Economic sludge treatment for beneficial reuse

A strategy for the cheapest acceptable means for managing future sludge operations in the Southern Water area is discussed with reference to processes, costs and final product use. Southern Water has over 400 sites producing sludge and will be faced with a doubling of sludge quantities between 1995 and 2015 primarily as a result of the implementation of the Urban Wastewater Treatment Directive (UWWTD) over the period to the year 2005. The paper reviews the population distribution and treatment and disposal methods in 1995 and compares this with the minimum future requirements. The principle legislation concerning sludge disposal is discussed. The paper reviews a number of different processes including recent novel developments. The following processes are discussed in detail with reference to final product reuse. digestion composting drying Planning matters and the logistics of sludge transport are discussed and related to the locations and number of sludge treatment centres. Disposal methods are discussed with reference to acceptability and costs. The final strategy adopted by Southern Water which is based on recycling of sludge products to agricultural land is described.