M. E. Kashfi; R. Kouhikamali; G. Khayati
Abstract
In this study, a mathematical model was used to predict the dynamic behaviour of the system under conditions of imperfect mixing in an Anaerobic Digestion (AD) process. To evaluate the system performance, the effect of mixing parameters by calculating the quantities of methane gas produced, system power, ...
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In this study, a mathematical model was used to predict the dynamic behaviour of the system under conditions of imperfect mixing in an Anaerobic Digestion (AD) process. To evaluate the system performance, the effect of mixing parameters by calculating the quantities of methane gas produced, system power, and effluent quality was investigated. Numerical results showed that with an increase in the mixing rate (α) by 20%, methane production rate, power production, and the effluent COD removal efficiency of the system increased by 19%, 19% and 12%, respectively. At an equal mixing rate, the amount of methane produced in influent with a concentration of 12.1% was 4.5 times higher than the influent with a concentration of 2.5%, while no significant change was observed in the effluent quality. Additionally, it was found that the mixing rate effect is more important than the mean cell retention time in the anaerobic reactor. The best fitted correlations for methane production rate and effluent COD removal efficiency using regression analogy at different organic loads of wastewater are presented.
M. Tamoor; M. Sagir; G. Abbas; M. Ans Zaka; P. ZakaUllah
Abstract
Developing countries like Pakistan are in serious energy crisis. Renewable energy resources are the best alternative for conventional energy sources. The use of indigenous resources to produce bioenergy is an excellent solution to meet the energy needs of developing countries. The aim of the study was ...
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Developing countries like Pakistan are in serious energy crisis. Renewable energy resources are the best alternative for conventional energy sources. The use of indigenous resources to produce bioenergy is an excellent solution to meet the energy needs of developing countries. The aim of the study was to design, construct and production of bioenergy generation from indigenous resources to fulfil bioenergy requirement for electricity, cooking and heating. This research introduces the Best Available Technology (BAT) and bioenergy plant was constructed with local materials at minimum cost to avoid economic burden on bioenergy production cost. An underground bio-digester unit with a volume of 10 cubic meter (7 m3 bioenergy digester tank plus 3 m3 bioenergy gas cap/holder) has been installed. The daily feed was approximately 160 kilogram of cow slurry (80 kg cow dung plus 80 litres/kg water). The retention period was approximately 44 days and the reported seasonal temperature was approximately 24˚C - 32˚C. The unit was thermally insulated, so the fluctuation in temperature was slightly about ±2˚C. In experimental setup, indigenous biomass resources were mixed with water in a mixing chamber. Whole mixture enters into digester through the inlet pipe and regularly feed up to selected retention time. Anaerobic bacteria decompose the biomass in the digester and produce bioenergy. A simulation was performed to estimate relevant model parameters from experimental data. The proposed model can predict methane production behaviour from some key indicators (such as organic matter and VFAs) in the anaerobic digestion process. Results obtained from the experiment showed that the plant could generate average volume of 3.18 m3 of bioenergy biogas at average pressure of 170 mbar in a day. Results also revealed that the rate of bioenergy generation increase with respect to time from 33 to 44 days of retention time, the pressure of bioenergy generated increase from 35 mbar to 175 mbar. From the results, it was observable that the more the pressure in the chamber, the more the volume of bioenergy generated; thus, at 175 mbars, it produced maximum volume of 3.2 m3 of bioenergy.
Chemical Engineering
M. Benali
Abstract
This paper presents the experimental investigation of biogas production from cow dung as an alternative for fossil fuels for energy consumption. This was carried out using an 18 Liters capacity plastic keg prototype biogas plant, constructed to investigate the anaerobic digestion for generation of biogas. ...
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This paper presents the experimental investigation of biogas production from cow dung as an alternative for fossil fuels for energy consumption. This was carried out using an 18 Liters capacity plastic keg prototype biogas plant, constructed to investigate the anaerobic digestion for generation of biogas. Batch experiment was operated and daily gas yield from the plant was monitored for duration of 30 days. The digester was charged with these wastes in the ratio of 1:1, of waste to water, respectively. The mesophilic temperature ranges attained within the testing period were 20 – 35 °C. The Biogas production from cow dung fluctuates from the first day to the thirtieth day between 0 and 340 ml. The pH of cow dung gradually reduced due to acid former and methanogenes within the 30 days retention period.
K. Mazur; K. Roman; K. Borek
Abstract
About methods of reduction of ammonia emissions and greenhouse gas (GHG) from livestock production were investigated. Many techniques required high investments costs by low reducing level of emissions. Among all known methods, the most effective method is slurry cooling and decreasing slurry pH to obtain ...
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About methods of reduction of ammonia emissions and greenhouse gas (GHG) from livestock production were investigated. Many techniques required high investments costs by low reducing level of emissions. Among all known methods, the most effective method is slurry cooling and decreasing slurry pH to obtain high ammonia emission reductions. When we talk about GHG, anaerobic digestion and slurry separation are desired solutions. Regarding sustainable development in agriculture production, not only environmental effects, but also economy is important.
A. Zentner; C. Dornack
Abstract
The mechanical biological treatment plant of Freienhufen is used to stabilize residual waste. Since the rural districts Elbe - Elster and Oberspreewald - Lausitz match their waste management with federal law, organic fraction of municipal solid waste (OFMSW) will be collected separately in future. Hence ...
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The mechanical biological treatment plant of Freienhufen is used to stabilize residual waste. Since the rural districts Elbe - Elster and Oberspreewald - Lausitz match their waste management with federal law, organic fraction of municipal solid waste (OFMSW) will be collected separately in future. Hence the anaerobic digestion process has to be converted. The accomplishment has to refer to the existing operating regime to reduce investment costs. This contains a wet fermentation. In order to facilitate the conversion of the operating process, suitable particle sizes and volumetric loads have to be examined. In addition, the liquid phase of the digestate shall be recirculated maximal to save both fresh water and waste water disposal costs. The one year lasting investigations were performed in lab-scale with a various number of reactors. Before feeding the bio-waste was pre-treated. In order to do that, the bio-waste was milled to particle sizes of 2, 4, 8, and 10 mm. In addition, the digestate was dewatered to gain process water. While using the process water fresh water was substituted in varying proportions. The feeding of the reactors was adjusted to the standards of the operating plant. For that reason, the dry matter content in the reactor was adjusted at 10.5 %. Depending on the delivered raw material, this restriction led both to unsteady water requirements and volumetric loading. As a result of investigations an optimal particle size as well as optimal proportion of recirculated process water were defined. For that reason, comprehensive analyses were conducted weekly to characterize the delivered raw material as well as the solid and liquid phase of the digestate in order to determine critical moments due to recirculation of process water. In conclusion, liquid and solid phase of the digestate should be evaluated with regards to application as fertilizer.
M. A. Sayid Mia; M. Nur-E-Alam; S. Huque; M. M. Rahman; H. Ratnaweera
Abstract
Annually about 85,000 tons of raw hides and skins are estimated to be processed for leather production in Bangladesh. Tannery generates huge amount of solid and liquid wastes. Anaerobic digestion (AD) is a potential treatment to stabilize waste and produce biogas for renewable energy. The aim of this ...
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Annually about 85,000 tons of raw hides and skins are estimated to be processed for leather production in Bangladesh. Tannery generates huge amount of solid and liquid wastes. Anaerobic digestion (AD) is a potential treatment to stabilize waste and produce biogas for renewable energy. The aim of this study was to investigate the potential of AD of tannery solid waste (TSW) generated from the pre-tanning operation and to compare the effect of cow dung as the substrate to TSW. For the reaction with TSW by mixing with different substrates, biogas production was observed starting on 4th day with a steady increase. The cumulative gas production from each of the test reactors operating at the various organic loading of tannery solid waste, domestic sewage, and cow dung were different. This study shows an optimal AD process of TSW by mixing with different substrates for the obtained optimum C/N ratio and also for the high volatile solids (VS). The COD removal rates for the series of 5 reactors (R1, R2, R3, R4 and R5) were 48.75, 50.84, 46.07, 45.94 and 47.78% respectively. Maximum COD removal was achieved from reactor R2 where maximum gas was also produced.
S. Jijai; G. Srisuwan; S. O-Thong; I. Norli; C. Siripatana
Abstract
This study aimed to evaluate the Biochemical Methane Potential (BMP) of different types of wastewaters and sizes of granules. The granules (CS: from a cassava, SS: a seafood, and PS: a palm oil factory) and wastewaters initial Chemical Oxygen Demand (COD) were 18,800, 4,200 ...
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This study aimed to evaluate the Biochemical Methane Potential (BMP) of different types of wastewaters and sizes of granules. The granules (CS: from a cassava, SS: a seafood, and PS: a palm oil factory) and wastewaters initial Chemical Oxygen Demand (COD) were 18,800, 4,200 and 100,000 mg/l respectively). Modified Gompertz equation was used to compare the data from the experiments. Wastewater from a cassava factory gave the highest BMP when used with only granules from its own source (CS). Wastewater from seafood factory had the highest nitrogen content thus, represented the most imbalance nutrient source. In this case, mix- granules (SS+CS) gave highest BMP. Palm oil mill effluent did not match COD: N ratio criterion and had too high COD level which caused substrate inhibition. Here the mix-granules (PS+CS) gave highest BMP. In general, the larger granule size and the nutrient balance could improve the efficiency and hence increase the biogas production rate. The initial COD or different substrate has a strong effect on BMP and the maximum specific methane rates whereas the different sizes of granule have an effect on the length of lag phase period. In most cases, it was sufficient to represent the experimental data with traditional modified Gompertz equation and Monod models.
