An evaluation was made of within-vessel municipal sludge composting systems manufactured by Biologische Abfallverwertungs Gesellschaft mbH & Co. (BAV). The major components of the BAV system include sludge dewatering and storage, sawdust storage, recycled compost handling, materials mixing and bioreactor insertion equipment, the bioreactor, the extraction mechanism for removal of compost from the bioreactor, and the curing piles. Based on experience with older facilities, BAV has made several significant mechanical modifications to improve the system and to overcome some of the concerns of the earlier reactors. However, they have yet to be tested over time.