Seasonal Variations in the Composition of Sewage Sludge in the Observation of a Sewage Treatment Plant

By evaluating sewage sludge analysis data from a large German sewage treatment plant (>1 million population equivalents), seasonal fluctuations in the composition of the sewage sludge could be identified. These fluctuations include a periodic decrease in carbon content and an increase in ash content in the middle of the year. Various wastewater and sludge treatment processes as well as climatic influences could be identified as causes for this trend. The investigation of the contents of various heavy metals and trace elements in the sewage sludge also showed partly strong fluctuations in the course of the year, which can have an influence on the utilization possibilities of the sewage sludge.