The over-dependence on fossil fuels as primary energy source has led to various problems such as greenhouse effect, human health problems and degradation of environment (climate change). Due to recent rise in oil and natural gas prices,... more
The over-dependence on fossil fuels as primary energy source has led to various problems such as greenhouse effect, human health problems and degradation of environment (climate change). Due to recent rise in oil and natural gas prices, renewable sources of energy are gaining more importance and leading the way is methane gas obtained from biomass waste fermentation. This study investigates the possibility of producing biogas from water hyacinth in co-digestion with sugarcane bagasse and cow dung – replacing firewood as a source of fuel. In this work, different proportion of water hyacinth and sugarcane bagasse are used keeping the amount of cow dung constant for anaerobic digestion and analysed for biogas yield after 15th, 20th and 25th day of inoculation.
The European Union's (EU) climate and energy package requires all EU countries to reduce their greenhouse gas (GHG) emissions by 20% by 2020. Based on current trends, Ireland is on track to miss this target with a projected reduction of... more
The European Union's (EU) climate and energy package requires all EU countries to reduce their greenhouse gas (GHG) emissions by 20% by 2020. Based on current trends, Ireland is on track to miss this target with a projected reduction of only 5% to 6%. The agriculture sector has consistently been the single largest contributor to Irish GHG emissions, representing 33% of all emissions in 2017. Small-scale anaerobic digestion (SSAD) holds promise as an attractive technology for the treatment of livestock manure and the organic fraction of municipal wastes, especially in low population communities or standalone waste treatment facilities. This study assesses the viability of SSAD in Ireland, by modelling the technical, economic, and environmental considerations of operating such plants on commercial Irish dairy farms. The study examines the integration of SSAD on dairy farms with various herd sizes ranging from 50 to 250 dairy cows, with co-digestion afforded by grass grown on available land. Results demonstrate feedstock quantities available on-farm to be sufficient to meet the farm's energy needs with surplus energy exported, representing between 73% and 79% of the total energy generated. All scenarios investigated demonstrate a net CO 2 reduction ranging between 2059-173,237 kg CO 2-eq. yr −1. The study found SSAD systems to be profitable within the plant's lifespan on farms with dairy herds sizes of >100 cows (with payback periods of 8-13 years). The simulated introduction of capital subvention grants similar to other EU countries was seen to significantly lower the plant payback periods. The insights generated from this study show SSAD to be an economically sustainable method for the mitigation of GHG emissions in the Irish agriculture sector.
The rate at which feedstock is added to the anaerobic digester (AD) reactor has to be adjusted for the growth rate of methanogens bacteria. Increase in biogas yield is as a result of improved mathanogens forming bacteria. Under loading... more
The rate at which feedstock is added to the anaerobic digester (AD) reactor has to be adjusted for the growth rate of methanogens bacteria. Increase in biogas yield is as a result of improved mathanogens forming bacteria. Under loading and over loading of feedstock in the AD reactor has effect on methanogens forming bacteria. If more feedstock is added than the bacteria are able to degrade, the process will become acidic. Feedstock has to been fed to the reactor at a uniform rate and volume. If feeding pattern has to change, this must be done gradually so that bacteria can adapt to the new conditions. For optimum biogas yield, required amount of feedstock must be added to the AD reactor. The aim of this research work is to determine the effect of organic loading rate (OLR) on biogas yield from food waste, water hyacinth, cow dung, waste water from abattoir, poultry dropping and pig dung. The experimental set up comprises of single stage and three-stage continuous AD reactors. The same quantity and composition of feedstock were used and this was subjected to a variation of OLR 0.5 kg/m 3 (1.5 kg/m 3 , 2 kg/m 3 , 2.5 kg/m 3 , and 3 kg/m 3). The experiment was conducted within a mesophilic temperature range of 36 0 C-37 0 C, percentage total solid (%TS) of 9.98% and percentage volatile solid (%VS) of 78%. pH meter was used to monitored the daily pH reading of the slurry. It was observed that the quantity of biogas yield from the feedstock increases with increasing organic load rate to the optimum value of 1.5 kg/m 3 and started decreasing above the optimum value for a single stage AD reactor but this was not the case for the three-stages continuous AD reactors that experienced continuous increase in biogas yield with a successive increase in OLR from 1-5 kg/m 3-3.0 kg/m 3 .
The purpose of this research is to study co-digestion of sewage sludge and pine needles. When we talk about the major problems we are facing now days, we come across one of the most debatable problem of depletion of non- conventional... more
The purpose of this research is to study co-digestion of sewage sludge and pine needles. When we talk about the major problems we are facing now days, we come across one of the most debatable problem of depletion of non- conventional energy sources. So, one should divert the attention to one of the economic alternative energy source, Biogas. Anaerobic digestion of sewage sludge and pine needles will alleviate a number of environmental concern associated with them. Biogas or Anaerobic digestion technology has become a reliable source of renewable energy, facing a large climatic variation. Anaerobic digestion can help to reduce the load on the landfill by recycling the organic material of sludge and reduce the number of pathogens. Co-digestion will help to maintain a nutrient balance in both substrate and increase the performance of biogas digester in low temperature range. The substrates were studied fortheir physicochemical characteristics, such as pH, Total solids, Volatile Solids, Total Organic Carbon, Total Kjeldahl Nitrogen, organic matter and C/N. The Cellulose, Hemicellulose and Lignin content of pine needles were also determined. The batch study was done in two different anaerobic digesters AD1 and AD2 of 45 L which consist of sludge and mixture of sewage sludge and pine needles for a retention time of 70 days during winter season and its continuation in the summer season for 55 days. Initial and final values of slurry before and after degradation process of various physico-chemical parameters like pH, Total solids, Volatile Solids, Alkalinity, Chemical Oxygen Demand were analyzed. The result from the study shows that adding pine needles to the sewage sludge significantly increased the biogas productioncaused by balanced C/N ratio of the digester.
El Sector Agropecuario Mexicano enfrenta el día de hoy diversos retos: lluvias más intensas y frecuentes en la Región Sur, y sequías prolongadas en la Región Norte, escasez en las materias primas que sirven para la producción de alimentos... more
El Sector Agropecuario Mexicano enfrenta el día de hoy diversos retos: lluvias más intensas y frecuentes en la Región Sur, y sequías prolongadas en la Región Norte, escasez en las materias primas que sirven para la producción de alimentos balanceados incrementado de forma continua sus precios, y energéticos cada vez más costos. La producción de energía a partir de los desechos orgánicos que genera el mismo Sector puede aliviar estos problemas. Este estudio tuvo como objetivo determinar el potencial de producción de metano a través de la co-digestión en el rango mesofílico de excretas vacunas y ensilado de sorgo. Se estudiaron 5 tratamientos con diferentes relaciones excreta: ensilado: 100:0, 75:25, 50:50, 25:75, y 0:100 %. Se encontró que el mayor potencial de producción de metano en el corto tiempo (27 días), se logró con el tratamiento con 100 % de excretas vacunas, 235 m3/tonelada de sólidos volátiles. En los tratamientos que contuvieron ensilado de sorgo, la producción y calidad del biogás fue menor, requiriendo un mayor tiempo de digestión para lograr el máximo potencial.
Anaerobic digestion (AD) of FW shows instability due to both the presence of high lipids and accumulation of volatile fatty acids. In this study, AD of food waste (FW) was optimized by removing lipids (LRFW) and by co-digestion with... more
Anaerobic digestion (AD) of FW shows instability due to both the presence of high lipids and accumulation of volatile fatty acids. In this study, AD of food waste (FW) was optimized by removing lipids (LRFW) and by co-digestion with sewage sludge (1:1w/w on dry matter). The results obtained showed that lipids extraction increased FW methane yield from 400 to 418mL-gVSadded(-1) under mesophilic conditions (35°C) and from 426 to 531mL-gVSadded(-1) in thermophilic conditions (55°C). Two degradation phases (k1 and k2) described FW and LRFW degradation. In the thermophilic, LRFW-k1 (0.1591d(-1)) was slightly higher than that of FW (k1 of 0.1543d(-1)) and in the second stage FW-k2 of 0.0552d(-1) was higher than that of LRFW (k2 of 0.0117d(-1)). The majority of LRFW was degraded in the first stage. FW and sewage sludge co-digestion reduced VFA accumulation, preventing media acidification and improving process stability.
