CN214780851U - System for treating landfill leachate membrane concentrate - Google Patents
System for treating landfill leachate membrane concentrate Download PDFInfo
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- CN214780851U CN214780851U CN202022740923.4U CN202022740923U CN214780851U CN 214780851 U CN214780851 U CN 214780851U CN 202022740923 U CN202022740923 U CN 202022740923U CN 214780851 U CN214780851 U CN 214780851U
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Abstract
The utility model discloses a processing system of landfill leachate membrane concentrate for: preprocessing nanofiltration and reverse osmosis concentrated solution, namely mother solution, from a landfill leachate membrane treatment process to remove solid wastes and other suspended particles in the mother solution; after pretreatment, the mother liquor is subjected to deep concentration and dehydration; pumping the mother liquor after impurity removal into a preheater and a heater through a pump, heating to a target temperature, then entering an evaporation device from the top, and directly contacting with gas from below to above to perform heat transfer and mass transfer; the evaporation device is connected with the condensation device, the wet and hot steam distilled from the top directly enters the condensation device from the bottom, condensed water from top to bottom is condensed to obtain condensed liquid, and the condensed liquid is mixed with nanofiltration clear liquid and then enters a reverse osmosis system for treatment; the wet and hot gas without water content is changed into cold gas, and then enters the evaporation device again to form a closed gas circulation system. The utility model discloses simple structure, factor of safety is high, and equipment investment is few, and energy utilization is high, and the degree of automation of a whole set of technology is high.
Description
Technical Field
The utility model relates to a processing system of landfill leachate membrane concentrate belongs to landfill leachate application.
Background
With the rapid expansion of urban construction scale and the gradual improvement of living standard of people, the yield of household garbage is larger and larger. The reduction and harmless treatment of domestic garbage become an important problem to be solved urgently in the environmental field of China. The main components of the landfill leachate depend on the landfill process of the landfill, the types and relevant proportions of the wastes processed by the landfill, the service time of the landfill, the climatic conditions, the compaction condition of the wastes, the stage of the landfill, the collection and drainage mode of the landfill leachate and other factors. Due to the influence of the above factors, the landfill leachate has the characteristics of complex water quality, high pollutant concentration, large water quantity change and the like, and the change rule is often difficult to master and control. Meanwhile, the leachate also has the water quality characteristics of strong toxicity, more difficultly-degradable substances, high nitrogen, low phosphorus and the like, so that the leachate treatment process is complicated, and the difficulty in leachate treatment is increased.
Therefore, the treatment of the landfill leachate is adapted to the characteristics of the landfill leachate as much as possible, and a reasonable treatment process is selected. Aiming at the treatment of the wastewater, technical specification for leachate treatment engineering in domestic refuse landfills was issued by the department of environmental protection in 2010. The method takes 'pretreatment + biological treatment + membrane component advanced treatment' as a recommended landfill leachate main treatment process, and the process is adopted in a plurality of landfill sites in China. After biochemical treatment, the landfill leachate can be discharged up to the standard through nanofiltration and reverse osmosis membrane advanced treatment. In the garbage percolate membrane treatment process, a nanofiltration membrane can effectively intercept divalent or multivalent ions and some organic matters with the molecular weight of more than 300, mainly humic substances such as humic acid and fulvic acid; the reverse osmosis membrane can effectively retain all substances including monovalent ions. Therefore, the membrane concentrated solution with the volume of about 13-30% generated by the landfill leachate through the membrane treatment process has the characteristics of high concentration of refractory organic matters, large salinity, poor biodegradability and the like, and is difficult to discharge after being directly treated to reach the standard.
The treatment mode of the membrane concentrated solution mainly comprises recharging, reduction treatment and harmless treatment. The percolate concentrate recharging technology can promote the degradation of degradable organic matters, but can also result in the enrichment of effluent COD, conductivity, ammonium ions and chloride ions. It is of concern that the process may cause groundwater contamination. The reduction process is mainly based on membrane technology and conventional evaporation technology. Due to the high concentration of humic and fulvic acids in the concentrate, irreversible membrane fouling can result. In addition, the high hardness of the concentrated solution is easy to cause scaling in the membrane treatment process, and the membrane treatment efficiency is seriously influenced. At present, the traditional evaporation techniques that have been applied in the treatment of landfill leachate concentrate include single-effect evaporation, multiple-effect evaporation, MVR evaporation, and the like. However, at the operating temperature of the above technology, the chloride ions enriched in the concentrated solution can cause serious corrosion to the equipment, and meanwhile, high-concentration humus and inorganic salt ions in the concentrated solution can easily cause serious scaling of the equipment, thereby reducing the heat exchange efficiency and the evaporation energy efficiency ratio and lowering the operation stability. Therefore, aiming at the problems and the defects of the technology, the high-efficiency, energy-saving and simple and feasible treatment process of the landfill leachate membrane concentrated solution is developed.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a processing system of rubbish leachate membrane concentrate. The system has the characteristics of simple structure, high safety factor, low energy consumption, high energy utilization rate, strong equipment operability, high automation degree, cleanness and no pollution.
The technical scheme is as follows:
a landfill leachate membrane concentrated solution treatment system comprises a pretreatment device, a preheater, a heater, an evaporation device, a condensation device, a circulating water cooler, a liquid-solid separator and an induced draft fan; the delivery port of preprocessing device communicates the cold side import of pre-heater, the cold side import of preprocessing device's cold side exit linkage heater, the cold side exit linkage evaporation plant's of heater water inlet, condensing equipment's air intake is connected to evaporation plant's air outlet, evaporation plant's dense liquid exit linkage liquid-solid separator, the delivery port of liquid-solid separator communicates the cold side import of pre-heater, the hot side import of pre-heater is connected to condensing equipment's delivery port, the water inlet of hot side exit linkage circulating water cooler of pre-heater, condensing equipment's water inlet is connected to circulating water cooler's delivery port, the air intake of draught fan is connected to condensing equipment's air outlet, evaporation plant's air intake is connected to the air outlet of draught fan. The preheater and the heater are both tube type heat exchangers, and the shell and the heat exchange tubes can be made of non-metal materials.
The treatment process of the landfill leachate membrane concentrated solution based on the system comprises the following steps: pretreating mother liquor of concentrated solution generated after landfill leachate membrane process treatment, then preheating and heating, feeding into an evaporation system after temperature is raised, collecting condensate from the top of an evaporation device through a condensing device, converting the damp-heat gas into cold gas, and returning to the evaporation device through a draught fan; the evaporated concentrated solution is discharged from the bottom of the evaporation device for liquid-solid separation, the liquid returns to the preheating process for continuous treatment, and the solid enters the next treatment process.
Furthermore, the pretreatment equipment is an automatic backwashing filter or a plate-and-frame filter press, preferably the automatic backwashing filter, and the filtering precision is higher than 30 mu m.
Further, heating the mother liquor of the concentrated solution of the membrane process to 60-80 ℃, and optimally 80 ℃.
Further, the mother liquor of the membrane process concentrated solution is fed in a spraying mode, and spray heads can be in the forms of vortex nozzles, spiral nozzles and splash nozzles, and the splash nozzles are more preferable.
Furthermore, the operation pressure of the evaporation device and the condensation device is normal pressure.
Further, the gas circulating among the induced draft fan, the evaporation plant and the condensing device is air or nitrogen, and the optimal gas is nitrogen.
Furthermore, a part of condensate of the condensing system is discharged as clear liquid and mixed with nanofiltration clear liquid to enter a reverse osmosis process in the garbage leachate membrane process, and a part of condensate is used as a heat source to preheat mother liquid and recycle part of heat.
Further, the liquid-solid separator adopts a centrifugal drier or a plate-and-frame filter press, and more preferably adopts a centrifugal drier.
Furthermore, the evaporation device and the condensation device adopt high-efficiency random packing, and the material is preferably PP. The evaporation and condensation device is similar to a spray tower in structure, heated materials in the evaporation device are from top to bottom, cold air is from bottom to top, the materials are in contact with each other in the packing layer to carry out gas-liquid mass transfer, and a heat source can adopt steam or other low-grade heat sources, including waste hot water, steam condensate water, methane combustion and the like; the condensing device is that condensed water is from top to bottom, damp and hot air is from bottom to top, gas-liquid mass transfer is carried out by mutual contact of the packing layer, and the cold source is circulating water.
Furthermore, steam and low-grade heat sources can be adopted as heat sources in the preheating and heating process.
Furthermore, a cold source in the condensing system can adopt industrial circulating water, and the condensed water can adopt industrial water or pure water.
Has the advantages that: the utility model discloses an independent operating unit carries out the concentration dehydration to the concentrate after membrane process handles, does not influence original processing technology, does not produce secondary pollution, can carry out the efficient handling to percolate membrane concentrate, obtains nearly solid concentrate, and discharged clear solution can select directly to discharge or mix with the clear solution of receiving to strain according to the actual processing quality of water condition and get into reverse osmosis treatment process. The utility model discloses an introduce simple chemical industry operation unit, the device is simple easily to be operated, and degree of automation is high, can open and shut down at any time, and the maintenance cycle is long, and equipment capital construction is simple, and factor of safety is high. Compared with the traditional process, the utility model discloses can not receive the restriction of high COD and high salt content, can adopt comparatively cheap non-metallic material, be difficult for the scale deposit, equipment investment cost is low. Meanwhile, if the fresh steam energy consumption of the heating system is basically equivalent to that of multi-effect evaporation, about 0.3t steam/t evaporation capacity is adopted, and if the waste low-grade heat of a factory is fully utilized as a heat source, the energy consumption is basically negligible. The utility model discloses the partial heat is retrieved through the pre-heater to the condensate of well production, has further reduced the energy consumption. The utility model discloses a whole set of processing technology adopts nitrogen gas as gas circulation system's circulating gas, has increased equipment operation's factor of safety.
Drawings
FIG. 1 is a flow diagram of a process for treating a landfill leachate membrane concentrate;
FIG. 2 is a flow diagram of the process for treating the membrane concentrate of landfill leachate according to example 1;
FIG. 3 is a flow diagram of the process for treating the membrane concentrate of landfill leachate according to example 2;
wherein 1 is a nanofiltration NF system, 2 is a reverse osmosis RO system, 3 is a water tank, 4 is a high-pressure pump, 5 is a concentrated solution pool, 6 is a mortar pump, 7 is a pretreatment device, 8 is a mother solution buffer tank, 9 is a mother solution pump, 10 is a preheater, 11 is a heater, 12 is an evaporation plant, 13 is a condensing unit, 14 is a circulating water cooler, 15 is a condensate circulating pump, 16 is a clean water pump, 17 is a sludge pump, 18 is a liquid-solid separator, and 19 is a draught fan.
Detailed Description
The utility model relates to a processing system of rubbish leachate membrane concentrate mainly includes pretreatment systems, heating system, vaporization system, condensing system and gas circulation system. The heating system is composed of a preheater 10 and a heater 11, and the preheater 10 is mainly used for recovering part of the heat of the system. The evaporation system is connected with the condensation system and comprises an evaporation device 12 and a condensation device 13, and the structure of the device is basically the same as that of the internal components. The gas circulation system mainly adopts closed circulation, and the main component of the gas circulation system is a fan 19.
The technical solution of the present invention will be further described with reference to the accompanying drawings.
Example 1
A process for treating a landfill leachate membrane concentrate, as shown in fig. 2, comprising the steps of: the treatment capacity of the mother liquor of the concentrated solution from a nanofiltration system 1 and a reverse osmosis system 2 in the garbage permeate liquid membrane treatment process is about 1000kg/h, and the water quality has the main indexes: COD was about 5000mg/L, conductivity was 40mS/cm, TDS was 10000 mg/L. The mother liquor enters a mother liquor buffer tank 8 after a part of large-particle solid impurities are removed by a mortar pump 6 and an automatic back-flushing filter 7, is pumped into a preheater 10 by a mother liquor pump, is preheated to 48 ℃, and then enters a heater 11, so that the temperature of a mother liquor outlet is raised to 60 ℃. The mother liquor enters from the top of the evaporator 12 in a spray mode and directly contacts with air from bottom to top, wherein the air is provided by a fan 19, and the flow rate is about 12000Nm3H is used as the reference value. Saturated hot air is distilled out from the top of the evaporation device through gas-liquid heat and mass transfer, and the temperature is about 58 ℃. The material flow directly enters from the bottom of the condensing device 13 and is contacted with normal-temperature pure water sprayed from top to bottom, and the temperature of the pure water rises to about 55 ℃ and is mixed with moisture in the air to form condensate. The main water quality index of the effluent is about 92mg/L of COD, 87 mu S/cm of conductivity and about 35mg/L of TDS, and other indexes including ammonia nitrogen, total nitrogen and the like all accord with the discharge standard of the landfill leachate. Therefore, part of the condensate directly reaches the standard and is discharged, part of the condensate flows back to the preheater 10, part of heat is recovered, and the condensate after primary cooling is further cooled to 38 ℃ through the circulating cooler and then enters a condensing system as a cold source. Meanwhile, the temperature of the saturated hot air is reduced to 40 ℃, and the saturated hot air enters the evaporation device 12 again through the fan to form a closed circulation system. Evaporation device and condensationThe device is directly connected, and the internal gas-liquid contact part is realized on the random high-efficiency packing made of PP materials. In addition, the concentrated solution dehydrated by the evaporation system is discharged from the bottom of the evaporation device in a near solid-liquid form, and is conveyed into a centrifugal drier for separation by a sludge pump, the solid still contains part of powdery black ash besides crystallized salt, and the part is used as solid waste and enters the next treatment process; the liquid is directly returned to the mother liquor tank 8, mixed with the pre-treatment mother liquor and re-enters the treatment process.
Example 2
A process for treating a landfill leachate membrane concentrate, as shown in fig. 3, comprising the steps of: the treatment capacity of the mother liquor of the concentrated solution from a nanofiltration system 1 and a reverse osmosis system 2 in the garbage permeate liquid membrane treatment process is about 1500kg/h, and the water quality has the main indexes: COD was approximately 10000mg/L, conductivity was 50mS/cm, TDS was 16000 mg/L. This mother liquor gets into mother liquor buffer tank 8 after getting rid of partial large granule solid impurity through mortar pump 6, plate and frame filter press 7, is pressed into pre-heater 10 by the mother liquor pump, preheats the temperature to 60 ℃, then gets into heater 11 for mother liquor outlet temperature rises to 80 ℃. The mother liquor enters from the top of the evaporator 12 in a spraying mode and directly contacts with air from bottom to top, wherein the air is provided by a fan 19, and the flow rate is about 6000Nm3H is used as the reference value. Saturated hot air is distilled out from the top of the evaporation device through gas-liquid heat and mass transfer, and the temperature is about 78 ℃. The material flow directly enters from the bottom of the condensing device 13 and is contacted with normal-temperature pure water sprayed from top to bottom, and the temperature of the pure water is raised to about 75 ℃ and is mixed with moisture in the air to form condensate. Because the mother liquor quality of water is comparatively complicated and the concentration is higher, the condensate can not reach the standard of direct discharge, and the condensate temperature is higher. Therefore, the condensate liquid completely flows back to the preheater 10, after a large amount of heat is recovered, the condensate liquid enters the circulating cooler to be further cooled to 38 ℃, a part of the condensate liquid enters the condensation system as a cold source, and a part of the condensate liquid is mixed with the nanofiltration clear liquid and then enters the reverse osmosis treatment process. Meanwhile, the temperature of the saturated hot air after passing through the condensing device is reduced to 40 ℃, and the saturated hot air enters the evaporating device 12 again through the fan to form a closed circulation system. The evaporation device is directly connected with the condensation device, and the internal gas-liquid contact parts are all arrangedThe random packing of PP material is realized. In addition, the concentrated solution dehydrated by the evaporation system is discharged from the bottom of the evaporation device in a near solid-liquid form, and is conveyed into a centrifugal drier for separation by a sludge pump, the solid still contains part of powdery black ash besides crystallized salt, and the part is used as solid waste and enters the next treatment process; the liquid is directly returned to the mother liquor tank 8, mixed with the pre-treatment mother liquor and re-enters the treatment process. In the embodiment, the concentrated solution has complex composition and high COD and salt content, so that the equipment is required to be cleaned in time after being shut down, and salt scale formation of the heat exchanger and the evaporation device is avoided, and further the normal operation of the equipment is influenced.
Claims (3)
1. A landfill leachate membrane concentrated solution treatment system is characterized by comprising a pretreatment device, a preheater, a heater, an evaporation device, a condensation device, a circulating water cooler, a liquid-solid separator and an induced draft fan; the delivery port of preprocessing device communicates the cold side import of pre-heater, the cold side import of preprocessing device's cold side exit linkage heater, the cold side exit linkage evaporation plant's of heater water inlet, condensing equipment's air intake is connected to evaporation plant's air outlet, evaporation plant's dense liquid exit linkage liquid-solid separator, the delivery port of liquid-solid separator communicates the cold side import of pre-heater, the hot side import of pre-heater is connected to condensing equipment's delivery port, the water inlet of hot side exit linkage circulating water cooler of pre-heater, condensing equipment's water inlet is connected to circulating water cooler's delivery port, the air intake of draught fan is connected to condensing equipment's air outlet, evaporation plant's air intake is connected to the air outlet of draught fan.
2. The landfill leachate membrane concentrate treatment system of claim 1, wherein the pretreatment device is an automatic backwash filter or a plate and frame filter press.
3. The landfill leachate membrane concentrate treatment system of claim 1, wherein the liquid-solid separator is a centrifugal dryer or a plate and frame filter press.
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