Page 35 - Wastewater Solids Incineration Systems

4 Wastewater Solids Incineration Systems

These programs are intended to build relationships and accountability with the
public. Most programs include ongoing communications and cover the following
topics related to public perception of biosolids:
• How biosolids are produced.

• Regulations and reporting requirements governing biosolids processing.
• Incineration and other solids treatment options evaluated.
• Project descriptions and local effects such as traffic, noise, odors, and
construction.

3.0 EMISSIONS: COMPARISON AND PERSPECTIVE

Emissions need to be compared on an “apples-to-apples” basis. Many programs that
involve long hauling distances generate more emissions during transportation than
is generated by incineration and hauling a much smaller volume of ash. Trucks pro-
duce non-point emissions that are sometimes overlooked, because they are not regu-
lated as wastewater or air-permitted sources. Also, truck emissions are regulated as
“best case” emissions within a controlled environment at constant speed, which is
significantly lower than actual on-the-road emissions.
In the past 10 years, both incinerator emissions and truck emissions have
been reduced significantly. The previous limit for particulate emissions for incin-
erators was 0.65 g/kg (1.3 lb/dry ton), whereas the newer fluid bed facilities or
upgraded multiple-hearth facilities with enhanced scrubbers are reporting partic-
ulates in the range of 0.05 to 0.25 g/kg (0.1 to 0.5 lb/dry ton). As for hydrocar-
bons, there are very few fluid bed facilities that are producing even 10% of the
maximum allowable 100 ppm total hydrocarbons (THC) limit prescribed in the 40
CFR Part 503. Multiple-hearth facilities have also been able to comply with the
THC limits. Nitrogen oxide (NOx) emissions for fluid bed incinerators have also
declined by more than 50%, from more than 2.5 to 1 g/kg (5 lb/dry ton to 2
lb/dry ton) or less.
For most people, emissions are what they see coming out of the stack. Most new
facilities and upgraded older facilities produce no visible emissions. Even vapor
plumes can be avoided with reheating or subcooling of exhaust gases.