Biological Wastes最新文献

Following mechanical separation of pig slurry, two pilot-scale reactors were used to treat aerobically the liquid fraction with a 4 day residence time and an operating temperature of 35°C. In one reactor redox potential (RP) was controlled to between −145 and −45 mVE_cal and, in the other, dissolved oxygenn (DO) to between 1–2 mg O₂ litre⁻¹. Unseparated and separated slurries and two aerobically-treated (RP and DO) slurries were applied to grassland plots at 8 litres m⁻² and a system of small wind tunnels used in the collection of odorous air samples and in the measurement of ammonia volatilisation. Odour measurements were conducted by dynamic dilution olfactometry. Both aerobic treatments reduced the total odour emission over 52 h by 55% compared with unseparated, untreated slurry, whilst separation alone gave a 26% reduction. However, during the first 2 h after spreading, when the rate of emission was highest, odour emission was 41·2, 29·8 and 21·6 odour units s⁻¹ for unseparated,separated and RP-treated slurry, respectively, but only 4·0 odour units s⁻¹ for DO-treated slurry. Aerobic treatment also reduced odour intensity and odour offensiveness. Both aerobic treatments followed by storage increased slurry pH, which led to an increase in the total loss of N through ammonia volatilisation after spreading on land.

Azotobacter spp, are known to produce growth-promoting substances and fix atmospheric nitrogen. Cyst-forming Azotobacter spp. were found in three samples of bovine waste: aseptically taken from the rectal passage, taken at the time of voiding by the animal, and from the effluent from a biogas digester. The multiplication of azotobacters at optimum moisture in cow dung suggests such a possibility in manured soil puddles. The dense population of these nitrogen-fixing bacteria, producing growth-promoting substances, could help in seedling establishment in the field.

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.

A study was conducted to assess the effect of in-situ incorporation of paddy straw along with microbial inoculants on the yield of wheat crops. Locally available, waste, paddy straw (shredded to 3–5 cm) was incorporated with and without a mesophilic cellulolytic fungal inoculum (Trichoderma viride) in alluvial sandy loam soil at 11·2 tonnes ha⁻¹ 15 days prior to sowing. Seed bacterization with a free-living nitrogen-fixer (Azotobacter chroococcum) and phosphate solubilizer (Pseudomonas striata) was done in the respective treatments. Application of a single microbial inoculant in combination with two fertilizers, urea and rock phosphate at 60 kg N ha⁻¹ and 60 kg P₂O₅ ha⁻¹, respectively, produced a significant effect on the yield of wheat grown in straw-amended soil. Combined inoculation with all the three organisms had a repressive effect on the yield of wheat.

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.

Three methods of predicting slurry production were compared with the volumes actually produced on a 150 sow breeding and fattening pig unit. The methods were based on (a) feed, water and slurry relationships measured in crated and penned pigs; (b) values given in the literature and used by ADAS to predict slurry outputs from pigs; (c) a method based on the digestibility of feed and of water measured at the actual piggery. Method (a) was not found appropriate because of the high overall water:meal ratio found in the unit (13:1). Method (b) was able to predict dry matter production accurately but underestimated the volume produced unless the ADAS allowance of 0·5 litres pig⁻¹ day⁻¹ for washing water and leaking drinkers was increased to 10 litres. Method (c) was the best method for estimating volume but underestimated dry matter production. Combining the better aspects of methods (b) and (c) allows volume, dry matter production and dry matter concentration to be predicted satisfactorily. The daily movements of slurry from the reception pit were very variable. The use of water meters on pig units is recommended to identify wastage.

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.