Compost derived by the biodegradation of the organic constituents of solid wastes and wastewater sludges. The major public health issues associated with composting using solid wastes mixed with sewage sludge are pathogens, heavy metal, and odors. The heat generated during composting, as a result of the activities of thermophilic organisms, is capable of killing bacteria, viruses, protozoa and helminths present in sewage sludge. The metallic elements in sludge of greatest concern to human health are cadmium, lead, arsenic, selenium, and mercury. Only cadmium is normally found in sewage sludge at levels which, when applied to soils, can be absorbed by plants, and accumulate in edible parts, thereby entering the food chain.
compost made from mixture of sewage sludge and compostable refuse or waste <D>