Environmental Impact of Fabric Filter Bag Incineration (FFB White Paper)

Introduction The issue of disposing used fabric filter bags (FFB) from baghouses of waste to energy (WTE) facilities has recently been revisited by some state regulatory offices. The main issue is to identify the best way to dispose of these used filter bags from WTE facilities. The current practice is to place the spent bags into a closed container and return them into the waste holding pit from where they are fed, by crane into the hopper of the combustion unit where the bags are incinerated along with the incoming waste feed. This follows the accepted waste management hierarchy that shows the preferred management methods of reuse, recycle and recovery of energy to be above disposal However, this practice has been recently questioned by some state regulatory agencies who specifically are trying to understand if it is better to transport and dispose the spent bags at an off-site hazardous waste treatment, storage and disposal facility (e.g., landfill or incineration) or to process them internally through the combustion facility, as is the current practice in most WTE plants in the U.S. and globally. Waste and the Materials and Energy Recovery Division of ASME have jointly investigated this issue. The scope of the investigation focused on the technical data pertaining to combusting the used bags in the furnace of the WTE plant. Also, a screening-level risk assessment of the potential human health risks associated with feeding used filter bags back into the WTE combustion unit was conducted. It should be noted that a review of the literature on this issue did not produce any publications that explicitly discuss this practice nor the impact of disposal of used FFB. Therefore, this study is the first one to quantify the environmental impacts of disposal of the used filter bags by means of in-plant incineration. Quantitative material balances were conducted for four representative waste-to-energy (WTE) plants to determine the number and weight of filter bags used in one year of operation, the weight of ash attached to used FFB, and the potential change in emissions of lead (Pb), cadmium (Cd) and mercury (Hg), which are considered the three primary metal pollutants of concern. The fourth pollutant of concern is polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo furans (dioxins and furans) that are captured on the activated carbon particles injected in the process gas which are then separated from the gas flow along with fly ash particles on …