Previous Action and Current Activity. The Council adopted a Mercury Reduction Strategy in April 1998. This strategy guides staff implementation activities and actions and is a demonstration of the Council’s commitment to mercury reduction. In addition to the efforts that are conducted as part of controlling discharges to the MDS, the strategy is intended to be implemented through a variety of approaches such as education, pollution prevention, research, monitoring and technology-based controls. This strategy is intended to go beyond the substantial reductions already achieved through the control of industrial and other dischargers to the MDS and to go beyond the current regulatory requirements for owners and operators of WWTPs.
Previous Action and Current Activity. A key part of our pretreatment program includes periodically providing information to the regulated community regarding potential sources of mercury in their facilities and processes and encouraging mercury elimination to avoid discharge to the collection system. For example, we are aware that mercury can contaminate a variety of industrial chemicals such as acids and caustics and have communicated this and other information to industrial users. In addition, staff write up case study information on “lessons learned”, as sources of mercury are identified and dealt with. This is done to help internal staff and outside industries that are looking to find and reduce sources of mercury being discharged to the MDS. MCES staff take every opportunity to communicate with our customers about various environmental issues and the impacts they may have on our facilities, operations and wastewater rates. We do this through a variety of communication methods including printed information to communities and industrial users, information posted on our website (xxx.xxxxxxxxxxxx.xxx), and when we make presentations or speeches to our customer communities, industry and other interest groups. These types of communications have the expressed purpose of educating people about potential mercury sources and reduction options. XXXX has participated in the preparation of mercury reduction materials by others. For example, MCES staff served on a 25-member advisory committee to assist the Western Lake Superior Sanitary District (WLSSD) in the development of the document titled “Blueprint for Mercury Elimination” (March 1997).
Previous Action and Current Activity. The Metro Plant processes the solids removed from the treated wastewater through combustion in six multiple hearth incinerators. Each incinerator has an associated air pollution control (“APC”) system which treats the exhaust gases from the combustion process. The existing APC systems are primarily composed of wet scrubber units. Because water from these scrubbers is recycled back into the plant, higher mercury concentrations are found in the solids than there would be without these recycle streams. When the solids are subsequently incinerated, this negates the incidental removal efficiency of the wet scrubber units. The Council has initiated the Metro Solids Processing Improvements Project to replace the aging multiple hearth incinerators and APC systems with new combustion technology (fluidized bed incinerators) and accompanying APC systems. Procurement of these new systems began in early 2000. The Council awarded a contract for design and construction of the fluidized bed incinerators and accompanying APC systems at its December 13, 2000 meeting. Issuance of the notice to proceed is dependent on the issuance of the air emissions permit amendment. Operation of the new facilities is scheduled to begin in 2005. Technology to achieve mercury removal from combustion exhaust gases at sewage sludge incineration (“SSI”) facilities is still being researched and developed. There is no known SSI facility in North America that has an APC system specifically designed to achieve mercury removal. Technology used in other industries to remove mercury from exhaust gases has not yet been demonstrated as effective in SSI facilities.
