Degradation Of Solid Waste Research Articles

Effect of inoculation with white-rot fungi and fungal consortium on the composting efficiency of municipal solid waste

An investigation was carried out on the effect of inoculation methods on the compost of an organic fraction of municipal solid waste. Three types of white-rot fungi (Phanerochaete chrysosporium, Trametes versicolor and Fomes fomentarius), and a consortium of these fungi, were used. The study assessed their influence on microbial enzymatic activities and the quality of the finished compost. It was found that the addition of white-rot fungi to municipal solid waste (after 37days of composting) could be a useful strategy for enhancing the properties of the final compost product. In comparison with the control sample (compost without inoculation), it accelerates degradation of solid waste as indicated by changes in C/N, electrical conductivity and pH. However, the effectiveness of waste degradation and compost maturation depends on the type of microorganism used for inoculation. The presence of inoculants, such as Trametes versicolor and Fomes fomentarius, led to a higher degrading ratio and a better degree of maturity. This resulted in an increase of enzymatic activities (especially dehydrogenase and protease) and a germination index in comparison with inoculation using Phanerochaete chrysosporium or a consortium of fungi.

Biodegradability of Formulated Enzymatic Solution: An Alternative Waste Reduction System

Solid waste and air pollution are never ending environmental problems that can be partially solved by turning waste into useful bio-products. In this study, enzymatic solutions were developed by formulating enzymatic solutions from fish intestines and fruit peels. This aimed to help in biodegradation of organic solid wastes. Organic waste samples were treated with formulated enzymatic solutions for 7 days in aerated set-up for aerobic degradation. Biodegradability and odor of the waste samples were compared with commercial enzymatic solution. Determination of evolved carbon dioxide (CO2) using gravimetric analysis (GA) was used to determine the percent biodegradability, Dt, of organic solid waste and odor-ranking method was used to determine the odor intensity of the organic waste samples. The result showed that the weight loss and percentage biodegradability of organic waste sample treated with formulated enzymatic solution is comparable with that of the commercial enzymatic solution. In terms of odor intensity, waste treated with the product, formulated enzymatic solution (FES) is also comparable to the waste treated with commercial enzymatic solution. Thus, implying that the developed FES is as efficient as that of the commercial enzymatic solution. These significant results will be helpful to future researchers in providing ways on improving the degradation of organic solid waste and mitigating the increasing glitches on our environment. Enzyme kinetics, physical and chemical properties studies of the solution were recommended for future researchers to accurately determine the effectiveness of the formulated enzymatic solution in the degradation of organic solid waste.

How to Establish a Bioregenerative Life Support System for Long-Term Crewed Missions to the Moon or Mars.

To conduct crewed simulation experiments of bioregenerative life support systems on the ground is a critical step for human life support in deep-space exploration. An artificial closed ecosystem named Lunar Palace 1 was built through integrating efficient higher plant cultivation, animal protein production, urine nitrogen recycling, and bioconversion of solid waste. Subsequently, a 105-day, multicrew, closed integrative bioregenerative life support systems experiment in Lunar Palace 1 was carried out from February through May 2014. The results show that environmental conditions as well as the gas balance between O2 and CO2 in the system were well maintained during the 105-day experiment. A total of 21 plant species in this system kept a harmonious coexistent relationship, and 20.5% nitrogen recovery from urine, 41% solid waste degradation, and a small amount of insect in situ production were achieved. During the 105-day experiment, oxygen and water were recycled, and 55% of the food was regenerated. Key Words: Bioregenerative life support systems (BLSS)-Space agriculture-Space life support-Waste recycle-Water recycle. Astrobiology 16, 925-936.

Combined Treatment of Old Sanitary Landfill Leachate

Landfill leachate presents hardly treatable, highly complex and very toxic environmental effluent originated in the municipal solid waste degradation process. Although, numerous treatment methods were developed so far, none of them alone could achieve permissible limits of the primary pollutants to discharge into natural recipients. The current study aimed to develop and apply the process to treat landfill leachate by simultaneous application of electrochemical methods, ultrasound, electromagnetic field and ozonation to achieve the legal criteria for its discharge into natural recipient and minimize its adverse environmental impacts. For this purpose, old landfill leachate was taken from the Piskornica (Koprivnica, Croatia) sanitary landfill. Prior to the treatment, the leachate was supplemented with NaCl (2 g/L) and subjected to simultaneous treatment with stainless steel electrode plates, ultrasound and recirculation through electromagnetic field. After 45 minutes, stainless steel electrode plates were replaced by iron electrodes and treated for another 10 minutes followed by 15 minutes of the treatment with aluminum electrode plates. Ultrasound and recirculation through electromagnetic field were also applied during Fe and Al electrode treatment. Finally, the electrodes were removed and the suspension was mixed with ozone for another 30 minutes and allowed to settle for an hour. Following the combined treatment, the removal efficiency for the turbidity, color, suspended solids, ammonium, phosphates and heavy metals was 99% or higher, while the removal of COD was 97%. All the measured parameters in the treated leachate were lower compared to upper permissible limit for discharge into natural recipient.

Targeted modification of organic components of municipal solid waste by short-term pre-aeration and its enhancement on anaerobic degradation in simulated landfill bioreactors

Pre-aeration is effective on regulating subsequent anaerobic degradation of municipal solid waste (MSW) with high organic fractions during landfilling. The strength of pre-aeration should be optimized to intentionally remove some easily biodegradable fractions while conserve bio-methane potential as much as possible. This study investigates the evolution of organic components in MSW during 2–14days pre-aeration process and its impacts on subsequent anaerobic degradation in simulated landfill bioreactors. Results showed that a 6-day pre-aeration enabled to develop a thermophilic stage, which significantly accelerated biodegradation of organics except lignocelluloses, with removal rates of 42.8%, 76.7% and 25.1% for proteins, carbohydrates and lipids, respectively. Particularly, ammonia from accelerated ammonification in the thermophilic stage neutralized VFAs generated from anaerobic landfilling. As a result, the MSW with 6-day pre-aeration obtained the highest methane yield 123.4NL/kg dry matter. Therefore, it is recommended to interrupt pre-aeration before its cooling stage to switch to anaerobic landfilling.

The impact of compaction and leachate recirculation on waste degradation in simulated landfills

This study investigated the impact of compaction and leachate recirculation on anaerobic degradation of municipal solid waste (MSW) at different methane formation phases. Two stainless steel lysimeters, C1 and C2, were constructed by equipping a hydraulic cylinder to apply pressure load (42kPs) on the MSW. When MSW started to produce methane, C1 was compacted, but C2 was compacted when the methane production rate declined from the peak generation rate. Methane production of C1was inhibited by the compaction and resulted in producing a total of 106L methane (44L/kgVS). However, the compaction in C2 promoted MSW degradation resulting in producing a total of 298L methane (125L/kgVS). The concentrations of volatile fatty acids and chemical oxygen demand showed temporary increases, when pressure load was applied. It was considered that the increased substrate accessibility within MSW by compaction could cause either the inhibition or the enhancement of methane production, depending the tolerability of methanogens on the acidic inhibition. Leachate recirculation also gave positive effects on methane generation from wet waste in the decelerated methanogenic phase by increasing mass transfer and the concentrations of volatile fatty acids.

Proposta de procedimento operacional padrão para o teste do Potencial Bioquímico do Metano aplicado a resíduos sólidos urbanos

RESUMO O biogás é proveniente da decomposição anaeróbia natural da matéria orgânica. A energia obtida através do principal componente, metano (CH4), representa uma faixa de 50 a 65% em volume do total de biogás gerado e um poder calorífico de, em média, 9,9 kWh/m3 em condições normais de temperatura e pressão (CNTP). Diante dos benefícios energéticos e da prevenção de emissões gases tóxicos, limitando-se a carência de normas técnicas (NBR's) no Brasil referente a um procedimento para a determinação da produção do biogás, foram estudados, testados e analisados alguns métodos de caracterizações e monitoramentos dos principais fatores envolvidos no processo de degradação dos resíduos sólidos urbanos (RSU) para o aproveitamento energético do biogás, resultando, desta forma, na proposta de um procedimento operacional para o teste do Potencial Bioquímico do Metano (BMP). O teste resultou em dados positivos comparados a trabalhos já realizados na literatura, o qual obteve um volume médio de 282,7 NL.kg-1MS de biogás em 90 dias.

Analytical Modeling to Simulate Gas Production for Various Tested Landfill Cells

AbstractThe gas extraction wells installed in landfills are used to control gas emission. The degradation of municipal solid waste (MSW) is the main influencing factor for gas production and migration. The symmetric equation of gas migration was established considering the gas extraction wells and peak behavior of the degradation rate. An analytical solution is presented. The peak behavior of degradation rate can be modeled by an equation. The steady degradation ratio of MSW is related to methane generation potential Lo in the LandGEM model. The extraction and injection tests can be well simulated by the symmetric change theory of gas pressure in landfills. From back analysis of the Brogborough test, both the MSW landfill degradation rate and the peak value of gas pressure increased with sludge addition. The degradation time at peak is less than about 700 days. The peak gas pressure in landfill with added sludge increases by 20%.

Endogenous mitigation of H2S inside of the landfills.

Vast quantities of hydrogen sulfide (H2S) emitted from landfill sites require urgent disposal. The current study focused on source control and examined the migration and conversion behavior of sulfur compounds in two lab-scale simulated landfills with different operation modes. It aimed to explore the possible strategies and mechanisms for H2S endogenous mitigation inside of landfills during decomposition. It was found that the strength of H2S emissions from the landfill sites was dependent on the municipal solid waste (MSW) degradation speed and vertical distribution of sulfide. Leachate recirculation can shorten both the H2S influence period and pollution risk to the surrounding environment. H2S endogenous mitigation may be achieved by chemical oxidation, biological oxidation, adsorption, and/or precipitation in different stages. Migration and conversion mainly affected H2S release behavior during the initial stabilization phase in the landfill. Microbial activities related to sulfur, nitrogen, and iron can further promote H2S endogenous mitigation during the high reducing phase. Thus, H2S endogenous mitigation can be effectively enhanced via control of the aforementioned processes.

Degradation of municipal solid waste in simulated landfill bioreactors under aerobic conditions

In this study the municipal solid waste degradation processes in simulated landfill bioreactors under aerobic and anaerobic conditions is investigated. The effect of waste aeration on the dynamics of the aerobic degradation processes in lysimeters as well as during anaerobic processes after completion of aeration is presented. The results are compared with the anaerobic degradation process to determine the stabilization stage of waste in both experimental modes. The experiments in aerobic lysimeters were carried out at small aeration rate (4.41⋅10−3lmin−1kg−1) and for two recirculation rates (24.9 and 1.58lm−3d−1). The change of leachate and formed gases composition showed that the application of even a small aeration rate favored the degradation of organic matter. The amount of CO2 and CH4 released from anaerobic lysimeter was about 5 times lower than that from the aerobic lysimeters. Better stabilization of the waste was obtained in the aerobic lysimeter with small recirculation, from which the amount of CO2 produced was larger by about 19% in comparison with that from the aerobic lysimeter with large leachate recirculation.

Impact of MSW compression on methane generation in decelerated methanogenic phase

This study investigated the impact of compaction on anaerobic degradation of municipal solid waste (MSW) during the phase of decelerated methane formation. Two stainless steel lysimeters were constructed by equipping a hydraulic cylinder to apply pressure load on the MSW. When methane production rates decreased from the peak rate of each column, pressure load was applied at different degrees of decomposition (DOD). Methane production rate increased when compaction was applied. However, the impact of compaction on the methane production rate varied according to DOD. The MSW compaction reduced MSW pore space, increasing the contact surface area among MSW lumps. It was hypothesized that the mass transfer of substrate and substrate accessibility could be enhanced due to the decrease of void space and the increase of the contact area among waste mass as a consequence of the compaction.

Microbial diversity of methanogenic communities in the systems for anaerobic treatment of organic waste

Methane production via anaerobic degradation of organic-contaminated wastewater, semiliquid, or solid municipal waste of complex composition by methanogenic microbial communities is a multistage process involving at least four groups of microorganisms. These are hydrolytic bacteria (polysaccharolytic, proteolytic, and lipolytic), fermentative bacteria, acetogenic bacteria (syntrophic, proton-reducing), and methanogenic archaea; complex trophic interactions exist between these groups. The review provides information concerning the diversity of the major microbial groups identified in the systems for wastewater and concentrated waste treatment, solid-phase anaerobic fermentation, and landfills for disposal of municipal solid waste, and also specifies the sources of isolation of the type strains. The research demonstrates that both new microorganisms and those previously isolated from natural habitats may be found in waste treatment systems. High microbial diversity in the systems for organic waste treatment provides for stable methanogenesis under fluctuating environmental conditions.

Microbial Fuel Cells in Waste Treatment: Recent Advances

The increasing awareness that there are limits to the availability of nonrenewable resources, as well as that there are limits to the biosphere’s ability to absorb wastes, are at the basis of the growing interest about Microbial Fuel Cells (MFCs) technology, with particular regards to their application to wastes treatment. MFCs, in fact, couple the direct electric power production to the degradation of organic compounds, liquid and solid wastes included. From municipal wastewater, to landfill leachate and solid waste, the application of MFCs to waste treatment achieved important results both in COD removal and power output. Unlike traditional Fuel Cells (FC), MFCs don't require chemical catalysts neither high working temperatures. Moreover, there is no net production of CO2. In the course of 20 years, the performances of MFC increased significantly and scaled prototypes were realized. The constant progresses achieved make a wide-scale application of MFC to waste treatment more reliable.

Enhanced Biogas Production from a Stimulated Landfill Bioreactor for the Co-disposal of Municipal Solid Waste and Coal Wastes

A laboratory experiment was carried out to determine the effect of landfill bioreactor with additives of fly ash and cinder, leachate recirculation, and pH adjustment on the disposal municipal solid waste. Four simulators were used with one sanitary landfill and three landfill bioreactors. The results showed that landfill bioreactors can significantly enhance the biodegradation and upgrade the biostablization, and the leachate recirculation and pH adjustment in the bioreactor had a positive effect on municipal solid waste degradation. The landfill bioreactors could increase 11.7% landfill space and reduce the concentration of chemical oxygen demand concentration in leachate by over 60% than a sanitary landfill.

Conversion of solid organic waste into compost using Trichoderma spp. and its application on some selected vegetables

This study was conducted to evaluate the potentiality of Trichoderma species as a bio-conversion agent for composting of solid organic waste and examine the effects of produced composts on the growth of two types of vegetables. The experiments were conducted both in vitro and in vivo processes. In vitro conversion of solid organic waste, the highest height and weight losses were found 42.64 and 31.45%, respectively using Trichoderma harzianum (IES-103) after 30 days of composting. In vivo conversion of solid organic waste for the same strain under aerobic condition, the highest height and weight losses were 33.22 and 61.25%, respectively. In the field application, the highest plant height of Amaranthus lividus (Amaranth Red Leaf) and Basella alba (Malabar spinach) were found 74 and 136 cm after 33 and 45 days, respectively of composting obtained using the strain of Trichoderma harzianum (IES-103). In this study, the results showed that Trichoderma harzianum (IES-103) was the most effective strain on the basis of height and weight loss (%) for the degradation of solid organic waste. It also illustrates that the compost obtained from the fungi Trichoderma harzianum could be used as an effective soil amendment and nutrient source (fertiliser) to improve growth and yields of vegetables.

LANDFILL LEACHATE RECIRCULATION. PART I: SOLID WASTE DEGRADATION AND BIOGAS PRODUCTION

Anaerobic degradation (AD) of municipal solid waste (MSW) depends on the moisture and nutrient distribution within the bioreactor; these factors are affected by leachate recirculation. In this work, the effects of leachate recirculation of 15 to 120 by volume percentage (%V) on AD were studied. The ojectives of this study are as follows: a) to determine which recirculation rate provides the best conditions for accelerated anaerobic degradation (AD) and b) to determine the optimal range of recirculation rates for methane (CH4) generation. In the first group of experiments, denoted as the exploratory range, laboratory-scale bioreactors (LSBs) were operated at leachate recirculation rates of 15, 30, 60 and 120% V. In a second group of experiments (denoted as narrowed range), a group of seven LSBs were operated at rates of 40, 60 and 80% V, and seven were employed as control, without recirculation. In this stage, LSBs were periodically dismantled to allow testing of the digested MSW. The AD rate was monitored for 201 days along with other variables, including the total volatile solids, holocellulose, lignin, organic carbon, total nitrogen and pH of the MSW matrix, the characteristics of the produced and recirculated leachates and CH4 production rates. The results indicated that methane production during the methanogenic fermentation stage is directly correlated with the recycling rates. The 120%V recirculation rate was observed to cause washout in the waste matrix. The suggested range on the basis of CH4 generation per liter of recirculated leachate was 30 to 40% V.

Special Issue on Bioreactor Landfills

Since the introduction of the concept of enhanced degradation of municipal solid waste (MSW) using liquid addition by the late Professor Pohland in 1975, MSW landfills have been designed, permitted, and operated as bioreactors for almost three decades in many developed countries including the United States. About 75% of the states within the United States allow bioreactor landfills, and the remaining states only approve bioreactor landfills on a caseby-case basis. Although short-term benefits of bioreactor landfills have been relatively well established, long-term benefits and challenges have not been fully understood or addressed. The short-term benefits of bioreactor landfills include (1) faster settlement of the waste resulting in airspace gain; (2) reduced leachate treatment costs if leachate is recirculated to enhance the biodegradation; and (3) greater rate of landfill gas generation, which can enhance the gas to energy production. Long-term benefits of bioreactor landfills that have not been fully understood include improvement in the postclosure leachate quality and mechanical properties of MSW. Key challenges associated with bioreactor landfills can be divided into three categories: (1) changes in mechanical properties; (2) targeting and monitoring of physical and chemical parameters; and (3) fluid management. This special issue contains 11 papers that address some of these challenges via lab-scale to field-scale experiments and using numerical models. The papers cover topics such as enhanced degradation of waste using septage and air; seismic imagining to monitor moisture content and to capture spatial changes in the dynamic properties of the waste; dual-phase flow and slope stability implications; coupled hydromechanical behavior and settlement; and seepage control. We believe that this special issue on bioreactor landfills can benefit practitioners, educators, and researchers. The articles provide the state of the art of bioreactor landfills to design and operate more efficient and environmentally robust bioreactor landfills.

Sulfide emissions from different areas of a municipal solid waste landfill in China

Degradation of municipal solid waste in landfills generates sulfide compounds, which are considered one of the main sources of odor emissions. Field sampling was conducted at surfaces of operating, inoperative, and soil-covered areas of a landfill site in northern China to characterize the sulfide compounds. The results showed that dimethyl disulfide dominated the sulfide compounds, accounting for up to 73.6% of the total detected sulfide. With the biggest odor concentration of 365, diethyl sulfide was the most significant sulfide compound. The estimated sulfide emission rates at surfaces of operating and soil-covered areas were similar, and the emission rate of dimethyl disulfide at Surface of Operating Area was up to 345.9μg/m3h. Dimethyl disulfide could be released from the fresh waste, and its normalized concentration at 0.2m beneath operating surface was 10.4 times that at 0.4m.

EDITORIAL

The problem of sewage and urban solid waste treatment has been increasing exponentially together with population and consumerism growth. There are many environmental questions about sewage and urban solid waste (including hospital waste), mainly when it is considered the fact that not the entire population has access to an adequate treatment system. Even with the current growing stage of development, part of the population does not have basic sanitation and, therefore has their waste disposed inadequately many times in rivers or creeks, and in garbage dumps and landfills. Human wastes are rich in organic material and do not comply with environmental laws standards for disposal in reception venues. In garbage dumps, the leachate that is produced by the urban solid waste degradation contaminates the soil, reaching the groundwater causing several diseases. Besides sewage, there are still other problems resulting from animal protein production, in which the animal confinement produces large amount of residuals with high organic load, causing serious problems when disposed directly in the environment. The thermal engineering community could contribute enormously to the search of solutions through the development of innovative engineering projects for the sewage and urban solid waste treatment, integrated with energy generation systems, contributing to green house gases emission reduction and the valorization of generated subproducts. Integrated complex systems could be conceived from existing technologies currently at an advanced development stage such as: biodigesters, microalgae cultivation photobioreactors, biofuels extraction and production, animal feed and human food supplies production, and electric energy generation. The developed technology, if conceived in modular fashion, would allow for the development of products that could supply a wide spectrum of market activities, either combined or separately, according to the demand.

ENHANCING METHANE OXIDATION IN LANDFILL COVER USING BREWERY SPENT GRAIN AS BIOCOVER

Landfill gas (LFG) is a potent greenhouse gas (GHG) generated by anaerobic degradation of decomposable municipal solid wastes (MSW). LFG contains (50-60%) of methane (CH4) and (40–50%) carbon dioxide (CO2). If a landfill is neither aerated nor equipped with gas capture systems, the LFG emissions, mainly CH4, in the cover soil is best reduced by using a biocover. Biocovers normally act as a biofilter to reduce emissions by improving the biological oxidation of CH4 to CO2. In this study, the optimal ratio for a biocover using mixture of brewery spent grain (BSG) and compost made out of grass and cow manure is determined. Thereafter, column experiments were carried out to investigate the best height level of the biocover. Batch incubation experiments were conducted for screening the best ratio of BSG to compost. A mixing ratio from 10% to 100% BSG to compost with 10% increment was tested. The best ratio of BSG to compost was 7:3. This ratio was later tested with different parameters such as pH, moisture content and temperature. Overall, the optimum biocover performance was at pH 6, moisture content of 66% (v/v) and temperature of 40°C. The column experiments showed that 100% CH4 oxidation occurred fastest at the height of 50cm. (Keywords: Greenhouse gas, methane oxidation, biocover, brewery spent grain, compost)