The agronomic potential of brewers' spent grains (BSG) was evaluated on two texturally contrasting tropical soils, using a split-plot design with three replications. The main plot treatments were the two soils S1 (Ultisol) and S2 (Entisol), whereas the subplot treatments were different rates of BSG and complete fertiliser (F): 0%, 2.5%, 2.5% + F, 5.0%, 7.5%, 10.0% and F. Complete fertiliser consisted of 60 ppm N, 15 ppmP, 60 ppm K and 20 ppm Mg. The test crop was maize Zea mays L. On both soils the highest plant height and dry matter yields were obtained at the 2.5% BSG rate. This rate out-performed the F treatment by 293% on S1 and 46% on S2. Generally there was higher maize response to BSG on the less fertile S1 than S2.Progressively increasing rates of BSG increased the residual organic matter contents, aggregate stability, moisture retention and available water capacity of both soils but did not alter the soils' pH levels. On the two soils a BSG rate of 10% was the best for optimizing these physical conditions. Increase in organic matteR contents of these soils following BSG additions accounted for more than 70% of the variability in the stability of the aggregates to water, between 58 and 66% of the variability in the moisture retained at different tensions by S1, and 51-82% of the variability in the moisture retained at different tensions and total and readily available water capacity in S2. The improvements in the productivity of these two fragile soils induced by the BSG amendment were due to high contents of N, P, K, Ca, Mg and carbon as well as the low C:N ratio of this waste product.
The paper is based on a study by the authors for the United Nations Centre for Human Settlement (UNCHS)-HABITAT, Nairobi, Kenya. These findings will be a part of comprehensive report compiled by UNCHS-HABITAT on refuse disposal systems for developing countries to promote recovery of waste materials. Municipal waste from Karachi (Pakistan), contains 89·5% (dry basis) total recyclable material with polyethylene/polyvinyl chloride/plastics (9·85%); paper/cardboard (10·1%); glass (1·24%); bones (1·85%); metal/tins (0·74%); leather/rubber (0·2%); organic vegetable matter (54·5%), identified as components. Four thousand five hundred tonnes of garbage produced daily in Karachi city had 250–318 tonnes polyethylene/PVC/plastics; 230–300 tonnes paper/cardboard; 26–34 tonnes glass; 43–56 tonnes bones; 13–17 tonnes metal/tins; 5–6 tonnes leather/rubber and 14–18 tonnes wood. These items are regularly recovered and used for reprocessing into new products. Garbage previously considered trash has become a valuable asset with 75–80% recovery.
In a first small silo study four mixtures of swine waste, wheat straw and cane molasses in various proportions were ensiled. The mixtures were adjusted to a moisture content of about 40% before a 42 days ensiling period at 28±2°C. Ensiled mixtures had an acceptable aroma and appearance similar to that of good quality haylage. In a second small silo study, three replicates of a factorial experiment were run in the laboratory for three levels of swine waste: 11, 22 and 44% (dry basis) and three levels of moisture content: 40·8±0·5, 54·4±0·7 and 69·0±0·6. After a 42 days ensiling period at 28±2°C, the silos were opened and evaluated. All mixtures preserved well and appeared to show typical haylage fermentation characteristics. Lactic acid concentration and pH indicated that good ensiling occurred in all mixtures. All mixtures were free of total and fecal coliforms, Salmonella, Shigella and Proteus organisms. As the proportions of swine waste in the mixtures decreased, percentages of crude protein and ether extract decreased linearly and quadratically (P<0·0.01). Crude fiber increased linearly as the proportion of swine waste decreased in the mixtures (P<0·01). Ash increased linearly as the proportion of manure increased in the mixtures (P<0·01).
In four full-scale bunker silos were ensiled 16·5 tons of different mixtures of swine waste, wheat straw and cane molasses. One mixture had 22% swine waste, and the other one 44% (DMB). Swine waste was collected from an open concrete growing-finishing swine feedlot. During the first six weeks samples were taken from the silos and analyzed for pH, lactic acid, total coliforms, clostridia and aerobic and lactic acid bacteria. After three months, silos were opened and evaluated for physico-chemical, microbiological and nutritional characteristics. Two performance trials on sheep were conducted, one to determine the nutritive value of the silages with 22 and 44% of swine waste and the other one to evaluate the inclusion of the silage with 44% swine waste at 20, 40, 60 and 80% (DMB) in sheep diets. Dry matter, crude protein, acid detergent fiber and neutral detergent fiber digestibilities were determined for silages with 22 and 44% swine waste in eight sheep. Evaluation of storage stability in samples from different levels in bunker silos indicated low stability in surface, bottom and side wall samples and fairly good stability in samples from 50 cm depth. Those samples had a pleasant aroma and appearance similar to that of a good quality haylage. Typical manure aroma was not present in waste silages. Twenty-two percent swine waste silage reached an average pH 4·4 while 44% swine waste silage reached an average pH4·6. After 7 days of fermentation, total coliforms were completely destroyed. Clostridia and aerobic bacteria tended to be decreased by ensiling. Average daily gain and digestibility of crude protein were higher for sheep fed 44% swine waste silage than sheep fed 22% swine waste silage, but lower than sheep fed basal diet (P < 0·01). Feed efficiency was different for the three diets (P < 0·01). Dry matter intake was similar for sheep fed 44 and 22% swine waste silage (P > 0·01) but lower than sheep fed basal diet (P < 0·01). Average daily gain and dry matter intake decreased with increasing levels of 44% swine waste silage (P < 0·01). Feed efficiency was not different between the four treatments (P < 0·01).
Results of experiments with the Rumen Simulation Technique (Rusitec) over the last 12 years were used to show that the content of diaminopimelic acid (DAP) in the undigested residue increased with digestibility of dry matter. The relation between these quantities can be used to predict the output of adherent matter (presumed bacteria) during incubations in Rusitec when only digestibility of the feed is determined.
Anaerobic digesters contain a variety of anaerobic cellulolytic bacteria but the presence of cellulolytic Sarcina has been undetected in this or other habitats. The present paper describes the isolation and characteristics of a cellulolytic Sarcina species from an anaerobic, mesophilic cattle-waste digester. It produces lactate as a major product.
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.
Candida utilis and Saccharomyces cerevisiae were grown on raintree-pod extract as a sole carbon and energy source. It was found that the pod extract could serve as a suitable medium for the cultivation of Candida utilis for the production of single cell protein.
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.
A laboratory-scale sequencing batch reactor was fed with synthetic wastewater based on sucrose to determine the biokinetics of the process. The values of umax and Ks 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.
Some physical parameters were determined on an organic product derived from a new phytodewatering process of anaerobic sludge, in order to verify its possible use as a substrate. Wetting-drying cycles were carried out with a sandy soil, and with mixtures of this soil with the organic product taken before and after the phytodewatering process. The phytodewatering process decreased bulk density while raising aggregate stability and friability.
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 NH4N 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 15NH4N ranged from 36 to 66% in diluted effluents and from 2 to 77% in undiluted effluents. Plant survival was not dependent entirely on NH4N concentrations or EC of the effluents.
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.
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.
The application of earthworm (vermial) biotechnology, in conjunction with indigenous microbial activity, has been suggested as a potentially efficient method for managing biological sludges and other labile organic matter on land. Studies were conducted in order to determine the effect of variable temperatures and seasonal changes on vermial and microbial activities. The results suggested that vermial activity and growth are accelerated under dynamic conditions of recurrently fluctuated temperatures—vermial and microbial stabilization of biological sludges on soil will persist under ambient conditions of temperature and seasonal changes—and the rate of stabilization and turnover of biological sludges is accelerated when vermial and microbial activities are combined.
The potency of orange peels of three species of orange were investigated using the randomised complete block design with four replicates. Statistically analysed results from this investigation showed that:
An anaerobic trickling filter fed with a synthetic medium ( volatile fatty acids mixtures) achieved a steady-state. Organic Loading Rate 5·3kg COD/m3. After 300 days of continuous operation it was subjected to changes in the feed medium to assess the possibility of isovalerate and 2-methylbutyrate degradation. The system was able to treat 6·3g isovalerate/litre day without intermediates accumulation and achieved a higher OLR (10·9 kg COD/m3 day). When 2-methylbutyrate was supplied, 1·4 2-methylbutyrate/litre day together with 4·9 g isovalerate/litre day were satisfactorily treated. Higher concentrations of the former metabolite caused propionate accumulation, even at lower OLR (8·8 kg COD/m3 day).
The use of ligninase enzyme produced from the fungus Phanerochaete chrysosporium to delignify and improve the digestibility of barley straw was examined. Ligninase treatments were applied in a 4 × 4 × 4 factorial design, using level of enzyme, time and treatment conditions (with or without veratryl alcohol, hydrogen peroxide or both) as main effects. Samples of the same milled straw were also treated for the same durations with two levels of sodium hydroxide. The in-vitro organic matter digestibility (OMD) of untreated and NaOH-treated straws (24 h, low and high levels) were 304, 513 and 661 g/kg OM. Analysis of variance of the data showed that levels of lignin were reduced (P < 0·01) from 116 (treated control) to 105 g/kg OM with both medium and high levels of ligninase. However, it was not possible to detect any positive significant difference in OMD between ligninase-treated and untreated samples, but there was much variation. The catalytic performance of the enzyme might be sub-optimal under the conditions described in this experiment.
The earthworm Eisenia fetida, known to contain bactericidal enzymes, was tested for virucidal activity using Cowpea mosaic virus (CPMV) and Tobacco mosaic virus (TMV) as model agents. Earthworms were fed cellulose saturated with a virus suspension and their excreted castings were analyzed for structurally intact virus protein using enzyme-linked immunosorbant assay (ELISA) and virus infectivity by local lesion assays. Observations of the feeding experiments indicated a considerable reduction in the infectivity of both viruses. Virucidal activity was also observed when virus suspensions were incubated with the earthworm enzyme extract and analyzed by local lesion assay. The observed reductions in the infectivity of both viruses suggest that E. fetida may possess a virucidal enzyme system and, accordingly, may contribute to the inactivation of pathogenic viruses potentially associated with land application of sewage sludges and livestock manures.
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.
