Organic Solid Waste Research Articles

Опыт использования беспилотных летательных аппаратов для выявления мест размещения отходов в водоохранных зонах

Disposal of industrial and consumer waste in water protection zones of water bodies is a violation of water legislation of the Russian Federation. The use of materials obtained with the help of unmanned aerial vehicles (UAVs) significantly expands the possibilities for determining stored waste. UAVs are used for prompt identification of unauthorized waste disposal sites within the boundaries of the water protection zones of the Tsimlyansk reservoir. The paper presents the possibilities of using orthophotoplans and photo materials obtained during field surveys carried out by the Russian Research Institute for the Integrated Use and Protection of Water Resources in 2019-2021. According to the research results, the largest accumulation of solid household waste is localized in the water protection zone of large cities and villages. The largest amount of waste stored in the water protection zone is located in the Dubovsky and Tsimplansk districts of the Rostov region, as well as in the Kalachyovsky district of the Volgograd region. Dumping sites detected with the help of UAVs based on the composition of the predominant waste were divided into five groups: solid household waste, construction waste, organic waste, metal, and waste of unknown composition. Up to 42 % of landfill waste in the water protection zone of the reservoir is solid domestic waste, at least 25 % of landfill sites are construction waste and 20 % are organ waste.

Iron and Nickel Supplementation Exerts a Significant Positive Effect on the Hydrogen and Methane Production from Organic Solid Waste in a Two-Stage Digestion

Two-stage anaerobic digestion and trace metals (TM) supplementation are promising techniques to improve biogas production. Fe2+ and Ni2+ can improve process stability since they are part of the cofactors of enzymes and microorganisms’ growth. This work attempted to evaluate the effect of Fe2+ and Ni2+ addition on H2-rich biogas production from organic solid waste and the CH4-rich biogas production from the acidogenic effluents (AEs) enriched with TM. The TM concentrations that enhanced the hydrogen yield in the batch were 0.25 mg/L of Ni2+ and 334 mg/L of Fe2+. These concentrations were evaluated in a two-stage system. The substrate for the batch tests and fermentative reactor (first stage) was OSW. The AE generated in the first stage was the substrate to produce CH4-rich biogas in the second stage. In the first stage, the productivity achieved was 1823 ± 160 mL H2/L/day. However, TM supplementation decreased productivity by 65% since the VS removal increased. Megasphaera genus predominated in the first stage. Regarding the methanogenic reactor, the undiluted AE without TM caused the fast decay of the process. Nevertheless, the reactor operated stably after using AE enriched with TM as a substrate, and CH4 yields increased by 42%. The highest productivity achieved in the second stage was 1278 ± 42 mL CH4/L/day, operating with an organic loading rate of 2.8 gVS/L/day. The genera Proteiniphilum, Thermovirga, DMER64, Anaerovorax, and Syntrophomonas predominated in the second stage. In conclusion, AE enriched with TM can be used to recover the stability of anaerobic digesters, increasing methane production.

A large-eddy simulation study of the transcritical mixing process in coaxial jet flow under supercritical condition

Supercritical water gasification (SCWG) is a promising clean energy technology for utilizing fossil fuels or organic solid waste with the challenge of delivering and dispersing liquid feedstock into the reactor. This paper investigates the transcritical mixing process in coaxial injections using large-eddy simulation. The results reveal that large temperature and density gradients exist between the inner injected water and the ambient fluid in the near field of transcritical water injection. Structure comparison demonstrates that the cross-section of the inner potential core shrinks more quickly in the non-premixing coaxial injection than the single injection, which can facilitate the dispersion and dilution of injected water during the heating process due to the shear mixing with the coaxial high-velocity outer injection. In addition, in the premixing coaxial injections, the substantial radial velocity fluctuation induced by the contracting cross-section leads to a much shorter inner potential core and more intensive heat and mass transfer. Swirling inlets can significantly strengthen the radial velocity fluctuation, thereby accelerating the temperature increase and species blending. Coaxial injections can effectively be used for dispersing feedstock in the SCWG process, particularly for high-viscosity materials.

Compost promotes biocrust and plant growth in greenhouse cocultures for dryland restoration

Biocrusts and plants are the main ground cover and provide multiple ecosystem functions in arid and semiarid areas. As land degradation worsens and waste management is ever more pressing, the use of composted waste appears as a sustainable restoration practice to enhance vegetation reestablishment, but its effects on biocrusts still remain largely understudied. Moreover, developing appropriate methods for the co‐introduction of plants and biocrusts can be an emerging approach to reconstruct the biocrust/plant interaction and their associated functions. We evaluated the effect of different compost types on biocrust and plant cocultivations. We performed a greenhouse mesocosm experiment using urban organic solid waste and sewage sludge composts to grow a moss‐dominated biocrust and seedlings of two pioneer shrubs (Senecio filaginoides and Acaena splendens) in the Patagonian steppe. Both compost types successfully enhanced biocrust cover and chlorophyll a development, with cultured biocrusts being compositionally similar to the natural inoculum. Only the addition of composted sewage sludge enhanced seedling growth, and biocrusts had significant but opposite effects (positive/negative) on the two plant species we used for experimentation. This difference in the biocrust/plant interaction outcome was likely mediated by the significant influence of biocrusts on the relative availability of ammonium and nitrate and possible plant species‐specific preferences for different inorganic nitrogen forms. We conclude that the application of sewage sludge compost effectively improves the success of biocrust and plant cocultures, but species‐specific differences in the performance of seedlings growing in biocrusted soils impose limits on attempts to promote biocrust and plant joint restoration.

Identifying the role of array electrodes in improving the compost quality of food waste during electric field-assisted aerobic composting

Low composting temperature and long maturation periods are two major problems during food waste composting. In this study, a novel array-based electric field-assisted aerobic composting (Pin-EAC) process was tested on food waste compost. Pin-EAC increase the composting temperature to 69.3 °C, and improved the germination index by 15%. The Pin-EAC took at least 40% less time to reach the standard compost maturity. The fluorescent spectroscopy results showed that Pin-EAC could increase humic acid and fulvic acid by 33% and 37%, respectively. Pin-EAC could increase the diversity of thermophilic bacteria during composting. The co-occurrence network shown that Pin-EAC are more closely related to oxygen and temperature. This work has initially shown that the use of an electric field could improve food waste composting quality, suggesting that the Pin-EAC process is an effective strategy for high-water and high-oil organic solid waste aerobic composting.

Gasification of organic solid waste for syngas: Physicochemical and conversion mechanism investigation

The syngas of organic solid waste (OSW) obtained through gasification is of great interest in energy and fuel production owing to its clean and environmentally friendly characteristics. In this study, the physicochemical properties of typical OSW were systematically studied, and the mechanism of the influence of OSW sample structure and composition on gasification behavior was studied by thermogravimetric mass spectrometry and gasification experiments. Scanning electron microscopy was used to observe the surface morphology of the samples, showing that waste wood chips (WWC) and Pennisetum giganteum (PG) have well-developed pore structures. Fourier transform infrared spectroscopy results indicated that polyurethane foam (PF) and polyethylene terephthalate (PET) have more oxygen-containing functional groups than WWC and PG. X-Ray diffraction showed that the order of crystallinity index was WWC > PET > PF > PG. X-ray photoelectron spectroscopy results showed the order of the surface alkali content was PG > PF > WWC. Furthermore, thermogravimetric and mass spectrometry experiments were used to explore the components released from volatiles during heating, demonstrating that WWC and PG produce mainly H2O, while PF and PET produce mainly CO2. Gasification experiments were carried out at different heating rates, and PET had the highest initial and final gasification temperatures. The distributed activation energy model was used to calculate the apparent activation energy, which was in the order WWC (153.7 kJ/mol) > PET (136.9 kJ/mol) > PG (81.2 kJ/mol) > PF (78.9 kJ/mol) and was consistent with the carbon ordering degree result.

ORGANIC FERTILIZER AN ALTERNATIVE TO CHEMICAL (INORGANIC) FERTILIZER FOR SUSTAINABLE SOIL PRODUCTIVITY IN THE ERA OF ECONOMIC CHALLENGES (A REVIEW)

The major constraint limiting crop yield in developing countries globally and especially in the tropical Africa is soil infertility. In order to improve the fertility of the soils for maximum food production and supplies, the use of inorganic (chemical) fertilizers was adopted and used extensively. However, the scarcity and high cost of the inorganic fertilizers in recent times due to economic and global challenges like covid 19 pandemic and wars is worrisome. Also, research has shown that the continuous use of inorganic fertilizer and total dependence on it for agricultural production have led to a decline in soil fertility, land degradation and rottening of certain crops especially tubers, hence the need for an alternative. This review work studies the need of producing organic fertilizers from various organic wastes (such as agricultural waste, sewage sludge, animal waste, municipal solid waste, food waste, etc) as alternative soil amendment using the technology advancement for solid organic waste management as obtained in the developed countries. This when adopted will not only enhance and sustain soil productivity but will help to free the environment of pollution and encourage economic growth. The work also provides insight to the production line of the organic fertilizer, sources or raw materials and advantages of substituting chemical (inorganic) fertilizer with organic fertilizer. It is obvious that organic fertilizer when produced will be affordable, available, cheaper and will improve and sustain the physical, chemical and biological conditions of the soils.

Identify the potential driving mechanism of reconstructed bacterial community in reduce CO2 emissions and promote humus formation during cow manure composting

The mineralization of organic components releases CO2 during composting, which not only leads to the loss of organic carbon, but has a direct negative impact on the environment. Malonic acid as a competitive inhibitor of succinate dehydrogenase could affect the tricarboxylic acid (TCA) cycle and reduce CO2 emissions. However, the bacterial interaction and organic component transformation has less known how to malonic acid reduce CO2 and improve of humus synthesis in complex composting. The aim of this study was to investigated the malonic acid on organic carbon sequestration and transforming cow manure waste into products with high humus content. Humus content was elevated by 16.8% and cumulative CO2 emissions (30 d)d reduced by 13.6% after malonic acid addition compared to the CK. SparCC analysis of bacterial interaction presented that the network complexity and stability was more higher with malonic acid addition, while a greater concentration of keystones and their ecological metabolic functions was observed, suggesting they weaken the influence of TCA cycle inhibition by enhancing interactions. PICRUSt predictions indicate that malonic acid might enhance humus content by promoting the synthesis of polyphenols and polymerization with amino acids. This study investigated the potential mechanism of regulators to enhance quality and reduce emissions during humification process, providing a new strategy for the resource utilization of organic solid waste.

Simultaneous enhancement on lignocellulose degradation and humic acid formation using the electric field coupled with an iron anode in the co-composting of food waste and agricultural waste

The co-composting of food waste and agricultural waste presents a promising biotechnology for mitigating the challenges of organic solid waste treatment. However, the low degradation rate of lignocellulosic content hindered its application. This study explored a novel approach that employs an electric field coupled with an Fe anode to accelerate crude fiber decomposition and humic acid formation in a composting system. The results demonstrated that the group subjected to direct current exposure matched Fe anode (EF) exhibited the lowest crude fiber content, supported by observed loose cellulose structures using a confocal laser scanning microscope. The humic acid content in EF was also superior, exceeding both the control group without direct current exposure (CK) and with direct current exposure matched carbon anode (EA) by 72.5% and 29.3%, respectively. Two-dimensional FTIR correlation spectroscopy analysis revealed that this technology leveraged the intermediate products of lignocellulose degradation to provide a stable core structure for humic acid formation, promoting the highest humification degree. Microbial community analysis indicated that the enriched dominant phylum Firmicutes in EF was responsible for crude fiber degradation. Metagenomics analysis further suggested that the upregulations of carbohydrate-active enzymes with the signal peptide and reactive oxygen species formation triggered by microorganisms contributed to the crude fiber decomposition. This study demonstrates an efficient technology for improving composting quality.

A Review on Advanced Processes of Biohydrogen Generation from Lignocellulosic Biomass with Special Emphasis on Thermochemical Conversion

The utilization of lignocellulosic biomass as an alternative energy source presents a promising opportunity to achieve a future energy system that is clean and free from CO2 emissions. To realize this potential, it is crucial to develop effective techniques for converting biomass and organic solid waste into secondary energy sources. Among the available options, hydrogen production stands out due to its numerous advantages, including its cleanliness, versatility in conversion and utilization technologies, high energy efficiency, and dense energy content per unit weight. This article offers a comprehensive overview of different conversion pathways and important technologies for generating hydrogen from biomass and organic solid waste. It specifically focuses on the thermochemical conversion process, which shows promise as an economically viable approach. While certain thermochemical conversion processes are still in the developmental phase, utilizing organic biomass for hydrogen production is widely recommended due to its ability to yield higher amounts of end products and its compatibility with existing facilities. However, it should be noted that this method necessitates a substantial amount of energy due to its endothermic nature. This article also explores alternative hydrogen conversion technologies and their potential for utilizing organic biomass as a feedstock, while addressing the challenges and limitations associated with these methods.

Conversion of organic solid waste into energy and functional materials using biochar catalyst: Bibliometric analysis, research progress, and directions

Much effort has been made to use biochar to catalyze organic solid waste conversion into value-added products. Biochar has a high specific surface area and abundant functional groups, making it a promising catalyst, but biochar is not used in industrial-scale applications. Presented here is a systematic literature review and bibliometric analysis of biochar-catalyzed solid waste research between 2000 and 2023 focused on the mechanisms involved in and factors affecting biochar catalytic performance during biomass and organic polymer conversion. In situ catalysis allows flexible and simple processes giving specific products but gives relatively poor conversion efficiencies. Catalytic conversion of organic solid waste by biochar has been a focus of research since 2006. A discussion of biochar catalysis applications, computational approaches, and sustainability is presented. The review indicates recent progress using biochars as catalysts for converting waste into valuable products and provides valuable insights that will advance environmental and waste management practices.

Agro-waste Mediated Biosynthesis of Zinc Oxide Nanoparticles and their Antibacterial Properties: Waste to Treat

Background: Biogenic fabrication of metal oxide nanoparticles has been gaining interest over conventional methods. Biological methods make use of plant materials and microbial agents as reducing as well as capping agents. The present work reports the biosynthesis of ZnO NPs from agricultural wastes produced in every household. Objective: A significant portion of municipal solid organic waste (MSOW) consists of agricultural waste. Utilization of this agricultural waste towards cleaning water of pathogens through the synthesis of nanoparticles has far-reaching implications, such as curbing soil pollution and water pollution. Method: Preliminary confirmation was done by the visual formation of a pale yellow/dirty white precipitate of ZnO NPs. These were further characterized by different spectroscopic techniques, such as FT-IR, SEM, EDAX, and HRTEM. Results: The HRTEM study revealed that NPs obtained had sizes between 30-52 nm. Fabricated ZnO NPs were analyzed for their antibacterial activity by disk diffusion method, and they exhibited striking antibacterial activity against E. coli and bacillus subtilis. Conclusion: Exploring the potential of waste and its conversion into a value-added product is a novel step. ZnO nanoparticles were successfully synthesized from agricultural wastes through an environmentally friendly synthetic route, and the synthesized ZnO NPs were found to be potent in inhibiting the growth of bacteria.

Anaerobic Digestion of Olive Mill Wastewater and Process Derivatives—Biomethane Potential, Operation of a Continuous Fixed Bed Digester, and Germination Index

Olive mill wastewater (OMW) management is an economic and environmental challenge for olive oil-producing countries. The recovery of components with high added value, such as antioxidants, is a highly researched approach that could help refinance performant wastewater treatment systems. Anaerobic (co-)digestion is a suitable process to valorize the energetic and nutritional content of OMW and OMW-derived waste streams from resource recovery processes. Issues of process stability, operation, and yields discourage industrial application. Deepening the understanding of biomethane potential, continuous anaerobic digester operational parameters, and co-substrates is key to large-scale implementation. The biomethane potential of different OMW-derived samples and organic solid market waste as co-substrate was 106–350 NL methane per kg volatile solids (VS). The highest yields were obtained with the co-substrate and depolyphenolized OMW mixed with retentate from an ultrafiltration pretreatment. Over 150 days, an anaerobic fixed-bed 300 L digester was operated with different OMW-derived substrates, including OMW with selectively reduced polyphenol concentrations. Different combinations of organic loading rate and hydraulic retention time were set. The biogas yields ranged from 0.97 to 0.99 L of biogas per g of volatile solids (VS) eliminated, with an average methane content in the produced biogas of 64%. Potential inhibition of the process due to high polyphenol concentrations or over-acidification through volatile fatty acids was avoided in the continuous process through process and substrate manipulation. High concentrations of potassium and low concentrations of nitrogen and phosphate end up in the digestate. Sulfate reduction results in high H2S concentrations in the biogas. The digestate was tested for phytotoxic properties via the germination index. Diluted digestate samples improved germination by up to 50%.

Exploring the nitrogen fixing strategy of bacterial communities in nitrogen cycling by adding calcium superphosphate at various periods during composting

Chicken manure, as an organic solid waste with a high nitrogen content, generates large amounts of ammonia during composting, which leads to pollution of the surrounding environment, and causes a reduction in the quality of the compost product. Nitrogen is transformed through the nitrogen cycle and bacterial communities are the main contributors to the transformation of the nitrogen cycle. The microbial composition changes dramatically at different stages during composting. Therefore, calcium superphosphate (SSP) was added to compost as a nitrogen-fixing agent to elucidate the strategy and function of the bacterial community involved in the nitrogen cycle. The results showed that the addition of SSP at the initial, high temperature and cooling stages increased the inorganic nitrogen (NH4+-N, NO3−-N) content by 51.99 %, 202.72 % and 173.37 % compared to CK, respectively. In addition, nitrogen cycle functional genes (gdh, nifH, pmoA-amoA, hao, nxrA, nirK, napA, nosZ, narG) abundance were determined by real-time qPCR. The nitrogen cycle genetic results showed that SSP addition at high temperature phase resulted in a 62.43 % down-regulation of ammonification genes, while nitrogen fixation and nitrification genes were enhanced. Random forests revealed a shift in the participation strategy of bacterial communities (e.g., Mycobacterium, Izemoplasmatales, Paracoccus, Ruminococcus) within the nitrogen cycle, leading to altered importance rankings despite involvement in different nitrogen cycle pathways. Moreover, Regression analysis and structural equation modelling revealed that SSP addition at high temperature stage stimulated the bacterial community engaged in nitrogen fixation and nitrification, resulting in increased nitrogen accumulation as NO3−-N during composting. This paper offers the potential to yield novel scientific insights into the impact of microbially mediated nitrogen transformation processes and reduce gaseous pollution.

Advancing sustainability in China's pulp and paper industry requires coordinated raw material supply and waste paper management

As the largest global producer and consumer of pulp and paper, China faces significant sustainability challenges in fiber supply and waste paper management. A comprehensive material flow analysis of China's pulp and paper industry (CPPI) is needed to understand the interaction between raw material supply and waste paper management. Here, we construct a closed-loop material flow analysis model for CPPI, examine the evolution patterns of material metabolism from 1990 to 2019, and explore the demand for paper production, waste paper recycling, and virgin fiber supply in 2030 and 2050 under multiple scenarios considering critical factors. Results show that the industry has undergone rapid expansion, increased material use efficiency, and a shift towards recycled pulp from 1990 to 2019. China's paper demand will grow to 186 Mt in the next 30 years, resulting in a significant increase in both demand for fibers (173 Mt) and the generation of waste paper (138 Mt). To ensure a sustainable fiber supply for CPPI, domestic waste paper recycling needs to be prioritized. However, attention should also be paid to the availability of virgin pulp supply and proper disposal of organic solid waste. Proper management of these factors is crucial for achieving a circular economy in the industry and reducing its environmental impact. The findings highlight the importance of addressing both raw material supply and waste paper management for CPPI's sustainable development.

Seawater as supplemental moisture: The effect of Co-hydrothermal carbonization products obtained from chicken manure and cornstalk

The use of seawater as a substitute for pure water as supplemental moisture raises questions about its effect on the physicochemical properties of hydrochar. Therefore, this study aimed to investigate the feasibility of using seawater as supplemental moisture by comparing the physicochemical properties of products obtained through Co-hydrothermal carbonization of chicken manure and cornstalk under seawater and deionized water conditions. By varying the HTC temperature and blending ratios of CM and CS to investigate comprehensively the effect of seawater. Results indicated that the hydrochar yield experienced a variation from 54.54% to 57.40%, while the IC value changed from 7.69% to 8.46% as the ratio of CM:CS shifted from 3:1 to 1:3 under seawater conditions. The higher heating value of the hydrochars obtained under seawater conditions was lower than those obtained under deionized water conditions. This suggests that seawater conditions promote the hydrolysis reaction of organic solid waste. Furthermore, it was observed that when no lignin hydrolysis reaction occurred, seawater conditions had no discernible effect on the fuel quality of the hydrochar. However, at an HTC temperature of 250 °C, the fuel quality of the hydrochar obtained under seawater conditions was notably inferior to that of the hydrochar obtained under deionized water. Thus, an HTC temperature lower than 250 °C is necessary for the hydrothermal carbonization of organic solid waste under seawater conditions. Moreover, the relative content of surface -C-(C, H)/CC of the hydrochar obtained under seawater conditions was lower than that obtained under deionized water conditions, indicating that the hydrochar had a low degree of aromatization. Additionally, there was a significant increase in the immobilized Mg atoms in the hydrochar under seawater conditions, which affected the hydrochar yield and higher heating value of the hydrochar. This research presents a theoretical foundation for preparing solid fuels and materials using hydrothermal carbonization of saltwater as supplemental moisture.

Estimation of biogas generation rate and carbon sequestration potential from two landfill sites in southern India.

Anaerobic digestion of organic solid waste is one of the mechanisms for sustainable development since it permits both the energy-efficient disposal of solid waste and the use of biogas. As a result, this study provides an assessment of the potential energy and emissions saved by using biogas energy generated from the biodegradation of solid waste. For present study two major cities are selected in south India namely Madurai, Tamil Nādu and Hyderabad, Telangana. The LandGEM 3.03 model is used to estimate the concentration of total landfill gases. The landfill in Madurai produced 2.162 × 106 cu. m per year of methane emissions in the year 2013. The production of biogas has increased over time would continue to increase until 2045, when a production rate of 6.32 × 107 cu. m per year was recorded as the largest concentration of biogas ever generated. For the Hyderabad landfill, methane concentrations during the year 2013 was recorded to be 2.5 × 107 cu. m per year and reached a peak in 2046 with a concentration of 3.7 × 108 cu. m per year, was found to have a potential to generate 2.1 × 106 kWh per year. For the Madurai dump site, the energy potential increases gradually and reaches a peak during the year 2047 with a value of 4.54 × 107 kWh per year. Whereas for Hyderabad dump site was found to have an energy equivalent of 2.1 × 108 kWh per year during 2024 and reaches a peak during 2046 with an energy equivalent of 5.1 × 108 kWh per year.

Removal of hazardous textile dye from simulated wastewater by municipal organic solid waste charcoal using machine learning approaches: Kinetics, isotherm, and thermodynamics

This study focuses on the probable use of municipal organic solid waste charcoal (MOSWC) as an adsorbent for Methyl orange (MO) adsorption. The prepared MOSWC is characterized by FE-SEM and FT-IR. Batch adsorption experiments were conducted with the influencing of different operational conditions namely time of contact (1–180 min), adsorbate concentration (60–140 mg/L), adsorbent dose (1–5 g/L), pH (3–11), and temperature (25–60 °C). The high coefficient value (R2 = 0.96) of the process optimization model suggests that this model was significant, where pH and adsorbent dose expressively stimulus adsorption efficiency including 40.11 mg/g at pH (3), MO concentration (100 mg/L), and MOSWC dose (1 g/L). Furthermore, the machine learning approaches (ANN and BB-RSM) revealed a good association between the tested and projected values. The highest monolayer adsorption capacity of MO was 90.909 mg/g. Pseudo-second-order was the well-suited kinetics, where Langmuir isotherm could explain better for equilibrium adsorption data. Thermodynamic study shows MO adsorption is favourable, exothermic, and spontaneous. Finally, this study indicates that MOSWC could be a potential candidate for the adsorption of MO from wastewater.

Dynamics of antibiotic resistance genes and bacterial community during pig manure, kitchen waste, and sewage sludge composting

Organic solid wastes (OSWs) are important reservoirs for antibiotic resistance genes (ARGs). Aerobic composting transforms OSWs into fertilizers. In this study, we investigated ARGs dynamics and their driving mechanisms in three OSW composts: pig manure (PM), kitchen waste (KC), and sewage sludge (SG). The dominant ARGs were different in each OSW, namely tetracycline, aminoglycoside, and macrolide resistance (PM); tetracyclines and aminoglycosides (KC); and sulfonamides (SG). ARGs abundance decreased in PM (71%) but increased in KC (5.9-fold) and SG (1.3-fold). Interestingly, the ARGs abundance was generally similar in all final composts, which was contributed to the similar bacterial community in final composts. In particular, sulfonamide and β-lactam resistant genes removed (100%) in PM, while sulfonamide in KC (38-fold) and tetracycline in SG (5-fold) increased the most. Additionally, ARGs abundance rebounded during the maturation period in all treatments. Firmicutes, Proteobacteria, and Actinobacteria were the main ARGs hosts. Several persistent and high-risk genes included tetW, aadA, aadE, tetX, strB, tetA, mefA, intl1, and intl2. The structural equation models showed ARGs removal was mainly affected by physicochemical parameters and bacterial communities in PM, the ARGs enrichment in KC composting correlated with increased mobile genetic elements (MGEs). In general, thermophilic aerobic composting can inhibit the vertical gene transfer (VGT) of pig manure and horizontal gene transfer (HGT) of sludge, but it increases the HGT of kitchen waste, resulting in a dramatic increase of ARGs in KC compost. More attention should be paid to the ARGs risk of kitchen waste composting.

Innovative production of value-added products using agro-industrial wastes via solid-state fermentation.

The prevalence of organic solid waste worldwide has turned into a problem that requires comprehensive treatment on all fronts. The amount of agricultural waste generated by agro-based industries has more than triplet. It not only pollutes the environment but also wastes a lot of beneficial biomass resources. These wastes may be utilized as a different option/source for the manufacturing of many goods, including biogas, biofertilizers, biofuel, mushrooms and tempeh as the primary ingredients in numerous industries. Utilizing agro-industrial wastes as good raw materials may provide cost reduction and lower environmental pollution levels. Agro-industrial wastes are converted into biofuels, enzymes, vitamin supplements, antioxidants, livestock feed, antibiotics, biofertilizers and other compounds via solid-state fermentation (SSF). By definition, SSF is a method used when there is little to no free water available. As a result, it permits the use of solid materials as biotransformation substrates. Through SSF methods, a variety of microorganisms are employed to produce these worthwhile things. SSFs are therefore reviewed and discussed along with their impact on the production of value-added items. This review will provide thorough essential details information on recycling and the use of agricultural waste.