Driven by changes in the Clean Air Act Amendment (CAAA), controlling odor in pulp and paper mills has received increased attention from both the mill and the surrounding communities.  Minimizing the hazards of hydrogen sulfide and other explosive gases is a primary concern within the mill.  Externally, mills desire to reduce odor complaints and maintain positive relations with the surrounding community.

Offensive odors are the result of the sulfur-containing process streams in a pulp or paper mill that provide sources of sulfides and other sulfur compounds.  Additionally, biological or chemical activity in waste and/or process streams generates sulfur odors.

Odor Control Solutions

ProSweet™ Odor Control Technology is a family of products that fall into three distinct categories of technology:

Scavengers
Inhibitors
Neutralizers

Scavengers
Sulfur-containing gases that cause odors can be neutralized by reacting them with organic scavengers, thereby, preventing the gases from entering the atmosphere.  These scavengers react with sulfide and mercaptan compounds, whether they are formed by biological activity or from the papermaking process chemistry.  As a result, the sulfur becomes chemically bound and can not be detected as an odor.  Since the scavengers react specifically with sulfides and mercaptans use rates are typically lower than commodity oxidant technology.  Commodity oxidants use rates are typically higher since oxidizable organics and other chemicals in the stream consume them.

Inhibitors
Many of the process and waste streams are typically deficient in oxygen, resulting in an environment ideal for the growth of anaerobic bacteria.  These bacteria produce hydrogen sulfide, volatile fatty acid (VFA) gases, and other potentially hazardous gases.  ProSweet inhibitors minimize the growth of these bacteria and therefore, by acting on their source, the production of offensive gases is prevented.

Neutralizers
Waste areas represent a significant odor source.  The odor is spread over a large area and the volume is often too large to treat in the water phase. ProSweet neutralizers are  used for these problems.  These chemicals are distributed around the odor sources and the odors are negated when they combine with the neutralizer in the air.  This technology will neutralize odors such as hydrogen sulfide, mercaptans, and VFAs commonly found in biological treatment systems.  The equipment used to feed this technology is simple to use and requires minimal capital. 

Typical Odor Sources

Typical odor sources that can be treated with ProSweet™ Odor Control Technology are:

Foul condensate 
Turpentine tank vents
Black liquor tank vents
Non-condensable gas systems
Scrubber stacks
Dissolving tank vent
Primary and secondary waste clarifiers
Sludge dewatering area
Lagoons and ponds

Recorded Benefits

The following benefits have been recorded from practical applications of ProSweet™ Odor Control Technology:

Reduced odor complaints from employees and the surrounding community
Reduced health concerns from hazardous gases
Improved community relations 
Minimal capital investment required
Easy to feed and handle
System pH is not affected
Reduced pre-maintenance downtime

Hercules is the global, exclusive distributor for GE Water Technologies products.  ProSweet is a GE Water Technologies trademark and is used under license.  This trademark may be registered in one or more countries.