Page 221 - Wastewater Solids Incineration Systems

Ash Handling and Recycling 187

ash mass. In some instances, a wetting agent is added to the water to enhance its
ability to penetrate the ash.

4.0 INSTRUMENTATION AND CONTROLS

Ash systems consist of multiple, sequential components that require integrated oper-
ation, monitoring, and control. The system components are often distributed over
several levels of a facility, are located both inside and outside the building, and are
always remote to manned control areas.
Regardless of the system used, key system monitoring parameters should be dis-
played and alarmed in the control room. Control room start-stop devices should be
grouped together and located adjacent to the parameter indicators to permit opera-
tion of the equipment as a system.
Electrical interlocking should be provided to permit automatic system shutdown
when a component fails. Interlock bypass controls should be available for mainte-
nance and safety purposes. Local start-stop-jog controls should be located as close to
the equipment as practical. These controls should include electrical lockout and
emergency stop features for personnel protection.

5.0 RECYCLING

The end product of incineration is ash, which is an inert material. Interest in benefi-
cial reuse of ash is increasing. Historically, the most common way to dispose of ash is
to a landfill. More recently, ash has been used as landfill cover, soil amendment, fill
material, in brick manufacturing, and in concrete and asphalt mixes. One more inno-
vative approach is in a vermiculture process. Detail regarding these options follows.
• Landfill—disposal of incinerator ash in a landfill is an option available to most
operators. Landfill tipping fees vary across the country. A beneficial use of ash
at landfills is to use it as a landfill cover or to blend it with soil and use as a
cover.
• Fill material—ash can be used as fill material for excavations. One utility, for
example, has a contractor using the material to fill old sludge lagoons. The
material can also be used as a flowable fill.

• Soil amendment—in some specific areas (particularly areas with high clay
soils), incinerator ash may be used as a soil amendment through an additive