(177a) Optimizing Mercury Removal Processes for Industrial Wastewaters

Although
typically occurring at ppb levels in wastewater discharge streams, the severe
toxicity of many mercury compounds and their tendency to bioaccumulate in
aquatic ecosystems has led to very stringent Hg discharge regulations being
proposed and implemented in many regions of the US.  Examples include the Ohio
River Valley Sanitation Commission (ORSANCO) standard of 12 ppt Hg for discharges
into the Ohio River and the Great Lakes Water Quality Initiative standard of
1.3 ppt Hg for discharges into bodies of water in the Great Lakes Basin. 
Meeting these limits presents a significant challenge to wastewater treatment engineers
and environmental managers in many industries, including coal burning power
plants, petroleum refineries, and chemical manufacturing plants.

This
presentation will describe bench-scale and pilot-scale methods that have been successfully
used to evaluate chemical additives and physical separation processes for their
effect on mercury removal.  Discussion will include how to use a total systems
approach to develop the most efficient treatment program that will meet current
and proposed Hg discharge standards.  Results of studies on a variety of industrial
wastewaters will be presented to demonstrate the mercury removal performance of
several traditional and non-traditional chemical/equipment treatment
combinations.  Data from studies using a novel polymeric organosulfide additive
will be highlighted for its proven ability to reduce mercury to low ppt
concentrations.