Sludge dewatering system based on eutectic solvent-microwave

Abstract

The utility model provides a deep eutectic solvent-microwave-based sludge dewatering system, and relates to the technical field of sludge resource utilization. The utility model provides a deep eutectic solvent-microwave-based sludge dewatering system. The deep eutectic solvent-microwave-based sludge dewatering system comprises a thermodynamic cycle system (1), a microwave treatment system (2) and a mechanical dewatering system (3) which are sequentially communicated through a sludge pipeline (4), the thermodynamic circulation system (1) comprises a hot water circulation system, and the hot water circulation system comprises a PV / T solar heat collector (11), a hot water pipeline (14), a water bath box (12) and a cold water pipeline (13); the sludge pipeline (4) penetrates through the water bath box (12), and a deep eutectic solvent inlet (43) is formed in the sludge pipeline (4) before penetrating through the water bath box (12). The sludge dewatering system provided by the utility model is used for dewatering sludge, the sludge dewatering rate is high, the energy consumption is low, and the obtained dewatered sludge can be used for boiler fuel.

Description

Technical Field

[0001] This utility model relates to the field of sludge resource utilization technology, specifically to a sludge dewatering system based on eutectic solvent-microwave. Background Technology

[0002] With the advancement of social productivity, large quantities of domestic sewage and industrial wastewater are discharged, resulting in a persistently high output of municipal sludge, an inevitable byproduct of sewage treatment. How to efficiently treat municipal sludge and fully exploit its residual value has become a pressing issue. Sludge disposal, through energy conversion and resource recovery, achieves a win-win situation for both environmental and economic benefits.

[0003] Municipal sludge primarily originates from primary sedimentation tanks, secondary sedimentation tanks, sludge thickening tanks, and mechanical dewatering units. Municipal sludge is highly hydrophilic, typically maintaining a high moisture content. Undewatered municipal sludge (i.e., sludge from sludge thickening tanks, with the addition of traditional flocculants such as Al2(SO4)3) generally has a moisture content exceeding 90%. Dewatering municipal sludge is challenging; the high moisture content not only increases the difficulty of sludge treatment but also significantly raises treatment costs. Improving the dewatering rate of sludge can greatly enhance its utilization potential. On the one hand, incinerating low-moisture sludge reduces fuel consumption and allows it to be used for power generation and biogas production, achieving secondary utilization and reducing carbon emissions. On the other hand, sludge volume can be reduced by 50-70%, significantly saving logistics costs and lowering transportation costs. Currently, some wastewater treatment plants use high-energy-consuming deep mechanical (centrifugal dewatering machine and plate and frame filter press) dewatering processes. The sludge after deep mechanical dewatering usually has a moisture content of 60-80%, and the moisture content of the dewatered sludge is still very high, which makes it difficult to meet the requirements of deep dewatering.

[0004] Existing dehydration systems (see) Figure 2 The process mainly involves concentration with traditional flocculants followed by conventional mechanical dewatering, resulting in dewatered sludge with a moisture content of approximately 87%, which is high. Utility Model Content

[0005] In view of this, the purpose of this utility model is to provide a sludge dewatering system based on a eutectic solvent-microwave. Using the sludge dewatering system provided by this utility model, the sludge dewatering rate is high, and the obtained dewatered sludge has a low moisture content.

[0006] To achieve the above-mentioned objectives, this utility model provides the following technical solution:

[0007] This utility model provides a sludge dewatering system based on eutectic solvent-microwave, including a thermal circulation system 1, a microwave processing system 2 and a mechanical dewatering system 3 connected in sequence through a sludge pipe 4;

[0008] The thermal circulation system 1 includes a hot water circulation system, which includes a PV / T collector 11, a hot water pipe 14, a water bath tank 12, and a cold water pipe 13; the outer surface of the water bath tank 12 is provided with a heat insulation layer.

[0009] The sludge pipe 4 passes through the water bath 12, and a eutectic solvent inlet 43 is provided on the sludge pipe 4 before it passes through the water bath 12.

[0010] Preferably, the thermal circulation system 1 is further provided with a data acquisition system 15, which is connected to the cold water pipe 13 and the hot water pipe 14 respectively; the data acquisition system 15 is also connected to a computer 19.

[0011] Preferably, the signals acquired by the data acquisition system 15 include temperature signals and / or electrical signals.

[0012] Preferably, the water bath 12 is provided with a baffle plate 121, and the outlet of the water bath is also provided with a sixth valve 122.

[0013] Preferably, the cold water pipe 13 is equipped with a water pump 131 and a fourth valve 132;

[0014] The cold water pipe 13 is also connected to a water supply pipe 16, which is equipped with a water supply pump 161 and a fifth valve 162.

[0015] Preferably, the PV / T collector 11 is connected to the MPPT controller 18, which is connected to the battery 17 and the computer 19.

[0016] Preferably, the sludge pipeline 4 is sequentially equipped with a sludge pump 41, a first valve 42, a eutectic solvent inlet 43, a second valve 44, and a third valve 45;

[0017] The second valve 44 is located between the thermal circulation system 1 and the microwave processing system 2, and the third valve 45 is located between the microwave processing system 2 and the mechanical dehydration system 3.

[0018] Preferably, the mechanical dewatering system 3 includes a centrifuge and / or a filter press.

[0019] Preferably, the end of the sludge pipe 4 is connected to a dewatered sludge storage tank 6.

[0020] Preferably, the sludge dewatering system is further provided with a sludge tank 5, the outlet of which is connected to the inlet of the sludge pump 41.

[0021] Traditional sludge dewatering technologies (such as thermal drying and mechanical dewatering) suffer from high energy consumption, large reagent dosages, and equipment corrosion. Existing solar-assisted dewatering systems have drawbacks such as low photothermal conversion efficiency and insufficient utilization of thermal energy. The sludge dewatering system provided by this invention utilizes an integrated photoelectric design. Based on the "floc breaking down - water release - mechanical separation" mechanism, it achieves deep sludge dewatering and resource recovery through the synergistic effect of low-eutectic solvent (DES) chemical pretreatment, PV / T collector water bath preheating of the sludge, and microwave physical field enhancement and mechanical separation via a microwave treatment system. Specifically, the use of low-eutectic solvent to treat the sludge converts bound water in the sludge into free water, which can be removed during the mechanical dewatering stage, reducing energy consumption in the thermal drying stage. Preheating the sludge through the thermal circulation system 1 fully activates the effect of the eutectic solvent, significantly improving the sludge dewatering rate. The heat energy generated by the PV / T solar collector is fully utilized, resulting in high photothermal conversion efficiency and significantly reducing energy consumption for sludge dewatering. Microwave treatment through the microwave processing system 2 accelerates the disintegration of sludge flocs, greatly improving the sludge dewatering rate. Mechanical dewatering is then performed through the mechanical dewatering system 3. The dewatered sludge prepared by the sludge dewatering system provided by this invention exhibits significantly improved slurry-forming characteristics, resulting in dewatered sludge with low moisture content and high calorific value. It allows for a large addition of sludge coke slurry, achieving higher sludge coke slurry concentration and lower viscosity with the same sludge dosage. The sludge coke slurry has a high calorific value, good fluidity, and strong stability. Furthermore, the dewatered sludge contains a large amount of organic matter, which easily combines with other components in the sludge coke slurry to form a three-dimensional network structure or flocculation, enhancing the structural strength of the sludge coke slurry. Adding dewatered sludge modified with a eutectic solvent reduces the pseudoplastic rheological characteristics of the sludge coke slurry. This invention eliminates the need for large amounts of flocculant and prevents equipment corrosion during sludge dewatering.

[0022] Furthermore, by utilizing PV / T solar collectors to simultaneously generate electricity (which can supply the microwave processing system) and provide heat (preheating sludge), the overall energy efficiency is improved. Attached Figure Description

[0023] Figure 1This utility model provides a schematic diagram of the structure of a sludge dewatering system based on a eutectic solvent and microwave. In this diagram, 1 is a thermal circulation system, 11 is a PV / T solar collector, 12 is a water bath, 121 is a baffle plate, 122 is the sixth valve, 13 is a cold water pipe, 131 is a water pump, 132 is the fourth valve, 14 is a hot water pipe, 15 is a data acquisition system, 16 is a water supply pipe, 161 is a water supply pump, and 162 is the fifth valve; 17 is a battery, 18 is an MPPT controller, and 19 is a computer; 2 is a microwave processing system; 3 is a mechanical dewatering system; 4 is a sludge pipe, 41 is a slurry pump, 42 is the first valve, 43 is the eutectic solvent inlet, 44 is the second valve, and 45 is the third valve; 5 is a sludge tank, and 6 is a dewatered sludge storage tank.

[0024] Figure 2 This is a schematic diagram of the sludge dewatering system used in the traditional sludge dewatering process in Example 1.

[0025] Figure 3 SEM image of the original sludge used in the example;

[0026] Figure 4 This is a SEM image of the dewatered sludge obtained under the optimal dewatering conditions in Example 2. Detailed Implementation

[0027] Figure 1 This is a schematic diagram of the sludge dewatering system based on eutectic solvent-microwave provided by this utility model. The following is a description of the system in conjunction with... Figure 1 A detailed description is provided for a sludge dewatering system based on eutectic solvent-microwave.

[0028] This utility model provides a sludge dewatering system based on eutectic solvent-microwave, including a thermal circulation system 1, a microwave processing system 2 and a mechanical dewatering system 3 connected in sequence through a sludge pipe 4;

[0029] The thermal circulation system 1 includes a hot water circulation system, which includes a PV / T collector 11, a hot water pipe 14, a water bath tank 12, and a cold water pipe 13; the outer surface of the water bath tank 12 is provided with a heat insulation layer.

[0030] The sludge pipe 4 passes through the water bath 12, and a eutectic solvent inlet 43 is provided on the sludge pipe 4 before it passes through the water bath 12.

[0031] The sludge dewatering system based on eutectic solvent-microwave provided by this utility model includes a thermal circulation system 1, which includes a hot water circulation system, which includes a PV / T collector 11, a hot water pipe 14, a water bath 12, and a cold water pipe 13; the outer surface of the water bath 12 is provided with a heat insulation layer.

[0032] In one embodiment of this invention, the temperature of the hot water in the hot water pipe 14 is preferably 40-60°C, and in specific embodiments, it can be 40°C, 45°C, 50°C, 55°C, or 60°C. In another embodiment of this invention, the temperature of the preheated sludge obtained by preheating the sludge through the thermal circulation system 1 is preferably 30-50°C, and in specific embodiments, it can be 30°C, 35°C, 40°C, 45°C, or 50°C. In this invention, the function of the hot water circulation system 1 is to preheat the sludge, thereby fully activating the effect of the eutectic solvent and greatly improving the dewatering rate of the sludge.

[0033] In one embodiment of this invention, the thermal circulation system 1 preferably further includes a data acquisition system 15, which is connected to both the cold water pipe 13 and the hot water pipe 14; the data acquisition system 15 is also preferably connected to a computer 19. In another embodiment of this invention, the signals acquired by the data acquisition system 15 preferably include temperature signals and / or electrical signals. The computer 19 is used to display the acquired signals.

[0034] In one embodiment of this invention, the insulation layer is made of polyurethane foam. In another embodiment, a baffle plate 121 is preferably provided inside the water bath 12, and a sixth valve 122 is preferably also provided at the outlet of the water bath 12; the baffle plate 121 enhances the heat exchange effect. In yet another embodiment, a spiral sludge pipe is preferably provided inside the water bath 12. The sludge undergoes convective heat exchange with the hot water in the water bath 12, thereby preheating the sludge.

[0035] In one embodiment of this utility model, the cold water pipe 13 is preferably equipped with a water pump 131 and a fourth valve 132.

[0036] In one embodiment of this utility model, the cold water pipe 13 is preferably also connected to a water supply pipe 16, and the water supply pipe 16 is preferably equipped with a water supply pump 161 and a fifth valve 162.

[0037] In one embodiment of this invention, the PV / T collector 11 is preferably connected to an MPPT (Maximum PowerPoint Tracking) controller 18, which is connected to a battery 17 and a computer 19. In another embodiment, the PV / T collector 11 is equipped with photovoltaic modules and a liquid-cooled collector; the PV / T collector 11 simultaneously outputs electrical energy and 40-60°C hot water through a circulating working fluid (water / antifreeze). The MPPT controller efficiently stores the electrical energy generated by the photovoltaic modules into the battery, with the core purpose of maximizing solar power generation efficiency while safely and intelligently managing battery charging. In the figure, the data acquisition system 15 collects data from the photovoltaic modules to the MPPT controller and then to the battery. The MPPT controller adjusts the circuit impedance in real time to keep the photovoltaic modules operating near the MPP (Maximum Power Point). Compared with traditional PWM controllers, it can improve energy capture efficiency by 10-30%. When connected to a battery, the MPPT controller can intelligently track the maximum power of the photovoltaic system and charge it safely and efficiently, significantly increasing power generation and protecting the battery. This reduces the total system cost in the long term, making it particularly suitable for off-grid solar systems and photovoltaic energy storage power stations.

[0038] The photovoltaic cells in the PV / T collector 11 absorb heat from solar radiation and transfer it to the absorber plate via heat conduction. Water in the flow channel then cools the absorber plate through convection heat exchange, thereby reducing the surface temperature of the cells. The PV / T collector 11 also functions as a heater, heating the water in the flow channel. Powered by the water pump 131, the hot water forms a stable thermodynamic cycle within the water bath 12 (which is equipped with baffles to enhance heat exchange). This fully utilizes the heat energy generated by the PV / T solar collector, resulting in high photothermal conversion efficiency and significantly reducing energy consumption for sludge dewatering.

[0039] The sludge dewatering system based on eutectic solvent-microwave provided by this utility model includes a microwave processing system 2. In one embodiment of this utility model, the preset temperature of the microwave processing system 2 is preferably 60-100℃, and in a specific embodiment it can be 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃ or 100℃; the heating rate to the preset temperature is preferably 5-20℃ / min, and in a specific embodiment it can be 5℃ / min, 8℃ / min, 10℃ / min, 12℃ / min, 15℃ / min, 18℃ / min or 20℃ / min; the holding time of the sludge at the preset temperature is preferably 0-10min, and in a specific embodiment it can be 0min, 1min, 2min, 3min, 4min, 5min, 6min, 7min, 8min, 9min or 10min; the power of the microwave processing system 2 is preferably 200-600W, and in a specific embodiment it can be 200W, 300W, 400W, 500W or 600W. In this invention, the microwave processing system 2 can accelerate the breaking down of sludge flocs and greatly improve the dewatering rate of sludge.

[0040] The sludge dewatering system based on eutectic solvent-microwave provided by this utility model includes a mechanical dewatering system 3. In one embodiment of this utility model, the mechanical dewatering system 3 preferably includes a centrifuge and / or a filter press. In another embodiment of this utility model, the rotational speed of the centrifuge is preferably 2500–4000 r / min, and in specific embodiments, it can be 2500 r / min, 2800 r / min, 3000 r / min, 3200 r / min, 3500 r / min, 3800 r / min, or 4000 r / min; the residence time of the sludge in the mechanical dewatering system 3 is preferably 0.5–3 min, and in specific embodiments, it can be 0.5 min, 1 min, 1.5 min, 2 min, 2.5 min, or 3 min; the solid component obtained after treatment by the centrifugal mechanical dewatering system 3 is dewatered sludge. In this invention, the mechanical dewatering system 3 is used to fully separate the solid components and water in the sludge, thereby improving the dewatering rate of the sludge. Dewatering using a filter press is a deep dewatering method. When mechanical dewatering is performed using a filter press, the moisture content of the dewatered sludge is significantly reduced compared to dewatering using a centrifuge.

[0041] The sludge dewatering system based on eutectic solvent-microwave provided by this utility model includes a sludge pipe 4. In one embodiment of this utility model, the sludge pipe 4 is sequentially equipped with a sludge pump 41, a first valve 42, an eutectic solvent inlet 43, a second valve 44, and a third valve 45; the second valve 44 is located between the thermal circulation system 1 and the microwave processing system 2, and the third valve 45 is located between the microwave processing system 2 and the mechanical dewatering system 3. This utility model does not have a special limitation on the material of the sludge pipe 4; any thermally conductive material well known to those skilled in the art can be used, such as aluminum, copper, aluminum alloy, or stainless steel.

[0042] As one embodiment of this utility model, the end of the sludge pipe 4 is preferably connected to a dewatered sludge storage tank 6.

[0043] In one embodiment of this invention, the sludge dewatering system based on eutectic solvent-microwave preferably further includes a sludge tank 5, the outlet of which is connected to the inlet of the sludge pump 41. In another embodiment of this invention, the sludge tank 5 preferably includes a secondary sedimentation tank.

[0044] In one embodiment of this invention, the eutectic solvent preferably comprises a hydrogen bond acceptor and a hydrogen bond donor; the hydrogen bond acceptor comprises choline chloride; the hydrogen bond donor comprises oxalic acid and / or ethylene glycol, more preferably oxalic acid or ethylene glycol; the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is preferably 1:1 to 3, and in specific embodiments it can be 1:1, 1:1.5, 1:2, 1:2.5 or 1:3. In one embodiment of this invention, the mass of the eutectic solvent is preferably 0.5% to 10% of the sludge mass, and in specific embodiments it can be 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%. In one embodiment of this invention, the moisture content of the sludge is preferably ≥90%, more preferably 95% to 99%. This invention uses a eutectic solvent to promote sludge dewatering. Specifically, the eutectic solvent can effectively promote the catalytic degradation of hydrophilic oxygen-containing functional groups (HOFG) in the sludge floc structure, reduce the hydrophilicity of the sludge, promote the conversion of bound water to free water, and thus significantly reduce the water content of the sludge, improve the slurry-forming characteristics of the sludge, and can be used to prepare high-quality slurry fuel.

[0045] This invention utilizes a eutectic solvent to treat sludge, converting bound water in the sludge into free water. This free water can be removed during mechanical dewatering, reducing energy consumption in the thermal drying process. Preheating the sludge via a thermal circulation system 1 fully activates the eutectic solvent, significantly improving the dewatering rate. Microwave treatment via a microwave system 2 accelerates the disintegration of sludge flocs, further enhancing the dewatering rate. Mechanical dewatering is then performed via a mechanical dewatering system 3. The dewatered sludge prepared using this invention exhibits significantly improved slurry-forming characteristics, resulting in low moisture content, high calorific value, and the ability to achieve higher sludge coke concentration and lower viscosity with the same sludge dosage. The sludge coke also boasts high calorific value, good fluidity, and strong stability. Furthermore, the dewatered sludge contains a large amount of organic matter, which readily combines with other components in the sludge coke to form a three-dimensional network structure or flocculation, enhancing the structural strength of the sludge coke. Adding dewatered sludge modified with a eutectic solvent reduces the pseudoplastic rheological characteristics of the sludge slurry. The sludge dewatering system provided by this invention utilizes a eutectic solvent to catalytically decompose the hydrophilic groups of the sludge, a PV / T collector 11 to preheat the sludge and activate the effect of the eutectic solvent, and microwave action to accelerate the disintegration of sludge flocs, thereby achieving synergistic dewatering of the sludge and resulting in a high dewatering rate. Furthermore, this invention utilizes hot water generated by the PV / T collector to preheat the sludge, directly utilizing solar energy and avoiding the multi-stage conversion process of light-electricity-heat, effectively improving energy conversion efficiency and significantly reducing the energy consumption of sludge dewatering.

[0046] To further illustrate this utility model, the following detailed description of the sludge dewatering system based on eutectic solvent-microwave provided by this utility model is provided in conjunction with the embodiments, but these descriptions should not be construed as limiting the scope of protection of this utility model.

[0047] The sludge used in the following examples and comparative examples was residual sludge (98.8% moisture content) from the secondary sedimentation tank of a wastewater treatment plant in Ningbo City. Before use, the sludge was placed in a refrigerator at 4°C and allowed to stand for 24 hours. The supernatant was then poured out and left to stand. The moisture content of the sludge after standing (referred to as the original sludge) was 95%. Sludge has a complex composition and is prone to self-fermentation and putrefaction. Refrigeration was used to maintain the sludge parameters at the time of sampling and to prevent changes in composition after prolonged storage in the laboratory, which would undermine the basis for consistent comparison.

[0048] In the following examples, the choline chloride-oxalic acid mixture (denoted as DES1) was stirred and mixed at 100°C in a 1:1 molar ratio until a clear liquid was obtained.

[0049] Example 1

[0050] (1) Taking 1 ton of raw sludge (untreated sludge with a moisture content of 95%) and an ambient temperature of 20℃ as an example, calculate the energy required under the traditional process (excluding the energy consumption of centrifugation).

[0051] Traditional process steps: using Figure 2 The system described above mixes raw sludge with flocculant (cationic polyacrylamide, 2% of the sludge mass), and then feeds the resulting mixture into a centrifuge and centrifuges it at 3500 r / min for 1 min to obtain dewatered sludge.

[0052] 1. Quality of dewatered sludge after traditional sludge treatment:

[0053] The mass of dry solids in the original sludge = 1000kg × (1-95%) = 50kg.

[0054] Mass of dewatered sludge (moisture content 87%) = Mass of dry solids of original sludge / Solid content of dewatered sludge = 50kg / (1-87%) = 384.62kg.

[0055] 2. Calculate the heat absorbed by the power plant in the wastewater from the dewatered sludge obtained by traditional treatment (water bath heating):

[0056] 2.1 The mass of water in the dewatered sludge (moisture content 87%) = 384.62 kg × 87% = 334.62 kg.

[0057] 2.2 Sensible heat Q of heating water to 100℃ heating =m water ×c water ×ΔT=334.62kg×4.18kJ / (kg·℃)×(100℃-20℃)=111897kJ, where the specific heat capacity of water is c water = 4.18 kJ / (kg·℃).

[0058] 2.3 Latent heat of vaporization of water Q vapor =m water ×L vapor = 334.62 kg × 2260 kJ / kg = 756241 kJ, where the latent heat of vaporization of water (standard atmosphere) L vapor =2260kJ / kg.

[0059] 2.4 Total heat absorption Q total =Q heating +Q vapor =111897kJ+756241kJ=868138kJ.

[0060] (2) Taking 1 ton of raw sludge (untreated sludge with a moisture content of 95%) at an ambient temperature of 20℃ as an example, the following method was adopted: Figure 1 Calculate the energy required for the sludge dewatering process (referred to as the novel process) of the system shown (excluding the energy consumption of centrifugation).

[0061] Novel process: Sludge and DES1 are mixed and then transported to a thermal circulation system 1 for preheating (heated from 20℃ to 30℃ in a water bath). Then, it is transported to a microwave processing system 2 for final microwave treatment, followed by centrifugation in a centrifuge 3 (centrifugation at 3500 r / min for 1 min) to obtain dewatered sludge. The mass of DES1 is 2% of the original sludge mass. Microwave treatment conditions: temperature is increased from 30℃ to 80℃ at a rate of 10℃ / min and held for 1 min; microwave power is 300W.

[0062] (2.1) Energy consumed by microwave heating

[0063] Preheating in thermal cycle system 1 (from a 20°C water bath to 30°C) is a waste heat reuse and does not consume additional energy.

[0064] 1000 kg of raw sludge with a moisture content of 95% was heated from 30°C to 80°C.

[0065] The mass of water in the original sludge = 1000 kg × 95% = 950 kg, and the mass of dry solids in the original sludge = 50 kg.

[0066] The heat absorbed by heating water in sludge to 80℃ = 950kg × 4.18kJ / (kg·℃) × (80℃-30℃) = 198550kJ.

[0067] The heat absorption of dry solids in sludge = 50kg × 1.5kJ / (kg·℃) × (80℃-30℃) = 3750kJ, where 1.5kJ / (kg·℃) is the specific heat capacity of dry solids (refer to the conventional value of sludge).

[0068] Total heat absorbed = 198550kJ + 3750kJ = 202300kJ.

[0069] Final result: Heating 1000 kg of sludge with a moisture content of 95% from 30℃ to 80℃ requires absorbing 202300 kJ of heat.

[0070] (2.2) Quality of sludge after treatment by the new process

[0071] During sludge dewatering, the mass of dry solids remains constant (mass conservation of dry solids). Let the mass of dry solids before dewatering be M. 干 1. The dry solids mass of the dewatered sludge obtained after dewatering (target moisture content 69%) is M. 干 2, then M 干 1 = M 干 2.

[0072] M 干 1=1000kg×(1-95%)=50kg=M 干 2.

[0073] Dewatered sludge quality (M) 湿 )=50kg / (1-69%)=161.29kg.

[0074] Conclusion: Dewatering 1 ton of sludge with a moisture content of 95% to a moisture content of 69% yielded a dewatered sludge mass of 161.29 kg.

[0075] (2.3) The heat absorbed by the wastewater from the sludge treated by the new process in the power plant

[0076] Water mass m in dewatered sludge 水 =161.29kg×69%=111.29kg.

[0077] The amount of heat required to heat water from 20℃ to 100℃ is Q1 = 111.29kg × 4.18kJ / (kg·℃) × (100℃ - 20℃) = 37212kJ.

[0078] The heat required for water to vaporize at 100℃ is calculated as Q2 = 111.29 kg × 2260 kJ / kg = 251515.4 kJ.

[0079] Total heat absorbed = Q1 + Q2 = 37212 kJ + 251515.4 kJ = 288727.4 kJ.

[0080] Conclusion: Heating the water in 161.29 kg of sludge with a moisture content of 69% from 20℃ to 100℃ and then vaporizing it requires absorbing 288727.4 kJ of heat.

[0081] (2.4) Total energy consumption Q 总 =202300kJ+288727.4kJ=491027.4kJ.

[0082] (3) Energy consumption comparison between new and traditional processes

[0083] The energy savings (Q) of the new process compared to the traditional process 节约 =Total energy consumption of traditional process - Total energy consumption of new process = 868138kJ - 491027.4kJ = 377110.6kJ.

[0084] (4) Comparison of transportation costs between new and traditional processes

[0085] The total mass of dewatered sludge obtained from traditional processing is 334.62 kg.

[0086] The total mass of dewatered sludge obtained from the new process is 161.29 kg.

[0087] The dewatering mass obtained by the new process is reduced by 51.80% compared with that obtained by the traditional process.

[0088] In summary, based on the dewatering of 1 ton of raw sludge, the traditional process consumes 868,138 kJ of energy to dewater the raw sludge to a moisture content of 87%, while the new process consumes only 491,027.4 kJ of energy to dewater the raw sludge to a moisture content of 69%. The total energy consumption of the new process is reduced by 377,110.6 kJ compared to the traditional process, representing a reduction of 43.44%. Furthermore, the transportation cost of the new process is reduced by 51.80% compared to the traditional process.

[0089] Example 2

[0090] Choline chloride-oxalic acid mixture (denoted as DES1): Mixed at 1:1 molar ratio at 100°C with stirring until a clear liquid is obtained.

[0091] The amount of eutectic solvent used is the percentage of eutectic solvent by mass of sludge.

[0092] Dewatering rate: The percentage of water removed from sludge relative to the total mass of sludge.

[0093] use Figure 1 The sludge dewatering system based on eutectic solvent and microwave, as shown, dewaters sludge through the following steps: The raw sludge is mixed with the eutectic solvent and then transported to a thermal circulation system 1 for preheating (water bath heating). It is then transported to a microwave processing system 2 for final microwave treatment, and finally centrifuged in a centrifuge 3 (at 3500 r / min for 1 min) to obtain dewatered sludge. The dewatering conditions, the dewatering rate of the raw sludge, and the moisture content of the dewatered sludge are shown in Table 1.

[0094] Comparative Example 1

[0095] The raw sludge underwent different treatments and was then centrifuged in centrifuge 3 (centrifuged at 3500 r / min for 1 min) to obtain dewatered sludge. The treatment methods were: water bath heating only, microwave treatment only, DES1 + water bath heating, and DES1 + microwave treatment. The treatment conditions, the dewatering rate of the raw sludge, and the moisture content of the dewatered sludge are shown in Table 1.

[0096] Table 1. Effects of DES and its activation methods on sludge dewatering rate

[0097]

[0098] Table 1 shows that the synergistic treatment of DES1 + water bath heating + microwave treatment + centrifugation resulted in the best sludge dewatering effect, with the lowest moisture content (66.03%). This represents a 21.21 percentage point reduction in moisture content compared to the dewatered sludge obtained using flocculant + centrifugation, a reduction of 24.31%. The optimal dewatering conditions were: addition of 2% DES1, followed by water bath heating (from 20℃ to 50℃), and then microwave treatment (from 50℃ to 80℃ and holding for 1 minute).

[0099] Compared to traditional sludge treatment in wastewater treatment plants ( Figure 2 The traditional flocculant + centrifugation system (with a conventional mechanical dewatering sludge moisture content of 87.24%) was replaced by the sludge dewatering system provided by this invention. The resulting dewatered sludge had a moisture content of 66.03–69.92%, representing a reduction of 19.85–24.31%.

[0100] Compared with dewatering methods such as mechanical dewatering (centrifugation only), preheating + centrifugation, DES + centrifugation, and DES + preheating + centrifugation, this utility model is based on the "floc breaking-moisture release-mechanical separation" mechanism. Through the synergistic effect of chemical pretreatment with eutectic solvent (DES), preheating of sludge, microwave physical field enhancement and mechanical separation, it achieves the goal of deep dewatering and resource recovery of sludge.

[0101] Figure 3 This is a SEM image of the original sludge in the example. Figure 4 The image shows the SEM image of the dewatered sludge obtained under the optimal dewatering conditions in Example 2. It can be seen that the original sludge surface is smooth and the flocs are densely adhered, making it difficult for bound water to be separated. After using DES to pretreat the sludge, and combining it with water bath heating and microwave synergy, the floc structure and extracellular polymers of the sludge are broken down, which promotes the conversion of bound water into free water, thereby greatly improving the conventional mechanical dewatering rate of the sludge.

[0102] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A sludge dewatering system based on a eutectic solvent-microwave, characterized in that, It includes a thermal circulation system (1), a microwave treatment system (2) and a mechanical dewatering system (3) connected in sequence through a sludge pipe (4); The thermal circulation system (1) includes a hot water circulation system, which includes a PV / T solar collector (11), hot water pipes (14), a water bath tank (12), and cold water pipes (13); the outer surface of the water bath tank (12) is provided with a heat insulation layer; The sludge pipe (4) passes through the water bath (12), and a eutectic solvent inlet (43) is provided on the sludge pipe (4) before it passes through the water bath (12).

2. The sludge dewatering system according to claim 1, characterized in that, The thermal circulation system (1) is also equipped with a data acquisition system (15), which is connected to the cold water pipe (13) and the hot water pipe (14) respectively; the data acquisition system (15) is also connected to a computer (19).

3. The sludge dewatering system according to claim 2, characterized in that, The data acquisition system (15) acquires signals including temperature signals and / or electrical signals.

4. The sludge dewatering system according to claim 1, characterized in that, The water bath (12) is equipped with a baffle plate (121), and the outlet of the water bath is also equipped with a sixth valve (122).

5. The sludge dewatering system according to claim 1, characterized in that, A water pump (131) and a fourth valve (132) are installed on the cold water pipe (13); The cold water pipe (13) is also connected to a water supply pipe (16), and the water supply pipe (16) is equipped with a water supply pump (161) and a fifth valve (162).

6. The sludge dewatering system according to claim 1, characterized in that, The PV / T solar collector (11) is connected to the MPPT controller (18), which is connected to the battery (17) and the computer (19).

7. The sludge dewatering system according to claim 1, characterized in that, The sludge pipeline (4) is sequentially equipped with a sludge pump (41), a first valve (42), a eutectic solvent inlet (43), a second valve (44), and a third valve (45); The second valve (44) is located between the thermal circulation system (1) and the microwave processing system (2), and the third valve (45) is located between the microwave processing system (2) and the mechanical dehydration system (3).

8. The sludge dewatering system according to claim 1 or 7, characterized in that, The mechanical dewatering system (3) includes a centrifuge and / or a filter press.

9. The sludge dewatering system according to any one of claims 1 to 7, characterized in that, The end of the sludge pipe (4) is connected to a dewatered sludge storage tank (6).

10. The sludge dewatering system according to claim 9, characterized in that, The sludge dewatering system is also equipped with a sludge tank (5), the outlet of which is connected to the inlet of a sludge pump (41).

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