Sewage sludge from water purification stations isdifficult to handle. The mechanical dehydration for sewagesludge is limited normally to about 35 percent of dry matter,higher values over 40 percent can only be achieved by drying.For mineral sludges these values are different. A solar sludgedryer, developed in Germany, has been successfully operatingthere since 1994. The annual drying capacity varies according tometeorological conditions, in southern Germany about 700kg/m~2 of water can be evaporated annually. The solar dryingrequires space, less investment cost and only 3-5 percent of theauxiliary energy of industrial drying processes. The solar dryingprocess may be used to dry any wet bulky material.
展开▼
