Improving the assessment of risk from pathogens in biosolids: fecal coliform regrowth, survival, enumeration, and assessment.
Reactivation or regrowth of fecal coliform bacteria in biosolids has recently become a concern due to knowledge that Class B materials may fail to meet this criterion after storage or even after land application. In this paper, data show the two types of fecal coliform increases that have been characterized: immediate reappearance of large concentrations directly after dewatering; and the rapid, but less immediate, increases that follow dewatering with some biosolids after dewatering. The latter phenomenon is shown to extend over a time period of days prior to gradual decrease in fecal coliform numbers. Modeling shows that anaerobic or fermentative growth cannot simulate the observed growth, but that a straightforward biokinetic model can duplicate the observed conditions if a doubling time of one hour is assumed, which is supported by literature. Thus regrowth cannot be ruled out as the underlying phenomenon.
Dentel
S K
SK
Department Civil & Environmental Engineering, University of Delaware, Newark, DE 19716, USA. dentel@udel.edu
Qi
Y
Y
Herson
D S
DS
D000693:Anaerobiosis; D019149:Bioreactors; D005243:Feces; D007700:Kinetics; D008954:Models, Biological; D018570:Risk Assessment / Q000379:methods*