Resources and Conservation最新文献

This experiment was aimed at studying the effects of adding coal fly ash and poultry manure to a sandy soil on the yields and elemental uptake of Brassica parachinensis and B. chinensis. Three rates of fly ash (0, 3 and 12% w/w) and three rates of poultry manure (0, 2.5 and 5.0% w/w) were mixed separately and in combinations (3% ash + 2.5% manure, 12% ash + 2.5% manure, 3% ash + 5% manure, 12% ash + 5% manure) with the sandy soil. Manure applications were effective in increasing crop yields for both species as compared with the control (sandy soil alone) or fertilizer treatment. Highest yields were recorded with the highest manure treatment. Addition of 12% ash + 2.5 or 5% manure decreased crop yields of B. chinensis but not those of B. parachinensis. Mean tissue concentrations of Zn and Mn were significantly lower (p < 0.05) with increase in ash application rate for both crops while Mo concentration was consistently higher. The changes in metal availability were possibly due to the high alkalinity of the soil after ash addition. The lower electrical conductivity and pH of the soil following cropping indicates the high leachability of elements in sandy soil. Therefore, continuous fertilization is essential if continuous cropping is carried out.

The technical background on energy recovery from biomass (all organic wastes, agricultural residues, and crops grown for energy recovery) is reviewed with a special emphasis on biogas production from “controlled landfilling”. Some of the problems and techniques of biogas production using a low-capital-cost batch digestion method are discussed. An example is given of Cairo, Egypt, for the application to municipal solid waste.

In the study of organic-refuse aerobic composting, the major problem is to promote and control the normal propagation of microbes. The key to making good-quality and hygienically safe compost is to utilize the heat generated by microbial metabolism. This paper gives a detailed description of the temperature-rising mechanism and the technology for its control.

Laboratory incubation studies (6 weeks at 26°C) were conducted to analyze the changes of chemical properties in three kinds of colliery spoils after addition of two sewage sludges (Dewmus and Yorkshire Bounty) and two animal manures (Chiguano and Poultry Manure). In the acidic Whitwood spoils, the nitrification was inhibited and NH₄⁺N became the dominant form of nitrogen. The neutral Thorne spoil had the quickest nitrification followed by Ashington. Addition of organic wastes significantly improved the nitrogen status of all spoils and the rate of nitrification was in the order of Poultry Manure > Chiguano > Dewmus > Yorkshire Bounty. Inorganic nitrogen fertilizer, ammonium sulphate, although supplying the highest amount of NH₄⁺N to spoils, increased nitrate nitrogen less than some of the organic wastes. The organic waste additions caused an immediate and significant increase in P content. Although the waste effect decreased as incubation proceeded, higher P content was found in spoil with waste amendments than in the control throughout incubation. Total nitrogen and phosphorus mineralization was relatively low in all treatments. This showed that microbial immobilization might be important.

Addition of animal manures significantly raised the pH of the two acidic spoils. Similar to the changes of P content, pH also followed a slight and gradual decline during incubation. Results further indicated that waste addition did not raise the spoil heavy-metal contents; it might even reduce the heavy-metal toxicities of spoil samples. This study shows that organic wastes are slow-releasing and complete fertilizers but that the degree of mineralization depends on the chemical nature of organic fraction of individual waste.

A simple mass balance model was developed to predict the contaminant levels which would arise if various fractions of process water were biologically treated, and then recycled within the paper mill. It is feasible to treat only a portion of the effluent prior to recycling and still maintain a sufficiently low concentration of contaminants so as to minimize any problems such as equipment plugging, runnability, or undesirable product appearance.

A low-capital biogas system for production of fuel gas from available organic residues is described with application to developing countries. As a specific example, the village of Nawagi in the SWAT Province of Pakistan was selected for presenting calculations. The system described is based on recent experience with fuel gas recovery from municipal solid waste (MSW) landfill sites via anaerobic digestion and from experiments on batch anaerobic digestion of combined agriculture residues. The “process” is low capital cost and a simple batch anaerobic digestion of the combined organic residues available from a populous area including: all municipal wastes (solid wastes, garbage, sewages sludge); industrial residues such as those from food processing; and agricultural residues such as wheat, rice, and barley straws as well as animal manures.

Future supply options in areas which import large quantities of aggregate are reviewed and applied as an example to the U.K. situation. Particular emphasis is given to wastes and lower-grade natural materials and their potential for use in concrete. Adequate alternatives from local sources exist in the U.K., but their future use will be restricted unless the cost of processing plant is reduced and/or objective data on performance are readily available.