Method for promoting efficient sludge composting by reducing negative regulatory effect of microplastics on organisms

Abstract

A method for promoting efficient sludge composting by reducing the negative regulatory effect of microplastics on organisms, relating to a method for promoting efficient sludge composting. The method comprises the steps of: step 1, setting and adding the background concentration of microplastics in sludge; step 2, treating the raw materials of a polyacrylamide-microplastic sludge composting-containing system; and step 3, constructing and operating the polyacrylamide-microplastic sludge composting-containing system. The problems of unstable sludge composting process and poor sludge composting efficiency caused by interference of exogenous pollutants are solved.

Description

Methods to reduce the negative regulatory impacts of microplastics to promote efficient composting of sewage sludge Technical Field

[0001] The invention relates to a method for promoting efficient composting of sludge, and belongs to the technical field of organic solid waste pile treatment. Background Art

[0002] In recent years, large quantities of sewage sludge have been discarded as a by-product, and its subsequent disposal has become a thorny issue for sewage treatment plants. It is reported that the annual production of dry sludge in the European Union is approximately 10 million tons, while China's sewage treatment plants discharge up to 11.2 million tons of dry sludge per year. Sludge is rich in 50-70% organic components (such as proteins and polysaccharides) and can serve as a promising raw material for further development and utilization to produce valuable products. Composting technology, driven by a complex metabolic network of diverse functional bacteria (psychrotrophic, mesophilic, and thermophilic), simultaneously achieves sludge reduction and resource recovery through the metabolic transformation of organic matter, making it a promising sludge treatment technology. However, interference from exogenous pollutants frequently leads to instability and poor efficiency in the sludge composting process.

[0003] Currently, global annual production of plastic (i.e., small plastic particles less than 5 mm in size) is approximately 300 million tons, and this amount is projected to double by 2040. The widespread use of plastic products has made microplastics ubiquitous in various environments, and wastewater treatment plants have been recognized as a significant pathway for microplastics to enter the environment. In China, for example, high concentrations of microplastics (1–10,044 particles / L) have been detected in the influent of wastewater treatment plants, and 0–447 particles / L have been detected in the effluent. During biological treatment, over 97% of microplastic particles are trapped and ultimately enriched in the sludge. Dry sludge has been reported to contain 22,700 particles / kg. Given that microplastics, due to their tiny size and associated chemicals, can have harmful effects on various organisms, they may impact sludge composting systems.

[0004] Studies have shown that microplastics such as PE and PVC have significant negative effects on the biomass composting process. Microplastics not only inhibit the degradation of organic matter during the composting process, but also significantly reduce the maturity of the compost. These negative effects are mainly related to the toxicity of the microplastics themselves or the toxic elements released during degradation during the composting process. Through toxic effects, the richness and diversity of bacterial communities in the composting system are reduced, which is not conducive to the microbial-driven biotransformation process of organic matter and ultimately inhibits biomass composting. Therefore, long-term exposure of microplastics in sludge poses a great threat to the stable operation of the composting system.

[0005] Research has demonstrated that binders can mitigate the toxic effects of nanoplastics on organisms by adsorbing onto them, offering insights into mitigating the toxic effects of microplastics on microorganisms during composting. Among flocculants widely used in wastewater treatment and sludge dewatering, cationic polyacrylamide is favored due to its relatively high affinity for microplastic surfaces. Polyacrylamide can embed and capture microplastics through strong ionic and van der Waals interactions with sludge and microplastics, and can also reduce interactions between microplastics and microbial communities. Therefore, we hypothesize that polyacrylamide can mitigate the adverse effects of microplastics on sludge composting. Summary of the Invention

[0006] The present invention aims to solve the problem of instability and poor efficiency of sludge composting process due to interference from exogenous pollutants, and further proposes a method for reducing the negative biological impact of microplastics to promote efficient sludge composting.

[0007] The technical solution adopted by the present invention to solve the above problems is: the steps of the present invention are:

[0008] Step 1: Set and add microplastic sludge background concentration;

[0009] Step 2: Processing the raw materials of the polyacrylamide-microplastic sludge composting system;

[0010] Step 3: Construct and operate a polyacrylamide-microplastic sludge composting system.

[0011] Furthermore, the steps for setting and adding the background concentration of microplastic sludge in step 1 are as follows:

[0012] Step 1 (i) Based on the background concentration of microplastics in the sludge, a certain amount of microplastics is added to the sludge to ensure that the concentration of microplastics in the sludge is consistent with the background concentration;

[0013] Step 1 (2): Place the sludge containing microplastics in a glass bottle and move it to a constant temperature rotary oscillator to ensure that the microplastics are evenly mixed in the sludge.

[0014] Furthermore, the sludge containing microplastics in step 1 (2) was rotated in an oscillator at 50°C and 200 rpm for 30 minutes.

[0015] Furthermore, the microplastics refer to PE and PVC.

[0016] Furthermore, the steps for processing the raw materials of the polyacrylamide-microplastic sludge composting system in step 2 are:

[0017] Step 2 (1): Take out the microplastic-containing sludge after uniform mixing, prepare a polyacrylamide stock solution of a certain concentration, and add the stock solution to the microplastic-containing sludge;

[0018] Step 2 (ii): Place the sludge containing microplastics after adding the reserve solution in a glass bottle and move it to a constant temperature rotary oscillator to ensure that the polyacrylamide is evenly mixed in the sludge containing microplastics.

[0019] Step 2 (3): Take out the sludge sample and use it as raw material for composting system.

[0020] Furthermore, the microplastic-containing sludge after adding the reserve solution in step 2 (ii) was rotated in an oscillator at 50°C and 200 rpm for 30 minutes.

[0021] Furthermore, the sludge sample obtained in step three is added to a composting device.

[0022] The beneficial effects of the present invention are:

[0023] 1. By adding cationic polyacrylamide with affinity to sludge containing microplastics, the present invention can directly reduce the interaction between microplastics and microorganisms in the composting system, thereby reducing the negative impact of microplastics on the sludge composting system, thereby improving the efficient degradation and conversion rate of organic matter components in the composting process and increasing the diversity and richness of the microbial community. Compared with directly composting sludge containing only microplastics, the present invention can effectively improve the sludge composting efficiency and achieve efficient composting.

[0024] 2. In the process of preparing the compost raw material (i.e., polyacrylamide-containing microplastic sludge), the present invention places the sludge in a constant temperature rotary oscillation and treats it at 50°C to ensure the temperature condition of the compost raw material. When the sludge is composted, the compost can be quickly started and heated, thereby accelerating the sludge composting process. Implementation Method

[0025] Specific embodiment 1: The method of reducing the negative biological effects of microplastics to promote efficient sludge composting described in this embodiment is achieved through the following steps:

[0026] Step 1: Set and add microplastic sludge background concentration;

[0027] Step 2: Processing the raw materials of the polyacrylamide-microplastic sludge composting system;

[0028] Step 3: Construct and operate a polyacrylamide-microplastic sludge composting system.

[0029] Specific embodiment 2: In step 1 of the method for reducing the negative biological effects of microplastics to promote efficient sludge composting described in this embodiment, the steps of setting and adding the background concentration of microplastic sludge are:

[0030] Step 1 (i) Based on the background concentration of microplastics in the sludge, a certain amount of microplastics is added to the sludge to ensure that the concentration of microplastics in the sludge is consistent with the background concentration;

[0031] Step 1 (2): Place the sludge containing microplastics in a glass bottle and move it to a constant temperature rotary oscillator to ensure that the microplastics are evenly mixed in the sludge.

[0032] Specific embodiment three: In step one (two) of the method for reducing the negative biological effects of microplastics to promote efficient composting of sludge described in this embodiment, the sludge containing microplastics is rotated in an oscillator at 50°C and 200 rpm for 30 minutes.

[0033] Specific embodiment 4: The microplastics described in the method of reducing the negative biological impact of microplastics to promote efficient sludge composting in this embodiment refer to PE and PVC.

[0034] Specific embodiment 5: In step 2 of the method for reducing the negative biological effects of microplastics to promote efficient sludge composting described in this embodiment, the steps of treating the raw materials of the polyacrylamide-microplastic-containing sludge composting system are as follows:

[0035] Step 2 (1): Take out the microplastic-containing sludge after uniform mixing, prepare a polyacrylamide stock solution of a certain concentration, and add the stock solution to the microplastic-containing sludge;

[0036] Step 2 (ii): Place the sludge containing microplastics after adding the reserve solution in a glass bottle and move it to a constant temperature rotary oscillator to ensure that the polyacrylamide is evenly mixed in the sludge containing microplastics.

[0037] Step 2 (3): Take out the sludge sample and use it as raw material for composting system.

[0038] Specific embodiment six: In step two (ii) of the method for reducing the negative biological effects of microplastics to promote efficient composting of sludge described in this embodiment, the microplastic-containing sludge after adding the reserve solution is rotated in an oscillator at 50°C and 200 rpm for 30 minutes.

[0039] Specific embodiment seven: In step three of the method for reducing the negative biological impact of microplastics to promote efficient sludge composting described in this embodiment, the obtained sludge sample is added to the composting device.

[0040] The composting device described in this embodiment is mainly composed of a heat storage tank, a hot air dryer, a heat pipe water-air heat exchanger, a high-temperature biological treatment machine, etc.

[0041] The temperature of the sludge sample after the treatment in step 2 reaches about 50°C. Directly adding it to the composting system as raw material can ensure that the temperature of the composting system meets the optimal composting conditions. When the composting system is started, it can achieve rapid temperature rise, high-temperature functional microorganisms are enriched in large quantities, and organic matter is efficiently and quickly degraded, thereby accelerating the humification process of sludge composting and promoting efficient sludge composting.

[0042] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical content disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement of the above embodiments made according to the technical essence of the present invention, within the spirit and principles of the present invention, without departing from the content of the technical solution of the present invention, shall still fall within the scope of protection of the technical solution of the present invention.

[0043] Type your sequence listing free description paragraph here.

Claims

1. A method for reducing the negative biological effects of microplastics to promote efficient composting of sludge, characterized by: The method for reducing the negative biological effects of microplastics to promote efficient composting of sludge is achieved by the following steps: Step 1: Setting and adding microplastic sludge background concentration; Step 2: Processing raw materials of polyacrylamide-containing microplastic sludge composting system; Step 3: Construct and operate a polyacrylamide-microplastic sludge composting system.

2. The method of reducing the negative biological effects of microplastics to promote efficient composting of sludge according to claim 1, characterized in that: The steps for setting and adding microplastic sludge background concentration in step 1 are: Step 1 (i) adding a certain amount of microplastics to the sludge according to the background concentration of microplastics in the sludge to ensure that the concentration of microplastics in the sludge is consistent with the background concentration; Step 1 (2): Place the sludge containing microplastics in a glass bottle and transfer it to a constant temperature rotary oscillator to ensure that the microplastics are evenly mixed in the sludge.

3. The method of reducing the negative biological effects of microplastics to promote efficient composting of sludge according to claim 2, characterized in that: The sludge containing microplastics in step 1 (2) was rotated in an oscillator at 50°C and 200 rpm for 30 minutes.

4. The method for reducing the negative biological effects of microplastics to promote efficient composting of sludge according to claim 1 or 2, characterized in that: The microplastics mentioned refer to PE and PVC.

5. The method of reducing the negative biological effects of microplastics to promote efficient composting of sludge according to claim 1, characterized in that: The steps for treating the raw materials of the polyacrylamide-microplastic sludge composting system in step 2 are: Step 2 (a), taking out the microplastic-containing sludge after uniform mixing, preparing a polyacrylamide stock solution of a certain concentration, and adding the stock solution to the microplastic-containing sludge; Step 2 (ii), placing the sludge containing microplastics after adding the reserve solution in a glass bottle and moving it to a constant temperature rotary oscillator to ensure that the polyacrylamide is evenly mixed in the sludge containing microplastics; Step 2 (3): Take out the sludge sample and use it as raw material for composting system.

6. The method of reducing the negative biological effects of microplastics to promote efficient composting of sludge according to claim 5, characterized in that: The microplastic-containing sludge after adding the reserve solution in step 2 (ii) was rotated in an oscillator at 50°C and 200 rpm for 30 minutes.

7. The method of reducing the negative biological effects of microplastics to promote efficient composting of sludge according to claim 1, characterized in that: In step three, the obtained sludge sample is added into the composting device.