An in-situ resource recovery method for BOD and ammonia nitrogen in leachate from community wet waste

Abstract

The present application relates to a kind of community wet garbage leachate BOD and in-situ resource utilization method of ammonia nitrogen.The in-situ resource utilization method includes the following steps: providing wet garbage leachate;The wet garbage leachate is pretreated, and the processing original solution is obtained;Providing filler tower, the filler tower includes sequentially arranged activated carbon section, biological filler I section and biological filler II section;The processing original solution is sequentially degraded and treated in the activated carbon section, the biological filler I section and the biological filler II section, and the degradation solution is obtained.The in-situ resource utilization method of the present application has simple process flow, low equipment requirement, low-cost raw materials and easy to obtain.

Description

Technical Field

[0001] This invention relates to the field of water pollution control and wastewater treatment technology, and in particular to an in-situ resource recovery method for BOD and ammonia nitrogen in leachate from community wet waste. Background Technology

[0002] Leachate from wet waste refers to wastewater formed during the storage, landfilling, transportation, or composting of wet waste due to the decomposition of organic matter in the waste, free water in the waste, and precipitation through compression and leaching.

[0003] After wet waste is separated, the resulting leachate is not only smelly and difficult to treat, but also corrosive and highly susceptible to bacterial growth and viral contamination. Existing small-scale wastewater treatment equipment cannot effectively reduce the BOD and ammonia nitrogen levels in the leachate simultaneously. Most of the treated wastewater still fails to meet the standards for municipal sewer system discharge. Therefore, currently, the only solution is to hire qualified third-party disposal companies to pump and treat the wastewater, which significantly increases treatment costs.

[0004] Currently, more and more residential communities are adopting aerobic composting technology to convert wet waste into organic fertilizer in situ, significantly saving on collection and transportation costs. However, the leachate produced during the composting process still fails to meet discharge or on-site utilization standards, which contradicts the concept of in-situ resource utilization. Therefore, the proper disposal of wet waste leachate is of paramount importance in filling the gap in in-situ wet waste treatment in communities.

[0005] The team conducted a three-month survey of nine residential communities in Shanghai's Putuo District (Changfu Building, Zichang Community, and Heyang Community); Shanghai's Yangpu District (Tongji New Village); and Ningbo, Zhejiang (Vanke Park Lane, Ningxing Royal Mansion, Jiuwu Garden, Mingchen Ziyue East District, and Mingchen Ziyue West District). The results showed that:

[0006] The main components of community wet waste are raw kitchen materials such as fruit peels and vegetables, and the resulting leachate is a high-concentration, complex organic wastewater. Test results show that the pH range of the community wet waste leachate is between 5 and 7, the average COD concentration is around 2500 mg / L, the BOD / C ratio is approximately 0.7, and the average ammonia nitrogen content is around 65 mg / L. The concentrations of COD, BOD, and ammonia nitrogen are all significantly lower than those in landfills, indicating good biodegradability. This makes it possible to develop a new, low-cost in-situ resource recovery technology for community wet waste leachate.

[0007] In 2022, my country received 622 patent applications related to leachate treatment. Existing invention patents on leachate treatment mostly focus on innovating and improving traditional bioreactors or membrane filtration technologies, using multiple processes in combination for large-scale centralized treatment, but the treatment cost remains high. In-situ treatment technologies are primarily aimed at landfills, employing pre-treatment followed by reinjection into bioreactor landfill systems. A technology specifically designed for communities that effectively reduces the BOD and ammonia nitrogen content in wet waste leachate, converting it into low-cost, on-site water resources for greening, remains a market gap. Summary of the Invention

[0008] To address the high costs of centralized treatment and transportation of leachate from community wet waste, the inability of existing small-scale wastewater treatment equipment to simultaneously and effectively reduce BOD and ammonia nitrogen levels, and the fact that treated leachate still fails to meet municipal sewer discharge standards, this invention provides an in-situ resource recovery method for BOD and ammonia nitrogen in community wet waste leachate. This invention features a simple, environmentally friendly, and low-cost process that effectively reduces BOD and ammonia nitrogen levels in community wet waste leachate, while also lowering turbidity and TDS, eliminating odor, and significantly reducing fecal coliform bacteria and ascarid eggs in the effluent. The leachate can then be used as high-quality water for direct irrigation of surrounding green spaces, achieving efficient and in-situ recycling of community wet waste leachate through harmless treatment and resource recovery.

[0009] The purpose of this invention is to provide an in-situ resource recovery method for BOD and ammonia nitrogen in leachate from community wet waste, comprising the following steps:

[0010] Provide wet waste leachate;

[0011] The wet landfill leachate was pretreated with hydrogen peroxide, wood ash, and a coagulant to obtain the treated stock solution.

[0012] A packed tower is provided, comprising an activated carbon section, a biological packing section I, and a biological packing section II arranged vertically in sequence; the activated carbon section is provided with a flow-blocking layer, and the flow-blocking layer is located at the upstream end of the activated carbon section;

[0013] The original treatment solution is sequentially passed through the activated carbon section, the biological packing section I, and the biological packing section II for in-situ degradation treatment to obtain a degradation solution; ozone is introduced when passing through the activated carbon section.

[0014] The activated carbon section, biological filler section I, and biological filler section II each independently include functional microspheres embedded with microorganisms; the activated carbon section is filled with activated carbon.

[0015] The microorganisms are selected from one or more of lactic acid bacteria, acetic acid bacteria, actinomycetes, Pseudomonas fluorescens, Bacillus subtilis, and yeast.

[0016] Specifically, wet waste leachate is untreated community wet waste leachate. Community wet waste refers to kitchen waste in urban and rural residential communities, which is mainly composed of vegetable leaves, fruit peels, eggshells, bones, etc. It is characterized by high water content, high sugar and high fiber.

[0017] Specifically, it should be noted that although the object of treatment here is community wet waste leachate, its application is by no means limited to the community. As long as the main components of wet waste are similar to the kitchen waste mentioned above, its leachate can be treated using this invention. The wet waste leachate is then separated and collected at the community waste sorting and collection point.

[0018] Specifically, wet waste leachate should be collected within 1 to 2 days after it is generated. This not only cleans the environment of the community waste site but also achieves the best treatment effect and extends the service life of the packing tower.

[0019] Specifically, this invention recommends using it in conjunction with a small-scale in-situ aerobic composting equipment for community wet waste. After the community wet waste is initially squeezed and crushed, the resulting leachate is treated using the process flow of this invention. The separated wet waste is treated using a small-scale composting equipment, and the leachate generated during the composting process is also treated using the process flow of this invention.

[0020] In one embodiment of the present invention, the specific steps of the preprocessing are as follows:

[0021] The wet waste leachate was mixed with hydrogen peroxide, and after the reaction was complete, intermediate treatment liquid I was obtained.

[0022] The plant ash is added to intermediate treatment solution I, stirred, and dissolved to obtain intermediate treatment solution II;

[0023] The coagulant is added to the intermediate treatment liquid II and stirred until the reaction is complete to obtain the original treatment liquid.

[0024] Specifically, hydrogen peroxide can be industrial hydrogen peroxide, and wood ash is the ash collected after in-situ burning of community greening waste (fallen leaves, branches, grass clippings, etc.).

[0025] Specifically, regarding the amount of hydrogen peroxide added, if the leachate from the wet waste has a pungent odor or if there is a lot of meat in this batch of wet waste, more can be added appropriately; conversely, less can be added appropriately. However, the amount added must be controlled within the given range, and attention should be paid to stirring evenly when adding it.

[0026] Specifically, after the hydrogen peroxide has fully reacted and basically no more bubbles are produced, add the wood ash. If more bubbles are produced after adding the powder or the leachate has a pungent odor, add more powder; otherwise, add less powder. However, the amount added must be controlled within the given range, and be sure to stir evenly when adding the powder.

[0027] Specifically, after the added wood ash has basically dissolved, the coagulant is added last for mixing and flocculation. If the turbidity of the leachate is high as visible to the naked eye, more can be added appropriately, and vice versa. However, the amount added must be controlled within the given range. When adding, pay attention to stirring evenly. After flocculation is completed and the leachate is stable, the pretreatment process is completed and the treated raw liquid is obtained.

[0028] In one embodiment of the present invention, at least one or more of the following conditions are satisfied:

[0029] (i) The amount of hydrogen peroxide added is 90-110 mL / L, and the mass concentration of the hydrogen peroxide is 50%;

[0030] (ii) The amount of plant ash added is 2-4 g / L, and the plant ash is the ash collected after the in-situ combustion of green waste;

[0031] (iii) The dosage of the coagulant is 25-40 mg / L, and the coagulant is selected from polyaluminum sulfate with a purity of 98-99%.

[0032] In one embodiment of the present invention, at least one or more of the following conditions are satisfied:

[0033] The functional microspheres also include a carrier and a curing agent; the curing agent is selected from one or more of calcium chloride, boric acid, and glutaraldehyde; the carrier is selected from one or more of sodium alginate, gelatin, and polyvinyl alcohol.

[0034] The mass concentration of the curing agent is 3.8–4.1%;

[0035] The mass concentration of the carrier is 3.9–4.2%;

[0036] The average diameter of the functional microspheres is 5–6 mm;

[0037] The length of the intercepting layer is 1 / 15 to 1 / 10 of the total length of the activated carbon section. The intercepting layer is part of the activated carbon section. If there are many flocculent substances generated in the original solution after coagulation, the length can be appropriately increased, and vice versa. However, the proportion must be controlled within the given range.

[0038] In one embodiment of the present invention, the biological packing material of the biological packing section I is composed of citrus peel, aerobic fermentation compost of wet waste, and sodium alginate pellets embedded with actinomycetes and Pseudomonas fluorescens. The mass ratio of the citrus peel, aerobic fermentation compost of wet waste, and sodium alginate pellets embedded with actinomycetes and Pseudomonas fluorescens is 1-1.5:6-7:1.5-2.

[0039] The biological packing material in the second stage is composed of citrus peel, aerobic fermentation compost of wet waste, and sodium alginate pellets embedded with Bacillus subtilis and yeast. The mass ratio of the citrus peel, aerobic fermentation compost of wet waste, and sodium alginate pellets embedded with Bacillus subtilis and yeast is 2-2.5:10-12:3-3.5.

[0040] In one embodiment of the present invention, the citrus peel is obtained through pretreatment, the steps of which are: crushing fresh citrus peel to a particle size of <1cm, adding enzyme preparation, and fermenting for 2-3 hours to obtain the product.

[0041] Specifically, the fresh citrus peels come from community wet waste or fresh citrus peels from nearby vegetable markets and fruit shops.

[0042] In one embodiment of the present invention, the enzyme preparation is selected from pectin dry enzyme preparation and / or cellulose dry enzyme preparation; the amount of pectin dry enzyme preparation is 0.09-0.12 g / kg; the amount of cellulose dry enzyme preparation is 0.18-0.21 g / kg.

[0043] In one embodiment of the present invention, the wet waste aerobic fermentation compost refers to the final fermented compost of community wet waste after a complete aerobic composting process, and should be fresh compost within 2 days after the material is removed.

[0044] Specifically, the aerobic fermentation compost of wet waste should come from the fermentation compost of the community's small-scale in-situ aerobic composting equipment for wet waste, and must be fresh compost produced within 2 days. If there is no small-scale processing equipment or fresh compost is temporarily unavailable in the community, compost can be purchased from a centralized processing station or fertilizer company, and then an aerobic fermentation agent with EM / YM bacteria or other aerobic bacteria as the main components can be added. The mass ratio of compost to agent dry weight should be 140-150:1. After mixing evenly, it can be used as a substitute for fresh compost.

[0045] In one embodiment of the present invention, the packed tower further includes an inlet section located upstream of the activated carbon section and an outlet section located downstream of the biological packing section II. A first turning connection section is provided between the inlet section and the activated carbon section, a second turning connection section is provided between the activated carbon section and the biological packing section I, a third turning connection section is provided between the biological packing section I and the biological packing section II, and a fourth turning connection section is provided between the biological packing section II and the outlet section.

[0046] The preparation method of the degradation solution includes the following steps:

[0047] Keep the first valve between the activated carbon section and the second turning connection section closed, inject the treatment stock solution from the inlet section, and the treatment stock solution sequentially passes through the first turning connection section, the first grid, the intercepting layer, and the second grid to enter the activated carbon section. Ozone is introduced into the activated carbon section through the first vent on the activated carbon section, and the first degradation intermediate liquid is obtained by fully reacting.

[0048] Keep the second valve between the biological packing section I and the third bend connecting section closed, open the first valve, and the first degradation intermediate liquid sequentially passes through the third grid between the second bend connecting section and the activated carbon section, the second bend connecting section, and the fourth grid between the second bend connecting section and the biological packing section I into the biological packing section I. Air is introduced into the biological packing section I through the second vent on the biological packing section I, and the reaction is fully completed to obtain the second degradation intermediate liquid.

[0049] Keep the third valve between the biological packing section II and the fourth bend connecting section closed, open the second valve, and the second degradation intermediate liquid sequentially passes through the fifth grid between the third bend connecting section and the biological packing section I, the third bend connecting section, and the sixth grid between the third bend connecting section and the biological packing section II into the biological packing section II. Air is introduced into the biological packing section II through the third vent on the biological packing section II, and the degradation liquid is obtained through sufficient reaction.

[0050] The degradation solution flows sequentially through the seventh grid between the second stage of the biological packing material and the fourth turning connection stage, and then through the fourth turning connection stage to the outlet stage. In addition, a new section of the treatment stock solution can be added at the inlet simultaneously, and the above steps can be repeated to achieve continuous treatment.

[0051] In one embodiment of the present invention, at least one or more of the following conditions are satisfied:

[0052] The activated carbon section, the biological packing section I, and the biological packing section II are arranged in parallel;

[0053] The activated carbon section, the biological packing section I, and the biological packing section II are each inclined downwards to form a slope of 2-3%.

[0054] The activated carbon section, the biological packing section I, and the biological packing section II have the same length, and are 5 to 6 times the length of the turning connection section;

[0055] The mesh is a double-layered plastic square mesh with an aperture of 3-4 mm;

[0056] The activated carbon section, the biological packing section I, and the biological packing section II are independently filled with packing material to fill the tube completely;

[0057] The filling degree of the treatment stock solution, the first degradation intermediate solution, and the second degradation intermediate solution shall not exceed 90%; preferably, each section of the added packing material shall be fully filled, but the filling degree of the leachate during operation shall be 82-88%. However, it should be noted that a lower filling degree operation mode is also allowed, but it will correspondingly increase the economic and time costs of treatment.

[0058] Furthermore, the entire treatment cycle for one section of leachate within the S-type three-section packed tower is 4 hours. After each section of packing is filled, the valve of the activated carbon section is closed, and the treatment stock solution is added from the inlet. The addition is stopped when the filling degree is approximately 85%.

[0059] The ozone refers to ozonated air produced on-site using an ozone generator with air as the gas source, wherein the ozone content is 2-3%.

[0060] The ozone introduction rate is 0.15–0.25 [L / (min·L)];

[0061] The air introduction rate is 0.18 to 0.24 [L / (min·L)].

[0062] Specifically, the preparation of functional microspheres, taking the preparation of sodium alginate microspheres encapsulating two microorganisms as an example, is carried out using the following specific method:

[0063] Both concentrations were prepared at approximately 1×10⁻⁶. 8 Microbial solution of 100 cells / mL;

[0064] Prepare a sodium alginate solution with a mass concentration of 3.9–4.2% and a calcium chloride solution with a mass concentration of 3.8–4.1%, using food-grade sodium alginate;

[0065] Take 5 mL of each of the two microbial solutions and mix them evenly with 10 mL of sodium alginate solution. Then, use a syringe to add the mixture dropwise from a distance of 10–12 cm from the surface of the calcium chloride solution. After addition, allow the mixture to solidify in the calcium chloride solution for 55–65 minutes, forming small spheres with an average diameter of 5–6 mm. Then, wash with distilled water. Finally, place the mixture in sterile physiological saline and store it in a refrigerator at 4°C for later use.

[0066] Specifically, the functional microsphere carrier can be sodium alginate with a mass concentration of 4%, but researchers in this field can of course also use different methods, such as using sodium alginate with a mass concentration of 3% + gelatin with a mass concentration of 3% for encapsulation.

[0067] Specifically, the intercepting layer packing should be replaced every 7-10 days, and the biological packing every 20-24 days. If the packing is to be used for an extended period, the extension should not exceed 5 days. The sodium alginate pellets in each section can be recycled after verification that the encapsulated microorganisms are of good activity. The intercepted flocculent material and the remaining parts of the replaced biological packing can be directly added to the aerobic fermentation pile of wet waste for in-situ treatment.

[0068] Specifically, the S-type three-section packed tower has a vertical tower structure, allowing the leachate to flow by gravity. Valves, vents, and connections between the packing sections and bends need to be inspected every 30 days to ensure proper operation; the grid needs to be cleaned or replaced every 15 days. The size of the packed tower should be determined based on the throughput. The packed tower operates continuously, without batch processing, treating leachate. When the previous leachate enters the biological packing section II, the new section's leachate can be added from the inlet to begin treatment. The packing sections can also be disassembled and replaced. Aeration is performed at the vents near the tail end of each horizontal section. When venting the biological packing section, the vent near the bottom of the vertical pipe connecting to the previous section should be opened. 1-2 minutes before the raw liquid or the first / second degradation liquid enters the next section, the vents on the vertical pipes connecting the two sections should be opened to create a negative pressure environment to facilitate liquid flow. The amount of air evacuation depends on the size of the packed tower and the smoothness of the raw liquid flow. If the three packing sections of an S-type three-section packed tower are built together with valves, then the grid should be in front and the valves behind.

[0069] Specifically, if conditions permit, the S-type three-section packed tower of this invention can be combined with an automatic control system, and computer software can be used to automatically control valve opening and closing and ventilation equipment, which will greatly improve operating efficiency and save human resource costs.

[0070] It is worth noting that the first valve is closed after the second degradation intermediate solution enters the second stage of the biological packing. Alternatively, a new treatment stock solution can be added to the inlet section simultaneously, and the above steps can be repeated to achieve continuous treatment.

[0071] In one embodiment of the present invention, the step of obtaining the first degradation intermediate liquid includes:

[0072] After the raw solution enters the activated carbon section for 4-6 minutes, ozone is introduced for 4-6 minutes. After an interval of 9-11 minutes, ozone is introduced again for 4-6 minutes. After another 4-6 minutes, the solution can proceed to the next stage. The treatment time is 25-35 minutes, yielding the first degradation intermediate solution. The ozone introduction rate is 0.15-0.25 [L / (min·L)]. By introducing ozone in multiple stages, the introduced gas is fully utilized, allowing sufficient adsorption time for activated carbon after the reaction. This minimizes the impact on the cutoff layer while killing harmful microorganisms that could affect subsequent reaction processes, adsorbing and removing more impurities, and thus facilitating the operation of subsequent stages.

[0073] Specifically, when introducing gas, the gas inlet pipe needs to be inserted deep into the packing section near the bottom so that the gas diffuses from bottom to top. The introduced ozone refers to ozonated air prepared on-site using an ozone generator with air as the gas source, in which the ozone content is 2-3 wt%, and the ozone introduction rate needs to be controlled at 0.15-0.25 [L / (min·L)].

[0074] In one embodiment of the present invention, the step of obtaining the second degradation intermediate liquid includes:

[0075] After the first degradation intermediate liquid enters the biological packing section I for 13-17 minutes, air is introduced for 13-17 minutes. After another 28-32 minutes, air is introduced again for 13-17 minutes. After another 13-17 minutes, the liquid can enter the next section. The processing time is 80-100 minutes to obtain the second degradation intermediate liquid. The air introduction rate is 0.15-0.25 [L / (min·L)].

[0076] Specifically, the air introduced is the ambient air. When introducing the gas, the ventilation pipe needs to be inserted deep into the packing section near the bottom so that the gas diffuses from bottom to top.

[0077] In one embodiment of the present invention, the step of obtaining the degradation solution further includes:

[0078] After the second degradation intermediate liquid enters the biological packing section II for 18-22 minutes, air is introduced for 18-22 minutes. After another 38-42 minutes, air is introduced for another 18-22 minutes. After another 18-22 minutes, the final degradation liquid can be collected. The processing time is 110-130 minutes.

[0079] In another embodiment of the present invention, a degradation solution prepared by any of the above-described in-situ resource recovery methods is provided for use as greening water in irrigating green spaces.

[0080] The technical solution of the present invention has the following advantages compared with the prior art:

[0081] 1. This invention mainly includes two stages: pretreatment and S-type three-stage packed tower treatment. In the pretreatment stage, H2O2 is added first, which not only oxidizes and reduces pollutants but also reduces ammonia nitrogen content and kills pathogens. Then, wood ash (mainly potassium carbonate) obtained from the in-situ combustion of community greening waste is added (slightly in excess) to adjust the pH to alkaline at low cost and increase the potassium content of the raw solution. Finally, coagulant PAS is added to reduce the turbidity of the raw solution through flocculation, preparing it for subsequent S-type three-stage packed tower treatment.

[0082] 2. In this invention, the first activated carbon section of the S-type three-stage packed tower has a intercepting layer at its front end, composed of sodium alginate spheres with an average diameter of 5mm embedded with lactic acid bacteria and acetic acid bacteria. This layer filters out most of the colloidal flocculent particles generated during pretreatment, extending the activated carbon's lifespan. Furthermore, the lactic acid bacteria and acetic acid bacteria use the intercepted flocculent material as a carbon source, working together to inhibit the activity of pathogenic microorganisms. It also facilitates the decomposition of lignin and cellulose, which are normally difficult to decompose. Excess acidic substances can be neutralized by the previously added wood ash. After a large accumulation of flocculent material, it can be directly fed into the aerobic fermentation pile of wet waste for further treatment. At the rear end, activated carbon further removes odors and impurities through adsorption, while ozone is introduced to further reduce ammonia nitrogen content and kill pathogens, preventing other microorganisms from affecting the function of the microorganisms in the subsequent biological packing section.

[0083] 3. This invention incorporates biological packing material in the second and third sections of an S-type three-section packed tower. This biological packing material consists of treated citrus peel, freshly composted wet waste from aerobic fermentation, and sodium alginate pellets containing embedded microorganisms. The aim is to utilize the active aerobic bacteria in the composted wet waste to maximize the degradation of BOD and ammonia nitrogen in the original liquid, while removing VOCs. The citrus peel, after treatment with fructase and cellulase, can serve as a carbon source in leachate with low BOD content and also enhances microbial activity. Furthermore, optimal treatment results are achieved by skillfully controlling the reaction time and air introduction intervals in each section.

[0084] 4. In the biological packing section I of this invention, sodium alginate microspheres encapsulate actinomycetes and *Pseudomonas fluorescens*, creating an environment conducive to the proliferation of aerobic bacteria and enhancing their activity while resisting pathogens and deodorizing. In the biological packing section II, sodium alginate microspheres encapsulate *Bacillus subtilis* and yeast. *Bacillus subtilis* can synergistically degrade organic impurities such as BOD and remove ammonia nitrogen; *Bacillus subtilis* can produce active substances that promote cell division. The sodium alginate microspheres used in both the biological packing section and the intercepting layer are recyclable, facilitating preparation.

[0085] 5. The process of this invention is simple, requires minimal equipment, and uses low-cost, readily available raw materials. It effectively fills the market gap in the in-situ resource utilization technology of community wet waste leachate, solving the problems of incomplete in-situ disposal of community wet waste by current small-scale composting devices and the inability of existing equipment to treat community wet waste leachate to meet standards on-site. The effluent, after testing, fully meets the requirements of the "Green Space Irrigation Water Quality GB / T 25499-2010" standard in the series of urban wastewater utilization standards. It is particularly effective in degrading BOD and ammonia nitrogen, and the seed germination rate reaches 105%, making it suitable for direct irrigation of surrounding green spaces with high-quality water. When used in conjunction with small-scale wet waste treatment equipment, it can achieve complete in-situ, harmless, and resource-based recycling of community wet waste, demonstrating excellent practical application prospects. Attached Figure Description

[0086] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0087] Figure 1 This is a schematic diagram of the structure of the packed tower of the present invention.

[0088] Explanation of reference numerals in the instruction manual:

[0089] 100. Inlet section; 110. First bend connecting section; 200. Activated carbon section; 210. Interceptor layer; 211. First grid; 212. Second grid; 220. Activated carbon layer; 221. Third grid; 222. First valve; 223. First vent; 230. Second bend connecting section; 231. Fourth vent; 300. Biological packing section I; 310. Fourth grid; 320. Fifth grid; 330. Second valve; 340. Third bend connecting section; 341. Fifth vent; 350. Second vent; 400. Biological packing section II; 410. Sixth grid; 420. Seventh grid; 430. Third valve; 440. Fourth bend connecting section; 450. Third vent; 500. Outlet section. Detailed Implementation

[0090] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0091] Example:

[0092] This embodiment provides an in-situ resource recovery method for BOD and ammonia nitrogen in leachate from community wet waste, which mainly includes two stages: pretreatment and treatment using an S-type three-stage packed tower. A simplified schematic diagram of the S-type three-stage packed tower is shown below. Figure 1As shown, the specific steps include the following:

[0093] (1) Pilot Project and Sampling: A "Wet Waste Not Leaving the Village" campaign has been implemented in a certain village, and a small-scale community wet waste in-situ treatment equipment has been installed and is operating well. The wet waste in Yudun Village is kitchen waste with vegetable leaves, fruit peels, eggshells, and bones as the main components. On the same day, the wet waste obtained from waste sorting in the village is initially squeezed and crushed to separate wet waste composting raw materials and wet waste leachate. The wet waste composting raw materials are put into the small-scale equipment for on-site disposal, and the leachate generated during the composting process is also collected for later treatment. This invention uses the wet waste leachate obtained from the aforementioned process for in-situ treatment.

[0094] (2) Preparation and filling of filler: Take green waste such as fallen leaves, branches and grass clippings in the village and burn them in situ to obtain wood ash; take 8 kg of fresh citrus peel collected from fruit cut retail stores in the village, add 0.8 g of pectin dry enzyme preparation and 1.6 g of cellulose dry enzyme preparation (enzyme preparation brand: SUNSON Xiasheng Enzyme, food grade) and mix evenly and ferment in a sealed container for 2.5 h for later use; take 30 kg of columnar granular activated carbon produced by Tianshun Charcoal Industry; take 44 kg of fresh output from aerobic fermentation of wet waste within 2 days in the village's small-scale equipment; prepare sodium alginate balls with an average diameter of 5 mm and containing acetic acid bacteria and lactic acid bacteria, 6.7 kg of sodium alginate balls containing actinomycetes and fluorescent Pseudomonas, and 7.3 kg of sodium alginate balls containing Bacillus subtilis and yeast according to the method indicated in this invention.

[0095] 30 kg of activated carbon is filled into activated carbon layer 220; 3.0 kg of sodium alginate pellets embedded with acetic acid bacteria and lactic acid bacteria are filled into intercepting layer 210 before activated carbon layer 220, and intercepting layer 210 and activated carbon layer 220 are connected to form activated carbon section 200; 4.3 kg of treated citrus peel is mixed evenly with 22 kg of fresh wet waste aerobic fermentation material and 6.7 kg of sodium alginate pellets embedded with actinomycetes and Pseudomonas fluorescens, and then filled into biological packing section I 300; 3.7 kg of treated citrus peel is mixed evenly with 22 kg of fresh wet waste aerobic fermentation material and 7.3 kg of sodium alginate pellets embedded with Bacillus subtilis and yeast, and then filled into biological packing section II 400; the filling degree of all the above fillings is 100%.

[0096] (3) Pretreatment: Take 50L of community wet waste leachate obtained in step (1), add 4.5L of 50wt% industrial hydrogen peroxide and stir evenly until almost no bubbles are generated; then add 150g of wood ash obtained by burning in step (2) and stir evenly until the powder is basically dissolved; finally add 2.0g of 98% pure polyaluminum sulfate coagulant solid powder, stir quickly and let stand until stable flocculent particles are generated in the solution to obtain the treatment stock solution, which can then enter the next stage of treatment process.

[0097] (4) Treatment is carried out using an S-type three-section packed tower: the main dimensional parameters of the three packing sections in the packed tower are as follows: length 1.30m, pipe diameter 0.25m, slope 2.5%; the cutoff layer 210 before the activated carbon section 200 is 0.1m long; the tower body is made of corrosion-resistant PVC material. A simplified structural diagram and attached diagram are provided. Figure 1 Similarly, all grids use double-layer plastic square grids with a mesh size of 3mm. The specific process flow is as follows:

[0098] ① Close the first valve 222 and pour all the treatment liquid obtained in step (3) into the inlet section 100. The liquid enters the activated carbon section 200 through the first turning connection section 110. After 5 minutes, open the first vent 223 on the activated carbon section 200 and introduce ozone into it at a rate of 9L / min for 5 minutes. After an interval of 10 minutes, introduce ozone again for 5 minutes. After another 5 minutes, the reaction is complete and the first degradation intermediate liquid is obtained, which can then proceed to the next step.

[0099] ② Close the second valve 330 and open the first valve 222, allowing the first degradation intermediate liquid from step ① to enter the biological packing section I 300 via the second turning connection section 230. Then close the first valve 222. After 15 minutes, open the second vent 350 on the biological packing section I 300 and the fourth vent 231 on the second turning connection section 230. Introduce air into the second vent 350 at a rate of 11 L / min for 15 minutes. After a 30-minute interval, introduce air again for 15 minutes. After another 15 minutes, the reaction is complete, and the second degradation intermediate liquid is obtained. Then proceed to the next step.

[0100] ③ Close the third valve 430 and open the second valve 330 to allow all the second degradation intermediate liquid obtained in step ② to enter the biological packing section II 400, then close the second valve 330. After 20 minutes, open the third vent 450 on the biological packing section II 400 and the fifth vent 341 on the third turning connection section 340. Similarly, introduce air into the third vent 450 at a rate of 11 L / min for 20 minutes. After a 40-minute interval, introduce air again for 20 minutes. After another 20 minutes, open the third valve 430 to collect the degradation liquid for use as green space landscaping water, thus completing the entire treatment process.

[0101] Additionally, it should be noted that to facilitate liquid flow, 1-2 minutes before the raw liquid enters the next section, the vent on the vertical pipe connecting the two sections should be opened to create a negative pressure environment. Here, ozone refers to ozonated air prepared on-site using an ozone generator with air as the gas source, containing 2.7 wt% ozone (by mass). On-site air is acceptable. The vent pipe extends deep into the packing section near the bottom, and the vent should be closed immediately after venting is complete.

[0102] In addition, combined with the appendix Figure 1 This further explains the process by which wet waste leachate is converted into degradation liquid via a packed tower.

[0103] like Figure 1 As shown, the packed tower includes an activated carbon section 200, a biological packing section I 300, and a biological packing section II 400 arranged sequentially.

[0104] The activated carbon section 200 includes a flow-blocking layer 210 and an activated carbon layer 220;

[0105] The packed tower also includes an inlet section 100 located upstream of the activated carbon section 200 and an outlet section 500 located downstream of the biological packing section II 400. A first bend connection section 110 is provided between the inlet section 100 and the activated carbon section 200, a second bend connection section 230 is provided between the activated carbon section 200 and the biological packing section I 300, a third bend connection section 340 is provided between the biological packing section I 300 and the biological packing section II 400, and a fourth bend connection section 440 is provided between the biological packing section II 400 and the outlet section 500.

[0106] Keep the first valve 222 between the activated carbon section 200 and the second turning connection section 230 closed. The treatment raw liquid is injected from the inlet section 100. The treatment raw liquid passes through the first turning connection section 110, the first grid 211, the intercepting layer 210, and the second grid 212 in sequence and enters the activated carbon layer 220. Ozone is introduced into the activated carbon section 200 through the first vent 223 on the activated carbon section 200. The reaction is fully carried out to obtain the first degradation intermediate liquid.

[0107] Keep the second valve 330 between the biological packing section I 300 and the third turning connection section 340 closed, open the first valve 222, and the first degradation intermediate liquid enters the biological packing section I 300 by passing through the third grid 221 between the second turning connection section 230 and the activated carbon section 200, the second turning connection section 230, the fourth grid 310 between the second turning connection section 230 and the biological packing section I 300, and introduce air into the biological packing section I 300 through the second vent 350 on the biological packing section I 300. At the same time, open the fourth vent 231 on the second turning connection section 230 to fully react and obtain the second degradation intermediate liquid.

[0108] Keep the third valve 430 between the biological packing section II 400 and the fourth bend connecting section 440 closed, open the second valve 330, and the second degradation intermediate liquid sequentially passes through the fifth grid 320 between the third bend connecting section 340 and the biological packing section I 300, the third bend connecting section 340, the sixth grid 410 between the third bend connecting section 340 and the biological packing section II 400 and enters the biological packing section II 400. Air is introduced into the biological packing section II 400 through the third vent 450 on the biological packing section II 400. At the same time, the fifth vent 341 on the third bend connecting section 340 is opened to allow for a full reaction and obtain the degradation liquid.

[0109] The degradation liquid flows sequentially through the seventh grid 420 between the biological packing section II 400 and the fourth bend connecting section 440, and then through the fourth bend connecting section 440 to the outlet section 500.

[0110] Comparative example:

[0111] This comparative example also uses the classic traditional in-situ wastewater treatment method: the sequencing batch reactor (SBR process) process. The same batch of community wet waste leachate from the examples was treated in situ for comparison. The specific process flow is as follows:

[0112] ① Take a small SBR reactor that is already available in the laboratory (maximum processing capacity: 60L, floor space similar to the apparatus in the example, approximately 1m²). 2 The reaction device is in standby mode, the supernatant after sedimentation has been drained, and the device contains a high concentration of activated sludge mixture.

[0113] ② Take 50L of untreated community wet waste leachate from the same source as in the example, add it all into the reaction device, stir it evenly and start the reaction: every 10 minutes, introduce on-site air from the bottom at a rate of 11L / min for 10 minutes, stop the air supply after 3 hours and enter the sedimentation process, stop the sedimentation after 1 hour, and the total treatment cycle is also 4 hours.

[0114] ③ Discharge the supernatant after sedimentation and restore the water level to the lowest level at the beginning of the cycle. Most of the settled activated sludge is used as return sludge for the next cycle, and the remaining sludge is discharged.

[0115] Test example:

[0116] In this invention, representative indicators were tested on the final effluent after the treatment process in both the examples and comparative examples. The test results are shown in Table 1 below:

[0117] Table 1

[0118]

[0119] It should be noted that the limit values ​​refer to the corresponding limits for non-restricted green spaces in the "Green Space Irrigation Water Quality GB / T25499-2010" standard in the series of standards for urban wastewater utilization.

[0120] The test results show that, within the same treatment time and area, the treatment effect of the process of this invention is significantly better than that of the traditional SBR process. In addition, the present invention can add a new stage of leachate when the raw liquid enters the biological packing stage II, and the actual waiting time for continuous treatment is only 2 hours, while that for the SBR process is 4 hours.

[0121] If a standby process is set up in the SBR process, the processing cycle will be longer. If it is not set up, the activity of microorganisms cannot be restored through endogenous respiration, leaving the microorganisms in the activated sludge in a state of starvation, which will result in a poorer treatment effect in the future. The residual sludge generated by the SBR process cannot be disposed of on-site, while the waste generated by this invention can be disposed of on-site or recycled.

[0122] The test results show that, compared with the traditional in-situ treatment process, this invention can not only effectively reduce the content of BOD and ammonia nitrogen in community wet waste leachate, but also reduce turbidity and TDS, eliminate odor, and significantly reduce fecal coliforms and ascarid eggs in the effluent. The seed germination rate reaches 105%, which fully meets the requirements of the "Green Space Irrigation Water Quality GB / T 25499-2010" series of standards for urban wastewater utilization. It can be used as high-quality greening water to directly irrigate surrounding green spaces. The treatment cycle is shorter and the treatment effect is better when running continuously, realizing the in-situ, harmless, and resource-efficient recycling of community wet waste leachate.

[0123] In addition, a month-long application pilot was conducted in the village mentioned in Example 1, using the process of the present invention in conjunction with the existing small-scale wet waste treatment equipment. The pilot results showed that the process of the present invention had good continuous operation performance and effectively solved the problem that the leachate generated by the small-scale composting device in the village could not be used on-site and its fate was unknown. The effluent can be directly used to irrigate the surrounding vegetable fields, and the compost output can also be used as fertilizer on-site, resulting in thriving vegetable growth.

[0124] In summary, this invention is rationally designed. Through two stages—pretreatment and S-type three-stage packed tower treatment—it transforms community wet waste leachate into high-quality greening water on-site. The effluent fully meets the "Green Space Irrigation Water Quality GB / T 25499-2010" standard in the series of urban wastewater utilization standards. It effectively fills the market gap in current technologies for the in-situ resource utilization of community wet waste leachate, solving the problems of incomplete on-site disposal of community wet waste by current small-scale composting devices and the inability of existing equipment to treat community wet waste leachate to meet standards on-site. When used in conjunction with small-scale wet waste treatment equipment, it can achieve complete on-site, harmless, and resource-based recycling of community wet waste, demonstrating promising practical application prospects.

[0125] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for in-situ resource utilization of BOD and ammonia nitrogen in community wet garbage leachate, characterized in that, The method comprises the following steps: Providing wet garbage leachate; Pretreating the wet garbage leachate with hydrogen peroxide, wood ash and coagulant to obtain a treatment stock solution; Providing a filler tower comprising an activated carbon section, a biological filler I section and a biological filler II section arranged in a vertical tower in sequence; the activated carbon section is provided with a interception layer, and the interception layer is arranged at the upstream end of the activated carbon section; In-situ degrading and treating the treatment stock solution in the activated carbon section, the biological filler I section and the biological filler II section in sequence to obtain a degradation solution; ozone is introduced when passing through the activated carbon section; The fillers of the interception layer, the biological filler I section and the biological filler II section each independently comprise functional small balls embedding microorganisms; The biological filler of the biological filler I section is composed of citrus peel, wet garbage aerobic fermentation compost and sodium alginate small balls embedding actinomycetes and fluorescent pseudomonas, and the mass ratio of the citrus peel, the wet garbage aerobic fermentation compost and the sodium alginate small balls embedding actinomycetes and fluorescent pseudomonas is 1-1.5:6-7:1.5-2; The biological filler of the biological filler II section is composed of citrus peel, wet garbage aerobic fermentation compost and sodium alginate small balls embedding bacillus subtilis and yeast, and the mass ratio of the citrus peel, the wet garbage aerobic fermentation compost and the sodium alginate small balls embedding bacillus subtilis and yeast is 2-2.5:10-12:3-3.5; The wet garbage aerobic fermentation compost refers to the final fermentation compost of community wet garbage after a complete aerobic composting process, and the fresh compost should be taken within 2 days after taking out the compost; The citrus peel is obtained by pretreating the fresh citrus peel, and the pretreatment process comprises the following steps: crushing the fresh citrus peel to a particle size of less than 1 cm, adding enzyme preparation, and fermenting for 2-3 hours. The interception layer is composed of sodium alginate small balls embedding lactic acid bacteria and acetic acid bacteria, and the average diameter of the small balls is 5 mm; The activated carbon section comprises an interception layer and an activated carbon layer.

2. The in situ resource utilization method of claim 1, wherein, At least one or more of the following conditions is met: (i) the dosage of the hydrogen peroxide is 90-110 mL / L, and the mass concentration of the hydrogen peroxide is 35-60%; (ii) the dosage of the wood ash is 2-4 g / L, and the wood ash is the ash collected after in-situ combustion of greenery waste; (iii) the dosage of the coagulant is 25-40 mg / L, and the coagulant is selected from polyaluminum sulfate with a purity of 98-99%.

3. The in situ remediation method of claim 1, wherein, The functional small balls further comprise a carrier and a solidifying agent; the solidifying agent is selected from one or more of calcium chloride, boric acid and glutaraldehyde; and the carrier is sodium alginate; The mass concentration of the solidifying agent is 3.8-4.1%; The mass concentration of the carrier is 3.9-4.2%; The length of the interception layer accounts for 1 / 15-1 / 10 of the total length of the activated carbon section.

4. The in situ remediation method of claim 1, wherein, The enzyme preparation is selected from pectinase preparation and / or cellulase preparation; the dosage of the pectinase preparation is 0.09-0.12 g / kg; and the dosage of the cellulase preparation is 0.18-0.21 g / kg.

5. The in situ remediation method of claim 1, wherein, The filler tower further comprises an inlet section arranged at the upstream end of the activated carbon section, an outlet section arranged at the downstream end of the biological filler II section, a first turning connecting section arranged between the inlet section and the activated carbon section, a second turning connecting section arranged between the activated carbon section and the biological filler I section, a third turning connecting section arranged between the biological filler I section and the biological filler II section, and a fourth turning connecting section arranged between the biological filler II section and the outlet section; The preparation method of the degradation liquid comprises the following steps: keeping the first valve between the activated carbon section and the second turning connecting section in a closed state, injecting the treatment stock solution from the inlet section, and the treatment stock solution sequentially passes through the first turning connecting section, the first grid, the interception layer, the second grid, and enters the activated carbon layer, introducing ozone into the activated carbon section through the first air inlet on the activated carbon section, and fully reacting to obtain a first degradation intermediate liquid; keeping the second valve between the biological filler I section and the third turning connecting section in a closed state, opening the first valve, and the first degradation intermediate liquid sequentially passes through the third grid between the second turning connecting section and the activated carbon section, the second turning connecting section, the fourth grid between the second turning connecting section and the biological filler I section, and enters the biological filler I section, introducing air into the biological filler I section through the second air inlet on the biological filler I section, fully reacting to obtain a second degradation intermediate liquid; keeping the third valve between the biological filler II section and the fourth turning connecting section in a closed state, opening the second valve, and the second degradation intermediate liquid sequentially passes through the fifth grid between the third turning connecting section and the biological filler I section, the third turning connecting section, the sixth grid between the third turning connecting section and the biological filler II section, and enters the biological filler II section, introducing air into the biological filler II section through the third air inlet on the biological filler II section, fully reacting to obtain the degradation liquid; The degradation liquid sequentially passes through the seventh grid between the biological filler II section and the fourth turning connecting section, and the fourth turning connecting section flows to the outlet section.

6. The in situ remediation method of claim 5, wherein, At least one or more of the following conditions is met: The activated carbon section, the biological filler I section, and the biological filler II section are arranged in parallel; The activated carbon section, the biological filler I section, and the biological filler II section are each independently inclined downward to form a slope of 2-3%; The lengths of the activated carbon section, the biological filler I section, and the biological filler II section are the same, and should be 5-6 times the length of the turning connecting section; The grid is a double-layer plastic grid with a pore size of 3-4 mm; The activated carbon section, the biological filler I section, and the biological filler II section are independently filled with filler full pipes; The fullness of the treatment stock solution, the first degradation intermediate liquid, and the second degradation intermediate liquid is not more than 90%; The ozone refers to ozone-containing air prepared on site by an ozone generator using air as the gas source, and the ozone content is 2-3 wt%; The passing rate of the ozone is 0.15-0.25 [L / (min·L)]; The passing rate of the air is 0.18-0.24 [L / (min·L)].

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