Effect of false flax oilcake in thermophilic biogas production

False flax oilcake has been found to be suitable for anaerobic fermentation in mixtures with cattle slurry and straw. In organic farms, digestion of cattle dung and wheat straw with 8 % dry matter content mixed with 5 % of total material weight false flax oilcake is a feasible option for utilizing false flax oilcake to produce farm-own renewable energy and offering farm-own high nitrogen (ammonia) content fertilizer (2.48 g kg-1 wet wt). In field digesters, the biogas yield of 8 % dry matter pure material under thermophilic condition was 0.24 l g-1 VS fed. The biogas yield could be increased by mixing 5 % false flax oilcake to get 0.37 l g-1 VS fed and a VS conversion efficiency with 0.83 l g-1 VS destroyed. Under laboratory controlled conditions, the biogas yield of slurry with 0.5 % oilcake was a little higher than biogas yield of the digestion of pure material, which was 0.26 and 0.24 l g-1 VS fed, respectively. Compared with the field experiment, only small amounts of biogas were produced in the lab-scale when 5 % oilcake was mixed in. The mixing can improve the biogas yield and substrate reduction in the digesters which have sufficient material. Further research is needed to find out the best controlled conditions (high-efficient bacteria, mixing frequency and time) and best equipment (for example: two phases digesters)

Biogas yield from various types of biodegradable materials

Cílem této bakalářské práce je popis výtěžnosti bioplynu z různých druhů substrátů. V úvodní části jsou zpracována základní fakta o anaerobní technologii, princip tvorby bioplynu a využití bioplynu v praxi. Hlavní část práce je věnována výtěžnosti bioplynu, je uvedeno několik druhů substrátů s uvedením výtěžnosti, jsou popsány vlivy kvality surovin a jejich předúpravy na výtěžnost bioplynu. Součástí práce je i jednoduchý výpočet výtěžnosti bioplynu ze zvoleného substrátu.The objective of this bachelor thesis is a description of the biogas yield from various types of biodegradable materials. In the introductory part there are presented facts about anaerobic technology, production principle of biogas and biogas utilization in practice. The document body deals with biogas yield, there are presented several types of biodegradable materials with biogas yield, there are described material quality effects and their preliminary treatment to biogas yield. Elementary calculation of the biogas yield from particular material is included.

Changing old habits: the case of feeding patterns in anaerobic digesters

A non-linear programming model was developed to maximize the economic profit from an anaerobic co-digester. The model consists of a combination of technical and economic equations, linked through the biogas production variable. Five scenarios were simulated. These differed with regard to substrate inlet mass flow rate, organic loading rate and hydraulic retention time. The impact on biogas production was investigated and an economic analysis was undertaken based on the concepts of profitability and Net Present Value. The model results indicate that varying the substrate inlet mass flow rate and organic loading rate could have a positive impact on the profitability of co-digesters in Flanders. This can be achieved either by increasing the interval time between feedstock input, or by feeding individual streams of feedstock separately into the system, while at the same time reducing the hydraulic retention. time

A Review on the Fate of Nutrients and Enhancement of Energy Recovery from Rice Straw through Anaerobic Digestion

Open field burning and tilling the rice straw (RS) back into the fields causes environmental threats by contributing to the increased greenhouse gas emissions. Energy and nutrient recovery from RS through anaerobic digestion (AD) is an effective solution for its utilization. Although RS has good methane potential, its characteristics make it a difficult substrate for AD. This paper reviews the characteristics of RS, mass balance, and distribution of nutrients into liquid and solid digestate in the AD. The present review also discusses the effect of temperature, co-digestion, mixing, inoculum, organic loading rate, recycling liquid digestate, the addition of trace elements, and their bioavailability on the enhancement of biogas/methane yield in the AD of RS. In addition, the digestion of RS at various scales is also covered in the review.BMBF, 01LY1508A, KMU-innovativ-Verbundprojekt Klimaschutz: Entwicklung und Integration eines innovativen Verfahrens zur Biogasherstellung aus Reisstroh in regionale Wertschöpfungsketten im ländlichen Raum in Südostasien unter Berücksichtigung nachhaltiger Entwicklung und Klimaschutz - Beispiel Vietnam, Teilprojekt 1DFG, 414044773, Open Access Publizieren 2019 - 2020 / Technische Universität Berli

Enhancement of biogas potential of primary sludge by co-digestion with cow manure and brewery sludge

Anaerobic digestion (AD) has long been used to treat different types of organic wastes especially in the developed world. However, organic wastes are still more often considered as a waste instead of a resource in the developing world, which contributes to environmental pollution arising from their disposal. This study has been conducted at Bugolobi Sewage Treatment Plant (BSTP), where two organic wastes, cow manure and brewery sludge were co-digested with primary sludge in different proportions. This study was done in lab-scale reactors at mesophilic temperature and sludge retention time of 20 d. The main objective was to evaluate the biodegradability of primary sludge generated at BSTP, Kampala, Uganda and enhance its ability of biogas production. When the brewery sludge was added to primary STP sludge at all proportions, the biogas production rate increased by a factor of 3. This was significantly (p<0.001) higher than observed gas yield (337 +/- 18 mL/(L.d)) in the control treatment containing (only STP sludge). Co-digesting STP sludge with cow manure did not show different results compared to the control treatment. In conclusion, Bugolobi STP sludge is poorly anaerobically degradable with low biogas production but co-digestion with brewery sludge enhanced the biogas production rate, while co-digestion with cow manure was not beneficial

Impact of different particle size distributions on anaerobic digestion of the organic fraction of municipal solid waste

Particle size may significantly affect the speed and stability of anaerobic digestion, and matching the choice of particle size reduction equipment to digester type can thus determine the success or failure of the process. In the current research the organic fraction of municipal solid waste was processed using a combination of a shear shredder, rotary cutter and wet macerator to produce streams with different particle size distributions. The pre-processed waste was used in trials in semi-continuous ‘wet’ and ‘dry’ digesters at organic loading rate (OLR) up to 6 kg volatile solids (VS) m?3 day?1. The results indicated that while difference in the particle size distribution did not change the specific biogas yield, the digester performance was affected. In the ‘dry’ digesters the finer particle size led to acidification and ultimately to process failure at the highest OLR. In ‘wet’ digestion a fine particle size led to severe foaming and the process could not be operated above 5 kg VS m?3 day?1. Although the trial was not designed as a direct comparison between ‘wet’ and ‘dry’ digestion, the specific biogas yield of the ‘dry’ digesters was 90% of that produced by ‘wet’ digesters fed on the same waste at the same OLR.<br/

EVALUATION OF BIOGAS POTENTIALS OF Cymbopogon citratus AS ALTERNATIVE ENERGY IN NIGERIA

This research explored the potentials of Cymbopogon citratus (Lemon Grass) for biogas production as a cost effective alternative energy source in Nigeria. The Cymbopogon citratus was crushed to small sizes between 20 to 50mm and pre-fermented for 40 days in a PVC drum. Six (6) kg of the pre-fermented Cymbopogon citratus was mixed with water in ratio 1:1 w/v to form slurry and digested for 30 days. The floating drum gas collection system was used to collect the gas after it was passed through water and lime respectively for scrubbing. A total of 0.125m3 (6.95x10-4 m3/kg/day) and 0.0897m3 (4.98x10-4 m3/kg/day) of biogas was produced from the Cymbopogon citratus before and after scrubbing respectively. The gas produced was used for cooking test. The scrubbed gas had higher cooking rates for both water and rice respectively (0.12L/min and 0.0052L/min) while the cooking rates for unscrubbed gas were 0.079L/min and 0.0036L/min respectively. During this period, daily ambient temperatures of the research environment varied from 310C to 420C while the digester temperature fluctuated between 28oC and 36.70C. The pH of the medium fluctuated optimally between 6.5 and 7.8. The research demonstrated that Biogas could be produced from Cymbopogon citratus in quantity and quality comparative with those in literatures

Dry anaerobic digestion of organic residues on-farm - a feasibility study

Objectives The feasibility study shall answer the following questions: Are there economical and ecological advantages of on-farm dry digestion biogas plants? How the construction and operation parameters of a dry digestion biogas plant influence environment, profit, and sustainability of on-farm biogas production? The aim of the feasibility study is to provide facts and figures for decision makers in Finland to support the development of the economically and environmentally most promising biogas technology on-farm. The results may encourage on-farm biogas plant manufacturers to develop and market dry anaerobic digestion technology as a complementary technology. This technology may be a competitive alternative for farms using a dry manure chain or even for stockless farms. Results Up to now farm scale dry digestion technology does not offer competitive advantages in biogas production compared to slurry based technology as far as only energy production is concerned. However, the results give an over-view of existing technical solutions of farm-scale dry digestion plants. The results also show that the ideal technical solution is not invented yet. This may be a challenge for farmers and entrepreneurs interested in planning and developing future dry digestion biogas plants on-farm. Development of new dry digestion prototype plants requires appropriate compensation for environmental benefits like closed energy and nutrient circles to improve the economy of biogas production. The prototype in Järna meets the objectives of the project since beside energy a new compost product from the solid fraction was generated. On the other hand the two-phase process consumes much energy and the investment costs are high (>2000 € m-3 reactor volume). Dry digestion on-farm offers the following advantages: Good process stability and reliability, no problems like foam or sedimentation, cheap modules for batch reactors, less reactor capacity, reduced transport costs due to reduced mass transfer in respect of the produced biogas quantity per mass unit, compost of solid digestion residues suitable as fertiliser also outside the farm gate, use of on-farm available technology for filling and discharging the reactor, less process energy for heating because of reduced reactor size, no process energy for stirring, reduced odour emissions, reduced nutrient run off during storage and distribution of residues because there is no liquid mass transfer, suitable for farms using deep litter systems. These advantages are compensated by following constraints: Up to 50% of digestion residues are needed as inoculation material (cattle manure does not need inoculation) requiring more reactor capacity and mixing facilities. Retention time of dry digestion is up to three times longer compared to wet digestion requiring more reactor capacity and more process energy, filling and discharging batch reactors is time and energy consuming. We conclude that only farm specific conditions may be in favour for dry digestion technology. Generally, four factors decide about the economy of biogas production on-farm: Income from waste disposal services, compensation for reduction of greenhouse gas emission, compensation for energy production and - most important for sustainable agriculture - nutrient recycling benefits. Evaluation of the results We did not find any refereed scientific paper that includes a documentation of an on-farm dry digestion biogas plant. It seems that we tried first. We also could not find any results about the biogas potential of oat husks, so we may have found these results first. Farm scale production of anaerobically treated solid manure for composting is new. Dry fermentation biogas plants offer the possibility to design solid manure compost by variation of fermentation process parameters. From different scientific publication databases we found about 10 000 references concerning biogas research during the past 10 years. Less than ten are dealing with biogas reactors for non-liquid substrates on-farm. Recent research mainly concentrates on basic research, biogas process research for communal waste, large-scale biogas plants, and research on laboratory level. This mirrors the fact, that production of research papers is rather financed than product development on site. Our conclusion is that it seems worldwide to be very difficult or even impossible to find financial support for on site research, especially for on-farm prototype biogas reactors. We suppose the following reasons for this fact: biogas plant research requires proficiency in many different scientific disciplines, lack of co-operation between engineering and life sciences, high development costs to transfer basic research results into practical technical solutions, low interest of researchers because on site and on-farm research enjoys low appreciation in terms of scientific credits, portability of farm specific design and process solutions is difficult. Our conclusion is that on site and on-farm research has to be supported by funding agencies if integration of biogas and bio energy into the farm organism is considered as an important target within the agricultural policy framework. Future research on both dry fermentation technique and biogas yield of solid organic residues may close present knowledge gaps. Prototype research may offer competitive alternatives to wet fermentation for farms using a solid manure chain and/or energy crops for biogas production. To encourage farmers and entrepreneurs to foster the development of dry fermentation technology support in terms of education and advisory services is also necessary

Analysis of soybean production and biogas yield to improve eco-marketing and circular economy

In the study attempts to analyze soybean production and possibility obtaining biogas from soybean biomass, in order to obtain energy inputs into the profit function and realized a circular economy. This paper presents the results of five-year studies of soybean production analysis in the world and in Serbia, and was also examined soybeans morphoproductive characteristics and on the biogas yield, of the Favorit variety, produced in Pančevo, Serbia. Serbia has excellent conditions for soybeans production. The maximum soybean biomass yield of soybean variety Favorit was 5 t ha-1. The average biogas yield, for tested five years, was 368 m3ha-1. The biogas yield was in positive statistically significant correlations on the plant height (r=0.65*) and in positive correlations with biomass yield. Soybean cultivar with their characteristics justify the sowing and can be used as a raw material in bio-fuels production