Sludge Management at the Middlesex County Utilities Authority

Abstract

The Middlesex County Utilities Authority (MCUA) currently disposes of sewage sludge at a 106 mile site in the New York Bight. In accordance with New Jersey State law, the ocean disposal of sewage sludge must terminate by March 17, 1991. In 1988 the MCUA initiated a land-based sludge management study to investigate the alternatives that are implementable by this deadline. This study included the evaluation of 24 alternatives, each of which included dewatering and subsequent disposal/reuse. It concluded that dewatering followed by chemical fixation represents a cost-effective, environmentally responsible, implementable reuse alternative for MCUA sludge management. A pilot study was undertaken to evaluate chemical fixation of MCUA dewatered sludge. The program included constructing test plots at the MCUA operated landfill, and collecting and evaluating data on the physical, chemical, and biological properties. These analyses were intended to determine the acceptability of using chemically fixed MCUA sludge as a supplement to conventional soil for daily and intermediate landfill cover. With the success of the pilot studies and the State's approval, the design of dewatering and chemical fixation facilities for approximately 192 dry tons per day was initiated early in 1989. This paper presents an overview of the sludge management and pilot studies and the facility design.