Agricultural Wastes最新文献

Urea and wheat straw moistened to 70% was stacked in the open for 12 or 9 days' natural fermentation. The urea was added at the rate of 4% on a dry straw basis. The fermentation was carried out by turning the stacks at 3- or 6-day intervals, or the stacks were not turned for the entire periods. About 84% to 87% was degraded during the fermentation, resulting in microbial-protein enrichment of the treated straw. A high stack temperature developed (65°C to 73°C) and the ammonia released penetrated the cell wall sufficiently to loosen the ligno-cellulose bonds. The microbes utilized hemicellulose and cellulose, without effecting the lignin content.

The daily dry matter intake (7·96kg) during a 4-month acceptability trial, using 12 day fermented straw with 2·0 kg fresh green fodder and minerals, showed the straw was palatable and was able to maintain the six adult buffaloes without affecting their body weight or health. Further metabolic trials with the different straw preparations showed that digestibilities of DM, OM, CF and cellulose, and N retention, were significantly (P < 0·01) improved in 9 day fermented straw as compared with the other straw preparations.

The results showed that, by 9 days' fermentation of wheat straw, the cellulose digestibility and apparent biological value were improved to the extent that fermented straw supplemented with adequate vitamins and minerals could be used as a sole maintenance ration for ruminants.

Attention was devoted to the delignification of the crude bagasse (CB) and cotton stalks (CS) by cheap commercial sodium hypochlorite solution.

Optimum delignification of these substrates was achieved by treatment with 0·7 g Cl g⁻¹ substrate (pH 7·0) for 20 h at room temperature, with a solid: liquid (S:L) ratio 1:20.

The delignified CB and CS were saccharified with an enzyme preparation from a potent local mutant of Trichoderma viride (253-M16). A satisfactory saccharification was obtained with most of the treatments used. The highest conversion yield (93%) was recorded with CB treated with sodium hypochlorite solution (S:L ratio 1:20), followed by NaOH (0·05 m).

Two basidiomycetes mould isolates were studied for the production of extracellular cellulases and ligninase in submerged shake culture using whole bagasse as substrate. The effects of some added carbohydrates on enzyme production, substrate decomposition and biomass formation were examined. In both cultures the addition of lactose stimulated biomass production and increased the decomposition of total carbohydrate and lignin contents of bagasse. Lactose was the only sugar which stimulated cellulase and ligninase in both cultures.

Thermochemical decomposition and catalytic conversion of rice hull and some other cellulosic materials in a fluidized bed reactor containing different catalysts as the bed material were studied. The use of catalyst invariably gave gas yields above that of the non-catalyzed gasification process and also changed the product distribution according to the nature of the catalyst. Generally, an acidic catalyst favored the formation of carbon monoxide and olefins while a supported-metal catalyst increased the amounts of hydrogen and carbon dioxide. Nickel catalyst yielded as much as 60% hydrogen at a reaction temperature of 650°C. The gas yield and product distribution are mainly decided by the properties of the catalyst and less by the properties of the biomass.

Jute (Corchorus capsularis L. and Corchorus olitorius L.) is a cash crop of India, Bangladesh and Thailand. Jute stick and caddis are by-products of its processing. These by-products are of little economic importance at the moment, and considerable quantities are wasted annually. The present paper reviews the potential of jute wastes for industrial utilization, such as in the manufacture of pulp and paper, rayon, board, cellulose derivatives and chemicals. Three of these processes have been tested at full-scale mill production.

Anaerobic digestion of rice crop residues-husk and straw—was carried out in 190-litre metallic digesters. One kilogram of rice straw yielded about 220 litres of biogas under batch digestion. However, rice husk did not perform well due to the high lignin content and unfavourble nonlignin-carbon to nitrogen ratio. A mixture of rice straw and cattle dung (1:1 dry weight basis) yielded 9·1% more gas than rice straw alone.

An integrated system for the bioconversion of poultry droppings for biogas production and utilization of the effluent for the production of the blue-green alga Spirulina platensis was studied. Poultry droppings produced 0·54 m³ of biogas per kilogram of Total SOlids (TS). The 2% TS biogas plant effluent as sole nutrient medium for Sprirulina yielded 7–8 g dry algae a day. The biomass was harvested by filtration. The sundried algal biomass has been used as a poultry feed component. In economic terms the system appears promising.