The SEMASS Resource Recovery Facility (SEMASS) is a processed refuse fuel (PRF) waste-to-energy plant serving much of Southeastern Massachusetts. Units 1 and 2 at the plant were designed with spray dryer absorbers (SDAs) and electrostatic precipitators (ESPs). A review of historical data from the plant indicated that in order to comply with the Environmental Protection Agency’s Municipal Waste Combustor (MWC) Rule (40 CFR Part 60, Subpart Cb), which is known as the Maximum Achievable Control Technology (MACT), improved emission performance would be required from the flue gas cleaning system on Units 1 and 2. A pilot test program was conducted which led to the installation of COHPAC, or CO mpact H ybrid PA rticulate C ollector units (i.e. flue gas polishing devices) downstream of the ESPs on these two combustion trains. The COHPAC units were successfully started up in June, 2000. In addition to these modifications, it was determined that further control of mercury emissions would be required. A system to inject powdered activated carbon into the flue gas was added to the plant. This paper describes that carbon injection system. A comparison between test data obtained at SEMASS is made with predictions based upon the EPA testing at the Ogden Martin Systems of Stanislaus, Inc. Municipal Waste Combustor Facility near Crows Landing, California and the EPA testing at the Camden County Municipal Waste Combustor in Camden, New Jersey. These are waste-to-energy plants, the former utilizing an SDA and a baghouse while the latter contains an SDA followed by an ESP. In addition, the effect of carbon injection location upon mercury reduction was investigated. The results of that study are also included.

This presentation will provide a historical perspective on the development of waste-to-energy (WTE) and conversion technologies in the 1970s and 1980s. During this time period, U.S. EPA provided grant assistance to a variety of projects and technologies including refuse derived fuel (RDF) production, RDF combustion, pyrolysis, gasification and anaerobic digestion. This presentation will also provide the latest, up-to-date information about WTE and alternative technologies, including data on costs, and current status of projects developing across North America as they exist in 2010. It will provide a review of WTE technologies as an element of integrated solid waste management systems and highlight some of the advances which have been moved into production units to make WTE environmentally friendly. It will also include a brief look at plants worldwide, followed with a focus on facilities, technologies and companies operating in the U.S. Specific examples of technologies and associated facilities will include: –Mass Burn; –Modular; –RDF - Processing & Combustion; –RDF - Processing Only; –RDF - Combustion Only. Municipal waste combustors are regulated under the federal Clean Air Act (CAA), originally passed by Congress in 1963 and amended in 1967, 1970, 1977, 1990 and 1995 and 1998. The U.S. EPA may implement and enforce the requirements or may delegate such authority to state or local regulatory agencies. The CAA places emissions limits on new municipal waste combustors. In addition, the 1995 amendments to the Clean Air Act (CAA) were developed to control the emissions of dioxins, mercury, hydrogen chloride and particulate matter. By modifications in the burning process and the use of activated carbon injection in the air pollution control system, dioxins and mercury, as well as hydrocarbons and other constituents, have effectively been removed from the gas stream. The presentation will also review the companies offering WTE in the form of alternative technologies being promoted and considered in the U.S., and several recent and current procurements will be reviewed. GBB tracks over 150 different companies offering technologies, facilities and services whose developmental stages range from engineering drawings and laboratory models to full-scale operating prototypes. The presentation will provide an overview of these systems and their status. Implementation of new WTE projects — whatever technology is selected — will involve local governments in the process because MSW management is a local responsibility. Implementation will involve risks for local government and any private entities involved. A comprehensive review of the risks and challenges associated with implementing various technologies will be provided. The presentation will conclude with key elements to keep in mind when implementing WTE and/or conversion technologies. The last new MSW-processing WTE facility constructed in the U.S. commenced operations in 1996. Since that time, no new greenfield commercial plant has been implemented. In the past few years, however, interest in WTE and waste conversion has begun to grow, again. This renewed interest in waste processing technologies is due to several factors: successful CAA retrofits, proven WTE track record, increasing cost of fossil fuels, growing interest in renewable energy, concern of greenhouse gases, reversal of the Carbone Supreme Court Case, and the change in U.S. EPA’s hierarchy, which now includes WTE. Since 2004, several municipalities commissioned reports in order to evaluate new and emerging waste management technologies and approaches. These will be summarized. With the passage of the American Recovery and Reinvestment Act of 2009, the U.S. DOE has been working to advance innovative green energy technologies, which can be applied to MSW as well as other bio-feedstocks. DOE has made a number of grant awards to projects where MSW is used as a feedstock. This presentation will summarize the status of these projects and discuss how they should be viewed when considering new projects. The presentation will also outline policies for governments to consider when considering recycling goals with WTE. This review will be done in the context of environmental and energy considerations as well as public policy considerations. Comments will be included regarding current legislation and regulations, specifically for greenhouse gas emissions, being considered by the U.S. or state governments. The presentation will provide participants with: –A historical reference for experiences with WTE/alternative technologies in the U.S. in the 1970s and 1980s; –Latest information on the state of WTE/alternative technologies in the U.S., including their environmental performance; –A global understanding of current technologies and trends; –Understanding of the risks and challenges associated with implementing various technologies; –Understanding the key elements to keep in mind when implementing WTE; –Suggested policy for recycling and WTE to co-exist as components of a local solid waste system; and –Comments about current legislation being considered by the U.S. and state governments.

In recent years since enactment of the NSPS, carbon injection has significantly reduced mercury emissions from MSW units. What is not well known is that carbon injection has also resulted in further unintentional reductions in PCDDs/PCDFs emissions from MSW emissions. These emissions reductions have taken place on a mass basis as well as a TEF weighted basis. The latter have been more pronounced on a percent reduction basis owing to changes in the PCDDs/PCDFs profile directly attributable to preferential adsorption of selected 2,3,7,8-substituted congeners on activated carbon injected in the gas stream for mercury removal. These lower molecular weight congeners are typically present in the gas phase and contribute more significantly to the TEF weighted sum.

Polk County owns and operates two starved air mass burn municipal solid waste combustors serving a five County region in rural Northwest Minnesota. The plant was constructed in 1987 and began burning MSW in 1988. Each unit has a combustion capacity of 40 tons per day producing energy in the form of saturated steam for two customers in the adjacent industrial park. The plant utilizes a two field electrostatic precipitator (ESP) as the air pollution control device for each unit. In 1996, a materials recovery system was constructed in front of the waste combustors to remove problem/objectionable items. This facility is providing many benefits including reduced stack emissions, lower O & M costs for the WTE units, and revenues from the sales of extracted recyclables. Both facilities have operated successfully since startup. EPA emission guidelines for existing small waste combustors were originally promulgated in December 1995. These guidelines set more stringent limits for pollutants currently regulated and added limits for several other pollutants previously unregulated. However, litigation set aside these 1995 emission guidelines for small waste combustors until they were re-established by EPA in December 2000. Pending release of the year 2000 emission guidelines, the Minnesota Pollution Control Agency stayed the State rule and issued a Rule variance in 1998 that included new limits for mercury, and dioxins/furans. In order to attain compliance with the new State limit for dioxin/furans, Polk began injecting powdered activated carbon into the flue gas of each unit upstream of the ESP. The emission guidelines are technology based, and EPA concluded that small existing waste combustors could maintain operation of the electrostatic precipitators. Compliance with the guidelines could be attained with an ESP upgrade or added collection field in conjunction with the addition of other pollution control equipment. Was the EPA right? Can this technology comply with the guidelines? This paper will discuss the development of an APC retrofit project for a small waste combustor whose goal was to attain full compliance with the revised air emission guidelines while maintaining operation of the existing electrostatic precipitators.

Following a 1986 decision by Montgomery County in Maryland to construct a municipal waste resource recovery facility near the town of Dickerson, the local community expressed concern regarding the potential human health effects from air emissions of dioxins and trace metals released through the stack of the proposed facility. To address this concern, the County conducted health risk studies and ambient monitoring programs before and after the facility became operational. The purpose of the health risk studies was to determine potential cancer and non-cancer risks to the nearby residents from the operations of the facility. The purpose of the ambient monitoring programs was to determine if any changes would occur in the ambient levels of certain target chemicals in the environmental media, and if such changes can be attributed to the operations of the facility. Accordingly, the County conducted a multiple pathway health risk assessment in 1989 prior to the construction of the facility. The pre-operational health risk assessment was based on estimated stack engineering parameters and available stack emissions data from municipal waste resource recovery facilities that were operating in the United States, Canada and Europe during the 1980’s. The health risk assessment used established procedures that were accepted by the U.S. Environmental Protection Agency (U.S. EPA) and many state agencies at that time. The Montgomery County Resource Recovery Facility (RRF) became operational in the spring of 1995. The facility is equipped with the state-of-the-art air pollution control (APC) equipment including a dry scrubber-fabric filter baghouse system to control organics and trace metals, ammonia injection system to control nitrogen oxides, and activated carbon injection system to control mercury. In 2003, the County retained ENSR International to update the 1989 health risk assessment study. In the 2003 operational-phase update, as-built engineering data and measured stack emissions data from a total of eighteen quarterly stack emissions tests were used. The study was conducted in accordance with the U.S. EPA’s Human Health Risk Assessment Protocol for Hazardous Waste Combustion Facilities published in 1998 [1], and an Errata, published in 1999 [2]. Both the 1989 study and the 2003 study demonstrated that there is a very low chance (less than one chance in a million) for occurrence of cancer and no adverse non-cancer health effects to the nearby community as a result of exposure to facility-related emissions. The multi-media ambient monitoring programs were conducted in abiotic and biotic environmental media. These programs included an air-monitoring component and a non-air monitoring component. The pre-operational phase of the air media and non-air media monitoring was conducted in 1994–1995. The pre-operational program was designed to produce baseline data for target chemicals in both air and non-air media. The operational-phase air media monitoring was conducted in 1997 and 2003. The operational-phase non-air media monitoring was conducted in 1997 and 2001. Target chemicals monitored in both air and non-air media included polychlorinated dioxins and furans (PCDDs/PCDFs) and selected toxic metals (arsenic, beryllium, cadmium, chromium, lead, mercury, and nickel). The non-air media included crops, farm pond surface water and fish tissue, and cow’s milk. The ambient levels of target chemicals monitored in the operational phase of the facility (1997, 2001 and 2003) demonstrated no measurable difference from the ambient levels of these chemicals monitored in the pre-operational phase (1994–95) of the facility, in both the air media and non-air media. The results of the health risk studies and ambient monitoring programs demonstrate that municipal waste combustion facilities that are equipped with the state-of-the-art air pollution control equipment pose no significant health risk to the population.

During the combustion of fuel in Waste-to-Energy (WTE) and coal-fired power plants, all of the mercury input in the feed is volatilized. The primary forms of mercury in stack gas are elemental mercury (Hg 0 ) and mercuric ions (Hg 2+ ) that are predominantly found as mercuric chloride. The most efficient way to remove mercury from the combustion gases is by means of dry scrubbing, followed by activated carbon injection and a fabric filter baghouse. Back in 1988, the U.S. WTE power plants emitted about 90 tons of mercury (Hg). By 2003, implementation of the EPA Maximum Achievable Control Technology (MACT) standards, at a cost of one billion dollars, reduced WTE mercury emissions to less than one ton of mercury. EPA now considers coal-fired power plants to be the largest remaining anthropogenic source of mercury emissions. Approximately 800 million short tons of coal, containing nearly 80 short tons of Hg are combusted annually in the U.S. for electricity production. About 40% of this amount is presently captured in the gas control systems of coal-fired utilities. Since the concentration of mercury in U.S. coal is ten times lower than in the MSW feed and the volume of gas to be cleaned 55 times higher, the cost of implementing MACT by the U.S. coal-fired utilities is estimated to be about $25 billion. However, when this retrofit cost is compared to the total capital investment and revenues of the two industries, it is concluded that MACT should be affordable. Per kilogram of mercury to be captured, the cost of MACT implementation by the utilities will be twenty times higher than was for the WTE industry. However, implementation of MACT by the utilities will also reduce the emissions of other gaseous contaminants and of particulate matter.

In the early 1980’s Polk County and four other partner counties in rural Northwest Minnesota made the decision to incorporate a waste to energy (WTE) plant into their solid waste management program. This decision was made to comply with the Minnesota hierarchy for solid waste management, to extend the life of the Polk County landfill, and to recover valuable energy from the waste. The plant was constructed in 1987 and began burning MSW in 1988. The processing technology consisted of two starved air mass burn municipal solid waste combustors each with a combustion capacity of 40 tons of MSW per day, and produced energy in the form of saturated steam for customers in the adjacent industrial park. Initially each train utilized a two field electrostatic precipitator (ESP) as the air pollution control (APC) device. In 1996, a materials recovery system (MRF) was constructed in front of the waste combustors to remove problem/objectionable items most of which are recyclable. This facility has been a tremendous success providing many benefits including reduced stack emissions, lower O & M costs for the WTE units, and revenues from the sales of extracted recyclables. In 1998 Polk began injecting powdered activated carbon (PAC) into the flue gas of each unit upstream of the ESP to attain compliance with new State limits for dioxin/furans and mercury. Then in 2000 Polk County proceeded with an APC retrofit project designed to meet revised EPA emission guidelines which set more stringent limits for pollutants currently regulated and added limits for several other pollutants previously unregulated. In 2001 and 2004 Polk County performed research demonstration projects substituting screened WTE combined ash for a portion of natural aggregate in two asphalt road construction projects. Both projects passed stringent environmental testing and demonstrated superior strength and flexibility performance compared to conventional asphalt. Polk County is now proceeding with the installation of a turbine/generator to produce renewable electricity with excess steam. The electricity produced will be used to reduce the demand for incoming power from the local utility. Initially this may be only a twenty-five percent reduction but has the potential to be more in the event one or more of the steam customers reduces their dependence on steam from the WTE plant. All of these projects received funding assistance from the State of Minnesota in the form of Capital Assistance Grants. In 2003 the WTE plant and MRF became debt free and Polk County lowered the tip fee resulting in a disposal rate that is fairly competitive with that of most out of state landfills. This paper will discuss the development, success, and benefits of this completely integrated solid waste management system for these five counties located in Northwest Minnesota.