Biological Wastes最新文献

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.

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.

Urea at five levels (0, 1, 2, 4 and 6%) and NaOH at two levels (2 and 4% of dry matter to each of 2 and 4% urea level) were added to a mixture consisting of seven parts distillers grain solubles, two parts pressed pig slurry solids and one part ground wheat straw, on a fresh weight basis.

After a fermentation period of 42 days at ambient temperature in 100-litre capacity silos, the pH dropped in the unsupplemented wastelage (3·90), but it increased after urea and NaOH supplementation (up to 7·14). Ammonia and acetate concentrations in wastelage were enhanced with urea addition. Increase of acetate and butyrate concentration was observed when NaOH was added.

In sacco degradability increased from 49·0% (untreated sample) to 67·0% when 2% urea and 4% NaOH were added. The rumen dry matter degradability of wastelages was significantly higher when sheep consumed a diet rich in roughages (57·5%) rather than a concentrate ration (50·1%). Sheep consumed about 1 kg dry matter daily when unsupplemented or when 1% urea-added wastelage was fed. Higher levels of chemicals decreased dry-matter intake.

Chemically-treated wastelage replaced about a half of wilted grass silage without any negative effect on daily weight gain in short-term feeding experiment with growing bulls.

This study was undertaken to evaluate the long-term effects of organic wastes on dry aggregate size distribution and on the C, N and available-P concentrations within the different aggregate fractions of some agricultural soils in North-Central Italy. Topsoils (0–20 cm) which had been amended for several years with either pig slurry (PS), cattle slurry (CS) or sewage sludge (SS) were separated into four macro-aggregate classes (4-2, 2-1, 1-0·5, 0·5-0·25 mm) and three micro-aggregate classes (0·25-0·125, 0·125-0·05 and < 0·05 mm) by dry sieving. Compared with the unamended soils, there was generally a slight increase in the proportion of the 4-2 mm macro-aggregate class following waste application. Irrespective of treatment, macro-aggregates (>0·25 mm) constituted > 70% of the total aggregate fractions.

Average increases of 17, 13 and 67% (organic C), 18, 13 and 57% (total N) and 430, 372 and 642% (available P) were obtained from additions of PS, CS and SS, respectively, and increases were found in all aggregate fractions following waste application. There was a close positive correlation between the concentrations of C, N and to a lesser extent P, in the aggregates and their silt-plus-clay contents. In terms of total contents, these elements were preferentially concentrated in the macro-aggregates. Only slight differences in the C/N ratios of the aggregates were observed but their C/P and N/P ratios decreased significantly (P ≤ 0·05) following waste application.

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.

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%.

The start-up of the dry anaerobic batch digestion by the BIOCEL-concept of the organic fraction of municipal solid waste (MSW) is unbalanced when a methanogenic inoculum (digested sewage sludge) is added to a total solids concentration of 35%. The unbalanced conditions are the result of the rapid degradation of easily-degradable compounds which are present in the organic fraction. Enhancement of the first start-up of the dry batch digestion was tried by applying an aerobic partial-composting step. By this aerobic treatment the easily degradable compounds are removed. After the composting step the anaerobic digestion will be limited by the conversion of the ligno-cellulose part of the organic fraction. It appeared that at least 19·5% of the volatile solids (VS) should be converted during the aerobic composting period before acid formation in the digestion was in balance with the methane formation. This amount of aerobically degraded VS means a 40% loss of potential biogas. The loss of a part of the biogas is a major drawback to the partial composting as a method for enhancing the start-up of the dry anaerobic digestion. A shorter composting period which is combined with another start-up method might be a feasible method to decrease the energy input of the dry digestion process.