Processing and Use of Organic Sludge and Liquid Agricultural Wastes

Disposal of organic sludge and liquid agricultural wastes is a universal problem. Their production cannot be halted and as steps are taken to maintain or improve the quality of rivers and lakes it grows in quanti ty. The Commission's early awareness of the need for action to prepare for substantial growth in the Community's' sludge disposal problem led to the setting up of the COST 68 project to coordinate and guide European research and development work with particular emphasis on recycling sludge to agricultural land. Two years ago the field of research activi ties was extended to liquid agricultural wastes. This Symposium is the latest opportunity to provide a comprehensive review of the results of the project, to define current trends in practice and to establish by discussion the priorities for research over the next few years. The development of instrumentation and of analytical techniques during the period has extended our knowledge of the organic and inorganic constituents of sewage sludge and agricultural wastes and enabled us more readily to identify and measure the risks to which our general environment may be exposed when disposing of it. This evolution of understanding is a continuing process and an essential guide to the modification of disposal practices to achieve safer and more efficient operations. However, it is important to take a broad view of the application of research findings in the light of the considerable contrast in conditions in different parts of the world.

Session 1 : Processing and Costs.- Overview of sewage sludge treatment processes : An outlook.- Treatment processes for farm wastes.- Stabilisation of sewage sludges and liquid animal manures by mesophilic anaerobic digestion ― an overview.- “State of the Art” on sludge composting.- Optimization of processing, managing and disposing of sewage sludge.- I : Treatment processes models.- II : Disposal options.- Alternative uses of sewage sludge.- Session 2 : Characterization of Sludge.- Sampling techniques for sludge, soil and plants.- Abundance and analysis of PCBs in sewage sludges.- Chemical methods for the biological characterization of metal in sludge and soil.- Characterization of the physical nature of sewage sludge with particular regard to its suitability as landfill.- Microbiological specifications of disinfected sewage sludge.- Inactivation of parasitic ova during disinfection and stabilisation of sludge.- Epidemiological studies related to the use of sewage sludge in agriculture.- Transport of viruses from sludge application sites.- Health risks of microbes and chemicals in sewage sludge applied to land ― recommendations to the world health organisation.- Session 3 : Management Considerations in Sludge and Effluent Disposal.- Recommendations on olfactometric measurements.- Manure nutrient composition : rapid methods of assessment.- Efficiency of utilisation of nitrogen in sludges and slurries.- Effect of a long term sludge disposal on the soil organic matter characteristics.- Contamination problems in relation to land use.- Long-term effects of contaminants.- Effect on a long term sludge disposal on cadmium and nickel toxicity to a continuous maize crop.- Trace metal regulations for sludge utilization in agriculture; a critical review.- Poster Session.- Leaching resulting from land application of sewage sludge.- Germination tests for the determination of sludges agricultural value.- Utilization of sewage sludge as fertilizer in energy plantations on peatland.- The use of composted agricultural waste as peat substitute in horticulture.- Labscale simulation of isman-cotton batch phase anaerobic digestion for prediction of plant design and performance.- Solid phase anaerobic digestion of farm wastes mixed with sewage sludge.- Aerobic stabilization in the solid state of partially dewatered sewage sludge.- Environmental impact assessment of agricultural use of sewage sludge.- Analytical characterization of biological sewage sludges especially about some organic compounds.- Sludge composting and utilization in West Switzerland.- Productivity and quality of cereal crops grown on sludge-treated soils.- Biological evaluation of sludge phytotoxicity.- The fate and behaviour of selected heavy metals during pyrolysis of sewage sludge.- Latest test results in sludge dewatering with the CHP-filter press.- A pot experience with a high level copper sewage sludge.- Chemical properties of sewage sludges produced in the Piedmontese area (Italy).- Autothermic sludge incineration.- Modification of heavy metals solubility in soil treated with sewage sludge.- Methods of treating pig slurry to increase the volumes which can be used on crops.- Chemical composition of sludges from sewage treatment systems in the Emilia Romagna region.- Application of CaCl2-extraction for assessment of cadmium and zinc mobility in a wastewater-polluted soil.- Anaerobic contact digestion of biochemical sludge (from simultaneous precipitation) ― results of a semi full-scale study.- The alternative “earthworm” in the organic wastes recycle.- Slurry meter instructions.- Composting of sewage sludge containing polyelectrolytes.- An alternative application for sewage sludge : black earth.- Toxic organic substances in sewage sludges : case study of transfer between soil and plant.- Varietal tolerance in cereals to metal contamination in a sewage treated soil.- Effect of sample storage on the extraction of metals from raw, activated and digested sludges.- Discussion.- Discussion.- Session Reports.- Processing and costs.- Characterization of sludge.- Management considerations in sludge and effluent disposal.- Conclusions and Recommendations.- Conclusions and Recommendations.- List of Participants.- Index of Authors.