Implementation of a Medium Temperature Belt Dryer in North Carolina to Produce Class A Biosolids – Case Study

The City of Mooresville is operating the Rocky River Wastewater Treatment plant. The capacity of the plant, originally around 20,800 m3/d (5.5 MGD), was upgraded with a package plant in 2009: final capacity of the plant: 28,400 m3/d (7.5 MGD). The upgarde was commissioned in March 2011.At the same time the engineering for a dryer system was almost finished: the biosolids handling consisting of belt press and drying beds was identified as insufficinet. The goal was to achieve quality of the biosolids suitable for land application.The evaluation and bid process for the dryer equipment was finished in November 2009. The decision and purchase order for the equipment was finalized with issuing the PO: June25th, 2010. The selection of the general contractor in mid 2011 was followed immediately by the construction and equipment installation:- Construction: utilities and foundation of building – July 2011- Delivery of main dryer components: August 2011- Dryer Installation: early September 2011- Dryer building, roof installation: November 2011- Mechanical and electrical installation: December 2011 to February 2012- Field Test and Start Up: April and May 2012The critical point of the project was reached when the existing dewatering system needed to be switched to the dryer system within five days – this was determined by the storage capacity of the holding tank for the WAS. It was crucial to have the system ready for operation when the storage tank for the dewatered sludge was moved into its place.