Organic Solid Waste Research Articles

Exogenous additive ferric sulfate regulates sulfur-oxidizing bacteria in cow manure composting to promote carbon fixation.

Enhancing carbon fixation in the composting process was of great significance in the era of massive generation of organic solid waste. In this study, the experimental results showed that the contents of dissolved organic matter (DOM) in the experimental group (CT) were 37.58% higher than those in the control group (CK). The CO2 emission peaked on day 5, and the value of CK was 1.34 times that of CT. Significant differences were observed between the contents of sulfur fractions in CT and CK. This phenomenon may be due to the suppression of sulfur-reducing gene expression in CT. On day 51 of composting, the abundance of sulfur-oxidizing bacteria (SOB) Rhodobacter (5.33%), Rhodovulum (14.76%), and Thioclava (23.83%) in CT was higher than that in CK. In summary, the composting fermentation regulated by Fe2(SO4)3 increased the sulfate content, enhanced the expression of sulfur-oxidizing genes and SOB, and ultimately promoted carbon sequestration during composting.

Forecasting the Mitigation Potential of Greenhouse Gas Emissions in Shenzhen through Municipal Solid Waste Treatment: A Combined Weight Forecasting Model

As a significant source of anthropogenic greenhouse gas emissions, the municipal solid waste sector’s greenhouse gas emission mode remains unknown, hampering effective decision-making on possible greenhouse gas emission reductions. Rapid urbanization and economic growth have resulted in massive volumes of municipal solid trash. As a result, identifying emission reduction routes for municipal solid waste treatment is critical. In this research, we investigate the potential of municipal solid waste treatment methods in lowering greenhouse gas (GHG) emissions in Shenzhen, a typical Chinese major city. The results showed that the combined treatment of 58% incineration, 2% landfill, and 40% anaerobic digestion (AD) had the lowest greenhouse gas emissions of about 5.91 million tons under all scenarios. The implementation of waste sorting and anaerobic digestion treatment of organic municipal solid waste after separate collection can reduce greenhouse gas emissions by simply increasing the incineration ratio.

Advancements in Bioelectrochemical Systems for Solid Organic Waste Valorization: A Comprehensive Review

Advancements in Bioelectrochemical Systems for Solid Organic Waste Valorization: A Comprehensive Review

Anaerobic co-digestion of municipal mixed sludge and mango peel biowaste: Performance and stability analysis for different ratios

In an urban context, municipal mixed sludge (MMS) and fruit and vegetable waste (FVW) are becoming the major organic solid wastes in human society. Thus, anaerobic digestion as a low carbon energy strategy to minimize their environmental polluting risk was studied. To overcome the drawbacks of anaerobic digestion of MMS, an alternative approach is proposed, involving the addition of increasing proportions of mango peel pulp (MPP) as a co-substrate. Different ratios of MMS:MPP (v:v) were studied: 80:20 (T1), 70:30 (T2), 60:40 (T3). The increase in the organic loading rate was well incorporated by the reactor's biomass activity, and it had no negative effects on the reactor stability and performance operational parameters. Results indicated that the addition of MPP had a beneficial effect on specific methane production, where the highest value was registered in T2 (0.47 L CH4/g VS added), with a 1.8-fold increase in this operational parameter. Moreover, bioenergy recovery within the same trial followed the same profile, representing a two-fold increment.

Bioconversion Progresses of Organic Solid Waste

With the increasing shortage of global resources and energy, the green recycling and utilization of organic solid waste have become global research hotspots. As representatives of green and clean technologies, the application of bioconversion in organic solid waste has achieved remarkable progress. In this article, the research progress on the major biotechnologies utilized in organic solid waste in recent years is summarized, including landfilling, composting, anaerobic digestion, and anaerobic fermentation. Then, the achievements of bioconversion in the reduction, harmlessness, and resource utilization of different kinds of organic solid waste, such as agricultural and forestry solid organic waste, food waste, and activated sludge, are discussed. Finally, the article provides suggestions for the future development of organic solid waste.

Lactic acid production from different sources of organic solid waste: evaluation of the inoculum type and operational optimization

AbstractThis work aimed to evaluate the effect of the sources of organic solid waste on lactic acid (HLa) production. Organic fractions from cafeteria (CW), market (MW), and recycling plant (RW) wastes were used as substrates. HLa production during the self-fermentation of CW, MW, and RW, as well as during the fermentation of each substrate with anaerobic sludge (CW + sludge, MW + sludge, and RW + sludge), was evaluated in batch tests at 37 °C, initial pH of 6.5, and 150 rpm. Subsequently, the initial pH and substrate concentration of self-fermentation of CW were optimized using a central composite design. The highest HLa production was observed in the self-fermentation of CW, where several Lactobacillus species predominated in the microbial community. The higher value of HLa production using CW (20.7 g/L) was obtained at a pH of 7.29 and 115.5 gVS/L. In the optimization tests, Lactobacillus and Weissella spp. were identified as the dominant lactic acid bacteria; however, only Lactobacillus species were associated with the highest HLa production.

Study of environmental risk levels due to organic solid waste on the Andrés Avelino Cáceres Platform in the District of José Luis Bustamante y Rivero-Arequipa

Study of environmental risk levels due to organic solid waste on the Andrés Avelino Cáceres Platform in the District of José Luis Bustamante y Rivero-Arequipa

Biogas upgrading and membrane anti-fouling mechanisms in electrochemical anaerobic membrane bioreactor (EC-AnMBR): Focusing on spatio-temporal distribution of metabolic functionality of microorganisms

Electrochemical anaerobic membrane bioreactor (EC-AnMBR) by integrating a composite anodic membrane (CAM), represents an effective method for promoting methanogenic performance and mitigating membrane fouling. However, the development and formation of electroactive biofilm on CAM, and the spatio-temporal distribution of key functional microorganisms, especially the degradation mechanism of organic pollutants in metabolic pathways were not well documented. In this work, two AnMBR systems (EC-AnMBR and traditional AnMBR) were constructed and operated to identify the role of CAM in metabolic pathway on biogas upgrading and mitigation of membrane fouling. The methane yield of EC-AnMBR at HRT of 20 days was 217.1 ± 25.6 mL-CH4/g COD, about 32.1 % higher compared to the traditional AnMBR. The 16S rRNA analysis revealed that the EC-AnMBR significantly promoted the growth of hydrolysis bacteria (Lactobacillus and SJA-15) and methanogenic archaea (Methanosaeta and Methanobacterium). Metagenomic analysis revealed that the EC-AnMBR promotes the upregulation of functional genes involved in carbohydrate metabolism (gap and kor) and methane metabolism (mtr, mcr, and hdr), improving the degradation of soluble microbial products (SMPs)/extracellular polymeric substances (EPS) on the CAM and enhancing the methanogens activity on the cathode. Moreover, CAM biofilm exhibits heterogeneity in the degradation of organic pollutants along its vertical depth. The bacteria with high hydrolyzing ability accumulated in the upper part, driving the feedstock degradation for higher starch, sucrose and galactose metabolism. A three-dimensional mesh-like cake structure with larger pores was formed as a biofilter in the middle and lower part of CAM, where the electroactive Geobacter sulfurreducens had high capabilities to directly store and transfer electrons for the degradation of organic pollutants. This outcome will further contribute to the comprehension of the metabolic mechanisms of CAM module on membrane fouling control and organic solid waste treatment and disposal.

Kinetics analysis of cellulose chemical-looping gasification using Ca–Fe oxygen carrier

Ca–Fe oxygen carrier (OC) is an effective material with high selectivity on H2 and CO to aid to the gasification of solid fuel materials such as organic solid waste or biomass in chemical-looping gasification (CLG). However, the reaction mechanism of raw materials with high volatiles such as cellulose remains unclear. Kinetics analysis is considered as the efficient method to investigate the reaction mode and mechanism. In this study, isothermal method was conducted and the tristate intermedia products were used as substrates to reveal the kinetics characteristic of cellulose conversion process in CLG. The results demonstrated that the reduction process of Ca–Fe OC could be divided into three stages, and the activation energies were 40.40 kJ/mol, 91.28 kJ/mol and 165.33 kJ/mol, respectively; this indicates that the lattice oxygen could be transferred easily in the first stage, but much more difficult in the later two stages. The weak oxidizing molecules such as CO2 could re-oxide the reduced OC quickly and the activation energy was 27.83 kJ/mol. The mechanism model on kinetic of tar cracking was similar to the reaction between H2 and OC, and the activation energy was 82.27 kJ/mol. The decomposition of char was recognized as the stochastic nuclear shrinkage process with an activation energy of 52.22 kJ/mol.

An Investigation Comparing the Properties and Nutrients of Vermi Compost and Domestic Organic Waste Compost

Composting is a commonly used technique for repurposing organic waste. This approach has been suggested as a method to help reintegrate materials back into the production cycle. Vermicomposting is an eco- friendly technology that reduces pollution and creates high-quality compost efficiently and cost-effectively. Earthworms, known as 'ecosystem engineers,' can alter and enhance soil quality, leading to increased plant growth. Earthworms have garnered significant interest for their potential in remediating soils contaminated with Potentially Toxic Elements (PTEs), either on their own or in conjunction with other soil organisms and additives. Food waste from households is disposed of in landfills, leading to a significant loss of resources and energy, contributing to the greenhouse effect, and endangering water sources. Composting is a widely used method for managing solid organic waste and may be utilised in every household to create high-quality compost. Households contribute significantly to overall food waste and play a crucial role in tackling food waste disposal challenges. This paper focuses on producing vermicompost from cow dung and home compost from kitchen waste, analyzing their nutrient content (moisture, NPK), and conducting laboratory tests. Collection of Soil and cow dung and kitchen waste was done from local area of Kargi Road Kota, District Bilaspur (CG) (LAT 22.290674, LONG 82.021537) and vermi samples and Domestic compost samples are also prepared in Kargi road Kota, District Bilaspur (CG).The Properties of samples of vermicompost and samples of domestic compost were analyzed and examined after 7, 15, and 30 days.

Sequential extraction of hesperidin, pectin, lignin, and cellulose from orange peels: towards valorization of agro‐waste

AbstractTo maximize the reuse of citrus fruit processing waste, which is generated in large amounts due to juice production, this work shows the results of a new renewable approach for the extraction of high‐added‐value compounds present in orange biomass, specifically in orange peels (OP). The method is based on the use of diluted Ca2+, acid, and base solutions for the extraction of hesperidin (HSD), pectin, lignin, and cellulose sequentially, without generating any organic solid waste at the end, and without the need for air drying the starting biomass. Good yields of hesperidin were recovered (~1.56%), with excellent purity (up to 95%), as well as lignin (yield ~2.2%) and cellulose (yield ~12%). Pectin obtained by this process showed a high amount of galacturonic acid (~88%) and a low degree of methylation (~16%). All products were thoroughly characterized by applying Fourier transform infrared (FTIR) spectroscopy and solid‐state cross‐polarization/magic angle spinning carbon‐13 nuclear magnetic resonance spectroscopy (CP/MAS 13C‐NMR). The products recovered from OP can be applied in a wide array of fields, such as food, medicine, and pharmaceuticals, among others.

Pilot-scale membrane-covered composting of food waste: Initial moisture, mature compost addition, aeration time and rate

The impact of different operational parameters on the composting efficiency and compost quality during pilot-scale membrane-covered composting (MCC) of food waste (FW) was evaluated. Four factors were assessed in an orthogonal experiment at three different levels: initial mixture moisture (IMM, 55 %, 60 %, and 65 %), aeration time (AT, 6, 9, and 12 h/d), aeration rate (AR, 0.2, 0.4, and 0.6 m3/h) and mature compost addition ratio (MC, 2 %, 4 %, and 6 %). Results indicated that 55 % IMM, 6 h/d AT, 0.4 m3/h AR, and 4 % MC addition ratio simultaneously provided the compost with the maximum cumulative temperature and the minimum moisture. It was shown that the IMM was the driving factor of this optimum composting process. On contrary, the optimal parameters for reducing carbon and nitrogen loss were 65 % IMM, 6 h/d AT, 0.4 m3/h AR, and 2 % MC addition ratio. The AR had the most influence on reducing carbon and nitrogen losses compared to all other factors. The optimal conditions for compost maturity were 55 % IMM, 9 h/d AT, 0.2 m3/h AR, and 6 % MC addition ratio. The primary element influencing the pH and electrical conductivity values was the AR, while the germination index was influenced by IMM. Protein was the main organic matter limiting the composting efficiency. The results of this study will provide guidance for the promotion and application of food waste MCC technology, and contribute to a better understanding of the mechanisms involved in MCC for organic solid waste treatment.

Vacuum ammonia stripping from liquid digestate: Effects of pH, alkalinity, temperature, negative pressure and process optimization

High ammonia-nitrogen digestate has become a key bottleneck limiting the anaerobic digestion of organic solid waste. Vacuum ammonia stripping can simultaneously remove and recover ammonia nitrogen, which has attracted a lot of attention in recent years. To investigate the parameter effects on the efficiency and mass transfer, five combination conditions (53 °C 15 kPa, 60 °C 20 kPa, 65 °C 25 kPa, 72 °C 35 kPa, and 81 °C 50 kPa) were conducted for ammonia stripping of sludge digestate. The results showed that 80% of ammonia nitrogen was stripped in 45 min for all experimental groups, but the ammonia transfer coefficient varied under different conditions, which increased with the rising of boiling point temperature, and reached the maximum value (39.0 mm/hr) at 81 °C 50 kPa. The ammonia nitrogen removal efficiency was more than 80% for 30 min vacuum stripping after adjusting the initial pH to above 9.5, and adjustment of the initial alkalinity also affects the pH value of liquid digestate. It was found that pH and alkalinity are the key factors influencing the ammonia nitrogen dissociation and removal efficiency, while temperature and vacuum mainly affect the ammonia nitrogen mass transfer and removal velocity. In terms of the mechanism of vacuum ammonia stripping, it underwent alkalinity destruction, pH enhancement, ammonia nitrogen dissociation, and free ammonia removal. In this study, two-stage experiments of alkalinity destruction and ammonia removal were also carried out, which showed that the two-stage configuration was beneficial for ammonia removal. It provides a theoretical basis and practical technology for the vacuum ammonia stripping from liquid digestate of organic solid waste.

Greenhouse gas emission characteristics during kitchen waste composting with biochar and zeolite addition

Aerobic kitchen waste composting can contribute to greenhouse gas (GHGs) emissions and global warming. This study investigated the effects of biochar and zeolite on GHGs emissions during composting. The findings demonstrated that biochar could reduce N2O and CH4 cumulative releases by 47.7 %and 47.9 %, respectively, and zeolite could reduce the cumulative release of CO2 by 28.4 %. Meanwhile, the biochar and zeolite addition could reduce the abundance of potential core microorganisms associated with GHGs emissions. In addition, biochar and zeolite reduced N2O emissions by regulating the abundance of nitrogen conversion functional genes. Biochar and zeolite were shown to reduce the impact of bacterial communities on GHGs emissions. In summary, this study revealed that biochar and zeolite can effectively reduce GHG emissions during composting by altering the compost microenvironment and regulating microbial community structure. Such findings are valuable for facilitating high-quality resource recovery of organic solid waste.

The effect of fermentation modes on the efficiency of organic waste treatment in batch bioreactors

The amount of solid organic waste is constantly growing. This is caused by the growth of industrial and agricultural capacities, and the inefficiency of existing waste processing technologies. Biotechnologies can provide effective environmentally friendly solutions for waste treatment. Therefore, the goal of our work was to compare the efficiency of strictly anaerobic fermentation of multi-component solid organic waste with hydrogen synthesis and waste treatment with pulsed air access in batch bioreactors.During fermentation, the following parameters were controlled: pH, redox potential (Eh), concentration of dissolved organics, and the content of H2, O2, and CO2 in the gas phase. The efficiency was evaluated via the process duration, calculation of the ratio of the initial and final weight of waste (Кd), and the yield of molecular hydrogen. Obtained results revealed high efficiency of organic waste degradation in both variants. The weight of waste 83-fold and 86-fold decreased, respectively. The time required for fermentation in strictly anaerobic conditions was 4 days, whereas 7 days were required for the mode with pulsed air access. The first variant provided a 2.8-fold higher hydrogen yield (54±4,1 L/kg of waste), and the second one provided a decrease in the concentration of dissolved organic compounds in the fermentation fluid. Fermentation is the effective approach for accelerated degradation of solid organic waste. Strictly anaerobic fermentation appeared to be useful in the need to accelerate the process. The mode with the pulsed air access can provide not only degradation of solid waste but also purification of the fermentation fluid.

Adsorption of humic acid from different organic solid waste compost to phenanthrene, is fluorescence excitation or quenching?

Humic acid (HA) from different organic solid waste (OSW) compost has been shown good adsorption properties for phenanthrene. However, the raw material of HA can affect its structure, resulting in differences in adsorption capacity. Therefore, this study focused on the adsorption characteristics of phenanthrene by HA from different OSW compost. In this work, chicken manure (CM), rice straw (RS) and lawn waste (LW) were selected as sources of composted HA. The adsorption mechanism of HA from different OSW compost were revealed through analytical techniques including three-dimensional fluorescence spectroscopy (EEM), two-dimensional correlation spectroscopy (2DCOS), and Fourier-transform infrared spectroscopy (FTIR). The results suggested that HA from LW compost had a better adsorption affinity for phenanthrene because of its more complex fluorescent component, where C1 as a simple component determined the adsorption process specifically. Furthermore, after HA from LW compost adsorbed phenanthrene, the increase in aromatic –COOH and –NH was the main reason for fluorescence quenching. These results indicated that HA from LW compost had better adsorption effect for phenanthrene. The results of this study were expected to provide a selection scheme for the control of phenanthrene pollution and environmental remediation.

Gaining insight into the effect of laccase expression on humic substance formation during lignocellulosic biomass composting

The aim is to enhance lignin humification by promoting laccase activities which can promote lignin depolymerization and reaggregation during composting. 1-Hydroxybenzotriazole (HBT) is employed to conduct laccase mediator system (LMS), application of oxidized graphene (GO) in combination to strengthen LMS. Compared with control, the addition of GO, HBT, and GH (GO coupled with HBT) significantly improved laccase expression and activities (P < 0.05), with lignin humification efficiency also increased by 68.6 %, 36.7 %, and 107.8 %. GH treatment induces microbial expression of laccase by increasing the abundance and synergy of core microbes. The unsupervised learning model, vector autoregressive model and Mantel test function were combined to elucidate the mechanism of action of exogenous materials. The results showed that GO stabilized the composting environment on the one hand, and acted as a support vector to stabilize the LMS and promote the function of laccase on the other. In GH treatment, degradation of macromolecules and humification of small molecules were promoted simultaneously by activating the dual function of laccase. Additionally, it also reveals the GH enhances the humification of lignocellulosic compost by converting phenolic pollutants into aggregates. These findings provide a new way to enhance the dual function of laccase and promote lignin humification during composting. It could effectively achieve the resource utilization of organic solid waste and reduce composting pollution.

Biodrying of municipal solid waste-correlations between moisture content, organic content, and end of the biodrying process time.

Biodrying refers to the decomposition of organic municipal solid waste (MSW) under aerobic conditions. This process usually lasts 14days and requires large amounts of air to be injected into the waste matrix. The efficiency of the biodrying process depends on several geotechnical parameters, including initial moisture content, initial organic content, bulk density, dry density, solid particle density, and porosity. To examine the potential influence of these parameters on the biodrying process, we analyzed 13 biodried MSW samples. The results revealed a strong positive linear relationship between the initial moisture content and the mass loss percentage. In the first three days of the biodrying process, the waste mass rapidly decreased; afterwards, the daily mass loss occurred at a less rapid, more constant rate. The established average mass removal ratio between the volatile solids and water was 1:6.38 with a standard deviation of 1.06. Dry and solid particle densities were preserved in all 13 experiments; thus, the corresponding void ratio remained unchanged. This finding suggests that the settlement and degradation of MSW that occur during the biodrying process did not significantly influence the airflow rate.

Acceleration of the biodegradation of cationic polyacrylamide by the coupling effect of thermophilic microorganisms and high temperature in hyperthermophilic composting.

As a flocculant of sewage sludge, cationic polyacrylamide (CPAM) enters the environment with sludge and exists for a long time, posing serious threats to the environment. Due to the environmental friendliness and high efficiency in the process of organic solid waste treatment, hyperthermophilic composting (HTC) has received increasing attention. However, it is still unclear whether the HTC process can effectively remove CPAM from sludge. In this study, the effects of HTC and conventional thermophilic composting (CTC) on CPAM in sludge were compared and analyzed. At the end of HTC and CTC, the concentrations of CPAM were 278.96mgkg-1 and 533.89mgkg-1, respectively, and the removal rates were 72.17% and 46.61%, respectively. The coupling effect of thermophilic microorganisms and high temperature improved the efficiency of HTC and accelerated the biodegradation of CPAM. The diversity and composition of microbial community changed dramatically during HTC. Geobacillus, Thermobispora, Pseudomonas, Brevundimonas, and Bacillus were the dominant bacteria responsible for the high HTC efficiency. To our knowledge, this is the first study in which CPAM-containing sludge is treated using HTC. The ideal performance and the presence of key microorganisms revealed that HTC is feasible for the treatment of CPAM-containing sludge.

Migration and transformation mechanisms of Pb/Cd with HCl in organic solid waste incineration flue gas on the composite-modified kaolinite surface

Cadmium/lead (Cd/Pb) pollutants from organic solid wastes (OSW) incineration are of global concern due to high volatility and biotoxicity. The strong interaction between modified kaolinite and Cd/Pb species inspires its utilization for the elimination of heavy metals. However, the specific mechanism of the migration and transformation of Cd/Pb species is yet unclear. Consequently, the migration and transformation mechanisms of Cd/Pb species on the modified kaolinite (001) surface are examined by density functional theory (DFT), considering the effect of HCl. The outcomes show that the HCl significantly alters the characteristics of the kaolinite, which enhances the surface activity of kaolinite and promotes the adsorption and transformation of Cd/Pb species. Furthermore, the chlorination routes of Cd0/Pb0 are fully elucidated in both 2-step and 1-step routes. The first step of the 2-step route obeys the Langmuir-Hinshelwood mechanism and the second step obeys the Eley-Rideal mechanism, while the 1-step chlorination route obeys the Eley-Rideal mechanism. In addition, the oxidation route of Cd0/Pb0 follows the Mars-van Krevelen mechanism. The comparison of the energy barriers shows that the 1-step Cd0/Pb0 chlorination route has the lowest energy barrier. The kaolinite surface is found to have elevated activity for the adsorptive trapping of Cd/Pb species in the presence of HCl, which offers a preliminary theoretical framework for pollutant control on the modified kaolinite surface.