OPERATIONAL AND COST EXPERIENCE OF A FLUID BED INCINERATION SYSTEM AT THE BAYSHORE RSA

The Bayshore Regional Sewerage Authority operates a 13.2 mgd annual average capacity wastewater treatment facility in Central New Jersey serving Union Beach and seven surrounding towns. Fluid bed incineration has been used as the sludge disposal method since the plant started up in 1973. In 1991, the Authority conducted a Facilities Planning Study examining future disposal options. This study recommended that incineration to be continued, based on economics and other factors. A second-generation fluid bed became operational in January 1996, with the original incinerator retained on standby as a backup.The original incinerator was a cold windbox type that was modified in 1982 to a warm windbox. The new unit is a hot windbox system. Other system configuration changes included the addition of a PLC/PC control system and a WESP and plume suppression system mandated by the State in addition to the venturi scrubber/tray tower, an altered method of ash disposal and the substitution of piston pump for screw conveyors.The new unit passed its performance and emission requirements on the initial test and the emission results as reported in the Compliance Test are among the lowest reported for an operating incinerator, including 0.4 ppmv CO, 0.52 ppmv THC, 0.00025 gr./dscf particulate. All regulated emissions, including metals, 2378 TCDD (tetrachloro dibenzo dioxin), benzene and benzo (a) pyrene were one to two orders of magnitude below allowable limits and in some cases below the detectable limits, with the exception of SO2 and NOx. The ash has consistently passed all required TCLP testing for off-site disposal.Normal operation of the system is 16 hours per day, 5 days per week and 8 hours on Saturdays and Sundays. With a single exception, the new unit has required only routine maintenance and has not experienced significant forced shutdowns due to operational problems. The plant uses a relatively unique caustic addition method for control of SO2 involving both the WESP and the tray tower. A comparison is provided of operational experience with the differences between the old and new systems, including hot versus cold windbox, piston versus progressive cavity pumps as well as PLC/PC versus hardwired control systems.The hot windbox unit with self-supported refractory arch distributor, allowing a windbox combustion air temperature up to 1200°F has significantly lowered auxiliary fuel consumption.Experience with the units, particularly the most recent installation, has proven that fluid bed incineration is an economic, environmentally acceptable method of sludge disposal, satisfactory to the Authority, the permitting agencies and the public it serves.