ABSTRACT
In the past decade the number of sewage facilities that compost their sludge has increased steadily, for a number of reasons. Difficulties in permitting and developing long-term sites to apply liquid sludge have spurred interest in sludge composting. Cocomposting sludge and yard waste is becoming a standard practice. Nearly one third of the composting facilities in operation today either report using yard waste as part of the compost mix or are planning to do so. Composting is a simple, age-old process. The composting process breaks down the organic matter in sewage sludge into stable humus. As the sludge decomposes the piles emit methane, water, and heat. The carbon-nitrogen ratio is the critical factor in the composting process, and the nitrogen-rich sludge must be mixed with a carbon-rich amendment to compost successfully. Static pile composting is the simplest method of composting, but is rarely used because of the potential for odor generation.
