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41.
B. KetheesanN. Nirmalakhandan 《International Journal of Hydrogen Energy》2011,36(18):11693-11701
Our previous studies had demonstrated enhanced fermentative hydrogen production from sucrose in batch reactors with dairy manure as a supplement providing nutrients, buffering, and hydrogen-producing organisms. In this study, manure leachate is evaluated as a supplement in glucose fermentation in batch and continuous flow reactors at 25 °C without any nutrient supplements, initial pH adjustments, buffering, or stirring. Hydrogen yields found in this study are comparable to or better than those reported at higher temperatures. When the heat energy expended to maintain the test temperatures is considered, positive net energy gain of ∼10 kJ/L of reactor volume was achieved while most literature reports translated to negative net energy gain. Anaerobic digestion (AD) and microbial fuel cells (MFC) were evaluated as follow-up processes to extract additional energy from the end products of dark fermentation (DF). This evaluation showed that DF followed by MFCs to produce electricity to be a more energy-efficient approach. 相似文献
42.
Optimization of an Oil Extraction Process for Algae from the Treatment of Manure Effluent 总被引:1,自引:0,他引:1
Walter Mulbry Shannon Kondrad Jeffrey Buyer Devanand L. Luthria 《Journal of the American Oil Chemists' Society》2009,86(9):909-915
Increasing interest in the coupling of biological wastewater treatment processes with the generation of value-added products
(such as oil containing ω-3 fatty acids (FA)) has stimulated efforts in adapting extraction methods for treatment byproducts.
This study’s objective was to compare a high temperature/pressure extraction method (accelerated solvent extraction) (ASE)
and a manual extraction method (modified Folch extraction) with regard to their ability to extract total oil from three algae
samples from the treatment of dairy manure effluent. The efficiency of total oil and FA extraction with three solvents (chloroform/methanol,
isopropanol/hexane, and hexane) was also evaluated using the ASE method. Results showed that the ASE method yielded higher
values for total oil content compared to the Folch method but similar values for FA content and composition after four extraction
cycles with chloroform/methanol. However, the ASE method yielded much higher amounts of FA in the first cycle (85–95% of total
extracted) compared to the Folch method (44–55% of total extracted in the first cycle). As expected, the extraction efficiency
of the ASE method for FA was dependent on the extraction solvent. FA content values using ASE with chloroform/methanol > isopropanol/hexane > hexane.
FA content values using the Folch method or ASE with chloroform/methanol were not significantly influenced by sample particle
size within the size range of 0.1–1 mm. 相似文献
43.
探讨了不同C/N的有机肥对油菜生物量、硝酸盐含量以及土壤EC的影响。结果表明:施用低量氮肥,增施M1能够增加油菜的生物量,硝酸盐含量无显著变化;增施M2、M3,能够降低油菜生物量和硝酸盐含量。当N用量为N0.067g kg-1土时(300kg hm-2),增施M1,油菜生物量和硝酸盐含量无显著变化;增施M2、M3时,显著降低生物量和硝酸盐含量。施用高氮肥,增施三种有机肥显著增加油菜生物量,硝酸盐含量无显著变化。三种不同C/N的有机肥在低量氮肥时对土壤EC的影响不显著,在高氮量时,增施M1能够增加土壤EC,增施M2、M3能够降低土壤EC。 相似文献
44.
对山东省1952年以来肥料的施用情况和养分平衡状况进行了分析,结果表明:山东省自1952年以来,化学肥料用量逐步增加,有机肥用量逐渐减少;2002年有机肥用量仅占肥料施用总量的35.50%,其中有机氮肥、磷肥和钾肥分别占氮、磷、钾肥用量的26.09%、34.55%和57.60%,而化学肥料用量占肥料施用总量的64.50%,其中无机氮、磷、肥占氮、磷、钾肥的比例分别为73.91%、65.45%和42.68%,化学肥料用量明显高于有机肥;而且全省137个县市之间养分分配极不平衡,单位耕地面积化肥用量相差数千倍。进一步对全省氮、磷、钾投入产出状况进行分析发现,氮素从1982年开始盈余,每年盈余的氮素在30万吨左右;磷素从1972年开始盈余,2002年盈余高达134.64万吨;自1952年以来,钾素一直处于亏缺状态,目前每年亏缺60万吨左右。 相似文献
45.
Quantifying the Reduction of Greenhouse Gas Emissions as a Resultof Composting Dairy and Beef Cattle Manure 总被引:1,自引:0,他引:1
E.?PatteyEmail author M.?K.?Trzcinski R.?L.?Desjardins 《Nutrient Cycling in Agroecosystems》2005,72(2):173-187
Greenhouse gas emissions from the agricultural sector can be reduced through implementation of improved management practices.
For example, the choice of manure storage method should be based on environmental decision criteria, as well as production
capacity. In this study, greenhouse gas emissions from three methods of storing dairy and beef cattle manure were compared
during the summer period. The emissions of CH4, N2O and CO2 from manure stored as slurry, stockpile, and compost were measured using a flow-through closed chamber. The largest combined
N2O–CH4 emissions in CO2 equivalent were observed from the slurry storage, followed by the stockpile and lastly the passively aerated compost. This
ranking was governed by CH4 emissions in relation to the degree of aerobic conditions within the manure. The radiative forcing in CO2 equivalent from the stockpiled manure was 1.46 times higher than from the compost for both types of cattle manure. It was
almost twice as high from the dairy cattle manure slurry and four to seven times higher from the beef cattle manure slurry
than from the compost. The potential reduction of GHG was estimated, by extrapolating the results of the study to all of Canada.
By composting all the cattle manure stored as slurry and stockpile, a reduction of 0.70 Tg CO2-eq year−1 would be achieved. Similarly, by collecting and burning CH4 emissions from existing slurry facilities, a reduction of 0.76 Tg CO2-eq year−1 would be achieved. New CH4 emission factors were estimated based on these results and incorporated into the IPCC methodology. For North-America under
cool conditions, the CH4 emission factors would be 45 kg CH4 hd−1 year−1 for dairy cattle manure rather than 36 kg CH4 hd−1 year−1, and 3 kg CH4 hd−1 year−1 for beef cattle manure rather than 1 kg CH4 hd−1 year−1. 相似文献
46.
The potential for a suite of isotope and chemical markers to differentiate sources of nitrate contamination: a review 总被引:3,自引:0,他引:3
Nitrate is naturally found within the environment as part of the nitrogen cycle. However, anthropogenic inputs have greatly increased nitrate loads within ground and surface waters. This has had a severe impact on aquatic ecosystems and has given rise to health considerations in humans and livestock. Therefore, the identification of nitrate sources is important in preserving water quality and achieving sustainability of our water resources. Nitrate sources can be determined based on the nitrate nitrogen (N) and oxygen (O) isotopic compositions (δ15N, δ18O). However, sewage and manure have overlapping δ15N and δ18O values making their differentiation on this basis problematic. The specific differentiation between sources of faecal contamination is of particular importance, because the risk to humans is usually considered higher from human faecal contamination (sewage) than from animal faecal contamination. This review summarises the current state of knowledge in using isotope tracers to differentiate various nitrate sources and identifies potential chemical tracers for differentiating sewage and manure. In particular, an in depth review of the current state of knowledge regarding the necessary considerations in using chemical markers, such as pharmaceuticals and food additives, to differentiate sewage and manure sources of nitrate contamination will be given, through an understanding of their use, occurrence and fate, in order to identify the most suitable potential chemical markers. 相似文献
47.
Polymer flocculation mechanism in animal slurry established by charge neutralization 总被引:2,自引:0,他引:2
Flocculation and filtration of animal manure is practically and environmentally beneficial. However, the flocculation mechanism in manure need to be clarified to use the technique efficiently rather than relying on trial-and-error. Manures were flocculated with polyacrylamides. Floc size, dewaterability, dry matter and turbidity were measured. At optimal polymer volume, the charge neutralization was determined, i.e. amount of negative manure particle charge neutralized by positive polymer charge. The optimal cationic polymer properties were linear and very high molecular weight, which caused efficient particle catching. And it had medium charge density, which caused efficient particle attachment. The required charge neutralization was 5-23% (15% for the optimal polymer). Polymer bridging proved the dominant flocculation mechanism; patch flocculation may be slightly significant for some polymers, while coagulation proved insignificant. Manure’s high ionic strength, high dry matter content and highly charged small molecules caused bridging to be more dominant in manure than in other typically flocculated media. 相似文献
48.
Gerardo Gordillo 《Fuel》2010,89(2):384-2300
Including dairy biomass (DB) as feedstock in gasification processes for locally based power generation could mitigate the environmental impact from DB produced in large US farms (56 million dry tons per year) and fossil-fuels emissions, since biomass is a CO2 neutral fuel. The current paper presents experimental results obtained from adiabatic, fixed bed gasification of DB using air and steam as oxidizers. The effect of equivalence ratio (ER) and steam to fuel ratio (S:F) ratio on temperature profile, gas composition (CO, CO2, H2, N2, CH4, and C2H6), gross heating value (HHV) and energy conversion efficiency (ECE) are discussed. The results show that the peak temperature (Tpeak), ECE, and CO decrease and H2 and CO2 increase with increase in ER; the increase in S:F at same ER increases H2, CO2, CH4, HHV, and ECE, and decreases CO. 相似文献
49.
Small-scale anaerobic digester installation has been a development objective of the Indian government to provide rural households clean fuel. Anaerobic digester installation is heavily subsidised. Depending on caste, the rate of subsidy offered for the smallest system available (1 m3) varies between 32.35% and 41.18% of the total installation price. Yet, there are gaps in knowledge regarding the usefulness of such subsidies from a sustainability perspective. A cost-benefit analysis was conducted to evaluate the circumstances required for digester sustainability. The analysis used household data collected from 115 cattle owning households in Odisha, India to evaluate profitability at three levels of subsidy (none, General caste subsidy, and Schedule Caste/Schedule Tribe subsidy). Additional analyses considered the effect of; taking a loan, replacing electric lighting with biogas lighting, and the wealth level of the household. The results indicated that access to subsidy improved profitability. Yet, profitability could be achieved without the use of subsidy. The level of benefit accrued by households was similar independent of wealth. However, the provision of subsidy was essential for ensuring profitability for those households required to take a loan to meet the expense of installation. Such findings highlight the importance of subsidy as a means of including the poor. 相似文献
50.
Sugar beet leaves (SBL), sugar beet top (SBT), sugar beet pulp (SBP) and desugared molasses (DM) are by-products from the sugar production. In the present study we investigated the potential of SBL, SBT and SBP as feedstock for biogas production. The maximum methane potential of SBL, SBT and SBP determined by batch assays was found to be 490, 500 and 240 mL-CH4/gVS-added respectively. Three reactor experiments were carried out to investigate the effect of co-digestion of SBP, DM and manure at different ratios, on biogas process efficiency and stability. The results showed that DM was potentially inhibiting the biogas process and the co-digestion of SBP and DM was only successful at high dilution with manure or water. In contrast, SBP was shown to be a good substrate for biogas production and the methane yield of 280 mL-CH4/gVS-added was obtained in a thermophilic continuously operated reactor, co-digesting 50% of SBP with cow manure. 相似文献