摘要:

Anaerobic digestion of cheese whey offers a two-fold benefit: pollution potential reduction and biogas production. The biogas, as an energy source, could be used to reduce the consumption of traditional fuels in the cheese plant. However, as a result of little or no buffering capacity of whey, the pH of the anaerobic digester drops drastically and the process is inhibited. In this study, the effect of controlling the pH of the second chamber of a two-stage, 150 L anaerobic digester operating on cheese whey on the quality and quantity of biogas and the pollution potential reduction, was investigated using sodium hydroxide. The digester was operated at a temperature of 35 C and a hydraulic retention time of 15 days for three runs (no pH control, pH control with no reseeding, and pH control with reseeding) each lasting 50 days. The results indicated that operating the digester without pH control resulted in a low pH (3.3) which inhibited the methanogenic bacteria. The inhibition was irreversible and the digester did not recover (no methane production) when the pH was restored to 7.0 without reseeding, as the observed increased gas production was a false indication of recovery because the gas was mainly carbon dioxide. The addition of base resulted in a total alkalinity of 12,000 mg L as CaCO3. When the system was reseeded and the pH controlled, the total volatile acid concentration was 15,100 mg L (as acetic acid), with acetic (28 %), propionic (21%), butyric (25%), valeric (8%), and caproic (15%) acids as the major constituents. The biogas production was 62.6 L d (0.84m3m3 d) and the methane content was 60.7%. Reductions of 27.3, 30.4 and 23.3 % in the total solids, chemical oxygen demand and total Kjeldahl nitrogen were obtained, respectively. The ammonium nitrogen content increased significantly (140%).

ISSN:0090-8312    

DOI:10.1080/00908319950014623

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor

摘要:

Charcoal is an important product of pyrolysis of biomass sources. Charcoal can be used for domestic, agricultural, metallurgical, and chemical purposes. In this study different characteristics of charcoal one of the rape seed plant straw-stalk pyrolysis product was researched and presented as candidates.

ISSN:0090-8312    

DOI:10.1080/00908319950014632

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor

摘要:

Fly ash samples were collected in November and December of 1994, from generating units at a Kentucky power station using high- and low-sulfur feed coals. The samples are part of a two-year study of the coal and coal combustion byproducts from the power station. The ashes were wet screened at 100, 200, 325, and 500 mesh (150, 75, 42, and 25 mu m, respectively). The size fractions were then dried, weighed, split for petrographic and chemical analysis, and analyzed for ash yield and carbon content. The low-sulfur ''heavy side'' and ''light side'' ashes each have a similar size distribution in the November samples. In contrast, the December fly ashes showed the trend observed in later months, the light-side ash being finer (over 20 % more ash in the 500 mesh [25 mu m] fraction) than the heavy-side ash. Carbon tended to be concentrated in the coarse fractions in the December samples. The dominance of the 325 mesh (42 mum) fractions in the overall size analysis implies, though, that carbon in the fine sizes may be an important consideration in the utilization of the fly ash. Element partitioning follows several patterns. Volatile elements, such as Zn and As, are enriched in the finer sizes, particularly in fly ashes collected at cooler, light-side electrostatic precipitator (ESP) temperatures. The latter trend is a function of precipitation at the cooler-ESP temperatures and of increasing concentration with the increased surface area of the finest fraction. Mercury concentrations are higher in high-carbon fly ashes, suggesting Hg adsorption on the fly ash carbon. Ni and Cr are associated, in part, with the spinel minerals in the fly ash.

ISSN:0090-8312    

DOI:10.1080/00908319950014641

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor

摘要:

This paper provides a picture of energy resources and their current use in rural Ethiopia and presents an analysis of energy supply patterns and consumption trends. This exercise aims to build an empirical knowledge of ''real'' energy systems in the country and also to synthesize and analyze the general and specific problems that exist within the current energy system. Based on these lines of analysis, a series of technical and policy-oriented recommendations for rural energy development are discussed.

ISSN:0090-8312    

DOI:10.1080/00908319950014650

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor

摘要:

The increasing concentration of CO2 and other greenhouse gases (GHG) in the atmosphere can warm up the earth's surface and cause drastic changes to the climate. This paper has prepared an inventory of GHG emissions from energy consumption activities in the iron and steel industry in East China. (The region comprises two provinces, Jiangsu and Zhejiang , and one municipality, Shanghai.) The emission were measured in 1990 following the conventions set in IPCC Guidelines (1995). Energy consumption by the iron and steel industry and GHG emissions (including CO2, CH4, and N2O) inventory data are further analyzed and evaluated. As can be seen from the statistics in this paper, solid fuel is the main type of fuel consumed by the iron and steel industry in East China; this type of fuel accounts for 86.8%, while liquid fuels and gas fuels account for only 12.6% and 0.6% of the total energy consumption, respectively. Accordingly, GHG emissions from the combustion of solid fuels are highest, while those from gas fuels are minimal. The energy consumption and GHG emissions by the iron and steel industry accounts for a large percentage, about 7.86%, of the total GHG emissions in this district. This paper also discusses available mitigation appropriate to the energy consumption and GHG emissions by the iron and steel industry in East China.

ISSN:0090-8312    

DOI:10.1080/00908319950014669

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor

摘要:

Because of the Gulf War in 1991 over 300 oil lakes formed in the Kuwait desert. The bulk volume of the oil-contaminated soils has been estimated as 18 million cubic meters. These soils threaten the environment and prohibit the development of these lands. Various methods have been proposed to clean these sands, but they have serious economical, technical, or environmental disadvantages. Thermal desorption appears to be one of the most promising technologies for application in Kuwait oil lakes. The method is based mainly on the evaporation and visbreaking of the fluids contained in the contaminated soil by heating it up to 500 600 C under atmospheric pressure. The factors that control the performance of the retorting process include temperature, oil type of occurrence, connate water, particle size and miner alogical composition of the soil, loose versus consolidated soil samples, evaporation versus thermal or catalytic cracking caused by the minerals and clays incorporated in soil, and so on. Analysis and characterization of the produced fluids were conducted. Experiments performed on samples of the oil-contaminated sands and rocks yielded potential quantities in a fairly short time of retorting. The method is low cost and has a high potential in upgrading the recovered oil. It solves also the problem of extracting oils that exist in the forms of sludge and emulsion.

ISSN:0090-8312    

DOI:10.1080/00908319950014678

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor