Treatment method of kitchen garbage wet slurry coalification wastewater

Abstract

The invention relates to the field of high-salt and high-concentration organic wastewater treatment, and discloses a treatment method of kitchen waste wet slurry coalification wastewater. According to the treatment method, after coalification zeolite is pretreated, a hot air evaporation condensation process is carried out by utilizing the boiling point of organic acid in the wastewater through catalytic oxidation, so that the salt content of the wastewater is reduced, the biodegradability of the wastewater is improved, and the inhibition and toxic effects of high-salt and high-concentration organic wastewater on a biochemical system in a traditional sewage biochemical treatment process are overcome; the problem that coalification wastewater is difficult to biochemically degrade is solved. Various pollutants such as grease, suspended solids, organic matters, ammonia nitrogen and the like in the wastewater are removed step by step through each technological process, and the standard discharge of the treated wastewater is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, relates to the field of high-salt and high-concentration organic wastewater treatment, and specifically relates to a method for treating kitchen waste wet slurry coalification wastewater. Background Art

[0002] With the rapid urbanization process, the output of urban solid waste has increased dramatically. my country has vigorously promoted the garbage classification system. The amount of kitchen waste to be processed is increasing day by day. It is easy to rot and produce stench, which will cause serious environmental problems. At present, in order to make kitchen waste resource-based, harmless and reduced, large kitchen waste treatment plants mainly use incineration, landfill, composting and anaerobic digestion technology. Its process characteristics are low operating cost, large land area and long production cycle; while some urban areas use new treatment technology for small kitchen waste treatment plants due to factors such as small land area and short treatment cycle.

[0003] The wet slurry of kitchen waste is coalified at a temperature of 180-250℃ and a pressure of 0.5-3MPa, and coalification wastewater with high concentration of organic pollutants, high chroma, odor, and oleic acid will be produced. Coalification wastewater refers to the wastewater produced after the wet slurry of kitchen waste is coalified.

[0004] The kitchen waste wet slurry coalification wastewater of the present invention is characterized by high concentration of organic pollutants and complex components, and contains a large amount of lactic acid, acids, alcohols, aldehydes, lipid compounds, aromatic compounds, heterocyclic compounds and other pollutants; the water quality of the kitchen waste wet slurry coalification wastewater is as follows: c (COD) = 50 ~ 80g / L, c (NH 3 -N) = 1.2 ~ 2.5g / L, c (ss) = 3 ~ 8g / L, pH = 3 ~ 4, the wastewater is dark brown, has a peculiar smell, high oil content, is viscous, and is a high-salt and high-concentration organic wastewater; the biological toxicity of coal chemical wastewater pollutants is low, but due to their large molecular weight, they have good chemical stability. The main reaction of wastewater treatment is biochemical treatment, which is difficult to biodegrade, and the biochemical treatment of wastewater is less effective.

[0005] For high-salt and high-concentration coalification wastewater, the current high-salt and high-concentration organic wastewater treatment process membrane treatment method and other processes, the high salt content in the wastewater will reduce the service life of the membrane, and the frequent replacement of membrane components will increase the operating costs, and at the same time, the wastewater concentrate will have long-term reflux, re-injection, and accumulation problems. The present invention provides a kitchen waste wet slurry coalification wastewater treatment method, which improves the biodegradability of coalification wastewater, quickly, stably and efficiently removes various pollutants in the wastewater, ensures that the effluent meets the discharge standards, and solves the problems of difficult biodegradation of wastewater and high treatment costs. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a method for treating kitchen waste wet slurry coalification wastewater to solve the problem that high-salt and high-concentration organic wastewater is difficult to treat.

[0007] The invention provides a method for treating kitchen waste wet slurry coalification wastewater, comprising a pretreatment system, a hot air evaporation system, a solid-liquid separation system, a catalytic oxidation system, a biochemical treatment system, and a disinfection tank. The technical method adopted by the present invention is implemented in the following steps: step 1, introducing kitchen waste wet slurry coalification wastewater into a pretreatment system to remove suspended oils and solid suspended matter in turn; step 2, the pretreated wastewater is introduced into a hot air evaporation system through a pump, and volatile small molecular organic matter is blown off by hot air evaporation, and the condensed water generated by the hot air evaporation system is condensed and collected, and then introduced into a biochemical system for deep treatment; after the coalification wastewater is concentrated and crystallized by hot air evaporation, it is subjected to a solid-liquid separation system to remove salt and macromolecular organic matter, and the separated liquid is introduced into a catalytic oxidation system to decompose the organic matter that is difficult to biodecompose into small molecular organic matter and improve the biodegradability, and then the wastewater after catalytic oxidation is introduced into a hot air evaporation system for acclimatization and evaporation; step 3, the condensed water is introduced into a biochemical treatment system, and neutralization, anaerobic, anoxic and aerobic process treatments are carried out in turn to remove pollutants in the wastewater; finally, the wastewater treated by the biochemical system is disinfected and discharged in compliance with the standards. The present invention uses an electrocatalytic oxidation system in coordination with a hot air evaporation system, as well as a circulating, stable and efficient control system, to decompose large-molecule organic matter that is difficult to biodegrade into small-molecule organic matter, and improve the biodegradability of wastewater. Various pollutants are gradually removed in each process, effectively improving the removal rate of pollutants in wastewater, and ultimately ensuring that wastewater discharge meets discharge standards.

[0008] Furthermore, the pretreatment system includes a grease trap, an oil collecting tank, a flocculation mixing tank, and a sedimentation tank. The flocculation mixing tank equipment is equipped with a mechanical stirring system, which achieves the effects of demulsification, flocculation, and sedimentation by step-by-step addition of demulsifiers, coagulants, and coagulant aids for stirring, and removes grease and suspended matter in the wastewater.

[0009] Preferably, the present invention uses an oil-soluble demulsifier that can form stable floccules in acidic oily wastewater.

[0010] Furthermore, the hot air evaporation system is a packed tower structure, including an atomization system, a packing layer, and an air blowing system; the atomization system is arranged on the upper layer of the tower packing, and the wastewater is formed into mist-like water droplets by the atomization system and contacts with the hot air. The volatile small molecular organic matter evaporates with the hot air, and the large molecular organic matter flows back through the packing layer; the bottom of the hot air evaporation system is provided with an aeration system, and hot air is continuously blown for diffusion and aeration.

[0011] Preferably, the hot air is controlled at a temperature of 120°C, 140°C, 160°C, 180°C, 200°C, or 220°C.

[0012] Preferably, the hot air controls the wind speed to be 4 m / s, 5 m / s, 6 m / s, 7 m / s, 8 m / s, or 9 m / s.

[0013] Preferably, the filler in the packed tower is preferably an iron-carbon micro-electrolysis filler which is spherical or ellipsoidal, with a particle size of 3-5 cm, a porosity greater than 60%, an iron-carbon ratio greater than 65%, a filling ratio of 55-65%, and an effective specific surface area of ​​400 m2 / m³-500 m2 / m³. It generates a 0.9-1.7 V potential difference discharge to form electrochemical treatment of the wastewater, thereby degrading organic pollutants in the wastewater.

[0014] Furthermore, the solid-liquid separation system adds a curing agent to the crystals precipitated from the hot air evaporation system to form a solid treatment product, and separates and removes fine suspended particles and colloidal particles in the wastewater through the solid-liquid separation system.

[0015] Furthermore, the catalytic oxidation system adds acid, catalyst and oxidant for supplementary adjustment according to the type and property of pollutants to be removed in the wastewater and the actual operating conditions. Hydroxyl free radicals with strong oxidizing ability will be generated in the catalytic oxidation system, and most of the organic matter in the coal chemical wastewater will be oxidized and decomposed or form salt precipitation. The difficult-to-degrade organic matter can be opened and broken to become small molecular organic matter. The coal chemical wastewater treated by the catalytic oxidation system is refluxed and circulated into the hot air evaporation system.

[0016] Furthermore, the biochemical treatment system includes an adjustment buffer zone, an anaerobic reaction zone, an anaerobic reaction zone, an aerobic reaction zone, and a sedimentation tank; the specific implementation steps of the biological treatment system are as follows: the hot air evaporation system utilizes the low boiling point and volatile characteristics of small molecule organic matter, and the condensed water produced by evaporation contains a large amount of small molecule organic acid. After the temperature and pH value of the adjustment buffer zone are adjusted, it provides sufficient carbon source as a biological treatment process. The wastewater undergoes hydrolysis and acidification reactions in the anaerobic reaction zone, further increasing the biodegradability of the wastewater and improving the biochemical treatment effect; the organic matter in the wastewater is continuously biodegraded in the anaerobic reaction zone and the aerobic reaction zone, and the pollutants in the wastewater are removed by utilizing a semi-short-range nitrification-denitrification process with a large reflux ratio in combination with a high-efficiency bacterial agent.

[0017] Furthermore, the effluent from the biochemical treatment system enters a disinfection pool, into which bactericidal disinfectants are added and retained for more than 1 hour to remove bacteria, microorganisms, etc. in the wastewater, ultimately making the effluent meet water quality discharge standards.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The pretreatment system uses a water-soluble demulsifier, which can stably form floccules in the mechanical stirring system and effectively reduce suspended matter in the wastewater.

[0020] 2. Coal chemical wastewater contains a large amount of small molecule organic acids. The hot air evaporation system treatment process is adopted. The boiling point of small molecule organic matter is utilized to evaporate and condense the small molecule organic matter in the coal chemical wastewater with water vapor, and then enter the wastewater biochemical treatment system without adding any external carbon source. The wastewater biochemical treatment requirements can be met and the discharge can reach the standard. The present invention realizes the deep treatment process of high-salt and high-concentration organic wastewater-kitchen waste wet slurry coal chemical wastewater.

[0021] 3. Coal chemical wastewater is acidic. It is pre-oxidized by using iron-carbon materials in the hot air evaporation system. The synergistic electrocatalytic oxidation technology is to form hydroxyl radicals through the free radical reaction between wastewater containing hydrogen peroxide and ozone in small bubbles, which is beneficial to convert large molecular organic pollutants in the wastewater into small molecular substances, saving the cost of reagents and removing pollutants in the wastewater.

[0022] 4. Use hot air evaporation + micro-electrolytic oxidation + Fenton catalytic oxidation process instead of membrane concentration filtration to improve the biodegradability of wastewater, reduce the salt content of wastewater, and improve the chromaticity of effluent water quality, thus overcoming the inhibitory and toxic effects of high-salt and high-concentration pollutants on the biochemical system in traditional wastewater biochemical treatment, which affects the unsatisfactory biochemical treatment effect.

[0023] 5. The biochemical treatment system + decolorization, sterilization and disinfection replaces the membrane filtration system, which can effectively improve the water quality of wastewater effluent. The system can avoid membrane clogging during the operation process, with low operating costs and simple management and operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a schematic diagram of the process flow of a method for treating kitchen waste wet slurry coalification wastewater. DETAILED DESCRIPTION

[0025] The specific implementation method is to further elaborate and illustrate the present invention. The specific implementation steps of a kitchen waste wet slurry coalification wastewater are as follows:

[0026] The wet slurry of kitchen waste coalification wastewater enters the grease trap, and 0.2kg / m³ demulsifier is added and stirred for 30 minutes through the mechanical stirring system in the grease trap to remove suspended matter and demulsify the wastewater.

[0027] Furthermore, in the embodiment, after the wastewater is treated, the wastewater enters the hot air evaporation system: (1) the system adopts a hot air evaporation system with a hot air volume of 6000m³ / h and a power of 75kW; (2) 2-3 layers of iron-carbon micro-electrolysis fillers are arranged in the middle and lower layers of the tower, and the wastewater is treated by iron-carbon micro-electrolysis to catalyze and oxidize some small molecular organic matter, while providing Fe for the subsequent Fenton reaction. 2+⑶ An atomizing spray system is provided at the top of the packing, through which the wastewater is atomized, and small molecular organic matter enters the subsequent biochemical treatment process with the condensed water. Part of the wastewater is sprayed on the iron-carbon micro-electrolysis packing and then flows into the water tank at the bottom of the cooling tower. A circulating water pump is used at the bottom to introduce the wastewater into the atomizing system for circulating spraying; ⑷ A micro-negative pressure system is used at the top of the packing tower to allow the generated evaporated condensed water to enter the hydrolysis acidification tank for hydrolysis acidification to ensure the stable operation of the subsequent deep treatment process. ⑸ The iron-carbon micro-electrolysis packing itself generates a potential difference of 0.9-1.7V, which forms an electrochemical treatment of the wastewater through discharge, thereby degrading the organic pollutants in the wastewater; (6) After the concentrated liquid treated by the hot air evaporation system is separated by a centrifugal device, the wastewater enters the electrocatalytic reactor for catalytic oxidation, and the oxidant input is 0.5kg / m³H 2 O 2 , mainly removes the difficult-to-biodegrade organic matter in the wastewater, and the reaction residence time is 4h. After the Fenton process is completed, it is circulated and sprayed in the hot air evaporation treatment system through a pump.

[0028] Furthermore, the biochemical treatment process "hydrolysis acidification tank + CAST reactor" in the embodiment adopts a plug flow method. The condensed water treated by the hot air evaporation system enters the CAST reactor: (1) the front buffer zone is used as a hydrolysis acidification tank to acidify and hydrolyze the organic matter in the wastewater, and at the same time, the wastewater is fully contacted with the return sludge, and the residence time is 2h; (2) then enters the anaerobic zone of the CAST reactor and operates under anaerobic conditions, so that the excessive phosphorus absorbed in the sludge is effectively released under anaerobic conditions. Operation load: 15kgCOD / (m³·d), residence time 72h; (3) the middle part of the anoxic reaction zone mainly removes organic matter through the adsorption of regenerated sludge, and at the same time, the operation under anaerobic and anoxic conditions promotes the further release of phosphorus and strengthens the denitrification process of nitrogen, further enhancing the removal of nitrate nitrogen. (4) The main reaction zone at the rear is opened and closed by the aeration system. The biochemical pool successively carries out aerobic nitrification reaction (aeration stage) and anoxic denitrification reaction (sedimentation stage), making full use of the rapid adsorption effect of activated sludge to accelerate the removal of soluble substrates. After a relatively low-load substrate decomposition and degradation process, the wastewater meets the discharge standards after deep treatment.

[0029] The wastewater treatment process of the present invention can improve the biodegradability of wastewater, and the treatment process gradually removes and degrades grease, COD and other substances in wastewater. cr , ammonia nitrogen, chromaticity, suspended solids and other pollutants to ensure that wastewater treatment meets discharge standards.

[0030] The present invention has been disclosed as above with preferred embodiments, which are not intended to limit the present invention. Any technician familiar with the art, without departing from the scope of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention shall fall within the scope of protection of the technical solution of the present invention without departing from the scope of the technical solution of the present invention.

Claims

1. A method for treating kitchen waste wet slurry coalification wastewater, characterized in that: It includes pretreatment system, hot air evaporation system, solid-liquid separation system, catalytic oxidation system, biochemical treatment system and disinfection pool; among which: The pretreatment system includes an oil separator, an oil collecting tank, a flocculation mixing tank, and a sedimentation tank; the flocculation mixing tank equipment is equipped with a mechanical stirring system, which achieves the effects of demulsification, flocculation, and sedimentation by step-by-step addition of demulsifiers, coagulants, and coagulants for stirring; the hot air evaporation system is a packed tower structure, including an atomization system, a packing layer, and an air blast system; the solid-liquid separation system adds a curing agent to the crystals precipitated from the hot air evaporation system to form a solid treatment product, and separates and removes fine suspended particles and colloidal particles in the wastewater through the solid-liquid separation system; the catalytic oxidation system is based on the needs of the wastewater. According to the types and properties of the pollutants to be removed and the actual operating conditions, acids, catalysts and oxidants are added for supplementary adjustment. Hydroxyl free radicals with strong oxidizing ability will be generated in the catalytic oxidation system, and most of the organic matter in the coal chemical wastewater will be oxidized and decomposed or form salt precipitation, and the difficult-to-degrade organic matter can be opened and broken to become small molecule organic matter. The coal chemical wastewater treated by the catalytic oxidation system is refluxed and circulated into the hot air evaporation system; the biochemical treatment system includes a regulating buffer zone, an anaerobic reaction zone, an anaerobic reaction zone, an aerobic reaction zone, and a sedimentation tank; the disinfection tank is added with a bactericidal disinfectant and stays for more than 1 hour.

2. A method for treating kitchen waste wet slurry coalification wastewater according to claim 1, characterized in that: The atomization system is arranged on the upper layer of the tower packing, and the waste water is formed into mist-like water droplets by the atomization system and contacts with the hot air. Volatile small-molecule organic matter evaporates with the hot air, and large-molecule organic matter refluxes through the packing layer; an aeration system is provided at the bottom of the hot air evaporation system, and hot air is continuously blown for diffusion aeration; the hot air evaporation system is preferably controlled at a temperature of 120°C, 140°C, 160°C, 180°C, 200°C, and 220°C; preferably, the hot air control wind speed is 4m / s, 5m / s, 6m / s, 7m / s, 8m / s, and 9m / s; preferably, the filler in the packing tower is preferably an iron-carbon micro-electrolysis filler that is spherical or ellipsoidal, with a particle size of 3-5cm, a porosity greater than 60%, an iron-carbon ratio greater than 65%, a filling ratio of 55-65%, and an effective specific surface area of ​​400㎡ / m³-500㎡ / m³, and generates a 0.9-1.7V potential difference discharge by itself to form an electrochemical treatment of the wastewater, thereby degrading the organic pollutants in the wastewater.

3. A method for treating kitchen waste wet slurry coalification wastewater according to claim 1, characterized in that: The specific implementation steps of the biological treatment system are as follows: the hot air evaporation system utilizes the low boiling point and volatile characteristics of small molecule organic matter. The condensed water produced by evaporation contains a large amount of small molecule organic acid. After adjusting the temperature and pH value in the buffer zone, it provides sufficient carbon source as a biological treatment process. The wastewater undergoes hydrolysis and acidification reactions in the anaerobic reaction zone, further increasing the biodegradability of the wastewater and improving the biochemical treatment effect; the organic matter in the wastewater is continuously biodegraded in the anaerobic reaction zone and the aerobic reaction zone, and the pollutants in the wastewater are removed by utilizing a semi-short-range nitrification-denitrification process with a large reflux ratio in combination with a high-efficiency bacterial agent.

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