ash-handling systems and then disposed at landfills. Sludge Incineration Multiple Hearth Furnace Ash from fluidized-bed units is very fine and can be Cost and Technical Feasibility removed with periodic sand changes and continuous Cooling ncineration is a sludge disposal option that Air Discharge scrubbing of the exhaust. Ash disposal is regulated hen considering whether or not to incinerate I involves the firing of sewage sludge at high under solid waste disposal regulations. Beneficial use Wsludge, or which incineration technology to temperatures in an enclosed structure. This process of this ash is actively being investigated. use, cost is always a major consideration. A sludge reduces the sludge to a mass of ash that is less than incinerator is a very mechanized and capital-intensive 20 percent of its original volume. EPA and the states Air Pollution Control Equipment investment that must be managed with a high level of generally support the beneficial use of sludge. Many Sewage expertise and attention to maintenance. Sludge urban sewage treatment facilities produce large Gas Inlet The incineration option is a long-term commitment volumes of sludge and have limited available space Exhaust n general, air pollution control devices are used to for sludge management. They are likely to see I either remove small particles and metals in the that is most cost-effective for large volume wastewater incineration as their most viable option. exhaust gas or to further decompose organics. Devices treatment systems or as a regional solution. In such as wet scrubbers and dry and wet electrostatic evaluating this option, communities must consider Sludge incineration eliminates some environmental precipitators are used to remove metals. Afterburners ash disposal, economies of scale, and air quality. and health problems by destroying pathogens and are used to more completely burn organics in exhaust How much will it cost to build and operate an toxic organic chemicals. Anyone who fires sludge in gases. More recently, regenerative thermal oxidizers an incinerator must meet the sludge incineration incinerator or upgrade and refurbish an existing (RTOs) are being utilized as part of the air pollution incinerator? The answer to that question depends on requirements in Subpart E of the Part 503 rule, which control system in incinerators. address pollutant limits for seven metals, limits for the site, how much sludge the wastewater treatment total hydrocarbons, general requirements and facility produces, and what other technically feasible options exist. Most sites within approximately a half management practices, frequency of monitoring Fluidized Bed Reactor requirements, and recordkeeping and reporting mile of a residential neighborhood are not good candidates for incineration facilities. requirements. In addition, states have their own air Exhaust quality requirements for incineration. and Ash While questions of technical feasibility and cost can Ash Discharge be examined through extensive site-specific Cooling Air Intake engineering studies, a general rule of thumb is that most incinerators should handle a sludge input rate Incineration Systems between 0.25 and 3 dry tons per hour. Anything less Fluidized-Bed Reactors, thought by many in the that 0.25 dry tons would most likely be too expensive ncineration systems generally consist of an industry to be the cleanest, are one of the newest for this technology; over 3 dry tons per hour tends to I incinerator (furnace) and one or more air incineration technologies and one of the least expensive exceed the limit of the technology and may require pollution control devices. In New England, the two for large-scale operations. These systems employ a layer multiple incinerators. of sand, which is “fluidized” by a constant, high- most commonly used incineration systems are Burner multiple hearth furnaces and fluidized-bed reactors. pressure stream of air. The air, essentially, “fans the Beneficial Use/Production of Energy There are also other types of incinerators. fire,” which results in a much more intense and complete burn and less ash than in an MHF. Multiple-Hearth Furnaces (MHFs), which have been nergy recovered from the incineration of sludge Fluidized-bed incinerators are also less mechanically utilized since the mid-1900s, employ a series of may be used to support some of the energy complex than MHF incinerators—making these units Sewage E vertically-stacked chambers, or hearths. Air is fed Sludge needs of the Wastewater Treatment Plant. Heat from substantially easier to operate. With less mechanical from the bottom, and sludge is fed from the top. The Inlet Fluidized the incinerator may be used to pre-dry the sludge. upkeep, equipment, staffing, and repair costs, fluidized sludge in each chamber is plowed to “drop holes,” Sand Bed Incinerators may also be utilized to assist in odor beds tend to be less expensive to operate and maintain where it falls into successive hearths below. The bulk control at a facility. Ash by-products may be used as a than MHFs. Most of the region’s newer incinerators use of the burning takes place in the center hearths; the substitute raw matter in the manufacturing of cement the fluidized-bed technology. ash cools at the bottom levels. and brick and as a landfill cover. All sludge incinerators use auxiliary fuel (e.g., oil or natural gas) to initiate and occasionally maintain Fluidized Air Intake burning. Ash is removed from MHF incinerators by For more information... A Residual of Worth

CT: Bob Norwood CT DEP – Water Compliance Unit ludge is an organic solid, semi-solid, or liquid 79 Elm Street, Hartford, CT 06106 by-product of the wastewater treatment process. (860) 424-3746 S [email protected] Sludge characteristics vary depending on each Sewage treatment facility’s wastestream and the processes that ME: David Wright ME DEP – Sludge Residuals Unit are used. Sludges that meet EPA standards for land 17 State House Station application, which include reduction or elimination of Augusta, ME 04333-0017 Sludge pathogens and very low limits for heavy metals, are (207) 287-2651 referred to as Biosolids. [email protected] MA: Larry Polese Although there has been significant research on the MA DEP Training Center, Residuals Section beneficial use of biosolids, and history has demon- 50 Route 20, Millbury, MA 01527 Incineration strated, in the U.S. and other regions of the world, that (508) 368-5606 [email protected] high quality biosolids can be beneficial soil additives and plant nutrients when applied properly, concerns NH: Richard Flanders NH DES still exist. These concerns relate primarily to the quality P.O. Box 95 of the biosolid material and its impact on soil 6 Hazen Drive, Concord, NH 03302 productivity, water resources, and adjacent land uses. (603) 271-3571 [email protected] To ensure that sludges that are used as biosolids are NJ: Mary Jo Aiello treated and managed in a manner that protects both NJ DEP – Bureau of Pretreatment and Residuals human health and the environment, Congress directed P.O. Box 029, Trenton, NJ 08625 EPA to develop a comprehensive national Sewage (609) 633-3823 [email protected] Sludge Program aimed at reducing risks and maximizing the beneficial uses of sludge. In February NY: Sally Rowland NYS DEC – Division of Solid & Hazardous of 1993, EPA issued its sewage sludge use or disposal Materials regulation, 40 CFR Part 503, commonly referred to as 625 Broadway, Albany, NY 12233 the “503s.” The 503s set minimum quality standards (518) 402-8704 and dictate proper management practices for all [email protected] sewage sludge that is used or disposed of through land RI: Alexandre Pinto P.E. application, surface disposal, and incineration. Many RI DEM – Office of Water Resources 235 Promenade St, Providence, RI 02908 states have more stringent rules. (401) 222-4700 [email protected] The Northeast States, NEIWPCC, and the EPA believe that, when managed and applied properly, biosolids VT: Cathy Jamieson VT DEC – Residuals Management Section can be valuable resources. With the phaseout of 103 So. Main St, Sewing Building Biosolids are a Natural Resource! unlined landfills, the federal ban on ocean dumping, Waterbury, VT 05671 and growing public awareness of environmental issues, (802) 241-3831 communities have begun to recognize that biosolids [email protected] can be a resource and not a waste. Many communities EPA: Thelma Murphy have discovered viable, safe, and environmentally US EPA – New England This fact sheet was funded through a grant 1 Congress Street, Suite 1100 (CMU) from EPA-New England to the sound options for the beneficial use of their biosolids. Boston, MA 02114 New England Interstate Water Pollution Some communities have implemented a single (617) 918-1615 Control Commission (NEIWPCC). beneficial use method, some employ a combination [email protected] The fact sheet was prepared by NEIWPCC’s of different sludge use and/or disposal methods, others Residuals Workgroup, which is comprised of NEIWPCC: the state sludge coordinators from have entered into regional solutions or contracted with Boott Mills South – 100 Foot of John Street the Northeast States. privately-owned facilities. In choosing an option, Lowell, MA 01852 (978) 323-7929 communities must consider cost, odor control, and

[email protected] ollution Control Commission siting issues. New England Interstate Water Water England Interstate New P October 2001 Boott Mills South 100 Foot of John Street Lowell, MA 01852-1124 Printed on recycled paper