Culturability of potential pathogenic bacteria in a co-digestion anaerobic digester system

Biogas;Anaerobic bacteria--Growth

Johnson, ShannonKleinheinz, Greg ;

University of Wisconsin

关键词: Biogas;    Anaerobic bacteria--Growth;   

Others  :  https://minds.wisconsin.edu/bitstream/handle/1793/77922/S%20Johnson%20Thesis.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: University of Wisconsin

【 摘 要 】

Anaerobic digestion (AD) has the potential to reduce organic wastes and producerenewable energy from the degradation of organic materials to produce biogas. However,mixed substrate anaerobic digesters may create a suitable environment for opportunisticpathogenic bacteria. The fate of potential bacterial pathogens has been studied in manure-based digesters but their survival is not well understood when digesters are co-fed withfood waste. Mixed substrates may change internal conditions and subsequently pathogensurvival, resulting in concerns for general environmental health. The purpose of thisstudy was to introduce and enumerate potentially pathogenic bacteria in a bench-scaleAD system while analyzing possible relationships between colony growth with typicalAD parameters: temperature, pH, and volatile fatty acids (VFAs). Food waste wasutilized as a substrate and percolate (a manure surrogate) was used as an inoculum toexamine the survival of five species of bacteria (Campylobacter jejuni, Staphylococcusaureus, Salmonella enterica, Enterococcus faecalis, and Escherichia coli) that wereselected on likelihood of entering a digester or that they are indicators for groupspotentially located in digesters. It is hypothesized that incomplete acidogenesis – frommixed substrates – may increase VFAs, lower pH, and therefore decrease pathogensurvival. A modified membrane filtration method, with selective and differential media,were used to enumerate the microorganisms. In the Enterococcus spp. experimentalgrowth system, linear regression analyses revealed that there is a relationship of colonyreduction with: temperature, pH, and total VFAs. The reduction of four of the fiveorganisms, early in AD, indicates that co-fed digesters can reduce pathogens and lowerenvironmental health risks.