A zero-carbon emission wastewater treatment system

Abstract

This invention relates to a zero-carbon emission wastewater treatment system. The carbon release module includes a wastewater treatment layer and a sludge-water separation layer. The carbon diversion module includes a separation and gas collection layer and a quantitative distribution layer. The separation and gas collection layer contains an alkaline solution chamber and an acid solution chamber. A first diversion pipe on one side of the sludge-water separation layer connects to the alkaline solution chamber. The alkaline solution chamber is connected to the acid solution chamber via a connecting diversion pipe. The acid solution chamber is connected to the quantitative distribution layer via a second diversion pipe. A non-carbon dioxide gas collection pipe is installed on the alkaline solution chamber and connects to the quantitative distribution layer. An alkaline solution flow valve is installed on the connecting diversion pipe. Flow meters are installed on both the second diversion pipe and the non-carbon dioxide gas collection pipe. The carbon recovery module includes multiple photosynthetic metabolism layers. The quantitative distribution layer is connected to the bottommost photosynthetic metabolism layer via a third diversion pipe. Microalgae are cultivated in each photosynthetic metabolism layer. Illumination lamps are installed on the inner wall of the carbon recovery module. The topmost photosynthetic metabolism layer is connected to the alkaline solution chamber via a return pipe. This invention achieves carbon emission reduction while treating wastewater.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically a zero-carbon emission wastewater treatment system. Background Technology

[0002] my country treats 40 billion tons of wastewater annually. Among existing technologies, the activated sludge process is the traditional mainstream technology, achieving effluent standards up to Class A. However, during the mineralization of pollutants in wastewater by microorganisms in the activated sludge, a corresponding amount of CO2 is continuously released into the atmosphere, contributing to greenhouse gas emissions. Currently, traditional wastewater treatment plants in my country using the activated sludge process generate 300-800 grams of CO2 eq (carbon dioxide emission equivalent) per ton of wastewater discharged to meet COD (chemical oxygen demand) standards, making a significant contribution to CO2 emissions. Therefore, developing and optimizing CO2 reduction technologies integrated with wastewater treatment processes is one of the effective means to achieve low-carbon wastewater treatment.

[0003] In the familiar Earth's ecosystem, microalgae are an important carbon sink system, playing a crucial role in absorbing greenhouse gases such as CO2 and mitigating global warming. Microalgae are a type of microscopic autotrophic plant widely distributed on land and in the ocean, rich in nutrients, and with high photosynthetic efficiency. Microalgae fix CO2 through photosynthesis more efficiently than terrestrial plants. This is partly due to the fact that the CO2 content in water is approximately 3000 times that in the air, and partly due to the refraction, diffraction, and scattering effects of water on light, allowing all surfaces of microalgae to receive light. Studies have shown that algal cells contain more than 50% carbon, and the production of 1 ton of microalgae can consume approximately 1.5 tons of CO2. Microalgae growth not only absorbs gaseous CO2 but also dissolved CO2 and HCO3 in water. - CO3 2- Microalgae can utilize inorganic carbon sources, as well as consume N and P nutrients in the culture medium and degrade organic pollutants, to specifically absorb and transform waste gas and wastewater before carbon emissions occur. Furthermore, microalgae biomass can be used to produce biofuels, feed, and extract useful substances, showing promising potential.

[0004] Currently, research and applications of microalgae in wastewater treatment mainly focus on screening and cultivating microalgae species with high photosynthetic efficiency and high added value, as well as efficiently extracting resource-based substances from algae. However, in mature wastewater treatment plants, technologies such as activated sludge and biofilm processes have already formed mature supporting facilities and are operating stably. Directly introducing microalgae into the system would inevitably increase the system's modification costs and the risk of unstable operation. In addition, microalgae have poor tolerance to high ammonia nitrogen wastewater and are difficult to operate synchronously with wastewater treatment systems. Summary of the Invention

[0005] The purpose of this invention is to provide a zero-carbon emission wastewater treatment system that uses activated sludge to treat organic matter in wastewater to form carbon dioxide, and uses microalgae to absorb and treat the carbon dioxide, thereby achieving carbon emission reduction targets while treating wastewater.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A zero-carbon emission wastewater treatment system includes a carbon release module, a carbon diversion module, and a carbon recovery module arranged sequentially from bottom to top. The carbon release module is internally divided into a lower wastewater treatment layer and an upper sludge-water separation layer by a sludge packing mesh. The wastewater treatment layer has an aeration head and an activated sludge input pipe at its bottom. The sludge-water separation layer contains a filter membrane assembly. The carbon diversion module includes a lower separation and gas collection layer and an upper quantitative distribution layer. The separation and gas collection layer contains an alkaline solution chamber and an acid solution chamber. A first diversion pipe extends into the separation and gas collection layer from one side of the sludge-water separation layer and connects to the input pipe of the alkaline solution chamber. The output end of the alkaline solution chamber is connected to the input end of the acid solution chamber via a connecting diversion pipe. A second diversion pipe connects to the quantitative distribution layer from one side of the separation and gas collection layer. The second guide pipe is connected to the output pipe of the acid chamber. Additionally, a non-carbon dioxide gas collection pipe is provided on the alkali chamber and communicates with the quantitative distribution layer. An alkali flow valve is provided on the connecting guide pipe, a carbon dioxide flow meter is provided on the second guide pipe, and a non-carbon dioxide flow meter is provided on the non-carbon dioxide gas collection pipe. The carbon recovery module includes multiple photosynthetic metabolism layers, and a third guide pipe is provided on one side of the quantitative distribution layer, communicating with the bottommost photosynthetic metabolism layer. Adjacent photosynthetic metabolism layers are separated by partitions, and one end of each partition has a gas guide plate with perforated vents. Microalgae are cultivated in each photosynthetic metabolism layer. An illumination lamp is provided on the inner wall of the carbon recovery module, and the illumination lamp passes through each photosynthetic metabolism layer. The topmost photosynthetic metabolism layer is connected to the alkali chamber through a reflux pipe.

[0008] The wastewater treatment layer is equipped with a wastewater inlet pipe and a sludge discharge pipe. The bottom of the separation and gas collection layer is equipped with a filter main pipe. Each filter membrane group in the sludge-water separation layer is equipped with a connecting pipe at its upper end, which is connected to the filter main pipe. The output end of the filter main pipe is connected to the purified water output pipe.

[0009] The bottom of the wastewater treatment layer is equipped with an aeration pipe with an aeration pump, and each aeration head at the bottom of the wastewater treatment layer is supplied with air through the aeration pipe.

[0010] The alkali chamber is equipped with a one-way exhaust pipe on one side and an alkali injection port on the other side.

[0011] The acid chamber has an acid injection port on one side and a salt discharge port on the other side.

[0012] The quantitative distribution layer is equipped with a pressure gauge on one side and a safety pressure relief port on the other side.

[0013] The carbon recovery module includes multiple photosynthetic metabolism layers, wherein the lowest photosynthetic metabolism layer is separated from the quantitative distribution layer by a bottom plate, and adjacent photosynthetic metabolism layers are separated by partitions. Microalgae are provided on both the bottom plate and the partitions.

[0014] The carbon recovery module has a flip-open cover at the top. The carbon recovery module is equipped with a temperature sensor and a pH sensor. In addition, the carbon recovery module is equipped with a light controller to control the illumination intensity of each lighting lamp.

[0015] In the wastewater treatment layer, organic matter in the wastewater is degraded by activated sludge under aeration conditions to form carbon dioxide gas. The carbon dioxide gas generated in the wastewater treatment layer, along with residual gas from aeration, rises and enters the alkaline solution chamber of the separation and gas collection layer through the first guide pipe and the input pipe. Upon entering the alkaline solution chamber, the carbon dioxide reacts with OH-. - The reaction produces CO3 2- The remaining non-carbon dioxide gases enter the quantitative distribution layer through the non-carbon dioxide gas collecting pipe, and the CO2 gas is absorbed by the alkaline solution to generate CO3. 2- It then continues to enter the acid chamber, where an acid-base neutralization reaction occurs, i.e., CO32-. 2- +H + →CO2+H2O, and then the regenerated CO2 gas enters the quantitative distribution layer through the second guide tube.

[0016] The microalgae growth process includes the photoperiod during the inoculation and replacement phase, the dark period during the inoculation and replacement phase, the photoperiod during the stable culture phase, and the dark period during the stable culture phase.

[0017] The advantages and positive effects of this invention are as follows:

[0018] 1. This invention includes a carbon release module, a carbon diversion module, and a carbon recovery module. The carbon release module utilizes activated sludge to degrade organic matter to produce carbon dioxide, while simultaneously achieving sludge-water separation and direct discharge of effluent. The carbon recovery module utilizes microalgae photosynthesis to absorb and consume CO2 from the gas, thereby achieving zero carbon emissions. Furthermore, the carbon recovery module is separate from the carbon release module, so microalgae cultivation is not affected by the properties of the wastewater. It also eliminates the need to rebuild a new activated sludge system containing microalgae in the wastewater treatment layer. In addition, considering that the CO2 content required by microalgae varies at different stages and cycles, this invention first uses the separation gas collection layer in the carbon diversion module to separate CO2 gas from non-CO2 gas, and then controls the quantitative input of CO2 gas and non-CO2 gas into the quantitative distribution layer of the carbon diversion module for mixing, thereby forming a gas that meets the needs of microalgae at different stages and cycles.

[0019] 2. In this invention, the separation and collection layer of the carbon guiding module utilizes an alkaline chamber and an acid chamber to separate CO2 gas from non-CO2 gas. The alkaline chamber is equipped with a non-CO2 gas collection pipe with a non-CO2 flow meter connected to the quantitative distribution layer. The acid chamber is connected to the quantitative distribution layer via a second guiding pipe with a CO2 flow meter. The alkaline chamber and acid chamber are connected by a connecting guiding pipe with an alkaline flow valve. After CO2 enters the alkaline chamber, it reacts with OH-. - The reaction produces CO3 2- The remaining non-carbon dioxide gases (including N2, O2, etc.) enter the quantitative distribution layer through the non-carbon dioxide gas collecting pipe, where an acid-base neutralization reaction occurs in the acid chamber, i.e., CO32-. 2- +H + →CO2+H2O, the regenerated CO2 gas enters the quantitative distribution layer through the second guide tube. This invention can control the CO2 concentration in the quantitative distribution layer by using a carbon dioxide flow meter, a non-carbon dioxide flow meter and an alkaline flow valve. The structure is simple and easy to control, and it also helps to ensure control accuracy.

[0020] 3. The photosynthetic metabolism layer at the top of the carbon recovery module of the present invention is connected to the alkaline chamber in the separation and gas collection layer through a reflux pipe, so that the residual carbon dioxide gas can re-enter the alkaline chamber for recycling.

[0021] 4. The carbon release module of this invention realizes the separation and discharge of mud and water in sewage, and the treated effluent can be directly discharged, which meets environmental protection requirements. At the same time, it avoids the effluent from carrying a large number of sewage microorganisms, which could cause biological invasion of the receiving water body.

[0022] 5. The microalgae obtained by the carbon recovery module after synthesis and metabolism in this invention shields harmful substances in wastewater, and the recovered algae can be used in pharmaceuticals, fuel, and nutrient preparation, etc., with higher added value of product utilization. As an industrial chain for the entire wastewater treatment cycle, it further reduces wastewater treatment costs and achieves carbon emission reduction targets while completing wastewater treatment. Attached Figure Description

[0023] Figure 1 This is a three-dimensional schematic diagram of the present invention.

[0024] Figure 2 for Figure 1 A magnified schematic diagram of the carbon flow guiding module in the middle.

[0025] Figure 3 for Figure 1 The structural front view of the present invention.

[0026] Figure 4 This is a schematic diagram illustrating the change in total organic carbon content within the wastewater treatment layer according to an embodiment of the present invention.

[0027] Figure 5 This is a schematic diagram illustrating the changes in cumulative microalgal biomass within the carbon recovery module of this invention.

[0028] Figure 6 This is a schematic diagram illustrating the changes in carbon dioxide release and recovery content in an embodiment of the present invention.

[0029] Among them, 1 is the sewage treatment layer, 101 is the sewage inlet pipe, 1011 is the sewage pump, 1012 is the sewage inlet, 102 is the purified water outlet pipe, 1021 is the purified water outlet pump, 103 is the aeration pipe, 1031 is the aeration pump, 1032 is the aeration head, 104 is the activated sludge inlet pipe, 1041 is the sludge inoculation pump, 1042 is the activated sludge inlet, 105 is the sludge discharge pipe, 1051 is the sludge discharge pump, 2 is the sludge-water separation layer, 201 is the sludge packing barrier net, 202 is the filter membrane assembly, 203 is the first guide pipe, 3 is the separation and gas collection layer, 301 is the alkali chamber, 3011 is the inlet pipe, 3012 is the non-carbon dioxide gas collection pipe, and 3013 is the one-way exhaust pipe. 3014 is the alkali solution injection port, 3015 is the non-carbon dioxide flow meter, 302 is the connecting guide pipe, 3021 is the alkali solution flow valve, 303 is the acid solution chamber, 3031 is the output pipe, 3032 is the acid solution injection port, 3033 is the salt discharge port, 304 is the second guide pipe, 305 is the carbon dioxide flow meter, 4 is the quantitative distribution layer, 401 is the third guide pipe, 402 is the return pipe, 403 is the pressure gauge, 404 is the safety pressure relief port, 5 is the photosynthetic metabolism layer, 501 is the base plate, 502 is the partition plate, 5021 is the gas guide plate, 503 is the cover plate, 504 is the lighting lamp, 505 is the discharge port, 506 is the temperature sensor, 507 is the pH sensor, and 508 is the light controller. Detailed Implementation

[0030] The invention will now be described in further detail with reference to the accompanying drawings.

[0031] like Figures 1-3As shown, the present invention includes a carbon release module, a carbon diversion module, and a carbon recovery module arranged sequentially from bottom to top. The carbon release module is internally divided into a lower wastewater treatment layer 1 and an upper sludge-water separation layer 2 by a sludge packing mesh 201. The wastewater treatment layer 1 has an aeration head 1032 and an activated sludge input pipe 104 at its bottom. The sludge-water separation layer 2 contains a filter membrane assembly 202. The carbon diversion module is internally divided into a lower separation and gas collection layer 3 and an upper fixed layer 3 by a middle partition. The quantitative distribution layer 4 includes an alkali chamber 301 and an acid chamber 303 within the separation and gas collection layer 3. A first guide pipe 203 extends into the separation and gas collection layer 3 from one side of the mud-water separation layer 2 and is connected to the input pipe 3011 of the alkali chamber 301. The output end of the alkali chamber 301 is connected to the input end of the acid chamber 303 via a connecting guide pipe 302. A second guide pipe 304 is provided on one side of the separation and gas collection layer 3 and communicates with the quantitative distribution layer 4. 4 is connected to the output pipe 3031 of the acid chamber 303. Additionally, the alkali chamber 301 is equipped with a non-carbon dioxide gas collection pipe 3012 connected to the quantitative distribution layer 4. An alkali flow valve 3021 is installed on the connecting guide pipe 302. A carbon dioxide flow meter 305 is installed on the second guide pipe 304, and a non-carbon dioxide flow meter 3015 is installed on the non-carbon dioxide gas collection pipe 3012. The carbon recovery module includes multiple photosynthetic metabolism layers 5, and the quantitative distribution layer 4 is located on one side. A third guide pipe 401 is provided to connect with the bottommost photosynthetic metabolism layer 5. Adjacent photosynthetic metabolism layers 5 are separated by a partition 502, and one end of the partition 502 is provided with an air guide plate 5021 with ventilation holes. Microalgae are cultivated in each photosynthetic metabolism layer 5. The inner wall of the carbon recovery module is provided with a lighting lamp 504, and each lighting lamp 504 is vertically arranged and passes through each photosynthetic metabolism layer 5. The uppermost photosynthetic metabolism layer 5 is connected to the alkaline solution chamber 301 through a return pipe 402.

[0032] like Figures 1-3 As shown, in this embodiment, the wastewater treatment layer 1 has a wastewater inlet pipe 101 with a wastewater pump 1011 on one side and a sludge discharge pipe 105 with a sludge discharge pump 1051 on the other side. The bottom of the wastewater treatment layer 1 has an activated sludge inlet pipe 104 with a sludge inoculation pump 1041 on one side, and an aeration pipe 103 with an aeration pump 1031 on the other side of the bottom. All aeration heads 1032 at the bottom of the wastewater treatment layer 1 are supplied with air through the aeration pipe 103. The bottom of the separation and air collection layer 3 has a filter main pipe, such as... Figure 3 As shown, each group of filter membranes 202 in the mud-water separation layer 2 is provided with a connecting pipe 2021 at the upper end, which is connected to the filter main pipe. The output end of the filter main pipe is connected to the water output pipe 102 provided with a water purification pump 1021.

[0033] In operation, wastewater is input into the wastewater treatment layer 1 through the wastewater input pipe 101. The solid portion of the wastewater cannot enter the sludge-water separation layer 2 due to the obstruction of the sludge packing barrier net 201. The liquid portion of the wastewater enters the sludge-water separation layer 2 through the sludge packing barrier net 201 to achieve sludge-water separation. The liquid entering the sludge-water separation layer 2 is filtered by each set of filter membranes 202 and finally forms purified water, which flows out through the purified water output pipe 102. The solid sludge remaining in the wastewater treatment layer 1 is discharged through the sludge discharge pipe 105. In addition, activated sludge for degrading organic matter is input into the wastewater treatment layer 1 through the activated sludge input pipe 104. Under aeration (air) conditions, the organic matter in the wastewater is degraded by the activated sludge to form carbon dioxide gas. The carbon dioxide gas generated in the wastewater treatment layer 1 and the residual air (mainly nitrogen and oxygen) from aeration rise into the sludge-water separation layer 2 and are output into the separation and gas collection layer 3 through the first guide pipe 203. Both the filter membrane module 202 and the activated sludge are technologies known in the art and are commercially available products.

[0034] like Figures 1-3 As shown, during operation, the carbon dioxide gas generated in the wastewater treatment layer 1, along with the residual air (mainly nitrogen and oxygen) from aeration, rises into the sludge-water separation layer 2 and passes through the first guide pipe 203 and the input pipe 3011 into the alkaline solution chamber 301 in the separation and gas collection layer 3 for treatment. The CO2, after entering the alkaline solution chamber 301, reacts with OH- within 24 hours. - The reaction produces CO3 2- The remaining non-carbon dioxide gases (including N2, O2, etc.) enter the quantitative distribution layer 4 through the non-carbon dioxide gas collecting pipe 3012, and the CO2 gas is absorbed by the alkaline solution to generate CO3. 2- It then continues to enter the acid chamber 303, where an acid-base neutralization reaction, i.e., CO32-, occurs. 2- +H +→CO2 + H2O, and then the regenerated CO2 gas enters the quantitative distribution layer 4 through the second guide pipe 304. The non-carbon dioxide flow meter 3015 detects the flow rate of non-carbon dioxide gas generated in the alkali chamber 301 and flowing into the quantitative distribution layer 4 in real time, while the carbon dioxide flow meter 305 monitors the flow rate of carbon dioxide gas output from the acid chamber 303 and flowing into the quantitative distribution layer 4 in real time. Furthermore, the present invention controls the flow rate of liquid entering the acid chamber 303 through the alkali flow valve 3021, thereby controlling the flow rate of carbon dioxide gas entering the quantitative distribution layer 4. In this way, non-carbon dioxide gas and carbon dioxide gas can be redistributed in the quantitative distribution layer 4 as needed to obtain the required carbon dioxide gas concentration. The carbon dioxide flow meter 305, the non-carbon dioxide flow meter 3015, and the alkali flow valve 3021 are all known technologies in the art and are commercially available products. In addition, each guide pipe is equipped with a one-way valve to ensure unidirectional gas flow and prevent backflow, which is also known technology in the art.

[0035] like Figure 2 As shown, the alkali chamber 301 is provided with a one-way exhaust pipe 3013 for venting residual gas on one side, and an alkali injection port 3014 for replenishing alkali on the other side. The acid chamber 303 is provided with an acid injection port 3032 for replenishing acid on one side, and a salt discharge port 3033 for venting residual substances on the other side.

[0036] like Figure 2 As shown, a pressure gauge 403 is provided on one side of the quantitative distribution chamber 4 for real-time monitoring of the internal pressure, and a safety pressure relief port 404 is provided on the other side of the quantitative distribution chamber 4 for safe pressure relief.

[0037] like Figures 1-3 As shown, the carbon recovery module includes multiple photosynthetic metabolism layers 5, wherein the lowest photosynthetic metabolism layer 5 is separated from the quantitative distribution layer 4 by a bottom plate 501, and adjacent photosynthetic metabolism layers 5 are separated by a partition 502. One end of the partition 502 is provided with a gas guide plate 5021 with a network of permeable holes, so that gas can rise layer by layer. Microalgae are provided on both the bottom plate 501 and the partition 502.

[0038] This invention utilizes the photosynthesis of microalgae to absorb and consume CO2 from the atmosphere, thereby achieving zero carbon emissions. While microalgae require light for growth, longer light exposure is not necessarily better; alternating light and dark periods are necessary, forming photoperiods and dark periods. During the photoperiod, microalgae photosynthesize with CO2 under light conditions, using CO2 to synthesize the organic matter needed for their reproduction, thus removing CO2. During the dark period, microalgae respire in the absence of light, decomposing their own organic matter and releasing CO2. However, because the intensity of photosynthesis is greater than that of respiration, the CO2 consumed by microalgae during the photoperiod is far greater than the CO2 released during the dark period. Therefore, the net effect is CO2 consumption, achieving zero CO2 emissions into the atmosphere. Microalgae require different CO2 concentrations at different stages of their growth. Therefore, this invention utilizes the adjustment of the quantitative distribution layer 4 to meet the CO2 concentration requirements of microalgae at different stages. In this embodiment, the photoperiod in the carbon recovery module is 12-16 hours of light cultivation with the illumination lamp 504 on, and 8-12 hours of dark cultivation with the illumination lamp 504 off. During the photoperiod of the stable cultivation stage, the CO2 concentration in the supplied gas must be 3%-10%, while during the darkperiod of the stable cultivation stage, the CO2 concentration in the supplied gas must be 0.03%-0.5%. In addition, during the photoperiod of the inoculation replacement stage, the CO2 concentration in the supplied gas must be 0.5%-3%, and during the darkperiod of the inoculation replacement stage, the CO2 concentration in the supplied gas must be 0.03%-0.05%.

[0039] like Figure 1 As shown, the carbon recovery module has a flip-open cover 503 at its upper end for placing microalgae, etc. The carbon recovery module contains a temperature sensor 506 and a pH sensor 507 for real-time monitoring of temperature and pH. Additionally, a light controller 508 at the upper end of the carbon recovery module controls the light intensity of each lighting lamp 504. Furthermore, the uppermost photosynthetic metabolism layer 5 is connected to the alkali chamber 301 via a reflux pipe 402, allowing residual carbon dioxide gas to re-enter the alkali chamber 301, thus achieving recycling. The temperature sensor 506, pH sensor 507, and light controller 508 are all technologies known in the art and are commercially available products.

[0040] The working principle of this invention is as follows:

[0041] In operation, the wastewater in the wastewater treatment layer 1 undergoes sludge-water separation via the sludge packing barrier mesh 201. The liquid entering the sludge-water separation layer 2 is filtered by various filter membrane groups 202, ultimately forming purified water which flows out through the purified water output pipe 102. Furthermore, the wastewater treatment layer 1 utilizes activated sludge to degrade organic matter in the wastewater. Under aeration (air) conditions, the organic matter in the wastewater is degraded by the activated sludge to form carbon dioxide gas, which, along with the remaining air (mainly nitrogen and oxygen), rises into the sludge-water separation layer 2 and then enters the separation and gas collection layer 3 via the first guide pipe 203. This invention utilizes the photosynthesis of microalgae to absorb and consume CO2 from the gas, thereby achieving zero carbon emissions. However, microalgae require different CO2 concentrations at different stages. Therefore, this invention utilizes the carbon diversion module to quantitatively redistribute carbon dioxide gas and other gases to meet the CO2 concentration requirements of the microalgae. The separation and gas collection layer 3 separates non-carbon dioxide gases from carbon dioxide gas. After entering the alkaline chamber 301, CO2 reacts with OH- to produce CO3 within 24 hours. 2 The remaining non-carbon dioxide gases (including N2, O2, etc.) enter the quantitative distribution layer 4 through the non-carbon dioxide gas collection pipe 3012, while the acid-base neutralization reaction occurs in the acid chamber 303, i.e., CO32-. 2 -+H + →CO2 + H2O, and then the regenerated CO2 gas enters the quantitative distribution layer 4 through the second guide pipe 304. This invention uses a non-CO2 flow meter 3015 to monitor the flow rate of non-CO2 gas flowing into the quantitative distribution layer 4 in real time, and a CO2 flow meter 305 to monitor the flow rate of CO2 gas flowing into the quantitative distribution layer 4 in real time. The flow rate of liquid entering the acid chamber 303 is controlled by the alkaline flow valve 3021, thereby controlling the flow rate of CO2 gas entering the quantitative distribution layer 4. This allows for the redistribution of non-CO2 gas and CO2 gas in the quantitative distribution layer 4 as needed to obtain the required CO2 gas concentration, thus meeting the gas supply needs of the microalgae in each photosynthetic metabolism layer 5 of the carbon recovery module at different cycles. Furthermore, the uppermost photosynthetic metabolism layer 5 is connected to the alkaline chamber 301 through a return pipe 402, allowing residual CO2 gas to re-enter the alkaline chamber 301, thereby achieving cyclic processing.

[0042] The following application example further illustrates the working principle of the present invention.

[0043] In this application example, the wastewater to be treated came from aquaculture wastewater discharged from a certain aquaculture farm. The influent indicators are shown in Table 1 below, with an influent COD content of 454.9 mg·L⁻¹. 1 BOD5 (five-day biochemical oxygen demand) was 163.8 mg·L⁻¹. 1The suspended solids (SS) content was 216.1 mg·L⁻¹. 1 The total nitrogen (TN) content was 31.2 mg·L⁻¹. 1 The ammonia nitrogen (NH3-N) content was 20.1 mg·L- 1 .

[0044] Table 1

[0045]

[0046] In this application example, the activated sludge in the wastewater treatment layer 1 of the carbon release module is specifically cultivated and acclimatized activated sludge. This embodiment adopts a sequential batch wastewater treatment operation mode to examine the changes in wastewater index parameters and the content and growth status of microalgae in the carbon recovery system during two operating cycles of 18 days of microalgae cultivation.

[0047] In this application example, activated sludge was inoculated into wastewater treatment layer 1 with a total volume of 50L, and the inoculation amount was 1260 mg·L⁻¹ based on the mixed liquor suspended solids concentration (MLSS). -1 40L of wastewater to be treated is pumped into wastewater treatment layer 1. Aeration pump 1031 is turned on for 24 hours. After treatment, aeration pump 1031 is turned off. After settling, effluent pump 1021 is turned on for drainage. Then, wastewater pump 1011 is turned on to start the next wastewater treatment cycle. The relevant parameters are shown in Table 2 below.

[0048] Table 2

[0049]

[0050] Additionally, pre-cultured mature microalgae were inoculated into the photosynthetic metabolism layer 5 of the carbon recovery module. In this application example, the microalgae used was *Chlorella vulgaris*, with optimal culture conditions of 25°C, pH 8.9, and light intensity of 4000 lux. *Chlorella vulgaris*, activated and cultured for 72 hours, was transferred to the fresh culture medium in the carbon recovery module at a 1:5 ratio (cultured algae solution: fresh culture medium). The culture medium used in this application example was BG11 medium. After inoculation, the carbon recovery module began operation under alternating light conditions of a 16-hour photoperiod and an 8-hour darkperiod. The first two days were the acclimatization period, followed by a 7-day stabilization period, with one operating cycle lasting 9 days. After 9 days of operation, 4 / 5 of the algae solution was drained from the outlet, and 4 / 5 of the fresh culture medium was injected to continue the next culture cycle.

[0051] During a wastewater treatment cycle, the carbon release module, carbon diversion module, and carbon recovery module are simultaneously activated. In the carbon diversion module, the flow rates of CO2 and non-CO2 gases into the quantitative distribution layer 4 are regulated by a CO2 flow meter 305 and a non-CO2 flow meter 3015, respectively. In this application example, for the inoculation and turnover period of microalgae cultivation, during the photoperiod, the control flow rate ratio of the CO2 flow meter and the non-CO2 flow meter is 0.3:9.7, resulting in a CO2 concentration of 3% flowing into the quantitative distribution layer 4 after mixing. During the darkperiod, the control flow rate ratio of the CO2 flow meter and the non-CO2 flow meter is 0.05:99.95, resulting in a CO2 concentration of 0.05% flowing into the quantitative distribution layer 4 after mixing. For the stabilization period of microalgae cultivation, during the light cycle, the control flow rate ratio of the CO2 flow meter and the non-CO2 flow meter is 1:9, and the CO2 concentration flowing into the quantitative distribution layer 4 after mixing reaches 10%. During the dark cycle, the control flow rate ratio of the CO2 flow meter and the non-CO2 flow meter is 0.05:99.95, and the CO2 concentration flowing into the CO2 quantitative distribution layer 4 after mixing reaches 0.05%.

[0052] Meanwhile, to coordinate with CO2 flow control, the alkali flow valve 3021 is set with different alkali flow rates to meet varying CO2 flow requirements. In this application example, the alkali solution in the alkali chamber 301 is 0.5 L of 3M (mol / L) NaOH (sodium hydroxide) solution, and the acid chamber 303 is 0.5 L of 2M (mol / L) H3PO4 (phosphoric acid) solution. During the photoperiod of the inoculation replacement period, the flow rate of the alkali flow valve 3021 is set to 0.5 mL / min. -1 During the dark period of the inoculation replacement cycle, the flow rate of the alkali solution flow valve 3021 was set to 0.05 mL / min. -1 During the stable operation period, the flow rate of the alkali solution at valve 3021 was set to 0.025 mL / min. -1 During the dark period of stable operation, the flow rate of the alkali solution flow valve 3021 is set to 0.0025 mL / min. -1 .

[0053] The changes in total organic carbon (TOC) content and residual average value in wastewater with treatment time were observed during each wastewater treatment cycle (24h). Figure 4 As shown, the results indicate that within each 24-hour treatment cycle, the TOC content tends to reach its limit at the end of the cycle, meaning that approximately all TOC is mineralized into CO2, indicating that the treatment endpoint has been reached. The detection indicators of the effluent from wastewater treatment layer 1 are shown in Table 1 above, with a COD content of 38 mg·L⁻¹. -1 BOD5 was 9.2 mg·L⁻¹. -1 The suspended solids (SS) content was 8.6 mg·L⁻¹. -1 The total nitrogen (TN) content was 12.6 mg·L⁻¹.-1 The ammonia nitrogen (NH3-N) content was 4.2 mg·L. -1 It meets the Class A standard of the "Discharge Standard of Pollutants for Urban Wastewater Treatment Plants" (GB18918-2002).

[0054] In the carbon recovery module, the cumulative biomass of microalgae over a complete 9-day operating cycle is measured using OD. 600 The absorbance value (absorbance of the liquid at a wavelength of 600 nm) represents the characteristic of its change with treatment time, as shown in the following figure. Figure 5 As shown, the microalgal biomass, after undergoing an initial inoculation adaptation period, an exponential growth period, and a stable period, approaches its decline phase at the end of the experiment, indicating that the carbon recovery module has reached its operational limit. If continued operation is required, the microalgal biomass needs to be replenished, entering the next inoculation and replenishment cycle. After carbon balance calculations, as shown... Figure 6 As shown, the cumulative amount of CO2 released in the carbon release module is approximately equal to the cumulative amount of CO2 utilized by microalgae as a raw material for biosynthesis and metabolism in the carbon recovery module. This indicates that the zero-carbon emission wastewater treatment system of the present invention not only has the basic function of wastewater treatment, but also achieves the carbon emission reduction target of recycling in the form of CO2.

Claims

1. A zero-carbon emission sewage treatment system characterized by: The carbon release module, the carbon flow guide module and the carbon recovery module are sequentially arranged from bottom to top, wherein the carbon release module is divided into a sewage treatment layer (1) at the lower side and a sludge-water separation layer (2) at the upper side by a sludge filler barrier net (201) inside the carbon release module, the sewage treatment layer (1) is provided with an aeration head (1032) and an activated sludge input pipe (104) at the bottom, and the sludge-water separation layer (2) is provided with a filter membrane group (202) inside; the carbon flow guide module comprises a separation gas collection layer (3) at the lower side and a quantitative distribution layer (4) at the upper side, the separation gas collection layer (3) is provided with an alkali liquid chamber (301) and an acid liquid chamber (303) inside, one side of the sludge-water separation layer (2) is provided with a first flow guide pipe (203) extending into the separation gas collection layer (3) and connected with an input pipe (3011) of the alkali liquid chamber (301), the output end of the alkali liquid chamber (301) is connected with the input end of the acid liquid chamber (303) through a connecting flow guide pipe (302), one side of the separation gas collection layer (3) is provided with a second flow guide pipe (304) in communication with the quantitative distribution layer (4), the second flow guide pipe (304) is connected with an output pipe (3031) of the acid liquid chamber (303), and in addition, the alkali liquid chamber (301) is provided with a non-carbon dioxide gas collection pipe (3012) in communication with the quantitative distribution layer (4), the connecting flow guide pipe (302) is provided with an alkali liquid flow valve (3021), the second flow guide pipe (304) is provided with a carbon dioxide flow meter (305), and the non-carbon dioxide gas collection pipe (3012) is provided with a non-carbon dioxide flow meter (3015); the carbon recovery module comprises a plurality of photosynthetic metabolism layers (5), one side of the quantitative distribution layer (4) is provided with a third flow guide pipe (401) in communication with the bottommost photosynthetic metabolism layer (5), adjacent photosynthetic metabolism layers (5) are separated by a partition plate (502), one end of the partition plate (502) is provided with a gas guide plate (5021) filled with gas permeable holes, microalgae are cultivated in each photosynthetic metabolism layer (5), and the inner wall of the carbon recovery module is provided with an illumination lamp (504) penetrating through each photosynthetic metabolism layer (5), and the topmost photosynthetic metabolism layer (5) is in communication with the alkali liquid chamber (301) through a reflux pipe (402).

2. The zero-carbon-emission wastewater treatment system of claim 1, wherein: The sewage treatment layer (1) is provided with a sewage input pipe (101) and a sludge discharge pipe (105), the separation gas collection layer (3) is provided with a filter main pipe at the bottom, the upper end of each filter membrane group (202) in the sludge-water separation layer (2) is provided with a connecting pipe (2021) connected with the filter main pipe, and the output end of the filter main pipe is connected with a clean water output pipe (102).

3. The zero-carbon-emission wastewater treatment system of claim 1, wherein: The bottom of the sewage treatment layer (1) is provided with an aeration pipe (103) with an aeration pump (1031), and each aeration head (1032) at the bottom of the sewage treatment layer (1) is supplied with air through the aeration pipe (103).

4. The zero-carbon-emission wastewater treatment system of claim 1, wherein: One side of the alkali liquid chamber (301) is provided with a one-way exhaust pipe (3013), and the other side is provided with an alkali liquid injection port (3014).

5. The zero-carbon-emission wastewater treatment system of claim 1, wherein: The acid liquid chamber (303) is provided with an acid liquid injection port (3032) on one side and a salt discharge port (3033) on the other side.

6. The zero-carbon-emission wastewater treatment system of claim 1, wherein: The quantitative distribution layer (4) is provided with a pressure gauge (403) on one side and a safety pressure relief port (404) on the other side.

7. The zero-carbon-emission wastewater treatment system of claim 1, wherein: The carbon recovery module comprises a plurality of photosynthetic metabolism layers (5), wherein the lowermost photosynthetic metabolism layer (5) is separated from the quantitative distribution layer (4) by a bottom plate (501), and adjacent photosynthetic metabolism layers (5) are separated by a partition plate (502), and the bottom plate (501) and the partition plate (502) are both provided with microalgae.

8. The zero-carbon-emission wastewater treatment system of claim 1, wherein: The upper end of the carbon recovery module is provided with a reversible cover plate (503), the inside of the carbon recovery module is provided with a temperature sensor (506) and a PH sensor (507), and in addition, the carbon recovery module is provided with a light controller (508) for controlling the light intensity of each illumination lamp (504).

9. The zero-carbon-emission wastewater treatment system of claim 1, wherein: In the sewage treatment layer (1), the organic matter in the sewage is degraded by activated sludge under aeration condition to form carbon dioxide gas, and the carbon dioxide gas generated in the sewage treatment layer (1) and the gas remaining after aeration rises and enters the alkali solution chamber (301) of the separation gas collection layer (3) through the first flow guide pipe (203) and the input pipe (3011), wherein the carbon dioxide enters the alkali solution chamber (301) and reacts with OH - to generate CO3 2- The remaining non-carbon dioxide gas enters the quantitative distribution layer (4) through the non-carbon dioxide gas collection pipe (3012), and the CO2 gas is absorbed by the alkali solution to generate CO3 2- which continues to enter the acid solution chamber (303), and an acid-base neutralization reaction occurs in the acid solution chamber (303), i.e., CO3 2- +H + →CO2+H2O, and then the newly generated CO2 gas enters the quantitative distribution layer (4) through the second flow guide pipe (304).

10. The zero-carbon-emission wastewater treatment system of claim 1, wherein: The microalgae growth process comprises a light period of a seed replacement stage, a dark period of the seed replacement stage, a light period of a stable culture stage, and a dark period of the stable culture stage.

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