Water Environment Research Foundation (WERF) anaerobic digestion and related processes, odour and health effects study

Abstract

Biosolids odour emissions can affect the ability of wastewater utilities to implement beneficial biosolids processing and reuse programs. Communities often become more sensitised and vocal about biosolids issues, once they experience odours emanating from a nearby site. Odour impacts from biosolids, including potential human health effects, have been targeted recently by many national and local newspapers, citizens' groups, and regulatory agencies, who have raised significant concerns, ranging from viable disposal methods/sites to outright bans. Many national and local regulatory agencies in the United States are considering biosolids disposal bans in their communities because of misinformation, poor science, and citizen pressure, but primarily because of odour impact concerns. The wastewater industry has a relatively poor understanding of the operations and treatment parameters that influence biosolids odour emissions. Thus, wastewater treatment plants are often unable to control the odour quality of the biosolids that are delivered into communities. A research study to demonstrate the influence of anaerobic digestion, mechanical dewatering, and storage design and operating parameters on the odour quality of the final product was performed and is the subject of this paper. Established and new sampling and analytical methods were used to measure biosolids odour emissions from 11 test sites in North America. By determining the impacts of these control variables on biosolids odour quality, design and operations of anaerobic digestion systems might be enhanced. This paper also summarises a corollary study performed as part of the WERF research study that addresses the health effects of biosolids odours.

Odour control at biowaste composting facilities

“…While malodours are not considered to cause health problems directly (Witherspoon et al, 2004), they may well be associated with diseases and negative health effects, which may cause defensive reactions of people due to psychological effects (Dalton, 2003). For these reasons, an adequate waste gas management strategy has to be implemented.…”

Full scale co-digestion of wastewater sludge and food waste: Bottlenecks and possibilities

“…Concern about offensive odours and disease risks from pathogens is also a major hurdle for biosolids reuse [52]. Odorous biosolids is usually rejected by farmers as offensive odour is an indication of unsafe materials.…”

Correlating Fecal Coliform Measurements and Odors in Biosolids Cake to Digester Performance Parameters

“…Researchers concluded that the 38 percent minimum volatile solids reduction standard did not discriminate among biosolids that did or did not produce odors, and, by implication, did or did not attract vectors, notably flies. For anaerobic digestion, the use of the "additional VS reduction" (AVSR) as a regulatorily-sanctioned measure of digester performance and as a measure of "residual biological activity," was believed to correlate with odorant emission potential (Witherspoon, Adams et al 2004). But, the WERF odor study likewise did not confirm that AVSR was correlated with odor potential.…”