Identification of the microbiological community in biogas systems and evaluation of microbial risks from gas usage.
The plans for introducing biogas produced from organic waste to the pipe system for natural gas has raised concerns about the risk of transmitting disease via the gas. To assess this risk, condensate water from gas pipes and gas from different parts of a biogas upgrading system were sampled and cultured for microbial content. On average, 10(5) cfu ml-1 were found in the condensate water throughout the system, while in the gas between 10 and 100 cfu m-3 were found. The microorganisms were subjected to further identification and found to represent a wide variety, e.g. fungi and spore-forming and non-spore-forming bacteria, including species such as Enterobacteriaceae. The number of microorganisms found in the biogas corresponded to the densities in sampled natural gas, which also held 10-100 cfu m-3. Since no pathogens were identified and since the exposure to gas from e.g. cookers and refuelling of cars may only result in the inhalation of small volumes of gas, the risk of spreading disease via biogas was judged to be very low.
Swedish University of Agricultural Sciences, Department of Biometry and Engineering, Box 7032, SE-750 07 Uppsala, Sweden. bjorn.vinneras@bt.slu.se
Björn
B
Vinnerås
Caroline
C
Schönning
Annika
A
Nordin
D001419:Bacteria / Q000302:isolation & purification; D001674:Bioelectric Energy Sources; D004784:Environmental Monitoring / Q000706:statistics & numerical data*; D005658:Fungi / Q000302:isolation & purification; D007218:Industrial Microbiology; D018570:Risk Assessment; D014871:Water Microbiology