The loss on ignition is the mass of organic substances that burn when a sample is heated to a high temperature (up to 550°C) and escape in the form of gas. In water and wastewater treatment, the loss on ignition is a measure of the proportion of organic substances in a sample, for example in sludge or suspended solids. The loss on ignition is often used to analyze sewage sludge in order to determine the organic content of the sludge, which serves as an indicator of the degradation status or the energy content.