In early 1998, the City of Ravenna, Italy, commissioned a fluid bed boiler/waste-to-energy system to combust approximately 50,000 tonnes per year of processed municipal waste and generate electrical power. Much of the fuel preparation and processing equipment was already in place and the primary focus of this project was to implement an environmentally acceptable energy conversion process compatible with the 6.0 tonnes per hour of fuel being processed. The fluid bed boiler system being provided incorporates state of the art environmental controls for abatement of all pollutants, including products of incomplete combustion (PIC’s), NOx, acid gases, and particulates. The project delivers an average of 70,000 pounds per hour of steam to generate approximately 7 MW of electricity.

On October 30, 2009 the U.S. Environmental Protection Agency (USEPA) promulgated the Mandatory Reporting of Greenhouse Gases (ghg) across virtually every industry sector in the U.S., including Waste-to-Energy (WTE) plants, emitting over 25,000 metric tons of carbon dioxide (CO 2 ) equivalent emissions per year. In conformance with 40CFR part 98, subpart C stationary fuel combustion sources, WTE plants were required to report 2010 CO 2 emissions by September 30, 2011, and annually thereafter by March 31 st . A key element of this process involves the quarterly collection of flue gas samples for characterization of mean biogenic CO 2 content. While this rule is in its infancy, it is clear that the Agency intends to regulate CO 2 emissions, especially the anthropogenic fraction, across all industry sectors. Currently, ecomaine’s sample results for its municipal waste combustor (MWC) contain, on average, 60% biogenic carbon with the remaining 40% fraction characterized by anthropogenic carbon. As ecomaine begins to optimize the removal of organic material through stepped up recycling efforts and the phase-in of large-scale composting operations, it is plausible that the biogenic carbon fraction will diminish over time, leaving a growing fraction of the less desirable anthropogenic carbon. Based on USEPA’s 2010 Municipal Solid Waste in the U.S. – 2009 Facts and Figures report (EPA-530R-10-012) , the organic fraction of municipal solid waste is approximately 62.5% by weight before recycling. The successful diversion of even 1/2 this material away from ecomaine’s MWC could result in a measurable reduction of biogenic carbon, possibly reversing the biogenic:anthropogenic fraction to 40%:60%. This paper will explore strategies, including Life Cycle Analyses of WTE, recycling, and composting operations that the WTE industry can employ to help frame anthropogenic carbon emissions in a better light and stave off future regulatory sanctions as the climate change debate advances to a new level in the years ahead.

Although the Energy from Waste (EfW) industry has made dramatic improvements in reducing dioxin emissions over the last two decades, the presence of any dioxins in the stack gases from EfW plants continues to be a negative to the acceptance and growth of the EfW industry in the United States. Covanta Energy owns and operates 40 EfW facilities in the U.S. with average dioxin emissions 10 times below the EPA MACT standard of 30 ng/dscm. This emission standard is expected to be reduced in the coming years as the EPA implements new MACT standards. Covanta has taken the position of being in the forefront of the legislation and has an ongoing commitment to continuously lower the emissions of existing plants below regulatory requirements. This commitment has led Covanta to team with CRI Catalyst Company (CRI) to evaluate the application of CRI’s dedioxin technology (SDDS ® ) in Covanta’s EfW plants.

The newly promulgated EPA MACT rules for solid waste incinerators require HCl to be mitigated to extremely low concentrations. Most existing air pollution control systems will probably not be able to satisfy these very low limits. To meet the new challenges, dry injection of sodium bicarbonate or trona is a low-cost solution that can be applied in the following situations: (1) Replace existing acid gas mitigation systems; (2) Supplement existing systems; (3) Install where no acid gas mitigation systems exist yet. In a dry sorbent injection system, sodium bicarbonate or trona is injected directly into hot flue gas. After injection, the sorbent is calcined into porous activated sodium carbonate. Its high surface area enables fast gas-solid reactions between acid gases (mainly HCl and SO 2 ) and Na 2 CO 3 to form NaCl and Na 2 SO 4 which are collected by either electrostatic precipitators (ESP) or fabric filters. The dry injection systems with sodium bicarbonate have shown over 99% removal of HCl and 95% removal of SO 2 at over 150 Waste-To-Energy plants in Europe. This paper will describe the concept of dry sorbent injection system with sodium bicarbonate or trona, provide performance data from several plants, and describe system design guidelines.

The dominant technology for large Waste-to-Energy (WTE) facilities is combustion on a moving grate of “as-received” municipal solid wastes (MSW). However, there are circumstances where a low-capacity plant (<100,000 tons per year) is required. This study examines the technical, economic, and environmental aspects of some small-scale WTE technologies currently in operation. The Energos technology was developed in Norway, in order to provide relatively small communities with an economically efficient alternative to mass-burn incineration with equally low emissions to the atmosphere and flexibility in feedstock. All operating plants treat MSW plus additional streams of commercial or industrial wastes. Prior to thermal treatment, the materials are shredded in a high-torque, low-rpm shredder and ferrous metals are removed magnetically. The feedstock is partially oxidized on a moving grate in the gasification chamber where the fixed carbon is completely burnt off. The volatilized gases are fully combusted in a second chamber and the heat is transferred to a heat recovery system for steam generation. The Energos gasification technology is currently in operation at six plants in Norway, one in Germany, and one in the UK. As expected, the capital cost per ton of annual ton of capacity increases with decreasing plant capacity, while there is a linear relationship between energy recovery and capacity. Some other small-scale technologies are investigated in this study and will be reported at the NAWTEC meeting. Low capacity (<80,000 tons) WTE facilities require a relatively small footprint (1.5 to 2 acres; <1 hectare) and it is believed that these facilities can be built at a capital cost per ton that is as low, or lower, than that of large mass burn WTE facilities.

Solid waste incinerators emit air pollutants such as SO 2 , HCl, and mercury. Dry sorbent injection of sodium sorbents has emerged as an important SO 2 , HCl, and mercury mitigation technology due to its (a) low capital cost; (b) small installation foot print; (c) ease of operation; and (d) flexibility to fuel changes. In a dry sorbent injection system, trona or sodium bicarbonate is injected directly into hot flue gas. After injection, the sorbent is calcined into porous sodium carbonate that reacts with acid gases (SO 2 , HCl and SO 3 ). This technology is able to achieve high removal rates for HCl (>99%) and SO 2 (>90%), and has been implemented at many waste incinerators in Europe and coal-fired power plants in the United States. With the promulgation of MACT rules, this technology will be a low-cost and easy-to-use option for waste-to-energy boiler owners.

As Energy-from-Waste (EfW) facilities make the leap into the twenty-first (21 st ) century, so does the demand for cost efficient air pollution control technology. In an effort to meet this rising demand, companies have to develop concepts that remove acid gases in an efficient, sustainable, and reliable way. The current market trend to provide the best available control technology (BACT) leads people searching for technologies that are: • Proven and have extensive records of success. • Highly efficient, resulting in low emission to the atmosphere, but requiring minimal investment. • Compact in design, simple, and low maintenance. • Offering high availability, low reagent consumption, and low residue levels. • Resulting in either clean or suppressed liquid effluents. This paper will specifically discuss the three main types of acid gas control technologies available in today’s marketplace, which include dry, semi-dry, and wet scrubbers. It will first focus on the acid gas control technology most commonly used in the US, the spray dryer absorber, followed by a typical Ring Jet® wet scrubber with packed bed, and finally, the Turbosorp® system. For each of the above technologies, this paper will present the concepts, advantages and disadvantages, achievable emissions, and capital and operating costs. It will then look at how each of these technologies is utilized at existing EfW facilities operating throughout the world and provide information on how each facility has been operating. Lastly, it will look towards the future of acid gas control technologies and provide insight into what advances are being made to meet the most stringent air emission regulation all over the world.

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.

A new WTE (Waste-to-Energy) power plant configuration combining municipal solid waste and gas turbines or landfill gas engines is proposed. The system has two objectives: increase the thermodynamic efficiency of the plant and avoid the corrosion in the MSW (Municipal Solid Waste) boiler caused by high tube metal temperatures. The difference between this concept and other existing configurations, such as the Zabalgarbi plant in Bilbao, Spain, is lower natural gas consumption, allowing an 80% waste contribution to the net energy exported or more. This high efficiency is achieved through four main steps: 1 . introducing condensing heat exchangers to capture low temperature heat from the boiler flue gases; the stack temperature can drop to 70°C; 2 . high steam temperatures in external superheaters using hot clean gases heated with duct burners; 3 . mixing the exhaust gases of a small gas turbine with hot air preheated in a specially designed heat exchangers. The resulting temperature of this gas mixture is almost the same as a standard gas turbine but with the flow similar to that of a large machine with a higher O 2 content; 4 . After the duct burner and heat exchangers, the oxygen content of the clean gas mixture is still high, nearly 18%, and the temperature is approximately 200°C. The gas is then used as combustion air to the MSW boiler such that all the energy stays in the system. The efficiency can be as high as 33% for the MSW part of the plant and 49% for the natural gas system. Since the natural gas consumption is almost ten times less than the existing designs, it can be replaced by landfill gas or gasified ethanol or biodiesel. Currently an 850 ton/day plant is being designed in Brazil in partnership with a large power company. Other advantages include, self generation of internal power and lower steam superheating temperatures in the MSW boiler. This concept can be used with any grate design.

Great River Energy operates a waste-to-energy plant in Elk River, Minnesota. The plant burns 850 tons per day of refuse derived fuel (RDF) in three boilers, and its three steam turbines can produce 32 MW of electricity. In the largest of the three units, the No. 3 Boiler, steam generation was restricted by carbon monoxide (CO) and nitrogen oxides (NO x ) emission limits. The plant had an interest in improving the combustion performance of the unit, thereby allowing higher average RDF firing rates while staying within emissions compliance. The project was initiated by an engineering site visit and evaluation. The boiler had a history of unstable burning on the stoker grate, which required periodic natural gas co-firing to reduce CO levels. As an outcome to the evaluation, it was decided to install a new overfire air (OFA) system to improve burnout of combustible gases above the grate. Current and new OFA arrangements were evaluated via Computational Fluid Dynamics (CFD) modeling. The results illustrated the limitations of the original OFA system (comprised of multiple rows of small OFA ports on the front and rear furnace walls), which generated inadequate mixing of air and combustible gases in the middle of the boiler. The modeling illustrated the advantages of large and fewer OFA nozzles placed on the side walls in an interlaced pattern, a configuration that has given excellent performance on over 45 biomass-fired boilers of similar design upgraded by Jansen Combustion and Boiler Technologies, Inc. (JANSEN). Installation of the new OFA system was completed in April of 2008. Subsequent testing of the No. 3 Boiler showed that it could reliably meet the state emission levels for CO and NO x (200 ppm and 250 ppm, respectively, corrected to 7% dry flue gas oxygen) while generating 24% more steam than a representative five month period prior to the upgrade. This paper describes the elements that led to a successful project, including: data collection, engineering analyses, CFD modeling, system design, equipment supply, installation, operator training, and startup assistance.

Plasma gasification is an efficient and environmentally responsible form of thermal treatment of wastes. In the plasma gasification process, extremely high temperature gases are used to break down the molecular structure of complex carboncontaining materials — such as municipal solid waste (MSW), tires, hazardous waste and sewage sludge — and convert them into synthesis gas (syngas) containing hydrogen and carbon monoxide that can be used to generate power or other sustainable sources of energy. Gasification occurs in an oxygen starved environment so the waste is gasified, not incinerated.

The management of municipal solid wastes (MSW) in Puerto Rico is becoming increasingly challenging. In recent years, several of the older landfills have closed due to lack of compliance with federal landfill requirements. Puerto Rico is an island community and there is limited space for construction of new landfills. Furthermore, Puerto Rico residents generate more waste per capita than people living on the continental US. Thermal treatment, or waste to energy (WTE) technologies are therefore a promising option for MSW management. It is critical to consider environmental impacts when making decisions related to MSW management. In this paper we quantify and compare the environmental implications of thermal treatment of MSW with modern landfilling for Puerto Rico from a life cycle perspective. The Caguas municipality is currently considering developing a thermal treatment plant. We compare this to an expansion of a landfill site in the Humacao municipality, which currently receives waste from Caguas. The scope of our analysis includes a broad suite of activities associated with management of MSW. We include: (i) the transportation of MSW; (ii) the impacts of managing waste (e.g., landfill gas emissions and potential aqueous run-off with landfills; air emissions of metals, dioxins and greenhouse gases) and (iii) the implications of energy and materials offsets from the waste management process (e.g., conversion of landfill gas to electricity, electricity produced in thermal treatment, and materials recovered from thermal treatment ash). We developed life cycle inventory models for different waste management processes, incorporating information from a wide range of sources — including peer reviewed life cycle inventory databases, the body of literature on environmental impact of waste management, and site-specific factors for Puerto Rico (e.g. waste composition, rainfall patterns, electricity mix). We managed uncertainty in data and models by constructing different scenarios for both technologies based on realistic ranges of emission factors. The results show that thermal treatment of the unrecyclable part of the waste stream is the preferred option for waste management when compared to modern landfilling. Furthermore, Eco-indicator 99 method is used to investigate the human health, ecosystem quality and resource use impact categories.

The proportional composition of cellulose, hemicellulose, lignin and minerals in a biomass plays a significant role in the proportion of pyrolysis products (bio-oil, char, and gases). Traditionally, the composition of biomass is chemically determined, which is a time consuming process. This paper presents the results of a preliminary investigation of a method using thermo-gravimetric analysis for predicting the fraction of cellulose and lignin in lignin-cellulose mixtures. The concept is based on a newly developed theory of Pyrolytic Unit Thermographs (PUT). The Pyrolytic Unit Thermograph (PUT) is a thermograph showing rate of change of biomass weight with respect to temperature for a unit weight loss. These PUTs were used as input for two predictive mathematical procedures that minimize noise to predict the fractional composition in unknown lignin-cellulose mixtures. The first model used linear correlations between cellulose/lignin content and peak decomposition rate while the second method used a system of linear equations. Results showed that both models predicted the composition of lignin-cellulose mixture within 7 to 18% of measured value. The promising results of this preliminary study will certainly motivate further refinement of this method through advanced research.

The U.S. generates about 370 million short tons of Municipal Solid Waste (MSW) each year. In 2002, an average of 26.9% of this material was either recycled or composted. Of the remainder, an estimated 242 million short tons were disposed of in landfills and about 29 million short tons were combusted in Waste to Energy (WTE) facilities to produce electricity and scrap metal. Effective management of MSW is becoming increasingly challenging, especially in densely populated regions, such as New York City, where there is little or no landfill capacity and the tipping fees have doubled and tripled in recent years. There is also a growing appreciation of the environmental implications of landfills. Even with modern landfill construction, impacts remain from the need for transfer stations to handle putrescible wastes, their transport to distant landfills, and finally landfill gas emissions and potential aqueous run-off. Environmental impacts of concern associated with disposal in WTEs include air emissions of metals, dioxins and greenhouse gases. In the U.S., there is also a strong negative public perception of WTE facilities. Decisions about waste management should be influenced by a consideration of the overall, quantified life-cycle environmental impacts of different options. In this paper we therefore develop a methodology to assess these impacts for landfilling and WTE waste management options. Specifically we attempt to compare these two options for New York City, a large urban area.

Plasma Resource Recovery (PRR) is a revolutionary technology that can treat virtually any type of waste by combining gasification with vitrification. Vitrification produces inert slag that can be used as a construction material. Gasification produces a fuel gas containing carbon monoxide (CO) and hydrogen (H 2 ), used for cogeneration of electricity and steam. The plasma fired eductor which is the core technology of the PRR system is presently being used commercially on a cruise ship at a scale of 5 TPD. The capabilities of the PRR technology have been demonstrated in a pilot plant, at a rate of up to 2 TPD of various types of waste. Because of the high intensity of the plasma flame and the reduced amounts of gases produced in a gasification system, compared to traditional combustion systems, the PRR system is typically very compact. As such, the PRR technology opens the door for a decentralized, small scale approach to waste management.

During incineration of municipal solid waste (MSW), various environmentally harmful elements and heavy metals are liberated either into bottom ash, or carried away with the off-gases and subsequently trapped in fly-ash. If these minor but harmful elements are not properly isolated and immobilized, it can lead to secondary environmental pollution to the air, soil and water. The stricter environmental regulations to be implemented in the near future in the Netherlands require a higher immobilization efficiency of the bottom ash treatment. In the present study, MSW incinerator bottom ash was vitrified at higher temperatures and the slag formed and metal recovered were examined. The behaviour of soluble elements that remain in the slag is evaluated by leaching extraction. The thermodynamics of slag and metal formation is discussed. The results obtained can provide a valuable route to treat the ashes from incinerators, and to make recycling and more efficient utilization of the bottom ash possible.

The Taiwan Kobin Bottom Ash Processing & Recycle Plant (Kobin-BAPRP) processes approximately one quarter million metric tons of bottom ashes from several municipal solid wastes the incinerators annually, generating fine aggregate finished products and ferrous recovery. The results from USEPA Method 1311 Toxicity Characteristic Leaching Procedure (TCLP) for un-treated bottom ash indicate that about 5% of the time that lead and less than 0.5% of the time, copper or cadmium may fail to meet leaching standards (i.e. 5 mg/L for Pb, 15 mg/L for Cu, and 1 mg/L for Cd ). Previously, Kobin applied phosphoric acid solution for stabilization, which caused strong odor problem, increased moisture content, and still about 1% of the time that TCLP-Pb failed to pass the standard, hence, required reprocessing. Recently, Kobin-BAPRP has switched its stabilization agent from the phosphoric acid solution to dry chemical dosage. In addition to having a better stabilized byproduct, the use of dry chemical further ensures worker safety. Dry chemical is water insoluble and fine calcium phosphate particles, with different combinations of buffers and complexing agents, such as Fe +2 , Fe +3 , Al +3 , or chloride. It took about 8 months for laboratory tests and plant trials to identify the optimum dosage as well as the best mixing point. Long term operation has demonstrated that dry chemical spread and mixing is safe to communities and workers, non-reactive with storage and handling materials, generates no toxic gases or odor, and most importantly, provides for effective and consistent Pb stabilization. The final stable family of mineral crystals includes complexed hydroxyapatite and chlorapatite minerals.

This study has been initiated to quantify the release of the Polycyclic Aromatic Hydrocarbon (PAH) species from Styrene Butadiene Copolymer (SBR) during gasification. The identification and quantification has been determined experimentally using Gas Chromatography/Mass Spectroscopy (GC/MS) coupled to a Thermo-Gravimetric Analysis (TGA) unit. SBR samples were pyrolysed in a TGA unit in a N 2 atmosphere. The identities and absolute concentrations of over 32 major and minor species have been established, including a large number of aromatics, substituted aromatics, and PAHs. The light hydrocarbon species also have been determined simultaneously and identified as H 2 , C 2 H 2 , CH 4 , C 2 H 6 , and C 4 H 10 with lower concentrations of other hydrocarbon gases. Significant amounts of ethyl benzene, toluene, and styrene were observed between 330°C and 500°C. The largest PAH detected was the family of C 24 H 14 (molecular weight 302), benzo[ghi]perylene with peak concentrations reaching 0.19 ppmv. The effluent species detected suggest that formation of PAH’s occurs either through hydrocarbon addition reactions or benzene ring re-combination reactions. In addition, the chemical structure of SBR lends itself gas phase release of benzene molecules or radicals, thus facilitating the PAH production route. Preliminary calculations done using MOPAC provided some insight into the energy required to break the benzene ligand bond from the butadiene structure. The measurements supply information on the identities and levels of hazardous air pollutants, and provide useful new data for the development and validation of detailed reaction mechanisms describing their origin and fate.