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The recent designation by the United States Environmental Protection Agency (USEPA) of biosolids incinerated at Publicly Owned Treatment Works (POTWs) as "nonhazardous solid waste" will greatly impact multiple hearth and fluidized bed incinerator installations and planning for existing and new sewage sludge incinerators (SSIs). Under this new definition, the limits for incinerator emissions will now be established using Maximum Achievable Control Technology (MACT) provisions under the CFR 129 Hazardous Waste Incineration regulations. The application of CFR 129 regulations to incinerators processing biosolids will make emission limits much more stringent. This paper presents the potential impacts on existing and new biosolids incinerators regulated under this new classification, particularly new emission control equipment needed to meet the new limits. This paper will provide planning guidance for owners of POTWS for the continuation of incineration or for implementing new incineration facilities.

The new Biosolids & Energy Recovery Facilities at the Irvine Ranch Water District (IRWD) Michelson Water Recycling Plant (MWRP) will include energy recovery from its anaerobic digestion biogas. As part of the design process, the IRWD conducted a study of to identify the most effective use of the biogas. The IRWD considered five biogas use options: use of biogas as an energy source for thermal drying process, cogeneration with microturbines or fuel cells, fuel source for engine driven pumps, and cleaning to near natural gas quality for injection into the natural gas pipelines. Prior to the evaluation of biogas utilization options, IRWD had identified fuel cell power generation as the preferred strategy because it maximized power generation and has the potential for financial incentives. However, as a result of the evaluation, microturbines were selected for implementation due to (1) the highest non-economic ratings, (2) cost effectiveness (only slightly higher cost than the base case), (3) lower sensitivity to fluctuations in financial incentives, and (4) added plant reliability. Key to the decision to implement microturbines rather than fuel cells is the uncertainty associated with California financial incentives.

Sewage sludge incinerators (SSIs) located at Publicly Owned Wastewater Treatment Works (POTWs) are subject to the recently enacted US Environmental Protection Agency (USEPA) 129 emission limits, often referred to as the MACT 129 rule. These regulations set a time limit of March 21, 2016 for compliance with emission limits for both multiple hearth incinerators (MHIs) and fluidized bed incinerators (FBIs). They also establish new, more restrictive limits for "new" MHIs and FBIs. As a result, owners of existing incinerators have been evaluating compliance strategies to continue incineration or to shut down their incinerators and determine alternatives for the future processing of their sludge. Although most utilities currently operating SSIs fall under the MACT rule's "existing" category for compliance, some are being classified as "new" per the MACT's "50 percent rule" (Rowan et al., 2011) and are required to meet stricter "new" MHI emission limits. This paper discusses both operational considerations and emission control equipment that may be required for "new" MHIs and FBIs. This paper discusses recent experience with emissions control compliance for MHIs and how this knowledge may be applied to other MACT compliance projects, particularly those POTWs faced with a decision on implementing emission controls to meet "new" MACT limits to continue operating, or who want to understand potential future emission limits that may be implemented for "existing" MHIs.