Search

Globally, the petroleum industry plays a very significant role in producing oil to fulfil the demand of the growing population. The improper management of abandoned quantity of petroleum sludge that is one of the byproducts of petroleum industry has posed many environmental as well as socio-economic issues in most of the developing countries. The petroleum sludge contains various toxic substances, like minerals, oil, and other chemicals which are very harmful for biotic as well as abiotic environment. Meanwhile, a huge quantity of livestock manure, especially buffalo dung, is produced in villages and burned as fuel after drying in open atmosphere for domestic application without any treatment which generates indoor air pollution. This study was formulated to analyze the biochemical methane potential of buffalo dung with petroleum sludge at different mixing ratios (i.e., 1:1, 1.5:0.5 and 0.5:1.5) through batch digestion system. The substrates were prepared and characterized before and after batch digestion by using standard methodology. The maximum methane was obtained as 268 Nml/gVS, followed by 326 Nml/gVS and 191 Nml/gVS at mixing ratios of 1:1, 1.5:0.5 and 0.5:1.5, respectively. The results and findings of the study indicated that the co-digestion of buffalo dung with petroleum sludge at mixing ratio of 1.5:0.5 through continuous batch digestion would be the best option to enhance methane production. [ABSTRACT FROM AUTHOR]

The meat industry's significant freshwater demand and the consequent generation of substantial wastewater require effective treatment methods. With a global increase in meat production, water consumption and wastewater generation are on the rise. Simultaneously, regulatory measures such as the "Fit for 55" package aim to reduce greenhouse gas emissions and preserve water resources. In response, the meat industry must explore sustainable practices, including reduction of water consumption and biomethane production through wastewater treatment. This study focuses on assessing the impact of hydrolysis on methane potential (MP) in slaughterhouse wastewater. To gauge hydrolysis efficiency, an in-house coagulation-based method was developed, proposing a new approach by comparing coagulation and filtration. Coagulation proves superior in presenting COD values closer to actual levels with less variation. Monitoring progress at 22 °C and 35 °C, with a consistent pH of 9, tests were conducted over 1, 2, 3, and 5 days. Methane production post-hydrolysis ranged from 178.8 to 242.6 CH4 Nml/gCOD across tested cases, aligning with existing literature. Optimal conditions for increased methane potential involved a 5-day hydrolysis at 35 °C, demonstrating a 30% average boost in specific wastewater methane production. This study provides a valuable exploration of hydrolysis effects on methane potential, offering insights for sustainable wastewater management in the meat industry. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of mechanical treatment through twin-screw extrusion for the enhancement of biomethane production. Four lignocellulosic biomasses (i.e., sweetcorn by-products, whole triticale, corn stover and wheat straw) were evaluated, and two different shear stress screw profiles were tested. Chemical composition, particle size reduction, tapped density and cellulose crystallinity were assessed to show the effect of extrusion pretreatment on substrate physico-chemical properties and their biochemical methane production (BMP) capacities. Both mechanical pretreatments allowed an increase in the proportion of particles with a diameter size less than 1 mm (from 3.7% to 72.7%). The most restrictive profile also allowed a significant solubilization of water soluble coumpounds, from 5.5% to 13%. This high-shear extrusion also revealed a reduction in cellulose crystallinity for corn stover (i.e., 8.6% reduction). Sweetcorn by-products revealed the highest BMP values (338–345 NmL/gVS), followed by corn stover (264–286 NmL/gVS), wheat straw (247–270 NmL/gVS) and whole triticale (233–247 NmL/gVS). However, no statistical improvement in maximal BMP production was provided by twin-screw extrusion. Nevertheless, BMP kinetic analysis proved that both extrusion pretreatments were able to increase the specific rate constant (from 13% to 56% for soft extrusion and from 66% to 107% for the high-shear one).

In this research, the methane potential of the codigestion of cattle manure (CM) with guinea pig manure (GPM) and dairy wastewater (DW) was evaluated. The effect of the addition of nutrients, inoculum (I) and co-substrates on methane production was studied. Later, two low-cost tubular biodigesters were implemented, at a rural farm in the cold climate municipality of Cumbal, fed with the mixture of CM and co-substrates that produced higher biogas production at the lab scale. The results evidenced that the addition of nutrients had no significant effect on methane potential. The mixture CM + GPM + DW + I, produced a theoretical biomethane potential (BMP) of 69.07%, significantly higher than the percentage of the theoretical BMP obtained individually, 43.81% and 34.49% for CM + I and DW+ I respectively. Further, it was observed that the addition of inoculum avoided problems of acidification. Finally, it was proved that this process can reduce environmental contamination and, at the same time, be a sustainable source of renewable energy for rural families in Cumbal (Nariño-Colombia). [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of mechanical treatment through twin-screw extrusion for the enhancement of biomethane production. Four lignocellulosic biomasses (i.e., sweetcorn by-products, whole triticale, corn stover and wheat straw) were evaluated, and two different shear stress screw profiles were tested. Chemical composition, particle size reduction, tapped density and cellulose crystallinity were assessed to show the effect of extrusion pretreatment on substrate physico-chemical properties and their biochemical methane production (BMP) capacities. Both mechanical pretreatments allowed an increase in the proportion of particles with a diameter size less than 1 mm (from 3.7% to 72.7%). The most restrictive profile also allowed a significant solubilization of water soluble coumpounds, from 5.5% to 13%. This high-shear extrusion also revealed a reduction in cellulose crystallinity for corn stover (i.e., 8.6% reduction). Sweetcorn by-products revealed the highest BMP values (338–345 NmL/gVS), followed by corn stover (264–286 NmL/gVS), wheat straw (247–270 NmL/gVS) and whole triticale (233–247 NmL/gVS). However, no statistical improvement in maximal BMP production was provided by twin-screw extrusion. Nevertheless, BMP kinetic analysis proved that both extrusion pretreatments were able to increase the specific rate constant (from 13% to 56% for soft extrusion and from 66% to 107% for the high-shear one). [ABSTRACT FROM AUTHOR]

Considerable amounts of slaughterhouse wastes (SHW) are generated in Indian urban centres causing serious environmental issues that demand effective treatment and disposal. The present study evaluates the effect of pasteurization (70 °C for 1 h) and extrusion pre-treatment on pathogen removal and methane production from SHW in anaerobic mono- and co-digestion with mixed vegetable, fruit and flower market wastes (VMW) under controlled batch anaerobic digestion (AD) tests. The complete destruction of pathogen was observed in post-pasteurized SHW, whereas the post-extruded SHW showed significant reduction (p < 0.05) in pathogen concentration (with a Salmonella count of 29.3 × 103 CFUs/g). The results of AD test revealed that the maximum specific methane yield (SMY) of 273.2 mLN/g oDM was obtained by anaerobic co-digestion of SHW:VMW in 1:3 proportion. Further enhancement in the SMY was obtained with extrusion pre-treatment of SHW (SHWE) by 11.5% (i.e. 304.8 mLN/g oDM) in 1:3 proportion of SHWE:VMW. Modified Gompertz and logistics models fitted the kinetic data of AD process well. Results confirmed that the proposed extrusion pre-treatment of SHW coupled with anaerobic co-digestion improved the oDM reduction, methane potentials and pathogen removal, thereby making it a suitable pre-treatment during anaerobic co-treatment of SHW with VMW from centralized wholesale markets from urban centres. [ABSTRACT FROM AUTHOR]

Anaerobic digestion for biomethane production is an important tool regarding sustainable energy production. The objective of this study was to investigate the effects of the substrate composition and operating parameters on biomethane production during anaerobic digestion, focusing on the use of flotates and slaughterhouse waste as substrates with a high organic content. A novelty here was the use of a moving bed biofilm reactor (MBBR) with circulation pump for the anaerobic treatment of flotates, slaughter waste (SW), and their mixture. Flotates and waste from slaughterhouses offer a substrate with a high organic content. In this work, it was shown that both substrates provide a high biochemical methane potential (BMP). The highest methane yield was achieved by mixing both substrates. In continuous operation, special challenges arose, due to the high nitrogen and fat content of the substrates. These could be overcome by mixing the substrates and using a circulation pump in the reactor for improved back-mixing. As a result, the highest average methane yield of 0.65 NLCH4·gTS eli−1 was achieved in mesophilic operation at an organic loading rate (OLR) of 4.2 gTS·L−1·d−1. [ABSTRACT FROM AUTHOR]

Intermediate crops (ICs) are grown on large areas in Sweden and elsewhere for their function as cover or catch crops and to increase soil fertility, and they are usually soil-incorporated. The aim of this study was to investigate if aboveground biomass from ICs can be a sustainable source of biofuel feedstock. For that, the biomass yield of fertilized and unfertilized ICs was studied in field experiments and their energy potential determined using methane potential assays. Furthermore, we estimated the economic viability of biogas vehicle fuel production using the IC biomass. Our results indicated that it is economically viable to produce biomethane gas for vehicle fuel quality, from several intermediate crops grown in Northwest Europe, when the intermediate crop biomass was harvested with a self-loading forage wagon, used fresh or as silage as biogas feedstock and processed to methane gas in a large scale biogas plant. Nitrogen fertilization of intermediate crops was useful only when the intermediate crop is established early enough for the plant to make use of the nitrogen and 3 of the 9 investigated IC species could be grown economically feasible even without nitrogen fertilization and covering the full feedstock production costs. Other factors important for economic viability were a high gross methane yield per hectare combined with a high dry matter content in the IC biomass, with high dry matter yields to be prioritized over a higher specific methane yield. Further research is needed on the impact of IC maturity on methane production and suitable harvest technology. [Display omitted] • Biomass and methane yield of intermediate crops (ICs) grown in Northwest Europe. • Economic viability for production of transportation fuel was assessed. • It was economic viable to produce fuel from several unfertilized and fertilized ICs. • High gross methane yield per hectare and high dry matter content were important. • Nitrogen fertilization was useful only when the ICs were established early enough. [ABSTRACT FROM AUTHOR]

Solid waste is one of the largest sources of greenhouse gases (GHGs) today. The carbon footprint of landfills also has a large impact on global warming. Therefore, it is becoming more urgent to study the possibility of better environmentally friendly approaches for solid waste management and its safe disposal. The digestion of solid waste is a biological process that breaks down the organic content of the solid waste and thus stabilizes it. It also allows the recovery of valuable resources (such as biogas) and the utilization of stabilized waste in various industries. In this study, six substrates were studied to determine their biomethane potential (BMP) in anaerobic digestion. The substrates were fermented and digested anaerobically, and the biogas production was measured. The methane yield of food waste substrates had a higher methane yield between 354 and 347 mL/g-TCOD, and a biodegradability of 89–87%. Wastewater sludge substrates yielded between 324 and 288 mL/g-TCOD with a biodegradability of 81–73%. A kinetics analysis using first-order and Gompertz models was performed for biodegradation and methane production. [ABSTRACT FROM AUTHOR]

The goal of our research was to fulfil the potential of traditional, underutilized and less known plant species of the families Brassicaceae and Fabaceae, which grow in the experimental plots of the "Alexandru Ciubotaru" National Botanical Garden (Institute), Chisinau, Republic of Moldova. The seeds and biomass of these plant species have high potential for use as food, forage and raw material for circular economy, including bioenergy production. The determination of physical and mechanical properties of seeds and agricultural products is important in the design of harvesting, handling and processing equipment. Our research revealed that the characteristic dimensions of seeds of the studied Brassicaceae species varied in the following ranges l: b: d = (1.98-12.60): (1.67-3.67): (1.63-2.05) mm; the angle of repose 1=24.6°-30.6° and the flow angle on steel is 1=15.8°-31.7°, on wood 1=18.1°-37.3° and on enamelled surface 1=15.3°-30.5°; M1000 = 4.30-9.73 g and bulk seed density 88.3-766.9 kg/m3. The seeds characteristic of the studied Fabaceae species was l: b: d = (1.53-8.00): (1.20-5.47): (1.47-5.01) mm; the angle of repose 1=21.5°-33.0°, flow angle on steel is 1=14.3°-27.7°, on wood 1=14.7°-29.8° and on enamelled surface 1 =14.2°-27.3°; M1000 = 1.35-170.04 g and bulk seed density 370.8-830.0 kg/m3. The harvested green mass from studied Brassicaceae species is characterized by 16.1-23.5%CP, 63.2-69.9% DMD, RFV=117-162, 10.21-11.20 MJ/kg ME, 5.18-6.76 MJ/kg NEl and from Fabaceae species 14.2-23.4% CP, 58.4-69.5% DMD, RFV=91-168, 9.51-11.15 MJ/kg ME, 5.53-7.17 MJ/kg NEl. The biochemical biomethane potential from vegetal substrates is 305-379 L/kg of organic matter. [ABSTRACT FROM AUTHOR]

The management of municipal solid waste (MSW) is a complex and expensive task. This is especially the case in developing countries, where waste generation rates are continuously increasing and where current MSW management strategies are focused on inadequate practices, such as landfilling and incineration, which result in numerous health and environmental problems. The anaerobic digestion (AD) of MSW has been implemented worldwide as a solution to decrease the amount of waste ending up in landfills. This process allows for the recovery of energy from the organic fraction of MSW (OFMSW) in the form of biogas, which is largely composed of methane. Therefore, the goal of the present study was to evaluate the biochemical methane potential (BMP) of the OFMSW generated within different socioeconomic strata of the Metropolitan Area of Guadalajara (MAG), Mexico. From a microscale perspective, the microbial communities within the experimental AD system were analyzed using high-throughput sequencing of the 16S rRNA gene to assess the relationship between these communities and the biogas composition. This microbial identification revealed a typical AD composition consisting of the following six phyla: Actinobacteria, Bacteroidetes, Chloroflexi, Euryarchaeota, Firmicutes, and Proteobacteria. Furthermore, through the identification of Methanobacterium and Methanosaeta, two methanogenesis pathways (hydrogenotrophic and acetoclastic) were pinpointed. From a macroscale perspective, a multi-stage Gompertz kinetic model was used to describe cumulative biogas production. This model considered the complex nature of the OFMSW substrate in order to estimate the potential level of biogas production in the MAG using a weighted average that was based on the size of the population in each socioeconomic stratum evaluated (732.8 mL⋅g−1 VS). This novel contribution to the literature provides an estimation of the potential economic, energetic, and environmental benefits of treating the OFMSW produced in the MAG through AD. Through this approach, an estimated 8.5 MWh·year−1 of electrical power could be produced, translating into 1.13 million USD of yearly revenue and resulting in reduced GHG emissions (10,519 tonne CO2eq⋅year−1).

The Cabinet of Ministers of Ukraine approved the National Waste Management Strategy until 2030. In this regard, the processing of biodegradable waste, including food waste, using controlled biotechnological processes, in which organic substances are transformed into biogas, is relevant. The article is devoted to determining the methane potential of food waste during its digestion in two stages and specifying the mathematical model of the dynamics of biogas yield. A test was performed to determine the methane potential of food waste under the condition that the process of anaerobic methane digestion was divided into two stages - hydrolysis and methanogenesis. The methane potential of food waste was assessed. The mathematical model of the dynamics of biogas yield was refined, taking into account the obtained experimental data, which made it possible to determine the duration of the hydrolysis stage, the duration of the methanogenesis stage, the biogas potential of the organic substrate, and the intensity of biogas yield. The main problem solved in this study was to ensure the stability of biogas output under the condition of rapid decomposition of organic matter during the digestion of food waste. The problem was solved by dividing the digestion process into two stages. This is explained by the fact that in this way the degree of inhibition of the methanogenesis process by decomposition products at the stage of hydrolysis decreased. The practical significance of the obtained results lies in their use for the design of industrial biogas stations, complexes or p lants in which food waste is digested. The duration of the stages for digestion of food waste makes it possible to determine the ratio between the volume of hydrolysis and methanogenesis reactors for industrial biogas plants. It was found that for the continuous mode of digestion of food waste, the volume of the container for storing the prepared daily loading dose and the hydrolysis reactor are the same. The yield of methane from a unit of the initial value of organic matter of food waste was estimated. It is shown that food waste is a promising organic substrate for obtaining biogas. In Ukraine, up to 500 million tons of waste is generated annually, a significant part of which is food waste from 35% to 49% with an organic matter content of 20% to 25%. The biogas potential of food waste is more than 500 m3 of biogas from a ton of organic matter. Bibl. 20, tabl. 6, fig. 2. [ABSTRACT FROM AUTHOR]

Solid waste is one of the largest sources of greenhouse gases (GHGs) today. The carbon footprint of landfills also has a large impact on global warming. Therefore, it is becoming more urgent to study the possibility of better environmentally friendly approaches for solid waste management and its safe disposal. The digestion of solid waste is a biological process that breaks down the organic content of the solid waste and thus stabilizes it. It also allows the recovery of valuable resources (such as biogas) and the utilization of stabilized waste in various industries. In this study, six substrates were studied to determine their biomethane potential (BMP) in anaerobic digestion. The substrates were fermented and digested anaerobically, and the biogas production was measured. The methane yield of food waste substrates had a higher methane yield between 354 and 347 mL/g-TCOD, and a biodegradability of 89–87%. Wastewater sludge substrates yielded between 324 and 288 mL/g-TCOD with a biodegradability of 81–73%. A kinetics analysis using first-order and Gompertz models was performed for biodegradation and methane production.

• Thermal pre-treatment alone has little effect on PLA hydrolysis. • KOH-based pre-treatment substantially increased PLA solubilization. • PLA pre-treatment 4 M KOH at 35°C for 48 h improved CH 4 yield 37 folds. • About 90 % of the theoretically producible CH 4 was achieved in 24 – 30 days. Replacing petroleum-based plastics with biodegradable polymers is a major challenge for modern society especially for food packaging applications. To date, poly(lactic acid) represents 25 % of the total biodegradable plastics and it is estimated that, in the future, it could become the main contributor to the biodegradable plastics industry. Anaerobic digestion is an interesting way for the poly(lactic acid) end of life, even if its biodegradability is limited in mesophilic conditions. The aims of this study were to identify the best pre-treatment for maximizing the methane yield, minimizing the anaerobic digestion duration and limiting residual plastic fragments in the digestate. A systematic comparison was carried out between thermal, chemical, and thermo-chemical pre-treatment. Pre-treatment with 4 M KOH for 48 h at 35°C was effective in improving the mesophilic anaerobic digestion of the poly(lactic acid). Such pre-treatment allows obtaining 90 % of the theoretical methane potential, in 24 - 30 days. Importantly, such pre-treatment completely solubilized the poly(lactic acid), leaving no solid residues in the digestate. In addition, using KOH permits to avoid the sodication of the soil due to the digestate application as fertilizer. [Display omitted] [ABSTRACT FROM AUTHOR]

Determining a methane potential of organic substrates is an important task at the design stage of biogas complex, plants or stations. The raw substrates differ in their composition throughout the year especially those that contain droppings or manure. Therefore laboratories are usually set up at biogas plants to check the characteristics of the raw substrate and perform test to determine its methane potential. The aim of the work is to research the yield of biogas depending on the ratio between the inoculum and the substrate. The condition under which the value of the ratio between inoculum and substrate can be considered rational is given, namely: it is necessary that the deviation of the value of biogas yield was insignificant relative to small changes in the ratio between inoculum and substrate. The results of experiments on methane anaerobic conversion of cow manure at different values of the ratio between inoculum and cow manure are presented. The yield and composition of biogas and the degree of degradation of volatile solids have been determined. The optimal value of the ratio between the inoculum and the cow manure has been determined. The necessity of substrate mixing during methane potential test in laboratory conditions was analyzed. It has been found that for organic substrates that are easily digested or sufficiently diluted with water, it is sufficient to shake the contents of the reactor manually once a day. If the organic substrate is composed of components that are difficult to digest or the organic substrate contains a high amount of dry matter, mixing is mandatory. The mixing method for the test for methane potential of organic substrates containing cow manure is given. There are two criteria according to which the choice of the ratio between the inoculum and the substrate for different types of organic substrates when determining their methane potential should be performed: the first criterion is the presence of its own cell biomass in the substrate; the second criterion is the presence of mostly easily fermentable components in the substrate. The required values of the ratio between the inoculum and the substrate are recommended for organic substrates that are promising and can be primarily used in biogas plants. Bibl. 20, table 3, fig. 1. [ABSTRACT FROM AUTHOR]

[Display omitted] • The superiority of ethanol-path anaerobic digestion was clarified via various means. • Liquid product presents higher recovery potential than gas product in carbon flux view. • The dominant microorganisms in the anaerobic digestion system are identified. To rapidly treat and stably utilize great quantities of fruit and vegetable waste (FVW), the strategies in anaerobic digestion pattern have been constantly improved. In this work, the efficiencies and capacities of carbon conversion in different FVW anaerobic digestion systems were studied. Compared to butyrate-path (BD) two-phase and single-phase anaerobic digestion (SD), the ethanol-path two-phase anaerobic digestion (ED) system showed the highest rate of converting insoluble into soluble carbon formation (82.2%) and methane yield conversed from soluble carbon which is 0.14 gCOD CH4 (gVSS d)−1. It was also found that the coexistence of Bacillus and Methanococcus in the methanogenic phase maintained fatty acids and methane generation. The advantage of carbon conversion efficiency in ED can be elucidated from the highest acetification rate (704.10 mgCOD (L h)−1) which means more converted acetate can be smoothly used for methane generation. Compared to methanogenesis converted from butyrate and propionate, the thermodynamic condition of methanogenesis converted from ethanol was more feasible. Also, the highest capacity of max methane production (197773.7 mL) of ED was simulated. ED might be an efficient and advantageous option for FVW methane digestion. Furthermore, comparison of acidogenic product and methane in conversion efficiency revealed that fatty acids should think as ideal anaerobic product rather than methane. [ABSTRACT FROM AUTHOR]

Potential energy recovery from Napier grass biomass was evaluated in batch mode and later compared with different digestion techniques, i.e., theoretical calculation and anaerobic digester operations. In the first part, different anaerobic digester sludges from pig farm, palm oil mill, and concentrated rubber latex factory, designated as PIG, PALM, and RUB in order, were evaluated for their ability as inoculant for biochemical methane potential (BMP) study. Using the first-order and Gompertz models, PIG and RUB were found to possess highest hydrolysis and methanogenesis activities, respectively. Prior to full BMP test on real biomass, suitable inoculum to substrate ratio (ISR) was identified, where ISR ≥1 g VSinoculum per g VSsubstrate was found statistically equivalent for the Napier grass substrate. Results from a series of BMP assays revealed a far more superior digestibility performance of the dual sludge inoculum over the individual PIG and RUB at 32% and 49%, respectively. The protocol proposed in this study could be used as an evaluation and selection guideline for BMP inoculum. In the second part, these BMP results were compared and contrasted with the theoretical methane potential and methane yields from wet and dry Napier grass digester operations in reference to the recoverable energy of this biomass. Gap between different methods suggests rooms for improvement and utilization of the residue. [ABSTRACT FROM AUTHOR]

Anaerobic digestion (AD) of sugarcane filter cake (SFC) was investigated by comparing the performance of pre-treatment methods in biochemical methane potential (BMP) tests and semi-continuous experiments. For that, SFC was pre-treated by autoclaving the substrate alone or with sodium hydroxide (NaOH). Experimental data from BMP tests were fitted to a kinetics model and further used for simulating the AD process in a continuous stirred-tank reactor (CSTR). BMP tests showed differences (p < 0.05) in total methane potential (S BMP), which have affected methane yields during simulation in a CSTR. Untreated produced 185 mL CH 4 g VS −1, autoclaved pre-treatment 174 mL CH 4 g VS −1 and autoclaved with NaOH pre-treatment 222 mL CH 4 g VS −1. Interestingly, such higher performance of autoclaved with NaOH pre-treatment was only observed at earlier stages during semi-continuous feeding experiment. At steady-state no significant differences (p > 0.05) in terms of methane yield were observed among the reactors (average of 224 mL CH 4 g VS −1). These results demonstrate that the benefits of pre-treatment could only be observed in BMP tests, which is likely explained by a better adaptation of the microbial community to the substrate during long term semi-continuous experiment, making SFC pre-treatment ineffective in a single-stage CSTR and under this feeding regime. Image 1 • Different pre-treatment methods were assessed on AD of SFC. • During BMP tests autoclave with NaOH improved (p < 0.05) methane potential. • Methane yield was not improved (p > 0.05) during semi-continuous experiments. • Microbial community adaptation might have influenced semi-continuous experiments. [ABSTRACT FROM AUTHOR]

Abstract Laminaria. sp. seaweeds have been recognised the potential to greatly contribute to the generation of renewable gaseous fuel via anaerobic digestion. Seaweed feedstock has been documented to consistently vary its biochemical composition with seasons, which affects stability of biomethane production. As currently seaweeds are too costly for use as third generation feedstock for biofuels, this paper investigates the biogas potential of the algal waste streams from the existing bio-industry. Analytical tests identified an improved digestibility of extracted residues (C:N > 20). Fermentation with and without inoculum acclimatation revealed the interaction between compositional seasonality and inoculum type to significantly affect methane production from the extracted samples. Summer's composition has the most significant impact on methane production, with best results achieved with acclimatised inoculum (433 ml CH 4 gVS−1 and final biodegradation of about 90%). Organics concentration (tCOD) and ash:volatile (A:V) ratio also play a major role in the bioconversion process. In particular, digestion with acclimatised inoculum better responds to A:V fluctuations across seasons, which produced the highest average methane yield of 334 ml gVS−1. Pretreatments are required to increase the biodegradation index in spring and summer when not using acclimatation. Highlights • Biorefined L. hyperborea residues demonstrated improved digestibility (C:N > 20). • Seasonal composition and inoculum type to significantly affect methane production. • The ratio of ash to volatile solids in spring and winter of 0.21 is the lowest recorded. • Summer yielded the most with 433 ml CH 4 gVS−1 with acclimatised inoculum. [ABSTRACT FROM AUTHOR]

Abstract A comprehensive sustainable Food Waste (FW) management is globally needed in order to reduce the environmental pollution and the financial costs due to FW disposal; anaerobic digestion is considered as one of the best environmental-friendly alternatives to this aim. A deep investigation of the chemical composition of different Food waste types (cooked kitchen waste (CKW), fruit and vegetable scraps (FVS) and organic fraction of municipal solid waste (OFMSW)) is here reported, in order to evaluate their relevant substance-specific properties and their impact on anaerobic biodegradability by means of a sophisticated automatic batch test system. Suitability for a mild thermal pre-treatment (T = 134 °C and p = 3.2 bar) to enhance the biological degradation of hardly accessible compounds was investigated. The pre-treatment affected significantly the carbohydrates solubilisation, and was able in reducing part of the lignocellulosic matrix. Moreover, in mesophilic conditions, the high solubilized sugars content favoured the initial recovery of hydrogen (not consumed by hydrogenotrophic methanogenesis), allowing to newly assess the extent of prompt fermentability. Pre-treatment enhanced hydrogen yields of FVS and OFMSW, with gains up to +50%, while the successive methane production, occurring in the same reactor, resulted affected by the lack of the soluble part of carbohydrates, "subtracted" for H 2 production. Only in thermophilic conditions, when no hydrogen in the biogas was detected, pre-treatment of OFMSW significantly increased methane yield (from 0.343 to 0.389 L CH 4 g−1 VS fed). A thermal pre-treatment seems the recommended solution in order to reduce part of the recalcitrant lignocellulosic matrix of food waste, to improve energy recovery and to eliminate the extra cost needed for pasteurization. Highlights • Food waste composition variability determined changes in pre-treatment effects. • Thermal pre-treatment increased H 2 production due to solubilized carbohydrates. • The extent of prompt fermentability from soluble sugars content was newly assessed. • Lignocellulosic matrix, when present, affected significantly BMP value. [ABSTRACT FROM AUTHOR]

Copyright of Algerian Journal of Environmental Science & Technology is the property of Algerian Journal of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

boyutlu partiküllerine göre elektrokimyasal, katalitik ve optik özellikler olmak üzere çok daha farklı fiziksel ve kimyasal özellikler göstermektedirler. Bu farklılaşmalardan dolayı endüstride kendilerine kolayca kullanım alanı bulmaktadırlar. Duş, bulaşık, çamaşır ve yağmur sularının nanopartikül içeren ürünlere teması ile suya karışan nanopartiküller, suyun izlediği yolu izlemekte ve bu şekilde nanopartiküller atıksu arıtma tesisine ulaşmaktadırlar. Bu çalışmada nanopartiküllerin endüstriyel kullanımları ve potansiyel toksik etkileri hakkında bilgi verilmiş, biyokütleden enerji üretiminde etkin bir şekilde kullanılan anaerobik parçalama prosesinin avantajlarına değinilmiş ve çevresel akıbetleri sonucunda atıksu arıtma tesislerinde anaerobik prosese dahil olan nanopartiküllerin bu prosesi nasıl etkilediğini araştıran çalışmalar incelenmiştir.

Innovative breeds of sugar cane yield up to 2.5 times as much organic matter as conventional breeds, resulting in a great potential for biogas production. The use of biogas production as a complementary solution to conventional and second-generation ethanol production in Brazil may increase the energy produced per hectare in the sugarcane sector. Herein, it was demonstrated that through ensiling, energy cane can be conserved for six months; the stored cane can then be fed into a continuous biogas process. This approach is necessary to achieve year-round biogas production at an industrial scale. Batch tests revealed specific biogas potentials between 400 and 600 LN/kgVS for both the ensiled and non-ensiled energy cane, and the specific biogas potential of a continuous biogas process fed with ensiled energy cane was in the same range. Peak biogas losses through ensiling of up to 27% after six months were observed. Finally, compared with second-generation ethanol production using energy cane, the results indicated that biogas production from energy cane may lead to higher energy yields per hectare, with an average energy yield of up to 162 MWh/ha. Finally, the Farm2CBG concept is introduced, showing an approach for decentralized biogas production.

Grass ley and whole-crop cereals used for biogas production are often finely chopped for subsequent ensiling and anaerobic digestion. Chopping can impact not only ensiling stability, digestibility and risk of process hick-ups in the digester but also harvesting capacity and fuel consumption. Based on field experiment data, the aim of this study was to investigate how three different nominal cutting lengths in the range of 3.5 mm to 12.5 mm impact methane yield and economic viability of grass ley and whole-crop cereals used as biogas substrate. A shorter cutting length affected the specific methane potential differently for the different crops, + 14 to − 25%. In biogas vehicle fuel production, balancing the additional energy and economic costs for shorter cutting length required an increased methane potential of less than 1% and 3%, respectively. As long as a decrease in cutting length increased the methane potential, the energy balance and economic result improved, despite higher energy inputs. However, mechanisms behind the impact on methane potential deserve further attention. In conclusion, we have shown that it is economically viable to produce methane gas, as a vehicle fuel, from several agricultural crops grown in the south of Sweden, i.e. grass ley and whole-crop rye and wheat, when they are harvested/chopped with a forager, ensiled as biogas feedstocks and processed to methane gas in a large-scale biogas plant. [ABSTRACT FROM AUTHOR]

The existing disposal method of fruit and vegetable wastes along with other waste has degraded the urban environment of Pakistan. This study was carried out which analyzes the feasibility of fruit and vegetable wastes for methane generation. From vegetable markets and fruit shops, the samples of fruit and vegetable waste were collected, respectively, by standard methodology. After collection, samples were analyzed for pH, alkalinity, volatile fatty acids, lignin content and proximate as well as ultimate analysis. Methane potential of fruit and vegetable wastes was found in the range of 265-444 Nml/gVS and 248-471 Nml/gVS, respectively. Also, the effect of substrate to inoculum ratio was studied. Findings of study led to conclude that maximum methane production from fruit and vegetable wastes could be achieved using lower substrate to inoculum ratio and vice versa. Therefore, it is recommended that dumping of fruit and vegetable wastes with other waste should be banned in Pakistan. Also the government of Pakistan should take a step immediately for mechanizing a system to separate biodegradable waste at source of generation for methane production. [ABSTRACT FROM AUTHOR]

The impacts of storage conditions, total solids content and silage additives were investigated at laboratory scale for cattle manure during up to 120 days. Wheat straw was used as co-substrate in the study of the effects of total solids content. Glucose and starch were used as model molecules of sugar-rich co-substrates. Single-handedly cattle manure lost 37% of its original methane potential after 120 days of anaerobic storage. This was essentially caused by the low total solids content and by the absence of water soluble carbohydrates in the feedstock. Wheat straw addition decreased moisture content and enabled cattle manure stabilization for a pH of 6.0. In contrast, extensive heterofermentative lactic acid bacteria fermentation occurred during co-ensiling with glucose and the pH quickly dropped to values below 4.0. Starch was used as substrate for fermentation but its hydrolysis limited bacterial activity and acidification. Finally, all the three co-substrates led to minimal methane potential losses after 120 days of storage. Co-ensiling will improve the energy efficiency of agricultural biogas plants that use stored cattle manure as feedstock. [ABSTRACT FROM AUTHOR]

Highlights • Biorefined seaweed residues demonstrated high potential for producing biogas. • Ambient extractions cascade improved the CH 4 and biodegradation potentials. • Average CH 4 yields on an annual basis were found between 107 and 405 mL gVS−1. • Seasonal composition and harvest site greatly affect digestion performance. Abstract Very recently, integrated biorefinery approaches are being developed with the aim to produce high-value products for a variety of industries in conjunction with green energy from sustainable biomass. Macroalgae (seaweed) have been regarded as more sustainable compared to terrestrial crops, since they do not occupy land for growth. Macroalgal biomass changes greatly according to species and harvest season, which affects its chemical energy potential. This study was conducted seasonally on five species of brown seaweed over a yearlong period to investigate the effects of chemical composition variations, bioproducts extraction processes and inoculum acclimatation on methane production. As a result of the bioproducts extraction, it was found the seaweed residues exhibit a great potential to produce methane. Stoichiometric methane yield and C:N ratio changed in favour of an improved digestibility with bioconversion rates greater than 70% in some instances, i.e. achieved by Laminaria species and on the West coast Fucus serratus. The two Laminaria species investigated also presented the highest CH 4 production rate, with Laminaria digitata reaching 523 mL CH 4 gVS−1 and L. saccharina peaking at 535 mL CH 4 gVS−1 with acclimatised and non-acclimatised sludge respectively. [ABSTRACT FROM AUTHOR]

The concept of year-round biogas production to increase the capacity factor of anaerobic digestion (AD) plants in sugarcane biorefineries was investigated for the first time in semi-continuous feeding mode. To simulate the use of sugarcane vinasse during the sugarcane season and sugarcane filter cake (SFC) during the off-season period, a two-stage reactor system based on an acidogenic continuous stirred-tank reactor (1st stage) followed by solid–liquid separation and an upflow anaerobic sludge blanket (UASB) reactor (2nd stage) to convert the COD-rich liquid fraction into biogas was operated. Additionally, to optimize the biogas production from SFC, the effects of its thermo-chemical pre-treatment on AD were investigated in a parallel reactor set-up. The saponification effect provided by autoclaving the substrate with sodium hydroxide improved the hydrolysis/fermentation of SFC in the acidogenic reactor, which in turn resulted in a 28% higher volumetric methane production in the methanogenic reactor ( p  < 0.05). However, the methane yields observed during operation of the two-stage reactor system were markedly lower than previously found in biochemical methane potential tests using SFC. In this case, the feed-in with low suspended solids required by UASB reactors prevented the utilization of the non-hydrolyzed/fermented solid fraction of SFC (> 60% of the substrate’s methane potential). Nevertheless, the capacity factor of the AD plants in sugarcane biorefineries could be increased from 0.55 up to 0.69 when considering a 200 d a −1 sugarcane season (0.66–0.83 for a longer season of 240 d a −1 ), representing an increase of 25.7%. The average capacity factor for biogas combined heat and power and upgrading units of around 0.91 (8000 h a −1 ) would be reached if further developments could improve the solubilization of non-hydrolyzed/fermented solids or alternatively allow their direct use in the methanogenic reactor. [ABSTRACT FROM AUTHOR]

The research carried out in this work determined the biochemical methane potential of the solid fraction remaining after acid fermentation with the recovery of volatile fatty acids and hydrogen, in which kitchen waste was used as the substrate. The methane fermentation process was carried out in bath bioreactors without pH regulation during the process, with the addition of digestate sludge from wastewater treatment plants and without its addition, at various substrate concentrations. It was found that the solid fraction after acid fermentation with the addition of digested sludge, is a good substrate for biogas production. The highest biochemical methane potential of 640 cm3 CH4×gsmo-1 was found in the process in which the waste solid fraction after acid fermentation concentration was 100 gm×dm-3. [ABSTRACT FROM AUTHOR]

Methane generation potential, L 0 , is a primary parameter of the first-order decay (FOD) model used for prediction and regulation of landfill gas (LFG) generation in municipal solid waste (MSW) landfills. The current US EPA AP-42 default value for L 0 , which has been in place for almost 20 years, is 100 m 3 CH 4 /Mg MSW as-discarded. Recent research suggests the yield of landfilled waste could be less than 60 m 3 CH 4 /Mg MSW. This study aimed to measure the L 0 of present-day residential and commercial as-discarded MSW. In doing so, 39 waste collection vehicles were sorted for composition before samples of each biodegradable fraction were analyzed for methane generation potential. Methane yields were determined for over 450 samples of 14 different biodegradable MSW fractions, later to be combined with moisture content and volatile solids data to calculate L 0 values for each waste load. An average value of 80 m 3 CH 4 /Mg MSW was determined for all samples with 95% of values in the interval 74–86 m 3 CH 4 /Mg MSW as-discarded. While no statistically significant difference was observed, commercial MSW yields (mean 85, median 88 m 3 CH 4 /Mg MSW) showed a higher average L 0 than residential MSW (mean 75, median 71 m 3 CH 4 /Mg MSW). Many methane potential values for individual fractions described in previous work were found within the range of values determined by BMP in this study. [ABSTRACT FROM AUTHOR]

The impact of formic acid and glucose addition on the co-ensiling of cattle manure with straw was assessed during 4 months at laboratory scale. Feedstock deprived of additives lost 67% of its methane potential for prolonged ensiling. This was mainly due to the lack of water-soluble carbohydrates and to the high methanogenic activity of cattle manure. The use of co-substrates enhanced biomass and energy conservation during ensiling. The best result was obtained for co-ensiling of cattle manure with glucose (100 g/kg of feedstock). For this condition, lactate production was extensive, which enabled biomass acidification, suppressed ammonia emissions and led to full preservation of methane potential after 4 months. Therefore, in field-scale storage, co-ensiling with a sugar-rich co-substrate appears to be the most resourceful method to optimize cattle manure preservation. Application of this promising technique will have a major impact on the methane yield of agricultural biogas plants where cattle manure has to be stored for long periods. [ABSTRACT FROM AUTHOR]

The continuously increasing demand for renewable energy sources renders anaerobic digestion one of the most promising technologies for renewable energy production. Due to the animal production intensification, manure is being used as the primary feedstock for most biogas plants. Thus, their economical profitable operation relies on increasing the methane yield from manure, and especially of its solid fraction which is not so easily degradable. In the present study, aqueous ammonia soaking (AAS) at six different concentrations in ammonia (5%, 10%, 15%, 20%, 25% and 32%) and for 1, 3 and 5 days at 22 °C was applied on digested fibers separated from the effluent of a manure-fed, full-scale anaerobic digester. A methane yield increase from 76% to 104% was achieved during the first series of experiments, while the difference in reagent concentration did not considerably affect the methane yield. It was shown that the optimal duration was three days for both 5% and 25% w/w reagent concentrations in ammonia tested. Carbohydrates and phosphorus content remained unaffected, while a slight decrease in Klason lignin and non-soluble organic nitrogen content was observed after AAS. It is concluded that AAS is a very promising treatment resulting to an overall increase of the methane yield of digested manure fibers from 76% to 265% depending on the conditions and the batch of digested fibers used (an even higher increase of 190%–265% was achieved during the 2nd series of experiments, where different AAS durations were tested, compared to the 1st series were different ammonia concentrations were applied).