Abstract

Plastic plug-flow bio-digesters have been promoted as a good option for improved treatment of manure and wastewater in developing countries although minimal information has been published on their hygienic status. This bench-scale study replicates bio-digester conditions to evaluate the reduction of pathogen and indicator microorganisms at three different hydraulic retention times (HRT) in the anaerobic treatment of pig manures at 30 degrees C for 50 days. Results showed that physicochemical values differed between HRTs. Gas production efficiency was better for longer HRTs. The accumulated sludge at the reactor's base increased with longer HRT. Phages and bacteria examined were reduced, but none was completely eliminated. Log(10) reduction of bacteria ranged from 0.54 to 2.47. Phages ranged from 1.60 to 3.42. The reduction of organisms at HRT = 30 days was about one log(10) unit higher than HRT = 15 days and about two log(10) units higher than HRT = 3 days. The results indicate that the reduction of tested organisms increases with HRT. However the hygienic quality of the liquid effluent does not meet required quality values for surface and irrigation water. Longer HRTs are recommended to increase gas yield and achieve higher pathogen reduction. More barriers should be applied while handling bio-digester outputs to minimise risks to environmental and human health.

Keywords

biogas; hygiene; microbial reduction; plastic bio-digester

Published in

Journal of Water and Health
2009, Volume: 7, number: 4, pages: 590-596
Publisher: I W A PUBLISHING

SLU Authors

• Vinnerås, Björn

  • Department of Energy and Technology, Swedish University of Agricultural Sciences
    

Sustainable Development Goals

SDG6 Ensure availability and sustainable management of water and sanitation for all
SDG17 Strengthen the means of implementation and revitalize the global partnership for sustainable development


UKÄ Subject classification

Environmental Sciences


Publication identifier

DOI: https://doi.org/10.2166/wh.2009.127

Permanent link to this page (URI)

https://res.slu.se/id/publ/48850