Biodegradable Fraction Research Articles

Energy from municipal solid wastes: Galati city case study

The municipal solid wastes (MSW) can be turned into resources through recycling and energy recovery. To obtain the maximum amount of energy, the appropriate technology must be applied to waste treatment. The composition and characteristics of municipal solid wastes are determinant for technologies choice for MSW in a city/region. Municipal authorities from the Galati city proposed a recovery rate of recyclable materials of 60% from MSW and treatment of the post-recycling MSW as follow: biodegradable fraction by anaerobic digestion and the combustible fraction by incineration or gasification. In this study traditional and innovative waste to energy technologies have been analysed and the potential of electrical energy of waste has been estimated. Results show that plasma gasification system of raw MSW coupled with gas turbine engine has almost the same electrical energy production (32.92 GWh/year) as conventional gasification of combustible material from MSW (17.21GWh/year) coupled with anaerobic digestion of organic fraction of MSW (11.65 GWh/year). By recovering and using the landfill gas from the Tirighina landfill, 6.68 GWh of electricity can be produced annually.

Comparative assessment of compositing and anaerobic digestion of municipal biodegradable waste in Harare, Zimbabwe

AbstractComposting and anaerobic digestion (AD) of biodegradable waste were assessed for their benefits from literature and environmental impacts using the life cycle impact assessment (LCIA) procedure. Literature review findings indicate an overall edge for AD over composting largely due to its renewable energy production capabilities, reduced exhaust emissions, and cost effectiveness considering the entire municipal solid waste (MSW) life cycle. LCIA results show that both AD and composting lead to increases across the four impact categories considered namely, global warming, human health, eutrophication, and acidification. AD however showed lower contributions than composting to global warming, human health, and acidification. Composting only showed lower contribution than AD with regards to eutrophication. Overall study results indicate an edge for AD over composting in treating and managing biodegradable fraction of MSW generated in Harare and its surrounding urban and peri urban environments of Chitungwiza, Epworth, Norton, and Ruwa.

Evaluation of biomethanization during co-digestion of thermally pretreated microalgae and waste activated sludge, and estimation of its kinetic parameters

The maximum methane yield that can be obtained from anaerobic co-digestion of microalgae and waste activated sludge (WAS) mixtures, after thermal pretreatment at 65 °C during 4 h, was investigated. Furthermore, the fitting of the experimental data by five kinetic models (first-order, second-order, modified Gompertz, Logistic, and two-substrate) was evaluated. Thermal pretreatment increased the methane yield of single microalgae and WAS digestion by ≈ 44 and by ≈ 52%, respectively. The results also showed that up to 60% of WAS can be co-digested with microalgae without impairing the methane yield, producing up to 338 mLCH4 gVS−1. Data from digestion of non-pretreated microalgae and WAS were well described by all kinetic models, but digestion of thermally pretreated microalgae, WAS, and their co-digestion mixtures, was best fitted by means of a two-substrate model, indicating that after pretreatment it is necessary to take into account the contribution of both rapidly and slowly biodegradable fractions.

Molecular weight distribution of the recalcitrant organic matter contained in kraft mill effluents and the identification of microbial consortia responsible for an anaerobic biodegradable fraction

The objective of this research was to evaluate the distribution of the molecular weights of the recalcitrant organic matter contained in kraft mill effluents and identify microbial consortia responsible for an anaerobic biodegradable fraction. As a result, the average removal efficiencies of chemical organic demand (COD) and biological oxygen demand (BOD5) during the entire period of operation were 28% and 53%, respectively. The non-biodegradable organic matter was detected at molecular weights less than 1000 Da. However, most of the organic matter was in the molecular weight fraction higher than 10000 Da with 32 ± 11.6% COD as well as color (42.3 ± 8.7%), total phenolic compounds (35.9 ± 7.9%) and adsorbable organic compounds (AOX) (13.0 ± 2.7%). Methanogenic acetoclastic archaea of the genera Methanomethylovorans and Methanosarcina were found in the surface and middle zones of the reactor. Moreover, Methanosaeta and Methanolinea were identified in the low zone of the reactor. In all zones of the reactor, Desulfomicrobium and Desulfovibrio were found to be the most dominant genera of sulfate-reducing bacteria (SRB).

Experimental Production of Biogas using Co-Digestion of Organic Waste

Environmental pollution is one of the major problems plaguing the modern world today. The environment and the various elements in the environment need energy to meet their need. So there is a need to produce energy from different sources. Solid Waste is one such material that can be used as a source for deriving energy. The studies on conversion of solid waste to energy have resulted several alternatives including the biogas production from biodegradable organic waste. There are several alternatives in the estimation of biogas yield from bio degradable fraction of solid waste. The different types of biodegradable organic waste may comprises of cow dung, pig waste, poultry manure, food waste, vegetable waste, kitchen waste etc[9]. The present study focuses on production of biogas using cow dung with vegetable waste and poultry manure. In this study, by doing experimentation it is observed that the production of biogas from co-digestion of different organic waste is more than individual waste. The highest yield of biogas is obtained from co-digestion of cow dung with poultry manure than co-digestion of cow dung with the vegetable waste. Waste produced after the production of biogas is used as natural fertilizers for the growth of crops and fields and it gives good yield. By experimentations like energy recovery from solid waste, the conservation of non renewable energy resources may be possible and it also helps to protect our environment [16]

Degradation of biochemical fractions in different temperature of food waste bioevaporation and their contribution to biogenerated heat

Abstract Bioevaporation is a treatment for highly concentrated organic wastewater that uses biogenerated heat from organic matter degradation to remove water from wastewater itself. The degradation of organics is important when investigating bioevaporation process. The aim of this study was to investigate organic compounds degradation in different temperature stages and evaluate their contribution to biogenerated heat during food waste (FW) bioevaporation by using biofilm-developed sponge (BF) as a clean, light and easy-to-prepare bulking agent and microbial carrier. Results showed that amylums were significantly decomposed in all stages and lipids were decomposed a lot except the warming 30 °C to top-temperature stage. Decomposition of amylums and lipids contributed to the main total volatile solids (VS) loss (75.63% and 77.87% in the 1st and 2nd cycle, respectively). Water soluble organic carbon (WSOC) variations were fluctuated especially at the thermophilic phase. The decomposition of hemicellulose (HEM) occurred until cooling 30 °C. However, the degradation of proteins and lignin (LIG) was not significant during the whole process. Carbohydrates and lipids successively served as main substrates for producing biogenerated heat and totally contributed 87.54% and 89.06%, in the 1st and 2nd cycle, respectively. Throughout the process, various organics contained in FW induced extracellular enzymes in different levels, resulting in different degradation performance. The foremost induced enzyme was amylase with activity of 114.50 mg reducing sugar g−1 TS (total solids) min−1 at warming 50 °C of the 2nd cycle, which facilitated amylums to be degraded preferentially. Fluorescence labeling further confirmed significant decrease of amylums and lipids and the slight decrease of proteins. However, decreasing fluorescence intensity of cellulose (CEL) in the top-temperature stage firmly reflected its degradation, which was covered by the content variations caused by readily biodegradable fractions.

Removal of oxyfluorfen from polluted effluents by combined bio-electro processes

In this work, the combination of biological and electrochemical processes to mineralize oxyfluorfen has been studied. First, an acclimatized mixed-culture biological treatment was used to degrade the biodegradable fraction of the pesticide, reaching up to 90% removal. After that, the non-biodegraded fraction was oxidised by electrolysis using boron-doped diamond as the anode. The results showed that the electrochemical technique was able to completely mineralize the residual pollutants. The study of the influence of the supporting electrolyte on the electrochemical process showed that the trace mineral solution used in the biological treatment was enough to completely mineralize the oxyfluorfen, resulting in total organic carbon removal rates that were well-fitted by a first-order model with a kinetic constant of 0.91 h−1. However, the first-order degradation rate increased approximately 20% when Na2SO4 was added as supporting electrolyte, reaching a degradation rate of 1.16 h−1 with a power consumption that was approximately 70% lower.

Fungal proliferation and hydrocarbon removal during biostimulation of oily sludge with high total petroleum hydrocarbon.

A laboratory-scale study was conducted to investigate the effect of bioaugmentation (BA) and biostimulation (BS) on the remediation of oily sludge with high total petroleum hydrocarbon (TPH) content (269,000mg/kg d.w. sludge). TPH concentration significantly decreased by 30.4% (P < 0.05) in the BS treatment after 13-week incubation, and 17.0 and 9.1% of TPH was removed in the BA and control treatments (amended with sterile water only), respectively. Aliphatic and other fractions (i.e., saturated n-alkanes and cyclic saturated alkanes) were reduced in the BS treatment, whereas no decrease in aromatic hydrocarbons occurred in any treatment. Gas chromatography-mass spectrometry analysis of aliphatic fractions showed that low-chain-length alkanes (C8-C20) were the most biodegradable fractions. The BS treatment supported fungal proliferation, with Sordariomycetes and Eurotiomycetes as the dominant classes. BS increased fungal diversity and decreased fungal abundance, and changed bacterial community structure. The findings show the potential of using BS to treat oily sludge with high TPH content. Graphical abstract.

Acid Hydrolysis of Waste Paper to Glucose

Waste paper stands for the major biodegradable organic fraction of most municipal waste. The potential of acid hydrolysis of waste paper for glucose production was investigated in this current work. This was carried out in two stages which involved the pretreatment of two samples (Computer printout and Newspaper), which was accompanied by first shredding the paper into pulp. Acid hydrolysis of waste paper was optimized to maximum glucose conversion, with a nitric acid concentration of 5.0 mL at 121 °C in an autoclave. The obtained results showed maximum percentage reducing sugar yield for 5 % w/v waste paper with 1 % v/v nitric acid at 72 h was 24.93. The obtained result showed that the maximum percentage reducing sugar yield for 5 % w/v waste paper with 5 % nitric acid at 72 h was17.59. The obtained results showed that the maximum percentage reducing sugar yield for 5 % w/v waste paper with 10 % v/v nitric acid at 72 h was 18.1. This research of acid hydrolysis is a promising method to improve waste paper conversion to glucose in order to control environmental pollution.

Pyrolysis of difficult biodegradable fractions and the real syngas bio-methanation performance

Sustainable approaches for the anaerobic digestion treatment of food waste to minimize environmental challenges and recover energy are some economic goals receiving global attention. Meeting global bio-energy demand from food waste and associated waste residues requires exploring alternative optimization routes. Pyrolysis process for the treatment and recycling of difficult biodegradable fractions in food waste processing facility, and the subsequent utilization of real syngas in anaerobic digestion as a food waste treatment were investigated to evaluate their effects on biofuel production via bio-methanation. Different proportions of syngas that are transformed into methane show that the carbon monoxide content in the reactors (G21, G23, G61, and G63) was completely degraded on 195, 195, 95, and 145 h. The higher hydrogen concentration in the simulated syngas expedites the carbon monoxide degradation rate. Application of two-stage pyrolysis to difficult biodegradable fractions treatment generated real syngas (Hydrogen 60: Carbon monoxide 20 vol%) for improved bio-methanation (100% methane) compared to the blank. The simulated syngas from the anaerobic digestion treatment of food waste generated methane (75–80%) than the control (45%). Results from both the simulated and real syngas show that high volume percent of hydrogen in the syngas positively influenced the degradation and transformation of carbon monoxide and promoted a higher rate of bio-methanation. Further study showed that pH values in the range 7.21–7.78, and low concentrations of volatile fatty acids and ammonia nitrogen indicated no toxicity from syngas bio-methanation with anaerobic digestion. This route is beneficial for enhancing the value of resources recovered from difficult biodegradable fractions pyrolysis, achieving a higher bio-methanation rate, and improving sludge stabilization with anaerobic digestion treatment of food waste.

Assessment of the Environmental, Technical and Economic Issues Associated with Energy Recovery from Municipal Solid Waste in Malaysia

Malaysia is a fast emerging economy country and its outlook on sustainable energy production are at the center of debate. Although waste to energy (WtE) technologies are well established but the disconformity of the municipal solid waste (MSW) composition, the complexity of the treatment facilities, and the pollutant emissions still express considerable issues for these technologies. Hence, this study focuses on WtE technologies in Malaysia by considering the energy potentials of the landfill sites and incineration plants as the most common effective MSW in Malaysia. The major environmental, technical and economic issues associated with WtE technologies were evaluated. An annual growth rate of 3.3% has been projected for MSW production in Malaysia. The most common used WtE technologies were incineration and controlled landfill to capture Landfill Gas (LFG). Malaysia MSW contains 60% biodegradable fraction, making landfills a potential source of LFG. Although, the potential of energy recovery from waste in Malaysia is high but the current production is less than 20 MW of electricity per day.

Efficient succinic acid production using a biochar-treated textile waste hydrolysate in an in situ fibrous bed bioreactor

Textile waste contains biodegradable fraction which can be used as an alternative feedstock for succinic acid production. The feasibility of bioconversion of biochar-treated textile waste hydrolysate into succinic acid was evaluated. A substrate loading of 9% was applied to hydrolyze mixed textile waste and the resultant glucose-rich hydrolysate with dyestuff was collected after enzymatic hydrolysis. Biochar from different pyrolysis temperatures (400–700 °C) and different dosages of the selected biochar (1–5%) were applied to remove colorants. The results showed that biochar had a good performance at a dosage of 2 w/w % on removal of colorant inhibitors. There was no negative effect observed during the subsequent fermentation. After optimization of fermentation media in shake flasks, the resultant succinic acid titer reached 19.6 g/L with a SA yield of 0.76 g/g, supplemented with 30 g/L tryptone. The in situ fibrous bed bioreactor (isFBB) can further improve SA titer, up to 28.8 g/L corresponding to a yield of 0.61 g/g without pH control. Furthermore, a shorter lag phase during succinic acid fermentation in isFBB was observed. It can be concluded that a novel textile waste-based biorefinery approach for succinic acid production aided by biochar sorption was successfully developed.

Amelioration of Physico-Chemical Parameters and Phytotoxicity of Landfill Leachate by Microbial Degradation

Objective: To understand the effect of microbial treatment on physico-chemical parameters and phytotoxicity of leachate arising from degradation of municipal solid waste. Methods and statistical Analysis: Landfill leachate samples were collected from a municipal landfill site in Mumbai, India at different phases of its degradation cycle. The leachate was subjected to anaerobic treatment using microbial consortium based product CleanMaxx ANB followed by its counterpart CleanMaxx for aerobic treatment. Post treatment, the physico-chemical properties were analysed and the phytotoxicity was assessed using seed germination assay. The results were interpreted using ANOVA. Findings: The physicochemical parameters of the old and fresh leachate samples were analyzed after biological treatment where the percentage COD reduction was 18.97% and 53.87%; percentage ammoniacal nitrogen reduction was 22.78% and 58.8 %; percentage reduction in TDS was 24.8% and 34.76%; percentage reduction in TSS was 24.05% and 23.5% and percentage colour reduction was 25.01% and 34.35% for old and fresh leachate respectively. The aging of landfill leachate sample may have reduced its biodegradable fraction with the increase in the concentration of high molecular compounds and highly toxic compounds, which may hinder with the microbial degradation process. The seed germination bioassay using Cicer arietinum (Bengal gram) seeds revealed that the percentage germination of seeds exposed to untreated leachate samples (both old and fresh) was 11.1 and 22.2% respectively (p<0.05). Microbial treatment of both these samples improved the germination percentage to 88.8% in both cases. Application/Improvements: The improvement in physicochemical properties and reduction in phytotoxicity indicates that the microbial remediation of landfill leachate could treat the top soils and groundwater tables at contaminated sites, making the surrounding land arable.Keywords: Landfill, Leachate, Microbial Degradation, Phytotoxicity

LCA-Based Comparison of Two Organic Fraction Municipal Solid Waste Collection Systems in Historical Centres in Spain

Municipal solid waste (MSW) collection is an important issue in the development and management of smart cities, having a significant influence on environmental sustainability. Door-to-door and pneumatic collection are two systems that represent a way of arranging waste collection in city´s historic areas in Spain where conventional street-side container collection is not feasible. Since door-to-door collection generates significant direct greenhouse gas emissions from trucks, pneumatic collection emerges as an alternative to the trucking system. While this technology apparently reduces local direct air emissions, it suffers from a large energy demand derived from vacuum production for waste suction. The introduction of new normative frameworks regarding the selective collection of the biodegradable fraction makes necessary a comprehensive analysis to assess the influence of this fraction collection and its subsequent recycling by anaerobic digestion. As a novelty, this work compares both conventional door-to-door and pneumatic collection systems from a life cycle approach focusing on the biodegradable waste. Results indicate that, in spite of the fact electricity production and consumption have a significant influence on the results, the energy savings from the recycling of the organic fraction are higher than the energy requirements. Therefore, the pneumatic collection could be an environmentally-friendly option for MSW management under a circular economy approach in Spanish city´s historic areas, since wastes could be a material or energy source opportunity.

The effectiveness of anaerobic digestion of bio-waste in replacing primary energies: An EU28 case study

Biodegradable fraction of waste is generally recognized as a sustainable source for renewable energy production and anaerobic digestion (AD) is the most used process for this purpose. The majority of AD facilities currently operating in the EU28 are equipped with gas engines fuelled by the biogas for production of electrical energy. There is growing interest in other energy recovery options whose implementation will rise significantly in the near future.AD of bio-waste can play an important role for the implementation of EU policy for renewable energy, i.e. EU 2030 goals, and waste management, i.e. recycling target. From this perspective, the present study performed an assessment of the capability of AD facilities currently operating in the EU28 for bio-waste processing, in replacing other fuels, energy and raw materials. For this purpose, the effectiveness of different energy/fuel recovery schemes were analysed and discussed. A life cycle approach was adopted defining a specific indicator, the hybrid primary energy (HPE) (MJ/Mg) based on the exploitation of the cumulative energy demand (CED) (MJ). Future research trends for AD were also presented and discussed.

Energy from waste: Plant design and control options for high efficiency and emissions’ compliance under waste variability

Variations in composition and charging rates of waste constituents in energy-from-waste (EfW) plants disturb throughput and power output from nominal design (ND) levels. Offgas flowrates and composition are affected, impinging on operating expenses, profitability and emissions. State-of-the-art facilities claim improved efficiency and emissions' compliance, by controlling the combustor via fluegas recirculation, fluegas heat recovery, excess air and oxygen enrichment. The work investigates the mutual influence of plant ND and of the above controls. Given a ND, it assesses the concurrent effect on performance and pollution abatement efficacy, under variability in key waste constituents. Based on the combined mass and enthalpy balance and on necessary and sufficient conditions for emissions’ compliance, it determines appropriate manipulations (directions, gains and ranges) for high efficiency and reduced emissions under large waste variability (e.g., biodegradable fraction varying by 50%). It quantifies how heat integration and oxygen enrichment enable higher throughput of poor constituents (by boosting combustion), whereas higher fluegas recirculation and excess air suppress it, enabling higher throughput and power production from rich waste constituents. Concurrent action of the control variables enhances performance. ND affects the directions (increase or decrease) and manipulation ranges and provides safety margins ensuring compliance over the entire waste uncertainty range.

Stabilisation of municipal solid waste after autoclaving in a passively aerated bioreactor.

Autoclaving of unsorted municipal solid waste is one of the solutions in waste management that maximises the amount of waste for recycling. After autoclaving, however, a large part of the waste is composed of unstabilised biodegradable fractions (organic remaining fraction, ORF), which may comprise up to 30% of autoclaved waste and cannot be landfilled without further stabilisation. Thus, the aim of this study was to investigate the effectiveness of aerobic stabilisation in a passively aerated reactor of organic remaining fraction after full-scale autoclaving of unsorted municipal solid waste. The organic remaining fraction had a volatile solids content of ca. 70%, a 4-day respiration activity test (AT4) of ca. 26 g O2 kg-1 total solids and a 21-day gas formation test (GP21) of ca. 235 dm3 kg-1 total solids. Stabilisation was conducted in a 550 L reactor with passive aeration (Stage I) and a periodically turned windrow (Stage II). The feedstocks consisted entirely of organic remaining fraction, or of organic remaining fraction with 10% inoculum (ORF + I). Inoculum constituted product of stabilisation of organic remaining fraction. During stabilisation of organic remaining fraction and ORF + I, thermophilic conditions were achieved, and the decreases of volatile solids, AT4 and GP21 could be described by 1 order kinetic models. The rate constants of volatile solids removal (kVS) were 0.033 and 0.068 d-1 for organic remaining fraction and ORF + I, respectively, and the thermophilic phase was shorter with ORF + I (25 days vs. 45 days). The decrease in GP21 corresponded to volatile solids decrease, but AT4 decreased sharply during the first 10 days of waste stabilisation in the reactor, indicating that the content of highly biodegradable organic matter decreased during this time.

Synergistic combination of pyrolysis, anaerobic digestion, and CHP plants.

The anaerobic digestion of biodegradable fraction of municipal solid waste (MSW) is a widely used process for biogas production. However, the biodegradable fraction of MSW also contains lignocellul ...

Effect of meteorological conditions on odour emission at biogas plants processing municipal waste – pilot research

Biogas plants processing municipal waste on the one hand represent a trend in waste management, and on the other hand constitute an alternative energy source. Next to their unquestionable benefits, due to the character of the provided activity, they can be a potential source of odours. Municipal waste, largely containing biodegradable fractions, is often subject to decomposition processes in uncontrolled conditions still before it is supplied to the mechanical biological treatment plant. One of the effects of the processes, both controlled and uncontrolled conditions, is emission of odorants. Their spread depends on the applied technologies and adherence to the technological regime during operation. One of the factors determining the types and concentrations of emitted odorants are also meteorological conditions in which waste is stored and processed. The paper presents results of two series of pilot research conducted at four plants, involving a preliminary analysis of the effect of meteorological conditions on the emission of odorants at biogas plants processing municipal waste.

Poder calorífico de la fracción orgánica biodegradable de los residuos sólidos urbanos generados en el sector sur de la ciudad de Quito

Se determinó el poder calorífico de la fracción orgánica biodegradable de los residuos sólidos urbanos (FOBRSU) generados en el sector sur de la ciudad de Quito, una zona representada en las subzonas residenciales de estrato socioeconómico medio, medio-bajo, bajo y en la zona de mercados y ferias, con el fin de hallar una diferente alternativa de disposición final mediante incineración. Los puntos de muestreo se obtuvieron con un análisis estadístico que determinó la necesidad de muestrear 21 puntos en las subzonas residenciales, igualmente se decidió muestrear los 5 mercados más grandes y representativos del sector. Se realizó un trabajo de campo para determinar los mayores porcentajes de orgánicos biodegradables. Se determinó el poder calorífico a través del método de análisis próximos y bomba calorimétrica. Se estimó que el porcentaje de reducción de volumen de los residuos que llegarán al relleno sanitario “El Inga” es 95,82%. Asimismo, la vida útil del relleno se alargaría en 4,9 años si se emplea la idea propuesta. La generación de energía mediante incineración de los FOBRSU requiere de una fuerte inversión inicial pero también generaría importantes beneficios para el municipio y abastecería de energía a 19.806 hogares.