ABSTRACT
The land application of sludge is as old as agriculture. The Chinese have used human waste as a fertilizer for thousands of years. The Japanese called it nightsoil and carried it out of town under the cover of darkness to apply to their orchards and gardens. Domestic wastewater contains material flushed into household drains from sinks, toilets, and tubs. Components of domestic sewage include soaps, shampoo, human excrement, toilet paper, foodstuffs, detergents, pesticides, household hazardous waste, and oil and grease. Sludge reuse improves the productivity of the land by adding organic matter and nutrients to the soil. In addition, there are a number of indirect advantages to human health and the environment. The major threats to human health and the environment in the land application of sludge are related to pathogens, metals, and persistent organic chemicals content.
