Biological Wastes最新文献

Laboratory trials were carried out to determine the suitability of guar and sorghum stalks from Sudan as basic materials for composite insulation boards manufacture using cement as binder. Lignocellulosic material-to-cement ratios of 1:15 and 1:2 were used. The results show that these raw materials could successfully be used for insulation boards, with density of 530–700 kg/m³, satisfactory strength, and very good heat-insulation properties making them suitable for building.

Pichia pinus was grown in a semi-continuous process on mango-peel extract medium. The yield was 8 g/litre after 12 h at the end of the logarithmic phase. The biomass of Pichia pinus contained 53·7% protein. Amino acid analyses of the protein revealed the presence of all amino acids in substantial amounts except for those containing sulphur, which were the limiting amino acids. When fed to rats the protein biomass exhibited good nutritional values (protein efficiency ratio, 2·77 ± 0·126; apparent digestibility, 71·54 ± 1·02) as compared to the casein diet (protein efficiency ratio, 2·913 ± 0·127; apparent digestibility, 90·156 ± 0·64). Alkaline phosphatase levels were insignificantly different from the control during the experimental period (21, 28, 35 and 42 feeding days). The transaminases, γ-glutamyl transferase activities and creatinine levels in the serum were significantly varied at the 35th and 42nd feeding days. The glutamate oxaloacetate transaminase, urea and uric acid levels in serum were significantly increased only after 35 feeding days. No histological changes were observed in either liver or kidney tissues.

Two downflow anaerobic filters with different plastic media of the same specific surface area, treating currant-finishing wastewater are described. COD removal for modular plastic media with a cross-flow design was 80% and 75% for loadings of 8 and 10 kg COD/m³ day respectively. COD removal for pall-rings media gradually decreased from 90% to 57% as loadings gradually increased from 0·6 to 6 kg/m³ day. The downflow anaerobic filters have a low performance compared with other high-rate anaerobic reactors, the UAF, UASB and AFB.

An overview of the availability of bagasse and cotton plant stalk in India for manufacture of pulp and paper is given. The properties of pulp and paper produced using both the raw materials separately and in blends have been discussed. The possibilities of using kraft pulp of cotton-plant stalk for blending with chemi-mechanical bagasse pulp, replacing hardwood pulp, have been explored. Addition of kraft pulp of cotton-plant stalk in various proportions yielded papers with improved properties.

Sugarcane trash, paddy straw and wheat straw are the main farm by-products and are mostly underutilized. A large portion of these farm products goes to waste. These by-products could be successfully utilized as thermal insulators, if used in a high-density, compressed wafer-form.

Vermicomposting has the potential to convert many organic wastes into useful plant growth media. However, the rotary screens previously employed to separate worms from vermicompost often became blinded, making worm separation slow and inefficient. An improved method was required. An experimental machine employing a novel combing action to achieve separation was therefore constructed and tested. The comb-type mechanical separator was shown to be effective with vermicomposts which were well-worked and had moisture contents of 80% wet basis or less. For example, using well-worked vermicompost derived from separated cattle solids and containing approximately 5 kg of worms/m³ and with a moisture content (wet basis) of 75%, a throughput of 1·5 m³/h of vermicompost was possible, with a separation efficiency of 95%. Vermicomposting beds are sometimes maintained at moisture contents higher than 80% wet basis, and the degree of worm-working achieved can vary. Further work is therefore required to assess the performance of the comb-type separator over a wider range of conditions.

Growth characteristics and N assimilation of water hyacinth (Eichhornia crassipes [Mart] solms) were evaluated for diluted and undiluted effluents from anaerobic digesters containing ¹⁵N-labeled water hyacinth as feedstock. The diluted effluents were an excellent growth media for plants and resulted in high dry weight gains. The highest gain in plant dry weight (18 gm⁻² day⁻¹) was noted for the diluted effluent having an initial NH₄N concentration of 65 mg liter⁻¹ and an electrical conductivity (EC) of 1·6 dSm⁻¹. Plant death was observed in four of the six undiluted effluents. Ammonium loss from the effluents was described with first-order kinetic rate constants which ranged from 0·175 to 0·593 day⁻¹. Plant assimilation of ¹⁵NH₄N ranged from 36 to 66% in diluted effluents and from 2 to 77% in undiluted effluents. Plant survival was not dependent entirely on NH₄N concentrations or EC of the effluents.

Broiler litter can serve as a source of nutrients for plants and ruminant animals. Analyses of litter samples collected from 106 sources in Alabama showed that the nutrient content of litter varies widely. Litter nitrogen averaged 4·0% (24·9% crude protein (CP)), but ranged from 2·3% (14·4% CP) to 6·0% (37·5% CP). Phosphorus averaged 1·56% and potassium 2·32% of dry matter. The average N:P:K ratio of the litter was 3:3:2. Ash was extremely variable, ranging from 8·9% to 64·3%, and averaging 24·7%. Ash content was higher p<0·05) in samples taken after the litter was removed from the broiler house (28·6%) than in samples taken directly from the broiler house (20·2%). Nitrogen and acid detergent soluble nitrogen were negatively correlated (p<0·01) with ash, while acid detergent fiber and most minerals were positively correlated with ash. At current prices, average quality broiler litter in Alabama is valued at US$113.67 Mg⁻¹ (US$104.95 Imperial ton⁻¹) as a potential low-cost feed ingredient for lactating beef cattle and US$31.23 Mg⁻¹ (US$27.59 Imperial ton⁻¹) as a fertilizer.

In inoculated batch digestions the maximum gas production from Parthenium was 35 litres (75% CH₄) per kg fresh plant at a TS concentration of 5%.

A laboratory-scale sequencing batch reactor was fed with synthetic wastewater based on sucrose to determine the biokinetics of the process. The values of u_max and K_s were found to be 0·32 h⁻¹ and 563 mg/litre, respectively, while the yield constant was determined to be 0·656 with a standard deviation of 0·102. COD removal was good. The relationship between the food:microorganisms (F/M) ratio and SVI was explored and results showed that increases in the F/M ratio led to decreases in SVI values. The initial adsorption of substrate was proportional to the amount of biomass in the reactor. Comparisons between changes in MLVSS and Total Viable Count were made and MLVSS was not found to be a good indicator for the viability of organisms in the reactor.