Abstract:Much sewage sludge have been abandoned randomly in China in the past which generated many non-sanitary simple sludge landfills that were potentially threatening to the environment. For the basic characteristics of aged sludge, a field investigation was conducted at a simple sludge landfill created by a Chemical Enterprise in Jiangsu Province and properties such as the organic matter content, moisture content, pH, total heavy metals, heavy metal leaching amount, permeability coefficient and leachate were tested. The results show that the organic matter content is still higher than 50% even after many years of degradation. The pH value of the sludge lies between 8.5 and 9.0, which fits for living conditions of methanogenic bacteria. The moisture contents within the sludge are higher than 90% and the water table located at a depth of 30cm beneath the surface of the sludge. As a result, anaerobic and saturation conditions exist beneath the 30cm depth. The concentration amounts of Zn and Mn were above the recommended standard levels but the heavy metal concentrations obtained from the leaching test and leachate are very low which indicates that heavy metals are not the major pollutants in simple sludge landfills. Concentrations of COD, BOD5, TN, NH4-N, and TP exceeded many times the recommended standard values which indicate the organic pollutants are the major pollutants in simple sludge landfills. The permeability coefficient of aged sludge was 10-8cm /s, which signifies the difficulty in sludge drainage and the unsuitability of the vacuum drainage preloading method for such base reinforcement projects.