Production of plant growth medium from sewage sludge comprises mixing sludge with mineral material and carbon source and composting mixture

摘要

Treatment of sewage sludge comprises mixing the sludge with a mineral material and a carbon source and maintaining the mixture in an aerated state, with a solids content of up to 80 %, to produce a plant growth medium containing simple humic substances resulting from aerobic digestion of organic matter in the sludge. The mineral material is added in an amount sufficient to reduce or prevent fermentation of the organic matter and the carbon source is added in an amount giving a carbon/nitrogen ratio above 8.5.