No abstract

Anaerobic digestion is a viable on-site treatment technology for rich organic waste streams such as food waste and blackwater. In contrast to large-scale municipal wastewater treatment plants which are typically located away from the community, the effluent from any type of on-site system is a potential pathogenic hazard because of the intimacy of the system to the community. The native concentrations of the pathogen indicators Escherichia coli, Clostridium perfringens and somatic coliphage were tracked for 30 days under stable operation (organic loading rate (OLR) = 1.8 kgCOD m(-3) day(-1), methane yield = 52% on a chemical oxygen demand (COD) basis) of a two-stage laboratory-scale digester treating a mixture of food waste and blackwater. E. coli numbers were reduced by a factor of 10(6.4) in the thermophilic stage, from 10(7.5±0.3) to 10(1.1±0.1) cfu 100 mL(-1), but regenerated by a factor of 10(4) in the mesophilic stage. Neither the thermophilic nor mesophilic stages had any significant impact on C. perfringens concentrations. Coliphage concentrations were reduced by a factor of 10(1.4) across the two stages. The study shows that anaerobic digestion only reduces pathogen counts marginally but that counts in effluent samples could be readily reduced to below detection limits by filtration through a 0.22 µm membrane, to investigate membrane filtration as a possible sanitation technique.

Agriculture offers considerable opportunities for the safe and sustainable re-use of water, be that water sourced from humans or animals. A key point is understanding the differences in pathogen profiles between wastewater from humans as compared with that derived from animals. Agricultural re-use also offers the opportunity to appropriately match the treatment level of the used water with the planned end-use. There is no doubt that the reuse of water in agriculture will be an increasing focus as Australian agriculture adapts to the challenges of food security in a changing world.

Campylobacter is a leading cause of foodborne illnesses both in Australia and internationally, and is frequently found in poultry. There is a need for sustainable options to support current farm management strategies that address food-safety. The use of bacteriophages provides a safe biocontrol option. A collaborative study by the Department of Agriculture and Fisheries (QLD), the University of Nottingham (UK) and the Institute of Environmental Science and Research (NZ) is focused on the control of Campylobacter in broiler chickens. Campylobacter bacteriophages were sourced from Queensland poultry farms and following extensive screening, suitable candidates to be used in cocktails were identified. This followed an on-farm proof of concept study on a small sample of chickens, using selected cocktail candidates, to provide an understanding of the hurdles for practical application. The trial demonstrated a 2-log CFU/g reduction of Campylobacter in the caeca of treated birds compared to non-treated (p < 0.05). Another important finding of this study was the absence of bacteriophage resistance, a concern with phage therapy. Work at ESR has addressed approaches to select and adapt bacteriophage cocktails to particular hosts, which included screening against NZ and Australian hosts. This approach enabled the formulation of high performing bacteriophage cocktails for Australian and international markets. Work in the UK is exploring the understanding of the host-bacteriophage relationships to ensure safety to meet regulatory requirements and support potential scale-up options. In summary, the work in progress via international collaborations is aimed at delivering a safe biocontrol option that can meet both commercial and regulatory needs aiming at controlling on-farm Campylobacter.