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1.
The winemaking process generates many by-products besides wastewater, mainly grape marcs, grape stalks, and wine lees. Anaerobic digestion is particularly suitable to treat winery waste because of its high content of nutrient-rich organic matter and for its noticeable energetic potential. To date, only results from mesophilic tests have been extensively reported. In this study, potential methane production and kinetic constants were determined by batch trials under thermophilic conditions and compared with mesophilic values already reported in literature. Grape marcs and wine lees appeared to be the most promising substrates with an estimated potential of 0.34 and 0.37 Nm3CH4/kgVSfed, respectively, while grape stalks generated only 0.13 Nm3CH4/kgVSfed. In order to assess the feasibility of a continuous anaerobic digestion process, a lab-scale semi-continuous reactor was constructed. Because of the consumption of buffer capacity, the biological process was difficult to control. On the other hand, biogas was produced when working with a hydraulic retention time of 40 d and with previously fermented grape marcs; a specific biogas production of 0.29 Nm3/kgVSfed was observed. The results of the continuous tests were used to calculate the potential energy recovery from grape marcs produced in Italy (808 thousands of tons per year) in terms of heat and electricity; about 245 GWh of heat and 201 GWh of electricity per annum could be generated in Italian scenario.  相似文献   

2.
Forage radish, a winter cover crop, was investigated as a co-substrate to increase biogas production from dairy manure-based anaerobic digestion. Batch digesters (300 cm3) were operated under mesophilic conditions during two experiments (BMP1; BMP2). In BMP1, the effect of co-digesting radish and manure on CH4 and H2S production was determined by increasing the mass fraction of fresh above-ground radish in the manure-based co-digestion mixture from 0 to 100%. Results showed that forage radish had 1.5-fold higher CH4 potential than dairy manure on a volatile solids basis. While no synergistic effect on CH4 production resulted from co-digestion, increasing the radish fraction in the co-digestion mixture significantly increased CH4 production. Initial H2S production increased as the radish fraction increased, but the sulfur-containing compounds were rapidly utilized, resulting in all treatments having similar H2S concentrations (0.10–0.14%) and higher CH4 content (48–70%) in the biogas over time. The 100% radish digester had the highest specific CH4 yield (372 ± 12 L kg−1 VS). The co-digestion mixture containing 40% radish had a lower specific CH4 yield (345 ± 2 L kg−1 VS) but also showed significantly less H2S production at start-up and high quality biogas (58% CH4). Results from BMP2 showed that the radish harvest date (October versus December) did not significantly influence radish C:N mass ratios or CH4 production during co-digestion with dairy manure. These results suggest that dairy farmers could utilize forage radish, a readily available substrate that does not compete with food supply, to increase CH4 production of manure digesters in the fall/winter.  相似文献   

3.
Sugarcane leaves and tops are lignocellulosic agricultural by-products which are considered a significant input for biogas production. Their potential pretreatment by sodium hydroxide prior to co-digestion with cow manure helps increase the methane (CH4) content, biodegradation efficiency of the lignocellulosic materials and CH4 yield. The untreated and pretreated sugarcane leaves and tops to cow manure and water of different ratios were digested and co-digested in the 5 L reactors by semi-continuous operation with hydraulic retention time of 40 days. The pretreated sugarcane leaves and tops to cow manure at the initial prepared ratio of 100 g:100 g, in 800 mL water which was corresponding to the organic loading rate (OLR) of 0.61 kg COD/m3·day was recommended. At this ratio, the chemical oxygen demand and total volatile solids degradation efficiency was 68.80 and 72.52%, respectively, the CH4 content was 44.52% and the CH4 yield was 331 L/kg COD degraded. According to the results, there is an average of 3.7% deviation between the practical model based on the thermodynamic balance equations carried out using the Aspen Plus and the experimental study. The highest exergy destruction rate is found at 21 kW where the sugarcane leaves and tops, and cow manure ratio is 100 g:100 g, in 800 mL water. The highest energy and exergy efficiencies of the overall system are calculated as 45.53% and 46.02%, respectively.  相似文献   

4.
This study investigates enhancing the biogas production of sunnhemp by pretreatment, before the anaerobic digestion and co-digestion processes, to address the complex and recalcitrant structure of the plant. Fresh sunnhemp harvested at a cutting interval of 50 days is used in the study. Five systems (each with a 5 litre useable volume) are operated semi-continuously with five different ratios of the feedstock by feeding separate feedstocks every five days with a hydraulic retention time (HRT) of 40 days. The system operates at room temperature (30 °C). The study uses sunnhemp as 20% of the feedstock and also considers sunnhemp mixed with cow manure at different ratios, with the weighed sunnhemp being pretreated with dilute sodium hydroxide. Pretreatment of sunnhemp before digestion produces a methane (CH4) yield 89% greater than that of the untreated sunnhemp. It requires 3.597 kg of dry sunnhemp to produce 1 m3 of CH4 and the annual CH4 yield per hectare is 19,015 m3. In the pretreatment of sunnhemp before co-digestion, the increased CH4 yield depends on the amount of pretreated sunnhemp in the feedstocks. However, the %CH4, the CH4 production level and the system stability depend on the optimal ratio of the sunnhemp to cow manure. The initially prepared sunnhemp to cow manure ratio is recommended at 10 g:10 g in 80 mL of water. At this ratio, the %CH4 and the CH4 yield are 53.84% and 313 kg chemical oxygen demand (COD) removed, respectively, and the COD removal efficiency is 56.4%. Sunnhemp has high potential and it is worth pretreating before producing biogas. Using sunnhemp to produce biogas is recommended to decrease greenhouse gas emissions and mitigate global warming.  相似文献   

5.
Buffalo grass and alkaline-pretreated buffalo grass samples were co-digested with cow manure separately to generate biogas in anaerobic reactors. The study considered a solid content of 20% (10% buffalo grass and 10% cow manure). The methane (CH4) content and CH4 yield of the distinct experiments were compared. For the untreated buffalo grass, the weighed buffalo grass was mixed with cow manure and water. For the alkaline-pretreated buffalo grass, the weighed buffalo grass was soaked in 1% sodium hydroxide for 1 day prior to being mixed with cow manure and water. The untreated and pretreated buffalo grass-manure were fed semi-continuously at the rate of 125 mL/day for five days feeding in a 5 L reactor, with 40 days hydraulic retention time. The experiments were conducted for approximately 100 days. Results were reported when the systems were in steady-state conditions. The chemical oxygen demand (COD) conversion efficiency of co-digestion of the untreated and pretreated buffalo grass-manure were 46.21 and 62.76%, respectively, and for the total volatile solids (TVS) were 68.50 and 71.80%, respectively. The CH4 contents generated from co-digestion of the untreated and pretreated buffalo grass-manure were 48.32% and 50.36%, respectively. The CH4 yields generated from co-digestion of the untreated and pretreated buffalo grass-manure were 328 and 385 L/kgTVS conversion, respectively. It was observed from the experiments that pretreatment of the buffalo grass prior to co-digestion provided system stability during biogas production.  相似文献   

6.
The present study focused on the mesophilic anaerobic bio-hydrogen production from PPS (pulp & paper sludge) and FW (food waste), and the subsequent anaerobic digestion of the effluent for the methane production under thermophilic conditions by a two-stage process. The maximum hydrogen yield of 64.48 mL g−1 VSfed and methane yield of 432.3 mL g−1 VSfed were obtained when PPS and FW were applied with 1: 1 VS ratio as the feedstock. No VFA were cumulated in the reactor during the period of hydrogen - methane fermentation, as well as no NH3–N and Na+ inhibition were found in the process. 71%–87% removal efficiencies of SCOD were attained for hydrogen and methane co-production. pH 4.8–6.4 and alkalinity 794–3316 mg CaCO3 L−1 for H2 fermentation, as well as pH 6.5–8.8 and alkalinity 4165–4679 mg CaCO3 L−1 for CH4 fermentation, were achieved without any adjustment. This work showed that anaerobic co-digestion of PPS and FW for hydrogen-methane co-production was a stable, reliable and effective way for energy recovery and bio-solid waste stabilization by the two-stage mesophilic–thermophilic process.  相似文献   

7.
The potential of semi-continuous mesophilic anaerobic digestion (AD) for the treatment of solid slaughterhouse waste, fruit-vegetable wastes, and manure in a co-digestion process has been experimentally evaluated. A study was made at laboratory scale using four 2 L reactors working semi-continuously at 35 °C. The effect of the organic loading rate (OLR) was initially examined (using equal proportion of the three components on a volatile solids, VS, basis). Anaerobic co-digestion with OLRs in the range 0.3–1.3 kg VS m−3 d−1 resulted in methane yields of 0.3 m3 kg−1 VS added, with a methane content in the biogas of 54–56%. However, at a further increased loading, the biogas production decreased and there was a reduction in the methane yield indicating organic overload or insufficient buffering capacity in the digester.In the second part of the investigation, co-digestion was studied in a mixture experiment using 10 different feed compositions. The digestion of mixed substrates was in all cases better than that of the pure substrates, with the exception of the mixture of equal amounts of (VS/VS) solid cattle–swine slaughterhouse waste (SCSSW) with fruit and vegetable waste (FVW). For all other mixtures, the steady-state biogas production for the mixture was in the range 1.1–1.6 L d−1, with a methane content of 50–57% after 60 days of operation. The methane yields were in the range 0.27–0.35 m3 kg−1 VS added and VS reductions of more than 50% and up to 67% were obtained.  相似文献   

8.
The objective of this study was to characterise anaerobic batch biodegradation of potato waste alone and when co-digested with sugar beet leaves. The effects of increasing concentration of potato waste expressed as percentage of total solids (TS) and the initial inoculum-to-substrate ratio (ISR) on methane yield and productivity were investigated. The ISRs studied were in the range 9.0–0.25 and increasing proportions of potato waste from 10% to 80% of TS. A maximum methane yield of 0.32 l CH4/g VSdegraded was obtained at 40% of TS and an ISR of 1.5. A methane content of up to 84% was obtained at this proportion of potato waste and ISR. Higher ISRs led to faster onset of biogas production and higher methane productivity. Furthermore, co-digestion of potato waste and sugar beet leaves in varying proportions was investigated at constant TS. Co-digestion improved the accumulated methane production and improved the methane yield by 31–62% compared with digestion of potato waste alone.  相似文献   

9.
Anaerobic digestion (AD) is a promising option for the environmentally friendly recycling of agricultural by-products. However, overloading of the digester with sugar, starch or protein might cause inhibition of the anaerobic processes. The aim of the present project was to investigate the AD of sugar beet, starch potato by-products and effect of pre-treatment by steam on methane yield of potatoes pulp. The investigated by-products have been: sugar beet pulp silage (SBP), sugar beet tail silage (SBT), potato pulp (PP), potato peel pulp (PPP) and potato fruit water (PFW). All by-products were digested in 1 l eudiometer-batch digesters at 37.5 °C during 28–38 days. The specific methane yields of SBP and SBT were 430 and 481 lN kg?1 volatile solids (VS), respectively. The specific methane yields of PP, PPP and PFW were 332, 377 and 323 lN (kg VS)?1. A steam pre-treatment significantly increased the specific methane yield of PP up to 373 lN (kg VS)?1.  相似文献   

10.
This study investigated two wildtype green algae, Micractinium sp. and Chlorella sp., for their growth in high nitrogen wastewater (mixture of sludge centrate and primary effluent wastewater) and subsequent anaerobic digestion under mesophilic conditions. Extraction and analysis of extracellular polymeric substances (EPS) in both algal species during cultivation showed that Micractinium generated larger quantity of EPS-proteins than Chlorella. Anaerobic digestion of harvested algae showed the opposite trend that Chlorella allowed a higher CH4 yield on the volatile solids fed the digester (VSfed) of 230 dm3 kg−1 than Micractinium (209 dm3 kg−1). These results suggested that different growth patterns of two types of algae, with different quantity of EPS expressed, affected anaerobic digestibility and biogas yield. Co-digestion of algae with waste activated sludge (WAS) improved the volatile solids reduction, hydrolysis efficiency as well as the biogas yields of algae.  相似文献   

11.
The aim of this laboratory-scale study was to investigate the long-term anaerobic fermentation of an extremely sour substrate, an energy crop, for continuous production of methane (CH4) as a source of renewable energy. The sugar beet silage was used as the mono-substrate, which had a low pH of around 3.3–3.4, without the addition of manure. The mesophilic biogas digester was operated in a hydraulic retention time (HRT) range between 15 and 9.5 days, and an organic loading rate (OLR) range of between 6.33 and 10 g VS l−1 d−1. The highest specific gas production rate (spec. GPR) and CH4 content were 0.67 l g VS−1 d−1 and 74%, respectively, obtained at an HRT of 9.5 days and OLR of 6.35 g VS l−1 d−1. The digester worked within the neutral pH range as well. Since this substrate lacked the availability of macro and micro nutrients, and the buffering capacity as well, external supplementation was definitely required to provide a stable and efficient operation, as provided using NH4Cl and KHCO3 in this case. The findings of this ongoing long-term fermentation of an extremely acidic biomass substrate without manure addition have reflected crucial information about how to appropriately maintain the operational and particularly the environmental parameters in an agricultural biogas plant.  相似文献   

12.
The biogas yield of solid manure from dairy cattle depends on its quality and the proportion of excreta and organic litter material contained within. The biogas yield of both faeces and straw is available in literature. Straw is a common litter material of mixed farms. However, straw is scarcely available on dairy farms. Oat husks are appropriate to replace or supplement straw for use as litter material. In this study, the actual methane yield and the total methane potential of oat husks were determined. Based on an optimized test with ground oat husks, the total methane potential resulted from regression and extrapolation of the experimental data. The total methane potential was determined with 242 LN CH4 kg−1 VS added. Additionally, the actual methane yield over retention time at a digestion temperature of 37 °C was determined, using untreated oat husks. For 42 days of retention, the methane yield was 202 LN CH4 kg−1 VS added at 52% CH4 content. Results indicate that the methane yield of oat husks reaches the same level as that of straw. The total methane potential is not higher, but digestion of oat husks may proceed faster. Verification of the laboratory results on-farm revealed that the contribution of oat husks to overall methane production of a prototype biogas plant for solid manure might reach up to 80%.  相似文献   

13.
《Biomass & bioenergy》2006,30(6):599-603
Two different approaches were attempted to try and enhance methane production from an industrial waste composed of 100% barley, which results from production of instant coffee substitutes. In previous work, this waste was co-digested with an excess of activated sludge produced in the wastewater treatment plant located in same industrial unit, resulting in a very poor methane yield (25 LCH4(STP)/kgVSinitial), and low reductions in total solids (31%) and in volatile solids (40%).When the barley waste (BW) was subjected to alkaline hydrolysis pre-treatment before co-digestion with activated sludge, the methane production increased to 222 LCH4(STP)/kgVSinitial and the total and volatile solids reductions increased to 67% and 84%, respectively.The second approach, followed in the present work, consisted of co-digestion with kitchen waste (40% BW, 60% kitchen waste). The methane production was 363 LCH4(STP)/kgVSinitial and the total and volatile solids reductions were 61% and 67%, respectively.  相似文献   

14.
Cassava pulp is a major by-product produced in a cassava starch factory, containing 50–60% of starch (dry basis). Therefore, in this study we are considering its potential as a raw material substrate for the production of methane. To ensure sufficient amounts of nutrients for the anaerobic digestion process, the potential of co-digestion of cassava pulp (CP) with pig manure (PM) was further examined. The effect of the co-substrate mixture ratio was carried out in a semi-continuously fed stirred tank reactor (CSTR) operated under mesophilic condition (37 °C) and at a constant OLR of 3.5 kg VS m?3 d?1 and a HRT of 15 days. The results showed that co-digestion resulted in higher methane production and reduction of volatile solids (VS) but lower buffering capacity. Compared to the digestion of PM alone, the specific methane yield increased 41% higher when co-digested with CP in concentrations up to 60% of the incoming VS. This was probably due to an increase in available easily degradable carbohydrates as the CP ratio in feedstock increased. The highest methane yield and VS removal of 306 mL g?1 VSadded and 61%, respectively, were achieved with good process stability (VFA:Alkalinity ratio < 0.1) when CP accounted for 60% of the feedstock VS. A further increase of CP of the feedstock led to a decrease in methane yield and solid reductions. This appeared to be caused by an extremely high C:N ratio of the feedstock resulting in a deficiency of ammonium nitrogen for microbial growth and buffering capacity.  相似文献   

15.
Overview analysis of bioenergy from livestock manure management in Taiwan   总被引:2,自引:0,他引:2  
The emissions of greenhouse gases (GHGs) from the livestock manure are becoming significant energy and environmental issues in Taiwan. However, the waste management (i.e., anaerobic digestion) can produce the biogas associated with its composition mostly consisting of methane (CH4), which is now considered as a renewable energy with emphasis on electricity generation and other energy uses. The objective of this paper was to present an overview analysis of biogas-to-bioenergy in Taiwan, which included five elements: current status of biogas sources and their energy utilizations, potential of biogas (methane) generation from livestock manure management, governmental regulations and policies for promoting biogas, benefits of GHGs (i.e., methane) emission reduction, and research and development status of utilizing livestock manure for biofuel production. In the study, using the livestock population data surveyed by the Council of Agriculture (Taiwan) and the emission factors recommended by the Intergovernmental Panel on Climate Change (IPCC), the potential of methane generation from livestock manure management in Taiwan during the period of 1995–2007 has been estimated to range from 36 to 56 Gg year−1, indicating that the biogas (methane) from swine and dairy cattle is abundant. Based on the characteristics of swine manure, the maximum potential of methane generation could reach to around 400 Gg year−1. With a practical basis of the total swine population (around 4300 thousand heads) from the farm scale of over 1000 heads, a preliminary analysis showed the following benefits: methane reduction of 21.5 Gg year−1, electricity generation of 7.2 × 107 kW-h year−1, equivalent electricity charge saving of 7.2 × 106 US$ year−1, and equivalent carbon dioxide mitigation of 500 Gg year−1.  相似文献   

16.
The performance of temperature phase anaerobic co-digestion (TPAcD) for sewage sludge and sugar beet pulp lixiviation (using the process of exchanging the digesting substrate between spatially separated thermophilic and mesophilic digesters) was tested and compared to both single-stage mesophilic and thermophilic anaerobic co-digestion. Two Hydraulic Retention Times (HRT) were studied in the thermophilic stage of anaerobic digestion in two temperature phases, maintaining the optimum time of the mesophilic stage at 10 days, obtained as such in single-stage anaerobic co-digestion. In this way, we obtained the advantages of both temperature regimes.Volatile solids removal efficiency from the TPAcD system depended on the sludge exchange rate, but fell within the 72.6–64.6% range. This was higher than the value of 46.8% obtained with single-stage thermophilic digestion and that of 40.5% obtained with mesophilic digestion. The specific methane yield was 424–468 ml CH4 per gram of volatile solids removed, similar to that of single-stage mesophilic anaerobic digestion. The increase in microbial activity inside the reactor was directly proportional to the organic loading rate (OLR) (or inversely proportional to the HRT) and inversely proportional to the size of the microbial population in single-stage anaerobic co-digestion systems.  相似文献   

17.
This study aims to study the methane generation potential (BMP tests) of different samples from the dark acid fermentation of sewage sludge:wine vinasse, and sewage sludge:wine vinasse:poultry manure. Specifically, mixtures of sewage sludge (S) and wine vinasse (V) were used in a 50:50 ratio and mixtures of sewage sludge and wine vinasse with 10 g/L of poultry manure (PM) (50:50 + 10 g/L) (S:V + PM). The goal was to determine the effect of the high ammonia concentrations in poultry manure when was used as co-substrate in the anaerobic methanogenic degradation of sewage sludge and vinasse. Results obtained show that the addition of 10 g/L of poultry manure to the SV mixture improves the production of methane generation, reaching values of 166 mL of accumulated methane. The SVPM mixture shows the highest purification percentages, with 63.90% TCOD removal, 79.51% SCOD removal and a yield of 52.05 mLCH4/gSVadded. The SVPM test showed a higher concentration of microorganisms during the BMP test, although the population of microorganisms for the SV test was doubled and presented greater activity with values of 2.27 versus 1.73E-11 LCH4/Cells.  相似文献   

18.
Continuous bio-methanization of an energy crop, namely the beet silage, was investigated in this laboratory-scale work as mono-substrate, using a mesophilic biogas digester controlled by a fuzzy logic control (FLC) technique and without using any supplementing or buffering agent, despite the low pH of the substrate around 3.80. The temperature, pH, redox potential (ORP), daily biogas production and composition of digester biogas were continuously measured online. During the operation, the hydraulic retention time (HRT) varied between 24.8 and 9 days, as the organic loading rate (OLR) ranged from 2.6 to 4.7 g L?1 d?1. The average pH, specific gas production rate (spec. GPR) and volumetric gas production rate (vol. GPR) were determined to be 7.12, 0.31 L g VS?1 d?1 and 1.084 L L?1 d?1, respectively. The average methane (CH4) content of digester biogas was about 56%. The FLC technique, which was developed at HAW Hamburg for anaerobic conversion of acidic energy crops to methane, determined the daily feeding volume (~ OLR/HRT) for the biogas digester, depending on the feedback from online pH and methane measurements, and on the calculation of the spec. GPR. The spec. GPR was calculated by the corrected daily biogas production. Through online monitoring of pH, biogas production rate and composition, and by use of the FLC technique, the acidic beet silage could continuously be converted to biogas, without using manure or any other kind of buffering or supplementing agent(s). The lab-scale anaerobic biogas digester performed stable and safe, without encountering any problems of instability, as indicated by an adequate amount of buffering capacity, a VFA content below 0.5 g L?1 and a neutral pH range throughout the study.  相似文献   

19.
Optimization of biogas production and quality from chicken droppings by anaerobic co-digestion with Cymbopogon citratus was investigated. The anaerobic digestions of chicken droppings, chicken droppings with C. citratus as well as C. citratus alone were carried out for a period of 30 days at an average ambient temperature of 33.1 ± 2 °C using identical reactors (A–C) respectively. Results obtained indicate that chicken droppings produced on the average 1.8 L/kg/day of biogas, co-digestion of chicken droppings and C. citratus produced 1.3 L/kg/day of biogas while C. citratus alone produced 1.0 L/kg/day with estimated average methane content of 41.71%, 66.20% and 71.95% for reactors A–C respectively. The water boiling rates of biogas from chicken droppings, chicken droppings with C. citratus, and C. citratus alone were 0.079 L/min, 0.091 L/min and 0.12 L/min respectively, after the gases were scrubbed with water and slaked lime. It was observed that notwithstanding the higher biogas volumetric yield from chicken droppings digested alone, the co-digestion of chicken droppings with C. citratus had better gas quality with respect to the methane content present and cooking rate. This study has shown that the methane content of biogas from animal manure substrates could be improved by co-digestion with energy plants.  相似文献   

20.
The high production of sugarcane in Brazil and its application of ethanol and sugar production results in a higher generation of vinasse and bagasse. The treatment of these residues can be carried out using anaerobic co-digestion procedures. Besides promoting waste treatment, it enables energy exploration through biogas and hydrogen generation. Bioenergy use can also generate steam in sugar and alcohol plants by burning, sugarcane milling, fueling vehicles for the transport of products, among others. These energy applications allow total and efficient, energetic exploring of sugarcane. Hence, this study estimated the production of methane, hydrogen, thermal and electrical energy generated from vinasse and bagasse in the autonomous and annexed Brazilian ethanol and sugar plants. Three scenarios present the use of biogas generated: Scenario 1: energy use of all methane from biogas; Scenario 2: hydrogen production from the remaining methane, after considering the energy autonomy of the ethanol plants; Scenario 3: hydrogen production from all the methane generated. All the scenarios which considered the use of methane led to energy self-sufficiency in the sector. However, only annexed plants present economic feasibility for implementing the project. Scenario 2 is highlighted in this study, once beyond the sector's energetic self-sufficiency, the operational conditions enabled the storage of 9.26E+07 Nm3.d?1 of hydrogen, equal 3.04E+08 ton per year. CH4 and H2 production seen in a global scenario of circular economy and energy security have high benefits, contributing to the gradual transformation of an economy dependent on non-renewable resources into a circular and renewable economy.  相似文献   

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