Biodegradation Of Municipal Solid Waste Research Articles

Unified assessment of mass loss behaviors in soluble, biodegradable, and internally erodible geomaterials

Dissolution of soluble soil, biodegradation of municipal solid waste (MSW), and internal erosion of gap-graded soil are typical mass loss processes of geomaterials, which result in various engineering problems. These three processes are conceptually analogous and examined by a unified assessment of their behaviors considering the initial properties of geomaterials and testing conditions. This study collected additional data from twelve soil dissolution tests and five long-term MSW biodegradation tests. We then established a comprehensive mass loss behavior dataset based on the available studies and the supplementary data obtained from this study. In addition to the flow-reactive fraction, two initial volumetric properties are also critical, which are void ratio before mass loss (esolid,0) and inert-to-reactive size ratio. A characteristic parameter (Λ), describing the ratio between the change in voids volume and the change in flow-reactive solids volume, is correlated with the strain and change in esolid. The volumetric and structural changes of all the flow-reactive geomaterials are categorized into Λ = -1 for pseudo-stable, -1 ≤ Λ < 0 for collapsible, 0 ≤ Λ <esolid,0 for hyper-collapsible, and Λ ≥ esolid,0 for readily densified. A three-dimensional plot constructed by the three critical initial properties is divided into eight zones based on the different Λ values, which correspond to distinct mass loss behaviors. The a priori Λ estimation and corresponding zonation for a wide variety of flow-reactive geomaterials is shown to be beneficial for research and practice.

Formulation of Novel Microbial Consortia for Rapid Composting of Biodegradable Municipal Solid Waste: An Approach in the Circular Economy

Urbanization and rapid industrialization have led to the escalation of municipal solid waste generation and accumulation. Composting is widely recognized as a sustainable solution for solid waste management. However, its long-term investment is considered a disadvantage. The present research study discusses the rapid biotransformation of solid waste into valorized compost. Bacteria were isolated from soil, solid waste, and leachate samples from open dump sites. From the 18 different bacterial consortia created using potential isolates, the five most promising consortia were selected based on concurrent different enzyme production. These selected consortia were incorporated into typical compost bins with Municipal Solid Waste (MSW). Daily monitoring of enzymatic activity, pH, conductivity, bulk density, moisture, and temperature, along with other composting parameters, was conducted. The study’s results demonstrated that consortium No. 5, comprising Bacillus haynesii, Bacillus amyloliquefaciens, and Bacillus safensis, exhibited significant (p&lt;0.05) enzyme activity of cellulase, amylase, lipase and proteinase enzymes during composting compared to the control and other treatment setups. Consortium No. 5 also facilitated rapid and successful composting, as evidenced by significant alterations of composting parameters by exhibiting a shorter average composting time, reducing it from 110±10 days to 20±3 days, showcasing the potential applicability of formulated bacterial consortium as a sustainable and greener approach to the global solid waste problem. The novelty of this study lies in the isolation of local bacterial strains from open dump sites soil, MSW, and MSW leachate samples, which were then utilized in the composting organic fraction of MSW, enhancing the potential for effective waste management.

Geothermal gradients in a high-organic content landfill

Geothermal gradients in a high-organic content landfill

Towards Sustainable Composting of Source-Separated Biodegradable Municipal Solid Waste—Insights from Long An Province, Vietnam

Inadequate municipal solid waste (MSW) management has become a pressing concern, resulting in significant environmental contamination, particularly in developing countries. Composting has demonstrated its practicality and feasibility for addressing this issue; however, the lack of at-source solid waste separation remains a major challenge. As a result, in this study, the first sustainable MSW separation at source was conducted in Tan An City, Long An Province. The objective of this study was to evaluate the compost process and quality using Tan An City’s separated biodegradable organic solid waste as the raw material, through a windrow composting process with active aeration. Biodegradable organic waste, slow-biodegradable organic waste and plastic waste accounted for 84.5%, 15.1% and 0.4%, respectively, of the total waste. The pH, moisture, volatile solid percentage, total nitrogen, total organic carbon and carbon-to-nitrogen ratio of the separated solid waste were 8.7 ± 0.4, 76.8 ± 1.9%, 68.3 ± 1.3%, 2.1 ± 0.1%, 35.7 ± 2.2% and 17 ± 0.8, respectively. Rice straw was mixed with solid waste as a bulking material in a 31%:69% ratio to achieve a moisture content of 55% in the mixture. After 10 weeks, an evaluation of the compost’s quality revealed its potential suitability for agricultural applications. Notably, Salmonella was not detected in the compost, and the heavy metal levels were below standard limits, indicating the safety of the compost. To ensure optimal nutrient levels for effective plant growth, a slight nitrogen and phosphorus supplement was recommended. Aligned with the C/N ratio of 12.1 and a consistent temperature of approximately 29 °C, this indicates a high degree of maturity and stability in the composting process. The framework of this study demonstrates the effectiveness of at-source MSW separation in paving a sustainable path for MSW management.

Application of an Integrated Granular and Suspended Sludge Methane Reactor for a Two-Stage Anaerobic Digestion System to Deal with Biodegradable Municipal Solid Waste

This study aims to investigate the performance of a two-stage anaerobic digestion system using a hybrid methane reactor to deal with biodegradable municipal solid waste. The reactor allowed both suspended sludge and granular sludge to work together. The feedstock was fermented in one continuous stirred tank at different pH conditions for 5 d. Furthermore, the liquid hydrolysate was diluted and pumped into a methane reactor with different organic loading rates. In the fermentative reactor, raising the pH condition from 4.5 to 6.5 caused a sharp increase in volatile fatty acids concentration, mainly due to the increase in acetate and propionate. The efficiency of the methane reactor was proven by the results of hydrodynamic analysis and biogas production. The relationship between biogas production and operating parameters in this reactor was modeled using a quadratic multivariate regression model. Overall, by maintaining the fermentative reactor at a pH of 6.0–6.5, the methane reactor was able to achieve an organic loading rate of 7.6 g-TS.L−1·d−1 with outstanding biogas quality and yield. In terms of microbiology, the most dominant phyla in the reactor included Firmicutes, Bacteroidetes, Proteobacteria, Euryarchaeota, Synergistetes, and Chloroflexi. Among them, the species with the highest relative abundance in granular sludge was Firmicutes, while that in suspended sludge was Bacteroidetes.

Tailoring the compost matrix with hybrid Bacillus commune to improve the biodegradation of municipal solid waste

Tailoring the compost matrix with hybrid Bacillus commune to improve the biodegradation of municipal solid waste

Consolidated bioprocessing of biodegradable municipal solid waste for transformation into biofertilizer formulations

Consolidated bioprocessing of biodegradable municipal solid waste for transformation into biofertilizer formulations

Methane production generated by the biodegradation of Municipal Solid Waste confined in lysimeters under a tropical climate

Methane production generated by the biodegradation of Municipal Solid Waste confined in lysimeters under a tropical climate

An approach for quantifying the benefits of treating biodegradable municipal solid waste: a case-study from the city of Jambi, Indonesia

An approach for quantifying the benefits of treating biodegradable municipal solid waste: a case-study from the city of Jambi, Indonesia

Quantitative Carbon Changes of Selected Organic Fractions during the Aerobic Biological Recycling of Biodegradable Municipal Solid Waste (MSW) as a Potential Soil Environment Improving Amendment—A Case Study

The aim of the investigation was to determine the quantitative changes of selected organic compounds during composting of municipal solid wastes (MSWs). The object of the study was a differently matured compost produced according the to open pile/windrow semi-dynamic technology from selectively collected biodegradable municipal solid waste. During the experiment, the temperature and moisture of the composted wastes were monitored. In the collected samples—taken from differently matured compost—the total organic carbon (TOC) and total nitrogen (TN) were determined. The organic matter fractionation method described by Stevenson and Adani et al. was adopted, which allows to determine the carbon content of the following groups of organic compounds: hydrophobic (HSC), hydrophilic (WEOC), acidophilic (CAC), cellulose (CCEL), core-HA (ligno-humic, CALK) and residual carbon (non-hydrolysing, CR). The TOC and TN content, as well as the origin and quality of the starting materials, allow the product tested to be classified for fertiliser purposes. The most intense changes were observed during the thermophilic composting phase. In spite of the optimal technological conditions of the process, the predominance of the CR and CCEL fraction was observed, and the share of humic compounds did not exceed 30% TOC. The investigated compost met legal, ecological and economic criteria for products of biological recycling, thus can be used as a good organic amendment to improve the soil organic matter balance, stimulate the soil biodiversity and carbon sequestration.

Statistical optimization of pretreatment of municipal solid waste by response surface methodology for fermentable sugar production

AbstractThis research aims to use low‐cost and easily available chemicals for chemical pretreatment to achieve a high yield of fermentable sugars using biodegradable municipal solid waste as a substrate. Biodegradable municipal solid waste was pretreated with locally available toilet cleaner (acidic in nature) and washing detergent (basic in nature) and to achieve maximum yield of reducing sugars, two variables; chemical concentration and time were selected for optimization using a central composite design. In Central composite design 13 runs for toilet cleaner (acidic in nature) and washing detergent (basic in nature) pretreatment models were created while ranges for two variables were selected as 1, 2, 3 days for time and 1%, 3%, 5% for chemical concentration. In the toilet cleaner (acidic in nature) pretreatment, optimum conditions were 5% (vol/vol) of toilet cleaner (acidic in nature) for 3 days. At optimal conditions, the model for toilet cleaner (acidic in nature) pretreatment released 167.755 g/L of reducing sugars and 2.684 MJ/L energy while the model for washing detergent (basic in nature) pretreatment released 159.141 g/L of reducing sugars and 2.546 MJ/L energy. An enzyme cocktail hydrolyzed the toilet cleaner (acidic in nature) pretreated sample, and the highest value of fermentable sugar was achieved at 36 h of 237.83 ± 11.028 g/L. Thus, the chemical pretreatment using toilet cleaner and washing detergent has a great potential for fermentable sugar production and effectively be used in industrial and household digesters for the conversion of waste into useful products.

Co-Treatment of Landfill Leachate and Liquid Fractions of Anaerobic Digestate in an Industrial-Scale Membrane Bioreactor System

The management of the liquid fraction of digestate produced from the anaerobic digestion of biodegradable municipal solid waste is a difficult affair, as its land application is limited due to high ammonium concentrations and the municipal waste that water treatment plants struggle to treat due to high pollutant loads. The amount of leachate and the pollutant load in the leachate produced by landfills usually decreases with the time, which increases the capacity of landfill leachate treatment plants (LLTPs) to treat additional wastewater. In order to solve the above two challenges, the co-treatment of landfill leachate and the liquid fraction of anaerobic digestate in an industrial-scale LLTP was investigated along with the long-term impacts of the liquid fraction of anaerobic digestate on biocoenosis and its impact on LLTP operational expenses. The co-treatment of landfill leachate and liquid fraction of anaerobic digestate was compared to conventional leachate treatment in an industrial-scale LLTP, which included the use of two parallel lanes (Lane-1 and Lane-2). The average nitrogen removal efficiencies in Lane-1 (co-treatment) were 93.4%, 95%, and 92%, respectively, for C/N ratios of 8.7, 8.9, and 9.4. The average nitrogen removal efficiency in Lane-2 (conventional landfill leachate treatment), meanwhile, was 88%, with a C/N ratio of 6.5. The LLTP’s average chemical oxygen demand (COD) removal efficiencies were 63.5%, 81%, and 78% during phases one, two, and three, respectively. As the volume ratios of the liquid fraction of anaerobic digestate increased, selective oxygen uptake rate experiments demonstrated the dominance of heterotrophic bacteria over ammonium and nitrite-oxidising organisms. The inclusion of the liquid fraction of anaerobic digestate during co-treatment did not cause a significant increase in operational resources, i.e., oxygen, the external carbon source, activated carbon, and energy.

Analysis and Evaluation of a Three-Stage Anaerobic Digestion Plant for Management of Biodegradable Municipal Solid Waste

Sub-Sahara Africa countries are faced with the problem of solid waste management and access to sustainable energy. There is a need to develop a technology that can help to manage the generated solid waste and the same time produce green energy that is sustainable. Hence, this research work that focused on the development of a novel three-stage anaerobic digestion (AD) plant for management of biodegradable portion of municipal solid waste. An experimental design and preliminary tests using co-digestion of municipal solid waste was conducted with the operation and process parameters utilized in this research work. Conceptual design was generated based on results of experimental design. The developed AD plant was evaluated for performance and the results obtained compared to an existing single stage fixed dome AD pilot plant using 100 kg of substrates with an organic loading rate of 3 kg/m3day for an operating time of 163 days. The cumulative biogas yield, and behaviour of the operation and process parameters utilized in this research work were evaluated. The results obtained reveal that unlike the single stage fixed dome AD pilot plant, the three-stage AD plant enables continuous production of biogas. Besides, optimum conditions of neutral pH range of 6.99 m to 7.01 m, slurry mesophilic temperature range of 37.05 °C to 37.15 °C, and organic loading rate of 3kg/m3d that favoured optimum biogas yield were established.

Coupled bio-hydro-thermo-mechanical interactions of landfilled MSW based on a multi-phase, multi-component numerical model

A clear understanding of long-term bio-hydro-thermo-mechanical (BHTM) behaviors of landfilled Municipal Solid Waste (MSW) is essential to better design and manage landfills, which requires the development of both analytical and numerical models that can represent typical behaviors of MSW. In this study, a novel multi-phase, multi-component numerical model, which incorporated the diffusion of landfill gas components, changes in the pH of leachate, and its solute migration as well as phase changes, was presented and adopted to investigate long-term coupled behaviors of MSW and the spatial and temporal variations of MSW properties. The numerical simulations were conducted on a typical landfill column and a landfill slope with relatively clear initial and boundary conditions to explore the coupled BHTM interactions of landfilled MSW. Based on the simulation results, the coupled mechanisms of MSW biodegradation, leachate and gas flows, MSW deformation, and heat transfer were revealed, and some significant insights on qualities of both leachate and landfill gas were also given. It has been found that the coupled model associated with its numerical code successfully predicted the long-term behaviors of landfilled MSW and qualities of leachate and landfill gas.

Kinetics of MSW Biodegradation with Different Inocula In Laboratory In-Vessel Reactor

The in-vessel composting is considered as an environmentally sound method for the treatment and disposal of Municipal Solid Waste (MSW) as it produces good quality compost with lesser environmental impacts. In this study, the process was accelerated and the composting time was reduced using various industrial organic wastes as inoculums in a vertical in-vessel reactor with stirrer arrangement. This study examined the process kinetics which aims to show the interdependency between biological, chemical &amp; physical factors. It is also the extension of the previous work which dealt with composting of the organic fraction of municipal solid waste. The rate of degradation of volatile solids, TOC and C/N ratio are presented in First-order kinetic model and reaction rate constants are determined. The different inoculums used are yeast sludge, spent wash, distillery effluent and sugar sludge. Yeast sludge has the highest R2 values such as 0.979, 0.978 and 0.986 for VS, TOC and C/N ratio respectively. The R2 value of C/N ratio for the sugar sludge is 0.983. From the kinetic study, it can be concluded that the yeast sludge can be a better option when compared with other sludge to accelerate the process of composting.

A polymeric Brønsted acid ionic liquid mediated liquefaction of municipal solid waste

The rapid industrialization and population explosion continuously generate massive amounts of municipal waste. Several conventional processes are in practice for the treatment of municipal waste, but the requirement of stringent operating conditions, incomplete conversion, longer processing time and emission of toxic gases, etc., are the major associated barriers. Thus, there is an urgent requirement for a sustainable, environmentally feasible process that can process waste into energy and fuel products. In the present manuscript, polyethylenimine functionalized polymeric Bronsted acid ionic liquid (PolyE-IL) catalysts have been explored for the Catalytic Thermo Liquefaction (CTL) of organic biodegradable municipal solid waste (MSW). A series of PolyE-IL catalysts with variable counter ions were examined for CTL of MSW. Of all the tested PolyE-IL catalysts, the integration of [PEI]+[HSO4]- gave excellent MSW conversion (>85%) and yield (>80%) of liquefied products (CTL-Oil) under non-stringent reaction conditions and without any formation char and gases. The influence of reaction conditions such as catalyst concentration, reaction temperature, time, slurry concentration, and type of feedstock of conversion and yield are studied. The column adsorption and membrane separation process was integrated to facilitate the catalyst and CTL-Oil separation. A series of commercially available hydrophobic resins were tested to separate catalyst and CTL-Oil. ICT005 showed the highest adsorption efficiency of all tested resins with 35.46 mg/mL of binding capacity and Kd of 0.02159. The physicochemical properties of CTL-Oil were studied in detail by using various analytical tools, which exhibited that CTL-Oil comprises a mixture of small and large molecular weight organic compounds and has a calorific value of 4000 kcal/kg; hence it could be used for further energy and fuel applications. Thus, the reported CTL process can be beneficial to resolve both environmental and fossil fuel dependency issues simultaneously by converting MSW into CTL-Oil.

Compost Quality and Markets Are Pivotal for Sustainability in Circular Food-Nutrient Systems: A Case Study of Sri Lanka

Sustainable management of municipal solid waste (MSW) is a critical issue around the world, especially in South Asia where waste generation is expected to double by 2050. Closing the food-nutrient cycle through composting biodegradable MSW has the potential to meet human needs, including sanitation and food security, while protecting the environment. We use an interdisciplinary case study approach including systems thinking to assess Sri Lanka's national MSW composting system, which primarily receives residential and commercial food waste. We embed quantitative compost quality analysis and interviews at 20 composting facilities within a broader qualitative assessment informed by ~60 stakeholders in total. This approach yields insights on how institutional, economic, social, and biophysical aspects of the system are interrelated, and how challenges and solutions can create undesirable and desirable cascading effects, respectively. Such dynamics can create risks of composting facility failure and unintended consequences, diminishing the chances of achieving a sustainable circular food–nutrient system. Compost quality, which was variable, plays a pivotal role within the system—a function of program design and implementation, as well as a determinant of value capture in a circular economy. We make several recommendations to inform future efforts to sustainably manage biodegradable MSW using composting, drawing on our case study of Sri Lanka and prior case studies from other nations. Key among these is the need for increased emphasis on compost product quality and markets in policy and program design and implementation. Targeted measures are needed to improve waste separation, boost compost quality, effectively use compost standards, encourage compost market development, ringfence the revenues generated at municipal compost plants, and identify efficient modes of compost distribution. Such measures require adequate space and infrastructure for composting, resource investment, local expertise to guide effective system management, strong links with the agriculture sector, and continued political support.

Numerical study of strain development in high-density polyethylene geomembrane liner system in landfills using a new constitutive model for municipal solid waste

Tensile strain development in high-density polyethylene (HDPE) geomembrane (GMB) liner systems in landfills was numerically investigated. A new constitutive model for municipal solid waste (MSW) that incorporates both mechanical creep and biodegradation was employed in the analyses. The MSW constitutive model is a Cam-Clay type of plasticity model and was implemented in the finite difference computer program FLAC™. The influence of the friction angle of the liner system interfaces, the biodegradation of MSW, and the MSW filling rate on tensile strains were investigated. Several design alternatives to reduce the maximum tensile strain under both short- and long-term waste settlement were evaluated. Results of the analyses indicate that landfill geometry, interface friction angles, and short- and long-term waste settlement are key factors in the development of tensile strains. The results show that long-term waste settlement can induce additional tensile strains after waste placement is complete. Using a HDPE GMB with a friction angle on its upper interface that is lower than the friction angle on the underlying interface, increasing the number of benches, and reducing the slope inclination are shown to mitigate the maximum tensile strain caused by waste placement and waste settlement.

Simulation of gas transport in a landfill with layered new and old municipal solid waste

Average biodegradation rate of newly filled municipal solid waste (MSW) in landfills is relatively fast, and the landfill gas produced by the new MSW biodegradation can cause great variations in gas pressure. To predict the gas pressure distribution in the MSW layer, a one-dimensional gas transport model is established in this study. The following factors are considered in this model: (1) the variation of gas permeability with depth; (2) the anisotropy ratio of gas permeability; (3) the settlement caused by waste biodegradation. Furthermore, a single peak model for gas production is applied as the source term of gas production. The equation for settlement caused by waste biodegradation is presented, and the time of peak gas production rate is obtained by fitting the settlement of the newly filled layer. The stratification of the unsaturated and saturated regions is taken into account by distinguishing the difference in gas saturation. The layering of the new and old waste layers is considered by distinguishing the difference in the length of time that waste has been degraded to produce gas. Based on the method of numerical calculation, the gas pressure distribution in the landfill with layered new and old MSW is well simulated. The position where the maximum gas pressure occurs is found. The sensitivity analysis shows that the influence of the anisotropy ratio on gas pressure distribution is more significant.

The influence of moisture enhancement on solid waste biodegradation

The objective of this study was to assess the influence of moisture enhancement strategies on biodegradation of municipal solid waste (MSW) in laboratory-scale reactors. Moisture enhancement strategies were varied with respect to dose volume (40, 80, 160, and 320 L/Mg-MSW) and dose frequency (dosing every ½, 1, 2, and 4 weeks). Biodegradation was evaluated based on methane generation to assess (i) the lag-time between the start of liquid dosing and onset of methane generation and (ii) the first-order decay rate for methane generation. In general, the decay rate increased with an increase in dose volume for a given dose frequency. In addition, trends of increasing decay rate and decreasing lag-time were observed for an increase in dose frequency for reactors operated with dose volumes of 40, 80, and 160 L/Mg-MSW. A key conclusion from this study was that reactors with more aggressive moisture enhancement attained more rapid methane generation that initiated at shorter elapsed times following the onset of dosing. An assessment of liquid dosing per month indicated that there were more pronounced impacts of increasing decay rate and decreasing lag-time as moisture enhancement increased from 40 L/Mg-MSW/month to 320 L/Mg-MSW/month as compared to the impact on both variables for an increase in liquid dosing above 320 L/Mg-MSW/month.