invention is simple in operation steps and low in treatment cost, and is a kitchen waste resourceful treatment process capable of turning waste into wealth. The COD (Chemical Oxygen Demand) of the treated kitchen waste wastewater is greater than or equal to 50000 mg / L, the content of total nitrogen and total phosphorus is obviously reduced, the content of small molecular organic matters in water is increased, the biodegradability is improved, the requirement of a sewage treatment plant for supplementing a carbon source is met, and the treated kitchen waste wastewater can be used as a carbon source for supplementing the carbon source for the sewage treatment plant.

Description

Technical Field

[0001] The invention belongs to the technical field of resource utilization of restaurant kitchen waste, and specifically relates to a resource treatment process for restaurant kitchen waste wastewater. Background Art

[0002] Restaurant kitchen waste refers to the waste generated in residents' daily life and other activities such as food processing, catering services, and unit catering. Restaurant kitchen waste includes waste edible oils and fats and kitchen waste. Waste edible oils and fats refer to inedible animal and plant oils and various oil-water mixtures, while kitchen waste refers to food residues and food processing waste, mainly solid residues in restaurant kitchen waste. Compared with other waste, restaurant kitchen waste is easy to ferment, deteriorate, and rot to produce a large amount of toxins. If it is not handled in time, it will not only affect the urban environmental sanitation, but also spread diseases and endanger human health.

[0003] The composition of restaurant kitchen waste is special, with high content of water, organic matter, oil and salt. The water content of restaurant kitchen waste is usually between 80-90%. Therefore, the subsequent treatment of restaurant kitchen waste will produce a large amount of wastewater. Restaurant kitchen waste wastewater is a high-concentration organic wastewater, containing a large amount of nutrients such as nitrogen, phosphorus, potassium, amino acids, etc., and has good biodegradability. The COD concentration in the water is generally between 70000-120000 mg / L, and the BOD5 concentration is between 35000-70000 mg / L. Depending on the treatment process, the total nitrogen and total phosphorus content in the wastewater will be different. For example, in the wastewater produced by the traditional restaurant kitchen waste treatment process, the TN concentration is 1500-2500 mg / L and the TP concentration is 50-1200 mg / L; in the wastewater produced by the fermentation treatment process of restaurant kitchen waste, that is, the fermentation liquid, the TN concentration is 3000-6000 mg / L and the TP concentration is 600-1200 mg / L.

[0004] Kitchen wastewater is a high-quality resource, but the conventional treatment method for kitchen wastewater is biochemical treatment plus membrane filtration, which is not only costly, but can only achieve harmless discharge, which is a waste of resources. For example, patent document CN111302559A discloses a method and system for treating kitchen waste fermentation liquid, wherein the treatment method is to first adjust the water quality and water quantity of the kitchen waste fermentation liquid, then centrifuge and dehydrate the adjusted fermentation liquid, and then perform demulsification flocculation treatment, air flotation treatment, primary denitrification reaction, primary nitrification reaction, secondary denitrification reaction and secondary nitrification reaction in sequence, and then perform flocculation precipitation, and then add disinfectant to the supernatant after flocculation precipitation treatment for oxidation reaction, first aerate the liquid after oxidation reaction to remove the disinfectant, and then perform aeration biological treatment on the liquid after the disinfectant is removed, and finally add disinfectant to the liquid after aeration biological treatment for disinfection and then discharge. The treatment method provided by the technical method has many steps and complex processes, and it is impossible to achieve low-cost treatment. Secondly, the substantial purpose of the technical solution is to harmlessly treat the fermented liquid of restaurant kitchen waste, rather than to utilize it as a resource, resulting in a waste of resources. Currently, there is no method for resource-based treatment of the restaurant kitchen waste wastewater.

[0005] In fact, with the large amount of food waste generated in my country every day, a large amount of food waste wastewater is also generated. Providing a low-cost, high-efficiency, and waste-to-treasure food waste wastewater resource treatment method is an effective way to effectively utilize the nutrients in food waste wastewater, and it is also a technical problem that needs to be urgently solved in this field. Summary of the invention

[0006] Based on the above background, the present invention provides an economical and efficient practical process for resource treatment of restaurant kitchen wastewater, the process operation steps are simple, the treatment cost is low, the COD of the treated restaurant kitchen wastewater is ≥50000mg / L, which meets the requirements of supplementing carbon sources in sewage treatment plants, and the ratios of BOD5 / COD, BOD5 / TN, and BOD5 / TP are significantly improved, indicating that the content of small molecular organic matter in the water increases after treatment, and the biodegradability is further increased; the total nitrogen and total phosphorus contents are significantly reduced, and the content of NH3-N is significantly reduced, and the discharge as sewage will not have a significant impact on the water quality of the sewage treatment plant. Therefore, the restaurant kitchen wastewater treated by the process provided by the present invention can be used as a carbon source to meet the needs of carbon source utilization in sewage treatment plants.

[0007] The present invention includes the following technical solutions:

[0008] In a first aspect of the present invention, the present invention provides an application of a treatment agent composition in resource treatment of food waste wastewater, wherein the treatment agent composition is composed of a ferrate composite oxidant, biological iron and denitrifying bacteria.

[0009] The ferrate composite oxidant is prepared by the following method:

[0010] a1) controlling the temperature of the reactor to 40-45° C., stirring and mixing 50% liquid caustic soda and 12% liquid sodium hypochlorite, wherein the mass ratio of the liquid caustic soda to the sodium hypochlorite is (2-3):1;

[0011] a2) slowly adding 40% liquid ferric chloride into the reaction kettle at a stirring speed of 1000-1500 rpm, wherein the added volume of the liquid ferric chloride is 1 / 3-1 / 2 of the liquid sodium hypochlorite, and stirring for 1-2 hours to prepare a ferrate composite oxidant.

[0012] Unless otherwise specified, the "concentration" mentioned in the present invention refers to mass concentration.

[0013] The biological iron is prepared by the following method:

[0014] b1) adding industrial-grade solid ferrous sulfate and water into a bioreactor to form an aqueous solution with a concentration of 400-450 g / L, adding inorganic salts so that the final concentrations in the solution meet (NH4)2SO4 1-1.5 g / L, KCL 0.1-0.2 g / L, K2HPO4 0.2-0.3 g / L, and MgSO4·7H2O 0.2-0.3 g / L, introducing bacterial strains, and preparing a microbial reaction solution, wherein the bacterial strains are a combination of Thiobacillus ferrooxidans and acidophilic bacteria, and the bacterial strain number ratio is (6-9):1;

[0015] b2) Control the dissolved oxygen in the solution to 4-5ppm, the reaction temperature to 20-40℃, and after 24 hours of reaction, when Fe 2+ When the concentration is lower than 0.1%, 30% of the liquid in the bioreactor is discharged and left to mature to obtain bio-iron;

[0016] b3) adding the raw materials described in step S1 to the bioreactor, repeating the reaction of step S2, and continuously circulating to obtain bio-iron.

[0017] The bio-iron prepared by the above method has a total iron content of 1-9%, a basicity of 10-22%, and an appearance of brown viscous liquid. The bio-iron described in the present invention can be replaced by chemically polymerized ferric sulfate with the same iron content. Therefore, chemically polymerized ferric sulfate is an equivalent replacement of the bio-iron provided by the present invention, and the treatment agent composition replacing bio-iron with chemically polymerized ferric sulfate also belongs to the scope of the technical solution of the present invention.

[0018] Theoretically, the denitrifying bacteria described in the present invention are all denitrifying bacteria with denitrification function conventionally used in the art. In a preferred embodiment of the present invention, the denitrifying bacteria are selected from one or a combination of two or more of Bacillus denitrificans, Bacillus cereus, Bacillus fluorescens, Micrococcus denitrificans, and Pseudomonas denitrificans; the most preferred is a combination of Bacillus denitrificans and Bacillus cereus, with the number of bacteria accounting for 50-90% and 10-50% respectively.

[0019] If not otherwise specified, the food waste in the present invention refers to food waste generated in food processing, catering services, unit catering and other activities, especially including food waste generated in restaurants, hotels, canteens and other places. The food waste includes waste edible oils and kitchen waste.

[0020] The restaurant wastewater of the present invention comprises wastewater produced by a traditional treatment process and / or a fermentation treatment process of restaurant waste, wherein the COD concentration of the restaurant wastewater is 70000-120000 mg / L, the BOD5 concentration is 35000-70000 mg / L, the TN concentration is 1500-6000 mg / L, and the TP concentration is 50-1200 mg / L.

[0021] The wastewater from the traditional food waste treatment process is the wastewater produced by food waste pulping, steam heating, and oil-water separation; the wastewater from the food waste fermentation treatment process is the wastewater produced by food waste pulping, steam heating, fermentation, and oil-water separation. In a specific embodiment of the present invention, the food waste fermentation treatment process specifically refers to the food waste recycling combined bioprocessing process, referred to as the CBP process.

[0022] Further, the concentration of TN in the wastewater of the food waste fermentation treatment process is 3000-6000 mg / L, the concentration of TP is 600-1200 mg / L, and the pH is 2-4. The extremely high total nitrogen and total phosphorus content in the wastewater is the biggest barrier to the resource utilization of wastewater. Those skilled in the art know that total nitrogen and total phosphorus will consume the BOD5 concentration in the water, reduce the organic matter content that can be used by microorganisms in the water, and reduce the biodegradability of the wastewater. Therefore, properly managing the total nitrogen and total phosphorus in the wastewater and ensuring the biodegradability of the wastewater are the top priorities for the resource treatment of food waste wastewater. The present invention uses the treatment agent composition in combination, so that the COD in the treated food waste wastewater is ≥50000 mg / L, the TN and TP concentrations are significantly reduced, and the pH reaches 6-9. At the same time, the ratios of BOD5 / COD, BOD5 / TN, and BOD5 / TP are all significantly improved, and the total nitrogen and total phosphorus contents are significantly reduced on the basis of improving the biodegradability of the wastewater. Therefore, the restaurant kitchen wastewater treated with the treatment agent composition provided by the present invention can be used as a carbon source for carbon source replenishment in a sewage treatment plant, truly achieving harmless discharge of restaurant kitchen wastewater and resource recycling.

[0023] In a second aspect of the present invention, the present invention provides a process for resource treatment of kitchen waste water, the process comprising:

[0024] c1) adding ferrate composite oxidant to the food waste wastewater to carry out simultaneous alkali adjustment and oxidation treatment;

[0025] c2) adding bio-iron or chemically polymerized ferric sulfate to the reaction system in the previous step, and stirring the reaction for 5-200 minutes;

[0026] c3) Continue to add denitrifying bacteria to the reaction system for denitrification treatment, and the supernatant is the kitchen waste resource treatment water.

[0027] The present invention does not impose any specific limitation on the denitrification time of denitrifying bacteria, which generally requires more than 0.5 hours. The longer the action time, the better. 0.5-24 hours is preferred, and 48, 72 or 96 hours are also acceptable. There is no limitation on the maximum time.

[0028] In the treatment process, the preparation method of the ferrate composite oxidant is as described in the first aspect of the present invention, and the addition amount of the ferrate composite oxidant is 1-100 kg / ton of food waste wastewater. For the food waste wastewater produced by the CBP process, the preferred addition amount is 10-25 kg / ton of food waste wastewater, and the most preferred amount is 20 kg / ton of food waste wastewater.

[0029] In the treatment process, the preparation method of the bio-iron is as described in the first aspect of the present invention, and the chemically prepared polyferric sulfate can be purchased through commercial channels. The amount of bio-iron or chemically prepared polyferric sulfate (calculated based on 1% iron content) added is 10-1000 kg / ton of food waste water, and the preferred amount of food waste water added for food waste water produced by the CBP process is 100-200 kg / ton of food waste water, and the most preferred amount is 200 kg / ton of food waste water.

[0030] In the treatment process, the denitrifying bacteria refers to all denitrifying bacteria with denitrification effect; preferably, the denitrifying bacteria are selected from one or more of denitrifying bacteria, Steinerella, Pseudomonas aeruginosa, denitrifying micrococcus, and denitrifying pseudomonas; most preferably, the denitrifying bacteria is a combination of denitrifying bacteria and Steinerella, and the number of bacteria accounts for 50-90% and 10-50% respectively. The addition amount of denitrifying bacteria is 0.01-10kg / ton of food waste wastewater. For the food waste wastewater produced by CBP process, the preferred addition amount is 0.2-0.5kg / ton of food waste wastewater, and the most preferred amount is 0.2kg / ton of food waste wastewater.

[0031] The ferrate composite oxidant provided by the present invention is a ready-made treatment agent that can simultaneously adjust the base and oxidize the food waste wastewater, decompose the macromolecular organic matter into small molecular VFAs, and remove part of the phosphorus. The inventors call it advanced oxidation treatment. Those skilled in the art know that conventional food waste wastewater is acidic, and its pH is usually 2-4. Although wastewater oxidation treatment is a routine operation of those skilled in the art, it is necessary to add alkali to adjust the solution pH to 6-9 before the oxidation reaction can begin. The present invention can achieve simultaneous alkali adjustment and oxidation by adding the self-prepared ferrate composite oxidant, significantly reducing costs and improving treatment efficiency. In addition, the ferrate composite oxidant provided by the present invention can also remove part of NH3-N and convert it into nitrite nitrogen or nitrate nitrogen, which is convenient for the subsequent use of denitrifying bacteria for denitrification treatment, creating favorable conditions for improving the BOD5 / TN ratio. In addition, the wastewater from restaurant kitchen waste is quite smelly, and ferrate can act as an oxidant and deodorize it. The principle is that it can oxidize odorous substances such as hydrogen sulfide, thiols and fecal matter, while killing microorganisms that produce odorous substances, greatly improving the working environment of employees.

[0032] The bio-iron provided by the present invention is a microbial polymerized ferric sulfate generated by microorganisms and ferrous sulfate heptahydrate, which mainly plays the role of dephosphorization in the present invention. At the same time, since the bio-iron has a good flocculation effect on macromolecular substances, adding bio-iron after alkali adjustment oxidation can flocculate and precipitate some difficult-to-degrade COD in the water body, and the difficult-to-degrade COD is COD that is not easily used by microorganisms. After flocculation and precipitation, the biodegradability of the kitchen waste water is indirectly improved. In addition, the reason why the present invention deliberately chooses to add bio-iron to react before denitrifying bacteria denitrification is that microorganisms will absorb phosphorus while denitrifying activities, and phosphorus absorption will consume a large amount of BOD5 (1P: 10-20BOD ratio), resulting in a reduction in precious BOD5 in the kitchen waste water. Therefore, the treatment method provided by the present invention first selects to add bio-iron to effectively remove phosphorus, and then denitrification and denitrification are carried out to avoid the consumption of precious BOD5 in the denitrification stage. In addition, the inventors also found that the bio-iron provided by the present invention has an obvious water purification effect on kitchen waste water.

[0033] Since the ferrate composite oxidant converts part of the NH3-N in the wastewater into nitrite nitrogen or nitrate nitrogen, favorable conditions are created for the use of denitrifying bacteria for denitrification treatment. The present invention selects denitrifying bacteria for denitrification treatment, effectively reduces the total nitrogen concentration in the wastewater, significantly improves the BOD5 / TN ratio, and increases the biodegradability of the wastewater. The denitrifying bacteria provided by the present invention can be selected from one or a combination of two or more of Denitrifying Bacillus, Steinerella, Fluorophora, Micrococcus denitrifying, and Pseudomonas denitrificans, and can be purchased through commercial channels or obtained by self-cultivation and screening. Through screening and optimization by the inventor, the best denitrifying bacteria obtained is a combination of Denitrifying Bacillus and Steinerella.

[0034] In the third aspect of the present invention, the present invention provides a food waste resource treatment water obtained by using food waste waste water as raw material, using the treatment agent composition provided by the first aspect of the present invention, and treating it according to the process provided by the second aspect of the present invention.

[0035] The COD concentration in the food waste resource treatment water is ≥50000 mg / L, the BOD5 concentration is ≥27000 mg / L, the NH3-N concentration is ≤200 mg / L, the TN concentration is ≤1500 mg / L, and the TP concentration is ≤60 mg / L.

[0036] The COD concentration of the kitchen waste resource treatment water obtained by the process provided by the present invention is ≥50000 mg / L, which meets the requirements of the sewage treatment plant for supplementing carbon sources, BOD5 / COD≥0.5, BOD5 / TN≥18, BOD5 / TP≥450, and the biodegradability is significantly improved compared with the untreated kitchen waste wastewater. Although the resource treatment water still contains a certain concentration of total nitrogen and total phosphorus, the carbon source supplementation of the sewage treatment plant is generally added at a ratio of one ten-thousandth, which is equivalent to adding 0.1 kg of carbon source per 1.0 t of water. After addition, without considering the removal of total nitrogen and total phosphorus, the total nitrogen and total phosphorus concentrations are reduced to very low levels, which will not have a significant impact on the water quality of the sewage treatment plant. Therefore, the kitchen waste resource treatment water prepared by the process provided by the present invention can be used as a carbon source for carbon source replenishment in sewage treatment plants.

[0037] In a fourth aspect of the present invention, the present invention provides a use of the food waste resource treatment water described in the third aspect of the present invention as a carbon source for a sewage treatment plant.

[0038] In a fifth aspect of the present invention, the present invention provides an application of the process provided in the second aspect of the present invention in at least one of the following:

[0039] d1) Application in resource treatment of restaurant kitchen wastewater;

[0040] d2) Application in the preparation of water for recycling kitchen waste.

[0041] The technical solution provided by the present invention has the following advantages:

[0042] The treatment process provided for restaurant kitchen wastewater has simple steps, convenient operation, low treatment cost, and convenient equipment maintenance, and can economically and efficiently solve the problem of difficult restaurant kitchen wastewater treatment. The restaurant kitchen wastewater treated by the process provided by the present invention is no longer sewage that needs to be discharged, but a carbon source required by a sewage treatment plant, and can be sold as a commodity to various sewage treatment plants for carbon source replenishment in sewage treatment plants.

[0043] At present, the carbon sources commonly used in sewage treatment plants on the market include methanol, sodium acetate and glucose products. Methanol is a Class A hazardous chemical, and microorganisms respond slowly to it; sodium acetate has a low equivalent COD and is expensive; glucose has poor dosing accuracy and is more likely to cause sludge bulking. The technical solution provided by the present invention can solve the above problems. Using restaurant kitchen waste water as raw material, the carbon source required by the sewage treatment plant can be prepared through a simple process and low processing cost. With the current continuous increase in the output of restaurant kitchen waste, the amount of carbon source prepared by this method is also stable.

[0044] The present invention successfully transforms the current status of harmless treatment of restaurant kitchen waste water into resource utilization, which not only solves the problem of restaurant kitchen waste water treatment, but also turns waste into treasure, thus having high economic and social environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Schematic diagram of the resource recovery process.

[0046] Figure 2 Comparison of samples of food waste wastewater produced by the CBP process before and after treatment, left: before treatment; right: after treatment.

[0047] Figure 3 Samples of food waste wastewater generated by the CBP process were sent for inspection before and after treatment. Left: after treatment; right: before treatment. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only some embodiments of the present invention, not all. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] Explanation of terms

[0050] COD: Chemical Oxygen Demand (COD) is a chemical method to measure the amount of reducing substances in a water sample that need to be oxidized. Under certain conditions, the amount of oxidant consumed to oxidize the reducing substances in 1 liter of water sample is used as an indicator, converted into milligrams of oxygen required for each liter of water sample to be completely oxidized, expressed in mg / L.

[0051] BOD5: 5-day biological oxygen demand BOD (Biochemical Oxygen Demand) refers to the amount of dissolved oxygen consumed by microorganisms to decompose certain oxidizable substances, especially organic matter in a certain volume of water within a certain period of time, expressed in mg / L.

[0052] TN: Total Nitrogen TN (Total Nitrogen) is the total amount of various forms of inorganic and organic nitrogen in water, including NO 3- 、NO 2- and NH 4+ Inorganic nitrogen such as protein, amino acids and organic nitrogen such as organic amines are calculated in milligrams of nitrogen per liter of water.

[0053] TP: Total Phosphorus TP (Total Phosphorus) is the sum of phosphorus in inorganic and organic forms in wastewater.

[0054] VFAs: Volatile fatty acids.

[0055] The technical solution of the present invention and the technical effects achieved by the technical solution will be described below in conjunction with specific embodiments.

[0056] Preparation Example 1 Preparation of ferrate composite oxidant

[0057] S1: Control the temperature of the reactor to 40-42°C, add 200 kg of liquid caustic soda with a mass concentration of 50% and 70 kg of liquid sodium hypochlorite with a mass concentration of 12% into the reactor, and stir to fully mix the liquid caustic soda and the sodium hypochlorite;

[0058] S2: At the same temperature, the stirrer speed in the reactor was controlled to be 1200 rpm, and 30 kg of liquid ferric chloride with a mass concentration of 40% was slowly added. After stirring for 1 hour, stirring was stopped to prepare 300 kg of ferrate composite oxidant. The liquid was translucent purple-red liquid. The ultraviolet spectrophotometer detected that 30% of the trivalent iron in the liquid system was converted into hexavalent iron.

[0059] Preparation Example 2 Preparation of Bio-Iron

[0060] S1: Add industrial-grade solid ferrous sulfate and water to the bioreactor to form a 450 g / L ferrous sulfate aqueous solution, add (NH4)2SO4, KCL, K2HPO4 and MgSO4·7H2O to make the final concentrations in the solution meet (NH4)2SO4 1 g / L, KCL 0.1 g / L, K2HPO4 0.2 g / L, MgSO4·7H2O 0.2 g / L, mix Thiobacillus ferrooxidans and acidophilus in a ratio of 9:1, introduce the mixed strains into the bioreactor to prepare a microbial reaction solution;

[0061] S2: Turn on the aeration device, control the dissolved oxygen in the solution to 4ppm, the reaction temperature to 38-40℃, and detect Fe in the solution after 24 hours of reaction. 2+ Concentration, when Fe 2+ When the concentration is lower than 0.1%, 30% of the liquid in the bioreactor is discharged and left to mature to obtain bio-iron;

[0062] S3) adding the raw materials described in step S1 to the bioreactor, and repeating the reaction of step S2, so as to continuously circulate and prepare bio-iron.

[0063] Preparation Example 3 Preparation of denitrifying bacteria

[0064] Purchase Denitrifying Bacillus and Steinernema, mix them in a ratio of 1:1 and use them as denitrifying bacteria.

[0065] Resourceful treatment of wastewater from food waste fermentation process

[0066] Example 1

[0067] This example uses the wastewater generated by the combined bioprocessing process (CBP process) of Sichuan Lixinglong Environmental Protection Technology Co., Ltd. as the treatment object, and the water quality monitoring data of the wastewater are shown in Table 1:

[0068] Table 1 CPB process water quality monitoring data

[0069]

[0070] The resource treatment process of the wastewater is as follows:

[0071] S1: Take the ferrate composite oxidant prepared in Preparation Example 1, add it into the wastewater at a ratio of 15 kg / ton of food wastewater, and react for 1 hour;

[0072] S2: The iron content of the biological iron prepared in Preparation Example 2 is 1%, and 100 kg / ton of kitchen waste water is added and reacted for 0.5 hours;

[0073] S3: Add the denitrifying bacteria prepared in Preparation Example 3 to the reaction system at a ratio of 0.2 kg / ton of food waste water, react for 6 hours, and obtain treated water. The water quality monitoring report of the treated water is shown in Table 2.

[0074] The appearance comparison results of the food waste CBP process wastewater before and after treatment in this embodiment are as follows: Figure 2 As shown in the figure, the left side is the sample before treatment, and the right side is the sample after treatment. It can be seen from the figure that the water before treatment is turbid and dark gray, and the water after treatment is more transparent, and the color depth becomes lighter, showing orange-yellow. The sample was sent for inspection, and the inspection picture is as shown Figure 3 The samples of the following examples and comparative examples have no significant difference in appearance from those of Example 1, and the present invention does not present specific pictures, and all samples obtained in the experiment are sent for inspection according to the above packaging state.

[0075] Example 2

[0076] The source of the wastewater is the same as in Example 1, and the resource treatment process of the wastewater is the same as in Example 1, except that the addition ratio of the ferrate composite oxidant is 20 kg / ton of food waste wastewater, and the addition ratio of the bio-iron is 200 kg / ton of food waste wastewater.

[0077] Example 3

[0078] The source of the wastewater is the same as in Example 1, and the resource treatment process of the wastewater is the same as in Example 1, except that the addition ratio of the ferrate composite oxidant is 20 kg / ton of food waste wastewater, and the addition ratio of the bio-iron is 300 kg / ton of food waste wastewater.

[0079] Example 4

[0080] The source of the wastewater is the same as in Example 1, and the resource treatment process of the wastewater is the same as in Example 1, except that the addition ratio of the ferrate composite oxidant is 25 kg / ton of food waste wastewater, and the addition ratio of the bio-iron is 200 kg / ton of food waste wastewater.

[0081] Table 2 Example Treatment Process Inlet and Outlet Water Quality Monitoring Report

[0082]

[0083] B / C, B / TN and B / TP in the table represent the ratios of BOD5 / COD, BOD5 / TN and BOD5 / TP.

[0084] From the monitoring data in Table 2, it can be seen that the COD concentration of the treated water obtained by the process provided by the present invention is ≥50000 mg / L, which meets the requirement of supplementing carbon source in sewage treatment plants. The BOD5 / COD ratio in Example 1 is slightly higher than that of wastewater, BOD5 / TN=18.5, BOD5 / TP=497.3, and the biodegradability of the treated water is significantly improved compared with that of the wastewater, indicating that the biodegradability of the wastewater obtained by the present invention is improved and can be used as a carbon source in sewage treatment plants.

[0085] Compared with Example 1, Example 2 increases the dosage of ferrate composite oxidant and biological iron. From the effluent data, it can be seen that the ratio of BOD5 / COD is increased to 0.5632, and the biodegradability of the wastewater is further improved. Example 3 further increases the dosage of biological iron on the basis of Example 2. From the effluent data, it can be seen that compared with Example 2, the improvement of each data is not significant. Compared with the significantly increased cost, the preferred dosage of biological iron in the present invention is 200kg / ton of food waste wastewater. Example 4 increases the dosage of ferrate composite oxidant on the basis of Example 2. From the effluent data, it can be seen that the BOD5 concentration in the water decreases, indicating that the increase of oxidants is not conducive to improving the biodegradability of the treated water. Therefore, the preferred dosage of ferrate composite oxidant in the present invention is 20kg / ton of food waste wastewater.

[0086] Comparative Example 1

[0087] The food waste water from the same source as in Example 1 was taken as the treatment object, sodium hydroxide was added to adjust the pH of the waste water to 6-9, and no oxidation was performed; the bio-iron obtained in Preparation Example 2 was added at a ratio of 200 kg / ton of food waste water, and the reaction was performed for 0.5 hours; the denitrifying bacteria prepared in Preparation Example 3 were added to the reaction system at a ratio of 0.2 kg / ton of food waste water, and the reaction was performed for 6 hours to obtain treated water, and the water quality monitoring report of the treated water is shown in Table 3.

[0088] Comparative Example 2

[0089] The kitchen waste water from the same source as in Example 1 was taken as the treatment object, sodium hydroxide was added to adjust the pH of the waste water to 6-9, and then ozone was added for oxidation, and the amount of the oxidant added was 5 kg / ton of kitchen waste water; the bio-iron obtained in Preparation Example 2 was added at a ratio of 200 kg / ton of kitchen waste water, and the reaction was carried out for 0.5 hours; the denitrifying bacteria prepared in Preparation Example 3 were added to the reaction system at a ratio of 0.2 kg / ton of kitchen waste water, and the reaction was carried out for 6 hours to obtain treated water, and the water quality monitoring report of the treated water is shown in Table 3.

[0090] Comparative Example 3

[0091] The kitchen waste water from the same source as in Example 1 was taken as the treatment object, and the ferrate composite oxidant prepared in Preparation Example 1 was added to the waste water at a ratio of 20 kg / ton of kitchen waste water, and the reaction was performed for 1 hour; in this embodiment, ferric chloride was used to replace biological iron, and the ratio was 20 kg / ton of kitchen waste water (calculated as 40% of the mass concentration of ferric chloride), and the reaction was performed for 0.5 hour; the denitrifying bacteria prepared in Preparation Example 3 were added to the reaction system at a ratio of 0.2 kg / ton of kitchen waste water, and the reaction was performed for 6 hours to obtain treated water, and the water quality monitoring report of the treated water is shown in Table 3.

[0092] Comparative Example 4

[0093] Take the restaurant wastewater from the same source as Example 1 as the treatment object, take the ferrate composite oxidant prepared in Preparation Example 1, add it to the wastewater at a ratio of 20 kg / ton of restaurant wastewater, and react for 1 hour; this embodiment uses chemically polymerized ferric sulfate to replace biological iron, and reacts for 0.5 hours according to 20 kg / ton of restaurant wastewater (calculated according to the iron content of chemically polymerized ferric sulfate of 10%); add the denitrifying bacteria prepared in Preparation Example 3 to the reaction system, add it at a ratio of 0.2 kg / ton of restaurant wastewater, react for 6 hours, and obtain treated water. The water quality monitoring report of the treated water is shown in Table 3.

[0094] Comparative Example 5

[0095] The kitchen wastewater from the same source as in Example 1 is taken as the treatment object, and the resource treatment process of the wastewater is the same as in Example 1, except that the order of steps S2 and S3 is swapped, that is, the resource treatment process of the wastewater is as follows:

[0096] S1: Take the ferrate composite oxidant prepared in Preparation Example 1, add it into the wastewater at a ratio of 20 kg / ton of food waste water, and react for 1 hour;

[0097] S2: adding the denitrifying bacteria prepared in Preparation Example 3 to the reaction system at a ratio of 0.2 kg / ton of food waste water, and reacting for 6 hours;

[0098] S3: Take the bio-iron prepared in Preparation Example 2, react in food waste water at a rate of 200 kg / ton, and obtain treated water for 0.5 hours. The water quality monitoring report of the treated water is shown in Table 3.

[0099] Table 3 Comparative treatment process inlet and outlet water quality monitoring report

[0100]

[0101]

[0102] From the effluent data of Comparative Example 1, it can be seen that in the case of only alkali adjustment without oxidation, the COD concentration does not change much, resulting in a BOD5 / COD ratio of only about 0.3, which seriously affects the biodegradability of the treated water. Secondly, the NH3-N concentration in the wastewater remains basically unchanged, which will also directly affect the subsequent denitrification treatment. On the basis of no oxidation, even if alkaloids and denitrifying bacteria are used for subsequent treatment, the total phosphorus and total nitrogen will not be reduced much after treatment.

[0103] From the effluent data of Comparative Example 2 in Table 3, it can be seen that although the method of first adjusting the base and then oxidizing by ozone can also reduce COD, the degree of reduction is not as good as that of the ferrate composite oxidant provided by the present invention. Secondly, the inventors found that conventional ozone oxidation has little effect on the NH3-N concentration in the wastewater, but the ferrate composite oxidant provided by the present invention can significantly reduce the NH3-N concentration in the wastewater, partially converting it into nitrite nitrogen or nitrate nitrogen, creating favorable conditions for subsequent denitrification.

[0104] According to the comparative example 3 data of Table 3, it can be seen that although ferric chloride can also achieve dephosphorization and eliminate part of COD, it cannot purify the water body, but causes the chloride of 5200mg / L to be increased in the treated water, which is not very popular with sewage treatment plants, and chloride can affect the activity of microorganisms, and needs to be processed again before use. In addition, the unexpected discovery of the inventors is that the COD content in the treated water produced by the second step reaction using ferric chloride is higher, resulting in a decrease in the BOD5 / COD ratio, and the biodegradability of the treated water is reduced. The inventors analyze that the biological iron provided by the present invention has the effect of difficultly degradable COD in the flocculation water, and the effect of ferric chloride in this respect is worse, resulting in a decrease in the COD decline of the treated water.

[0105] From the process effluent data of Comparative Example 4 in Table 3, it can be seen that although the chemical method polyferric sulfate can achieve a treatment effect that is not much different from the biological iron provided by the present invention, the chemical method polyferric sulfate has a large cost. The price of chemical method polyferric sulfate is about 1,000 yuan / ton. According to the ratio of 20kg / ton of restaurant kitchen waste water, the cost of this item is 20 yuan / catering kitchen waste water. The price of biological iron is about 10 yuan / ton. According to the ratio of 200kg / ton of restaurant kitchen waste water, the cost of this item is 2 yuan / catering kitchen waste water. Therefore, compared with chemical method polyferric sulfate, the biological iron provided by the present invention is more preferred.

[0106] From the data of comparative example 5 in Table 3, it can be seen that when denitrifying bacteria are used for denitrification first and then biological iron is added for reaction, since the phosphorus content in the system is high during denitrification, microorganisms will absorb phosphorus while denitrifying, and phosphorus absorption will consume a large amount of BOD5, resulting in a decrease in the BOD5 content in the effluent of comparative example 5, thereby reducing the BOD5 / COD ratio and reducing the biodegradability of the treated water. Therefore, the sequence of adding biological iron for reaction first and then adding denitrifying bacteria for denitrification after oxidation treatment with ferrate composite oxidant is the best treatment process flow.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. Application of a treatment agent composition in the resource treatment of restaurant kitchen wastewater, the treatment agent composition consisting of a ferrate composite oxidant, biological iron and denitrifying bacteria; The ferrate composite oxidant is prepared by the following method: a1) controlling the temperature of the reactor to 40-45° C., stirring and mixing 50% liquid caustic soda and 12% liquid sodium hypochlorite, wherein the mass ratio of the liquid caustic soda to the sodium hypochlorite is (2-3):1; a2) slowly adding 40% liquid ferric chloride to the reaction kettle at a stirring speed of 1000-1500 rpm, wherein the added volume of the liquid ferric chloride is 1 / 3-1 / 2 of the liquid sodium hypochlorite, and stirring for 1-2 hours to prepare a ferrate composite oxidant; The biological iron is prepared by the following method: b1) adding industrial-grade solid ferrous sulfate and water into a bioreactor to form an aqueous solution with a concentration of 400-450 g / L, adding inorganic salts so that the final concentrations in the solution meet (NH4)2SO4 1-1.5 g / L, KCL 0.1-0.2 g / L, K2HPO4 0.2-0.3 g / L, and MgSO4·7H2O 0.2-0.3 g / L, introducing bacterial strains, and preparing a microbial reaction solution, wherein the bacterial strains are a combination of Thiobacillus ferrooxidans and acidophilic bacteria, and the bacterial strain number ratio is (6-9):1; b2) Control the dissolved oxygen in the solution to 4-5ppm, the reaction temperature to 20-40℃, and after 24 hours of reaction, when Fe 2+ When the concentration is lower than 0.1%, 30% of the liquid in the bioreactor is discharged and left to mature to obtain bio-iron; b3) adding the raw materials described in step S1 to the bioreactor, repeating the reaction of step S2, and continuously circulating to obtain bio-iron; The denitrifying bacteria is a combination of Denitrifying Bacillus and Steinernea, with the bacterial species accounting for 50-90% and 10-50% respectively.

2. The use according to claim 1, characterized in that: The COD concentration in the restaurant waste water is 70000-120000 mg / L, the BOD5 concentration is 35000-70000 mg / L, the TN concentration is 1500-6000 mg / L, and the TP concentration is 50-1200 mg / L. The restaurant waste water includes waste water generated by restaurant waste through traditional treatment processes and / or fermentation treatment processes.

3. The use according to claim 2, characterized in that: The restaurant waste wastewater is selected from wastewater generated by a restaurant waste fermentation treatment process, which refers to a restaurant waste recycling combined bioprocessing process, referred to as the CBP process, in which the concentration of TN in the wastewater is 3000-6000 mg / L, the concentration of TP is 600-1200 mg / L, and the pH is 2-4.

4. A process for resource treatment of kitchen waste water, the process comprising: c1) adding ferrate composite oxidant to the food waste wastewater to carry out simultaneous alkali adjustment and oxidation treatment; c2) adding bio-iron or chemically polymerized ferric sulfate to the reaction system in the previous step, and stirring the reaction for 5-200 minutes; c3) Continue to add denitrifying bacteria to the reaction system for denitrification treatment, and the supernatant is the kitchen waste resource treatment water.

5. The process according to claim 4, characterized in that In the treatment process, the amount of ferrate composite oxidant added is 1-100 kg / ton of restaurant waste water; calculated based on the iron content of 1%, the amount of biological iron or chemically prepared polyferric sulfate added is 10-1000 kg / ton of restaurant waste water; and the amount of denitrifying bacteria added is 0.01-10 kg / ton of restaurant waste water.

6. The process according to claim 5, characterized in that For the food waste water produced by CBP process, the amount of ferrate composite oxidant added is 10-25kg / ton of food waste water; calculated based on the iron content of 1%, the amount of biological iron or chemical polyferric sulfate added is 100-200kg / ton of food waste water; the amount of denitrifying bacteria added is 0.2-0.5kg / ton of food waste water.

7. The process according to claim 6, characterized in that For the food waste water produced by CBP process, the amount of ferrate composite oxidant added is 20kg / ton of food waste water; calculated based on the iron content of 1%, the amount of biological iron or chemical polyferric sulfate added is 200kg / ton of food waste water; the amount of denitrifying bacteria added is 0.2kg / ton of food waste water.

8. A method of using food waste wastewater as raw material, using the treatment agent composition according to any one of claims 1 to 3, and treating the food waste resource treatment water according to any one of claims 4 to 7.

9. Use of the food waste resource treatment water according to claim 8 as a carbon source for a sewage treatment plant.

10. Use of the process according to any one of claims 4 to 7 in at least one of the following: d1) Application in resource treatment of restaurant kitchen wastewater; d2) Application in the preparation of water for resource recovery of kitchen waste.

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