Biological Wastes最新文献

The aerial parts of Vicia faba collected at seed maturation stage have no economic utility and are, therefore, discarded. However, these leaves and stems contain a considerable amount of flavonol glycosides. Two extraction procedures have been assayed: one using methanol-water as extraction solvent and another using alkaline water. The extraction yield (about 1 g of flavonoid/kg fresh plant material) was slightly higher when extracting with alkaline water, but this extraction hydrolyzes the acetyl derivatives, leaving almost exclusively the deacetylated compounds.

Newly-hatched larvae of the green hover fly Ornidia obesa (Diptera: Syrphidae) were allowed to grow on coffee pulp that had started to decompose for two days and taken from the anaerobic portion of a heap. This substrate was maintained in Petri dishes at room conditions (25 ± 5°C, 43·0 ± 12.9% air relative humidity) so as to obtain a better understanding about the larval growth of the above species on coffee pulp. A sigmoid model indicated that the maximum larval growth rate was 16·8 mg (wet basis) day⁻¹ at 13·9 days after hatching, that the period of most rapid growth was 10·0–18·9 days and that the larvae reached almost their full development 25 days after they emerged from eggs. It was also found that a comparatively slight decrease of substrate moisture caused a lowering of larval weight.

Maturation during composting was investigated in three composts prepared from lignocellulosic wastes. We used the cress seed germination (Lepidium sativum L.) bioassay and phytotoxicity assays of Helianthus annuus plants to determine a series of physiological parameters. Germination of Lepidium sativum and leaf weight of Helianthus annuus revealed increasing maturity of all three composts during the initial period of composting, i.e. the thermophilic period. In general, the data then showed a period of transition, followed by a substage of mesophilic activity (30–60 days) when compost reached optimum ripeness, and a second mesophilic substage during the final period of composting (60–90 days). The results of cress germination tests during these periods suggest that the rate of maturation tended to stabilize, whereas some of the Helianthus annuus physiological parameters indicated a slight decrease in the quality of the matured compost. Stem length of sunflower plants was found to be too insensitive as an indicator to detect changes in the degree of maturation during composting.

Pollard and bran were fermented by a selection of filamentous fungi to increase the protein content and availability for use as animal feed. Aspergillus terreus produced a product containing 32·6% crude protein (CP) after 16 days. Under identical environmental conditions, shallow-layer solid-state fermentations achieved higher CP yields than did tumbled or packed-column systems. When crude xylanase was added with A. terreus inoculum, a 5-day reduction in fermentation time was achieved resulting in a maximum CP content of 27%. A. terreus, Chaetomium virescens, Schizophyllum commune or Trichoderma reesei, in dual culture with one another or in combination with Phanerochaete chrysosporium, did not achieve higher final CP yields (after 16 days) than A. terreus alone. P. chrysosporium in combination with T. reesei and with S. commune resulted in the most rapid CP development of 26·1% and 26·4%, respectively, during the first 10 days.

A comprehensive literature review was conducted on psychrophilic anaerobic digestion and design of anaerobic digesters for treating animal manures. Anaerobic digestion of caged layer manure was studied in the laboratory at low temperatures (14–23°C). The digesters were operated to determine combinations of temperature and loading rate that gave acceptable methane yield. Acceptable methane yield was obtained for loading rates ranging between 0·15 kg VS/m day and 0·57 kg VS/m³ day for temperatures of 14°C and 23°C, respectively. The resulting data along with that taken from similar tests documented in the literature was found to approximate the van't Hoff-Arrhenius equation. This equation is then suggested as a technique for determining suitable loading rates for psychrophilic digesters based on data for digesters operated at higher temperatures.

The potentiality of some plant wastes plus poultry litter as feedstocks for biogas production was determined. Some wastes could substitute for cowdung when dung is in short supply.

A set of ten upflow sludge blanket digesters was examined as five pairs (one control and four test reactors) to assess the way in which controlled nutrient variations affected the performance of the reactors in treating a simulated ice-cream wastewater. An alternative carbon source was used and additional concentrations of calcium and cobalt were examined. The results show that the waste itself is capable of being treated by the UASB process, with granulation commencing after 60–70 days. However, of the supplements, only calcium had any significant effect.

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.