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Objectionable odors can arise from a number of sources. Reduced sulfur odors, causing a “rotten egg” smell, have been associated with emissions from kraft mills, although recent control requirements have greatly reduced these odors. At an increasing number of kraft mills, process-related odors are noticed in communities only during intermittent process upsets. Reduced sulfur compounds as well as other types of compounds (e.g., certain organic acids) can also create odors that are noticed in the vicinity of virgin and recycled paper mill waste treatment facilities.

Recycled paper mills do not have the reduced sulfur process-related odors that are associated with kraft mills, but other common sources of community odor are not related to whether a mill is a recycled or virgin mill. Odors can arise from sludge dewatering areas (hydrogen sulfide and volatile organic acids) as well as the wastewater treatment area. If sulfate is present in the wastewater, it can be converted to hydrogen sulfide by sulfate-reducing bacteria, especially if anaerobic conditions are present during wastewater treatment. Hydrosulfite, which is commonly used to bleach recycled fiber, can provide a source of sulfate in the wastewater. These issues are often avoided by maintaining an oxidative environment in the wastewater treatment system.

When considering these aspects in the context of comparing recycled and virgin fiber, note that trade-offs undertaken at an individual mill site ultimately have cascading effects through the overall industry’s fiber cycle. Given that the recycled and virgin fiber cycles are inherently interrelated [See Overview], shifts in environmental aspects due to changes in the usage of one fiber type versus another result in shifts elsewhere in the fiber cycle. Life cycle assessment (LCA) is a tool that can help examine these interactions. LCA, particularly in the context of looking at the manufacturing of recycled versus virgin fiber pulp, is discussed in NCASI Technical Bulletin No. 1003.