Organic Fraction Of Municipal Solid Waste Research Articles

Pilot-Scale Polyhydroxyalkanoate Production from Organic Waste: Process Characteristics at High pH and High Ammonium Concentration

Polyhydroxyalkanoate (PHA) accumulating microbial enrichment was established on volatile fatty acids (VFAs) containing leachate derived from the organic fraction of municipal solid waste (OFMSW). The enrichment was based on a 12-h feast-famine batch cycle and an exchange ratio of 50% in which VFAs were completely consumed in less than 50 min during stable periods of operation. No pH control was applied in the system, and the pH went as high as 9 due to the presence of amongst others, ammonia [500 mg·L−1 total ammonia nitrogen (TAN) on average]. The degree of enrichment was evaluated with fluorescence in situ hybridization (FISH), and a yet unknown genus of large (3–5 μm diameter) beta-proteobacteria appeared dominant in the culture. A method for estimating the fraction of PHA accumulating active biomass in the total volatile suspended solids was established, and the results indicated an increase of this fraction from 25% to 56% after implementing two modifications in the operational protocol: (1) a pretreatment of the substrate removing virtually all settleable solids; and (2) a settling phase in the enrichment reactor after the feast phase, selectively removing nonsettleable solids and slowly degradable substrates. The PHA accumulation potential of the culture was 77±18 wt% PHA (n=3) after 3 h in batch accumulation experiments. The results suggest the potential feasibility of PHA production under conditions that were previously considered economically favorable but technically difficult.

Evaluation of organic fractions of municipal solid waste as renewable feedstock for succinic acid production

BackgroundDespite its high market potential, bio-based succinic acid production experienced recently a declining trend because the initial investments did not meet the expectations for rapid market growth. Thus, reducing the succinic acid production cost is imperative to ensure industrial implementation.ResultsSuccinic acid production has been evaluated using hydrolysates from the organic fraction of municipal solid waste (OFMSW) collected from MSW treatment plants. A tailor-made enzymatic cocktail was used for OFMSW hydrolysate production containing up to 107.3 g/L carbon sources and up to 638.7 mg/L free amino nitrogen. The bacterial strains Actinobacillus succinogenes and Basfia succiniciproducens were evaluated for succinic acid production with the latter strain being less efficient due to high lactic acid production. Batch A. succinogenes cultures supplemented with 5 g/L yeast extract and 5 g/L MgCO3 reached 29.4 g/L succinic acid with productivity of 0.89 g/L/h and yield of 0.56 g/g. Continuous cultures at dilution rate of 0.06 h−1 reached 21.2 g/L succinic acid with yield of 0.47 g/g and productivity of 1.27 g/L/h. Downstream separation and purification of succinic acid was achieved by centrifugation, treatment with activated carbon, acidification with cation exchange resins, evaporation and drying, reaching more than 99% purity. Preliminary techno-economic evaluation has been employed to evaluate the profitability potential of bio-based succinic acid production.ConclusionsThe use of OFMSW hydrolysate in continuous cultures could lead to a minimum selling price of 2.5 $/kg at annual production capacity of 40,000 t succinic acid and OFMSW hydrolysate production cost of 25 $/t sugars.

Integration of Microalgae Cultivation in a Biogas Production Process from Organic Municipal Solid Waste: From Laboratory to Pilot Scale

In this study, the feasibility of integrating microalgae cultivation in a biogas production process that treats the organic fraction of municipal solid waste (OFMSW) was investigated. In particular, the biomass growth performances in the liquid fraction of the digestate, characterized by high ammonia concentrations and turbidity, were assessed together with the nutrient removal efficiency. Preliminary laboratory-scale experiments were first carried out in photobioreactors operating in a continuous mode (Continuous-flow Stirred-Tank Reactor, CSTR), to gain preliminary data aimed at aiding the subsequent scaling up to a pilot scale facility. An outdoor experimental campaign, operated from July to October 2019, was then performed in a pilot scale raceway pond (4.5 m2), located in Arzignano (VI), Italy, to assess the performances under real environmental conditions. The results show that microalgae could grow well in this complex substrate, although dilution was necessary to enhance light penetration in the culture. In outdoor conditions, nitrification by autotrophic bacteria appeared to be significant, while the photosynthetic nitrogen removal was around 12% with respect to the inlet. On the other hand, phosphorus was almost completely removed from the medium under all the conditions tested, and a biomass production between 2–7 g m−2 d−1 was obtained.

Valorisation of organic fraction municipal solid waste via anaerobic co-digestion of Malaysia tropical fruit for biogas production

The acceleration of MSW generation is one of the world’s critical challenge that contributed to the serious environmental and socio-economic problems involving pollutions and shortage of waste disposal area. The population growth, economic growth and urbanization are the key contributors to the MSW generation. Precisely, organic waste is the world highest contributor of MSW compared to other inorganic waste. This massive amount of putrescible waste consumption has a great global warming potential through the unutilized methane gas released from the landfill. In this regard, the waste treatment method through energy recovery Organic Fraction of Municipal Solid Waste (OFMSW) via Anaerobic Digestion (AD) has become the best way to utilize the high valuable energy (methane) resource potential and sustaining the environment. Moreover, AD process could be further enhanced through co-digestion process with various of substrates. Malaysia tropical fruit are among the potential of substrate for the anaerobic co-digestion that receiving extensive attention. This short article reviewed the potential of the selected Malaysia tropical fruit residues as substrates for anaerobic co-digestion with OFMSW.

Bromatological, Proximate and Ultimate Analysis of OFMSW for Different Seasons and Collection Systems

In order to study the quality of organic fractions of municipal solid waste (OFMSW), five different municipalities in Tuscany were chosen for sampling according to the peculiarities of their collection systems. The five collection systems selected were sampled four times: during March, June, September and December, for a total of 20 picking analyses. In addition, emphasis was also given to the study of the variability of OFMSW composition related to ultimate, proximate and bromatological analyses. Road container collection systems proved to have a higher content of non-compostable and undesirable fractions (22%±1%) when compared to door-to-door systems (6% ± 1%). During months with lower temperature (March and December), the garden waste content in the OFMSW was negligible, with kitchen waste prevailing. This altered the physical chemical composition of OFMSW, which had a lower lignin content and higher methane production in the months with lower temperatures (272 ± 23 NLCH4 kgTVS−1) compared to June and September (238 ± 14 NLCH4 kgTVS−1). In general, the Tuscan OFMSW had a higher dry matter content (42%) than observed in previous studies. In conclusion, the result could direct possible future operators of anaerobic digestion plants towards the choice of dry and semi-dry technologies.

Enzymatic pretreatment and anaerobic co-digestion as a new technology to high-methane production.

The population growth is causing an increase in the generation of effluents (mainly organic fraction of municipal solid waste (OFMSW) and agro-industrial waste), which is an old problem in agro-industrial countries such as Brazil. Contrastingly, it is possible to add value to these residual biomasses (residues) through the application of new technologies for the production of bioenergy. Anaerobic digestion (AD) of sewage sludge is being applied in many effluent treatment plants for the sustainable and economically viable production of biogas. However, the biogas produced from AD (sludge) or co-digestion (sludge with other residues) presents a concentration of methane between 60 and 70% on average, which is relatively low. This review is aimed at analyzing studies involving (i) production of lipases by solid-state fermentation (SSF) by different microorganisms for the application in enzymatic pretreatments prior to the anaerobic treatment of effluents; (ii) pretreatment followed by AD of various residues, with an emphasis on OFMSW and sewage sludge; and (iii) more recent studies on anaerobic co-digestion (AcoD) and hybrid technologies (pretreatment + AD or AcoD). There are many studies in the literature that demonstrate the enzymatic pretreatment or AcoD applied to the optimization of methane production. Nevertheless, few studies report the combination of these two technologies, which can improve the process and reduce or eliminate the costs of biogas purification, which are major challenges for the viability of this route of bioenergy production. KEY POINTS: • Municipal and agro-industrial wastes have potential as medium for lipase production. • Enzymatic pretreatment and anaerobic co-digestion are low cost for high-methane production. Graphical abstract Interactions among various factors optimization methane production from enzymatic pretreatment and AcoD.

Robust microorganisms for biofuel and chemical production from municipal solid waste

BackgroundWorldwide 3.4 billion tonnes of municipal solid waste (MSW) will be produced annually by 2050, however, current approaches to MSW management predominantly involve unsustainable practices like landfilling and incineration. The organic fraction of MSW (OMSW) typically comprises ~ 50% lignocellulose-rich material but is underexplored as a biomanufacturing feedstock due to its highly inconsistent and heterogeneous composition. This study sought to overcome the limitations associated with studying MSW-derived feedstocks by using OMSW produced from a realistic and reproducible MSW mixture on a commercial autoclave system. The resulting OMSW fibre was enzymatically hydrolysed and used to screen diverse microorganisms of biotechnological interest to identify robust species capable of fermenting this complex feedstock.ResultsThe autoclave pre-treated OMSW fibre contained a polysaccharide fraction comprising 38% cellulose and 4% hemicellulose. Enzymatic hydrolysate of OMSW fibre was high in d-glucose (5.5% w/v) and d-xylose (1.8%w/v) but deficient in nitrogen and phosphate. Although relatively low levels of levulinic acid (30 mM) and vanillin (2 mM) were detected and furfural and 5-hydroxymethylfurfural were absent, the hydrolysate contained an abundance of potentially toxic metals (0.6% w/v). Hydrolysate supplemented with 1% yeast extract to alleviate nutrient limitation was used in a substrate-oriented shake-flask screen with eight biotechnologically useful microorganisms (Clostridium saccharoperbutylacetonicum, Escherichia coli, Geobacillus thermoglucosidasius, Pseudomonas putida, Rhodococcus opacus, Saccharomyces cerevisiae, Schizosaccharomyces pombe and Zymomonas mobilis). Each species’ growth and productivity were characterised and three species were identified that robustly and efficiently fermented OMSW fibre hydrolysate without significant substrate inhibition: Z. mobilis, S. cerevisiae and R. opacus, respectively produced product to 69%, 70% and 72% of the maximum theoretical fermentation yield and could theoretically produce 136 kg and 139 kg of ethanol and 91 kg of triacylglycerol (TAG) per tonne of OMSW.ConclusionsDeveloping an integrated biorefinery around MSW has the potential to significantly alleviate the environmental burden of current waste management practices. Substrate-oriented screening of a representative and reproducible OMSW-derived fibre identified microorganisms intrinsically suited to growth on OMSW hydrolysates. These species are promising candidates for developing an MSW biorefining platform and provide a foundation for future studies aiming to valorise this underexplored feedstock.

Economic and environmental life cycle assessment of organic waste treatment by means of incineration and biogasification. Is source segregation of biowaste justified in Germany?

In the realm of the German scope, four different waste treatment options for the Organic Fraction of Municipal Solid Waste (OFMSW) were evaluated against the environmental and economic background: (i) anaerobic digestion followed by composting, (ii) incineration of OFMSW, (iii) incineration of separately pre-dried OFMSW and (iv) a cascaded treatment system, which couples anaerobic digestion with incineration (i.e. incineration of digestate). Environmental life cycle assessment (eLCA) and a calculation of the levelized costs of exergy (LCOE) were performed to map the sustainability aspects of the different product systems. Within a hybrid approach, consisting of literature data evaluation, theoretical modelling, the conduct of lab-scaled experiments and a substrate analysis, a comprehensive assessment was compiled.Within the eLCA, the main drivers of the total environmental impact were the categories global warming potential (GWP) and the fossil depletion potential (FDP). (i) Anaerobic digestion followed by composting and (ii) incineration were hereby characterized by the fewest environmental impacts. With regards to the base case, the GWP was calculated to ~500 g CO2-Eq/kWh exergy for these options. The FDP was <0.05 kg oil-Eq/kWh exergy for anaerobic digestion and ~0.075 kg oil-Eq/kWh exergy for incineration. The other examined treatment options were characterized by a significantly higher GWP and FDP.The economic assessment showed median LCOE of 27 ct/kWh exergy for anaerobic digestion followed by composting and thus outcompeted incineration (median: 55 ct/kWh Exergy). Separate pre-drying prior to incineration increased the economic burdens marginally. Anaerobic digestion followed by incineration showed the highest economic expenses (89 ct/kWh exergy). In conclusion, anaerobic digestion followed by composting was marked by an overall preferential environmental and economic constellation and source segregation is thereof justified and should further be maintained.

Assessment of environmental, energy and economic prospective of anaerobic digestion of organic municipal solid waste in Malaysia

The continuous increase in population, higher living standards and economic development resulted in the inevitable increase of waste generation, energy consumption, carbon emissions and environmental degradation. The current average operating expenditure (OPEX) of a landfill is RM148/tonne/day for disposing municipal solid waste (MSW) which is an economic burden to the government. Thus, this study investigates the feasibility of biogas production from organic MSW as a renewable source of energy via anaerobic digestion. The economic and environmental benefits including the sales of electricity and fertilizer were investigated. Organic fraction municipal solid waste (OFMSW) was collected at Sahom landfill, Kampar. Waste composition was analyzed to determine the percentage of organic waste. Approximate and ultimate analysis were conducted to characterize the organic samples and to measure the calorific value. The biogas and bio-fertilizer yield were estimated. It was found that OFMSW consists 45% of the total MSW. Conversion of OFMSW to electricity and fertilizer via anaerobic digestion (AD) resulted in 3,274,812.51 m3/day of biogas which consists of 56.62% CH4 and 43.38% carbon dioxide. This can be resulted in 7,494.08 MWh/day of electrical energy and a daily yield of 13,013.73 tonnes of bio-fertilizer. This transforms the economic burden of solid waste management expenditures into an income generating movement.

The Composition and Properties of Polish Waste Focused on Biostabilisation in MBT Plants during the Heating Season

This paper presents the morphological composition of fraction &lt;80 mm, being separated from municipal solid waste (MSW) and delivered in the winter season to the 21 mechanical-biological treatment (MBT) plants throughout several regions of Poland. This fraction is hereinafter referred to as OFMSW (organic fraction of municipal solid waste). Their properties are considered while using parameters such as: moisture, loss on ignition and organic carbon content, as well as moisture and loss on ignition of screen fractions &lt;10 mm and 10–20 mm that are found within. The main aim of this research was to test waste from 21 industrial installations, and to prove that ash content (fine fractions) in waste intended for MBT was about 1/3 of the mass of overall OFMSW mass. These quantities exceed the limits that were approved for the correct operation of MBT installations. The effect of their high content in MSW during the heating season is low moisture (from 25.4% to 58.3%) and the low loss on ignition (from 23.1% to 54.3% DM [dry matter]), which might even determine their inaptness in terms of biological treatment and incineration. The &lt;10 mm fraction contained on average 31.7 ± 7.5% of water and showed a loss on ignition of 29.8 ± 7.1% DM. These values for the 10–20 mm fraction were respectively: 36.6 ± 12.5% DM and 37.3 ± 8.8% DM, respectively.

From Upstream to Purification: Production of Lactic Acid from the Organic Fraction of Municipal Solid Waste

The implementation of an efficient and sustainable management of the organic fraction of municipal solid wastes (OFMSW) is a topic of intensive discussion in EU countries. Recently, the OFMSW has been investigated as a potential substrate for the production of lactic acid (LA) through fermentation. Nevertheless, none of the reports available in the literature covers all the stages of the conversion process. The present research article is a comprehensive study which includes the upstream, fermentation and downstream for the conversion of OFMSW into LA. Several batches of OFMSW were analysed for the evaluation of sugars released and LA content before the fermentation. Fermentations were performed to study the effect of hydrolysate quality on the LA production using Bacillus coagulans A166. Purification of LA, based on electrodialysis, was carried out after pilot scale fermentation of OFMSW hydrolysates. Results showed that variations in the concentrations of sugars and LA are observed from batch to batch of OFMSW. More specifically, LA can reach high concentrations even before the substrates are hydrolysed, limiting the potential applications of the final product due to low enantiomeric purities. In general, fermentations of the hydrolysate were efficient, with conversion yields of 0.65 g g−1 without the addition of extra nutrients. Downstream is still a challenging stage of the process. A LA recovery of 55% was obtained, with the most significant losses observed during the micro- and nanofiltrations. Overall, a conversion of 10% from OFMSW substrate (dry basis) to LA was achieved.Graphic

An insight to municipal solid waste management of Varanasi city, India, and appraisal of vermicomposting as its efficient management approach

Varanasi, India's historic cultural capital, struggles with efficient waste management practices. This impacts environment and human well-being in terms of waste generation that is estimated around 550-650 TPD with a generation rate of 0.42kg capita-1day-1 (n = 117). The present study aims to explore and characterize wastes, current practices, ecological profiling, and phytotoxicity of an abandoned open dumping site, and vermicomposting of organic fraction of municipal solid waste (OFMSW) as sustainable waste management approach. Compositional analysis of waste indicates organic fraction (46.13%) as a major component along with a considerable amount of heavy metals. The calorific value and moisture content of municipal solid waste (MSW) was 2351.4calg-1 and 34.72%, respectively. Ecological profiling of the dumping site revealed that floral diversity and ecological species/indicators were negatively affected. Likewise, phytotoxicity results displayed a negative impact on germination and physiology of maize (Zea mays L.) plants grown on dumping site soil. Vermistabilization of OFMSW showed a significant increase in N (56.10-89.48%), P (33.93-82.87%), and K (25.55-50.42%) and a decrease in total organic carbon (15.15-24.81%). Similarly, C/N and C/P ratios decreased by 1.89-2.51 and 1.72-2.18 folds, respectively. A survey of stakeholders suggested that open dumping was the main practice adopted by Varanasi Municipal Corporation (VMC) during 2013-2015. Recently (2017-2018), VMC adopted different methods, such as door-to-door collection and source segregation for effective waste management. Waste characteristics and nutrient profile of the vermicompost explains that vermicomposting could be used for efficient waste management in Varanasi, further reducing the collection, transportation, and disposal costs of waste, which enables to close the loop and move towards a circular economy. Moreover, implications of existing waste management practices and possible management options need to be addressed scientifically. Therefore, this research outcome will help in designing a successful wastemanagement plan for Varanasi and other cities with similar waste characteristics.

Effects of Different Seed Substances on Anaerobic Degradation of Municipal Solid Waste in Recirculated Bioreactor

Alternatively, to traditional landfilling, using bioreactor landfilling and anaerobic treatment technology has been increasing recently, which facilitates more controlled conditions for the degradation of wastes. The aim of this study is to investigate the effects of different seed sludges inoculation on the anaerobic degradation performance of the organic fraction of municipal solid wastes (OFMSWs) in the simulated bioreactors. In this respect, Bio-One™, Anaerobic, and Karahayit sludge as seed materials were tested for the performance on the degradation of OFMSW. Besides methane quantity and percentage, the leachate characteristics and methanogenic microflora were also determined. At the end of the 90 days, the cumulative methane quantity and percentage of inoculated reactors were higher than the control. The highest methanogen diversity was found at Anaerobic and Karahayit seed sludge inoculated bioreactors. The methanogen species belonging to the Methanobacteriales, Methanomicrobiales, and Methanosarcinales were detected except Methanococcales and Methanopyrales orders in bioreactor systems.

Influence of temperature on enhancement of volatile fatty acids fermentation from organic fraction of municipal solid waste: Synergism between food and paper components

This study explores individual contributions and synergistic effects of food and paper, main components of organic fraction of municipal solid waste (OFMSW) towards volatile fatty acids (VFA) fermentation under different temperatures (25, 37, 42 and 52 °C). Thanks to the synergism of food and paper component (FC & PC), the results revealed that OFMSW is suitable for VFA production. Maximum VFA production was noticed to be 21.5 mg/L at 42 °C, ~2.1, and 1.42 times higher than fermentation of PC and FC. Enhanced hydrolysis of PC occurred at >37 °C, increasing alkalinity in leachate to 6.7 g/L at 42 °C, thus maintaining a stable pH (5.4–5.6) during acidogenic fermentation. Additionally, 74% of COD is hydrolyzed, of which 79% is converted to VFA based on biodegradable carbon at 42 °C. It is suggested that co-existence of FC and PC can enhance VFA production of OFMSW, and targeted VFA production can be maximized through process optimization.

Novel approach for the treatment of the organic fraction of municipal solid waste: Coupling thermal hydrolysis with anaerobic digestion and photo-fermentation

In this study, two different organic fractions of municipal solid waste (OFMSW) served as raw material in a novel treatment process that combines thermal hydrolysis (TH) pretreatment at different times, followed by anaerobic digestion of the solid fraction and photo-fermentation of the liquid fraction. The results indicate that both wastes performed similarly, and no statistically relevant differences stand out on the overall performance regarding TH times. The thermal pretreatment improves the biodegradability of the solid fraction during anaerobic digestion compensating the loss of the organic matter in the liquid fraction. The produced biogas may feed a combined heat and power (CHP) system, making the process energetically positive in all studied scenarios. In addition, the combination of TH and anaerobic digestion decreased the volume of the waste to be disposed by 59–61%, which is 5–11% higher than that obtained with the traditional treatment of anaerobic digestion process. Specific phototrophic activity tests were performed on the liquid phase using a mixed culture of purple phototrophic bacteria (PPB) that consumed up to 80% of the soluble organics. The assays yielded an average 52% efficiency on specific phototrophic activity (kM) and 62% on biomass yield (YX/S), compared to an optimized growth medium. PPB was also capable of producing polyhydroxyalkanoates, bioH2 and single-cell protein without optimization. Apart from methane, the overall mass balances showed yields up to 150 g of high added-value products per Kg of initial total solids on this proof-of-concept platform.

Enhancement of biogas production from organic fraction of municipal solid waste using alkali pretreatment

Anaerobic digestion is one of the most prospective and economical techniques to recover energy and simultaneously treat organic fraction of municipal solid waste (OFMSW). However, more often than not, the complex polymeric structure of lignocellulosic fraction and high lipid content of Indian OFMSW prove to be hindrances in realizing the full potential of energy recovery through anaerobic digestion. Pretreatment of OFMSW is an effective method to enhance the efficiency of anaerobic digestion. This paper explores the effect of alkali pretreatment on change in characteristics of OFMSW in India and its subsequent impact on biogas generation. Pretreatment was carried out using 5 M sodium hydroxide (NaOH) solution and varying the initial pH of OFMSW in the range of 8–13 for 24 h. Thereafter, batch anaerobic digestion assays of untreated and pretreated OFMSW were carried out using cow excrement as inoculum. Results indicate that NaOH pretreatment was advantageous in solubilizing the organic matter of OFMSW, thus increasing biogas yield and reduced digestion time. The cumulative biogas generation increased by 19.6–34.8% post-NaOH pretreatment. OFMSW pretreated with NaOH at pH 10 had maximum biogas yield of 407.1 mL/gVS with 68.9% methane content, as compared to 301.9 mL/gVS and 50.3% of untreated OFMSW. A preliminary cost assessment indicated a positive net profit for pretreatment of OFMSW with NaOH at pH ranges of 8–10.

A spatial modeling approach for siting, sizing and economic assessment of centralized biogas plants in organic waste management

Disposal of organic fraction of municipal solid waste (OFMSW) at landfills and direct application of livestock manure onto soil are often restricted by regulations due to environmental concerns. These regulations require the application of different technologies, such as anaerobic digestion, in the management of OFMSW and livestock manure, and creates an opportunity for resource recovery. Since these waste sources are geographically dispersed, siting and sizing of resource recovery facilities to minimize transfer distances are critical for the sustainable management of these waste. This study aims to investigate the sizing, siting, and economic feasibility of municipality owned centralized biogas plants in the management of OFMSW and livestock manure through application of spatial modeling. A stepwise land suitability analysis was performed to determine potential plant sites followed by a location-allocation analysis to analyze siting, sizing and transportation costs for increasing number of plants. Finally, an economic assessment was conducted to compare unit cost of electric energy and existing feed-in tariff for biogas plants. The methodology was applied to the city of Izmir in Turkey. 8 biogas plants could be built in Izmir with a total installation size of 92 MWe and 10 $ cent/kWh unit cost of electric energy. This study represents an important step in the establishment of a local decision support system in Turkey for the utilization of regional bioenergy sources, and organic waste management.

Formic acid pretreatment for enhanced production of bioenergy and biochemicals from organic solid waste

Organic solid waste is one of the most promising feedstocks for the implementation of the circular economy principles in waste management. Its anaerobic treatment can indeed promote organic matter conversion into a number of value-added products as well as energy carriers. However, the identification of sustainable strategies to handle organic solid waste in a biorefinery framework still poses technological as well as economic challenges. The aim of this study was in enhancing the potential of the organic fraction of municipal solid waste (OFMSW) to produce bioenergy and biochemicals by combining dark fermentation with a formic acid pretreatment. Hydrogen yields up to 31.6 ml/gVS were obtained pre-treating the OFMSW with 5% formic acid, at 80 °C for 70 min. Concomitantly, a wide range of metabolites of market significance, including acetic acid, butyric acid and ethanol, accumulated. The concentration of these metabolites further enhanced after the dark fermentation of the pretreated substrates. Experimental tests highlighted the influence of the different pretreatment operating conditions on the relative production of hydrogen and main metabolites as well as the related pathways. It was found that the acid concentration plays a key role in promoting the biological conversion of OFMSW and that the adjustment of the operating temperature and treatment time can be targeted towards the production of either building blocks or energy carriers, so as to ensure the viability of the process for its scale up.

Organic Fraction of Municipal Solid Waste (OFMSW) Using Continuous-Flow Anaerobic Reactor

This manuscript describes the particle size distribution based model.This model accounts for the degradation and methane production from the anaerobic digestion of the (OFMSW) organic fraction of municipal solid waste. The model also shows the reduction in cost of solid waste treatment. Analysis was done based on laboratory test, carried out to test the operating parameter such as Ammonia, PH, Temperature, volume of gas, total solid, volatile solid, nitrate, nitrite, phosphate and conductivity while Volatile fatty acid was negligible. The organic waste samples used was cow dung, and was digested using a continuous flow stirred reactor, which was constructed locally at the institution hydraulic laboratory. Results from the test and analysis reveals high concentration of ammonia which inhibited the production of gas. The total solid content was observed to determine the rate of organic loading of the reactor. The biogas production from the continuous flow reactor, contains ammonia concentration of 460mg/l ,385mg/l, 300mg/l, 193mg/l, 120mg/l and 130mg/l, under similar operating PH of 6.68. There was no contribution of biogas production from inoculation. Total volume of biogas produced was calculated and was found to be 0.036m3, 0.040m3, 0.055m3 0.053m3and varied according to PH range of 6.67 to 7.2. The result also shows that at a PH of 7.2, ammonia concentration was high, limiting the methane production rate. The highest form or concentration of nitrate and nitrite occurs at the end of the detention period. Decrease in the PH value and conductivity was a strong indication of the present of nitrate and nitrite in the solution of the waste sample.

Modeling and optimization of biomethane production from solid-state anaerobic co-digestion of organic fraction municipal solid waste and other co-substrates

ABSTRACT One of the simplest methods for increasing productivity in biogas production is co-digestion. Co-digestion leads to more biogas yield as well as more nutrient bioavailability. This study reports the modeling and optimization of biomethane potential tests from different combinations of organic fraction of municipal solid wastes (OFMSW), cow manure (CM), and municipal sewage sludge (MSS) in solid-state. The simplex-centroid mixture design (SCMD) and artificial neural network (ANN) models were validated with a high correlation to the real data (R2 = 0.99). Experimental results indicated that the maximum amount of CH4 production of 436 mL CH4/g VS occurs at the identical weight percent of the three substances (33.33%). The maximum methane yield was found to be 445.9 mL CH4/g VS as obtained by the genetic algorithm (GA) optimization process, while 448.5 mL CH4/g VS (448.5 ± 3.05) of methane was produced experimentally. Therefore, integration of the SCMD and ANN model with the GA optimization is useful in the prediction of biomethane production. This research is the first in providing the best combination of co-treating and co-utilizing OFMSW with CM and MSS in the solid-state for biowaste management.