Biological Wastes最新文献

The production of the thermostable pullulanase of Thermoactinomyces thalpophilus isolated from cow dung was studied in shake-flask cultures. Maximum production of pullulanase was obtained with 5% (w/v) soybean meal, 2% (w/v) yam starch, and Sr²⁺, at an initial culture pH of 5·0. The time-course of the synthesis of pullulanase indicated maximum production of the enzyme at 36 h, corresponding with the culture pH of 6·2.

An experiment to measure the respiration rate of treated piggery slurry is described. Calculations using data from the experiment estimate the effect that the wind-mediated transfer of oxygen from the atmosphere into the slurry in a storage tank or lagoon might have upon the time of the return of an offensive odour.

The study shows that the effect of wind aeration is potentially far greater than that of even a fourfold increase in the solids residence time of the prior aerobic treatment. For example, storing aerobically-treated piggery slurry in a lagoon of maximum depth 2 m could permit wind aeration sufficient to increase the period for which the odours would not be offensive from a maximum of 30 days after a 4-day solids retention time (SRT) treatment to more than 180 days, even when the slurry had had only a 1-day SRT treatment.

The purpose of this study was to evaluate the inhibitory effect of representative wood resin compounds on the activity of methanogenic bacteria. Resin is by definition the mixture of wood components that are extractable with apolar solvents. Major resin constituents are long-chain fatty acids, terpenes, resin acids, lignans and apolar phenols. The methanogenic inhibition was determined at a temperature of 30°C in standardized toxicity assays utilizing anaerobic granular sludge. An apolar phenol, 4-hydroxystilbene, was the most toxic of the compounds studied, with a 50% inhibiting concentration of 20 mg/litre. Resin acids and volatile terpenes were also highly toxic to methanogenic activity. Concentrations causing 50% inhibition ranged from 43 to 330 mg/litre. In contrast, triterpenes were non-toxic at relatively high concentrations, 1000–1300 mg/litre. These results suggest that wood resin constituents play an important role in the anaerobic inhibition exerted by several forest industry wastewaters.

Linseed stalk is a source of good quality fibre. A major part of the produce goes as waste due to the non-availability of a suitable flax-scutching machine for efficient extraction of fibre. A manually operated machine was, therefore developed and tested. Its capacity was 3·30 kg stalk per hour with 81·13% extraction efficiency and cleanliness percentage of 60·7. The fibre obtained had the tenacity of 22·88 g/tex, fineness of 4·0 tex, colour percentage of 50·16 and lustre of 0·993. The cost of operation per hour worked out to be Rs. 6·70 for production of fibre worth Rs. 11·88 indicating its suitability for use at farmers' level for enhancing their income.

Corn (maize)—processing effluents, known as nejayote, were aerobically treated in a 50-liter laboratory-scale rotating biological reactor. Removal of organic compounds, evaluated as chemical and biochemical oxygen demand (COD and BOD), as well as reducing sugars, was monitored. Operating conditions were: feed COD, 6·4 g/liter; rotational disc speed, 16 rpm; hydraulic retention time, 2·5 days. A comparison with previous experiments, carried out in a 150liter reactor, to consider scaling-up effects (1:3) was performed. Final COD removal was 84·6%. The application of an exponential model to reducing-sugars degradation was highly satisfactory, and the value of the constant was −0·352. Generated biomass was bromatologically evaluated, and average results in per cent of total dry biomass were: protein content, 41·5; fat, 3·4; fiber, 14·8; ash, 15·1.

The average density of viable microorganisms in poultry pine-sawdust litter was 6·3 × 10⁷/g dry material (DP); 1·6% of the population were aerobic heterotrophic bacteria. Acidophile bacteria, aerobic spore-forming bacteria, actinomycetes and fungi were, respectively 4·8 × 10⁴, 8·1 × 10⁴, 5·2 × 10⁴ and 8·9 × 10⁴ CFU/g DP. However the latter did not have a measurable mycelium. Algae were in low densities (18/g DP) and cyanobacteria were not detected. Most of the population had proteolytic and ammonificant capacities, but there were very few ammonium oxidizers and nitrite oxidizers. Denitrifiers were in relatively high density and the anaerobic free-nitrogen fixers were more abundant than the aerobic ones. Aerobic cellulolytics were scarce, but anaerobic cellulolytics, amylolytics and pectolytics showed a similar, and relatively high average density. Sulphate reducers and anaerobic mineralizers of organic sulphur were more abundant than the elementary-sulphur oxidizers, and sulphide oxidizers were not detected. Except for algae, microbial populations generally tended to decrease with time of use of the litter. This decline affected mainly nitrifiers, anaerobic and aerobic cellulolytics and amylolytics while sulphate reducers and anaerobic free-nitrogen fixers increased.

The production of humic substances and their retention capacities for phosphorus and calcium released during composting of wheat straw with two types of low-grade rock phosphate were examined. Relative quantities of humic acids increased with increase of composting time, while fulvic acids production decreased after 30 days of composting. The addition of both Mussoorie and Hyperphos retarded humic acids production and enhanced fulvic acids production. Molasses incorporation had no effect on humic acids but increased fulvic acids production. The production of humic acids and their retention capacity for P and Ca were greater in the presence of Mussoorie phosphate than in the presence of Hyperphos, but fulvic acids formation was higher with Hyperphos. About 80–85% P and 90–95% Ca retained by the total humic substances were found in the fulvic acids fraction.

Ground-water quality was monitored for three years at two sites around clay-lined animal waste lagoons on the Delmarva Peninsula. A swine waste lagoon located in an Evesboro loamy sand soil (excessively well-drained) was having a severe impact on ground-water quality. Ammonium nitrogen concentrations above 1000 mg/liter N have been measured in shallow monitoring wells around the lagoon. Chloride and total dissolved solids concentrations were also high. At the second site which has three lagoons and a settling pond in poorly drained soils, some seepage was occurring. Ammonium nitrogen, nitrate nitrogen, chloride and total dissolved solids were above background concentrations in some of the monitoring wells. There was a strong correlation between nitrate nitrogen and chloride concentrations in the monitoring wells. The results indicated that clay-lined animal waste lagoons located in sandy loam or loamy sand soils with high water tables may lead to degradation of ground-water quality.