Aerobic digestion describes the microbial transformation of organic matter into water, heat and CO2 in presence of oxygen. Aerobic digestion is used in wastewater treatment to both organic matter and the volume of sludge. As for anaerobic digestion, process rates increases with increasing temperature. Aerobic sludge digestion facilities may be designed for batch or continuous flow operations and the process results in approximately 50% reduction in solids content for typical municipal wastewaters. Typical wastewater treatments, using aerobic digestion are activated sludge systems, trickling filters, aerobic ponds etc.