TY - JOUR
T1 - Inactivation of Salmonella during dry co-digestion of food waste and pig manure
AU - Jiang, Yan
AU - Dennehy, Conor
AU - Lawlor, Peadar G.
AU - Hu, Zhenhu
AU - Yang, Qingfeng
AU - McCarthy, Gemma
AU - Tan, Shiau Pin
AU - Zhan, Xinmin
AU - Gardiner, Gillian E.
N1 - Funding Information:
This work was funded by the Green Farm project supported by a Science Foundation Ireland Investigator Project Award (Ref: 12/IP/1519 ). Xinmin is also grateful for the support of the Natural Science Foundation of China (Ref: 51728801 ). We would also like to thank Dr. Kavita Walia for her help in serotyping of Salmonella using O- and H-group antigens method.
Publisher Copyright:
© 2018 Elsevier Ltd
PY - 2018/12
Y1 - 2018/12
N2 - Extremely high volatile fatty acids (VFAs) and ammonia concentrations can accumulate during dry co-digestion of organic wastes, which may inactivate pathogenic microorganisms. In this study, inactivation of Salmonella during dry co-digestion of pig manure (PM) and food waste (FW), which are both reservoirs of zoonotic pathogens, was examined. The effects of pH, VFAs, ammonia and their interactions were assessed on three inoculated Salmonella serotypes. The results show that dry co-digestion significantly decreased the Salmonella inactivation time from several months (in wet digestion) to as short as 6–7 days. A modified Weibull distribution was proposed to simulate Salmonella reduction and to calculate or predict the minimum inhibitory concentrations (MIC) of VFAs and ammonia. Statistical analysis showed that all the factors (pH, VFA type, VFA/ammonia concentration and Salmonella serotype) significantly impacted Salmonella inactivation (P < 0.01). The inhibitory effect sequence was pH > VFA concentration > VFA type > Salmonella serotype in VFA MIC tests, and ammonia concentration > pH > Salmonella serotype in ammonia MIC tests. The toxicity of VFAs was much greater than that of ammonia, and an antagonistic effect was found between VFAs and ammonia on Salmonella inactivation. Apart from the toxicity of free VFAs and free ammonia, the inhibitory effects of pH alone, ionized VFAs and ammonium were also observed.
AB - Extremely high volatile fatty acids (VFAs) and ammonia concentrations can accumulate during dry co-digestion of organic wastes, which may inactivate pathogenic microorganisms. In this study, inactivation of Salmonella during dry co-digestion of pig manure (PM) and food waste (FW), which are both reservoirs of zoonotic pathogens, was examined. The effects of pH, VFAs, ammonia and their interactions were assessed on three inoculated Salmonella serotypes. The results show that dry co-digestion significantly decreased the Salmonella inactivation time from several months (in wet digestion) to as short as 6–7 days. A modified Weibull distribution was proposed to simulate Salmonella reduction and to calculate or predict the minimum inhibitory concentrations (MIC) of VFAs and ammonia. Statistical analysis showed that all the factors (pH, VFA type, VFA/ammonia concentration and Salmonella serotype) significantly impacted Salmonella inactivation (P < 0.01). The inhibitory effect sequence was pH > VFA concentration > VFA type > Salmonella serotype in VFA MIC tests, and ammonia concentration > pH > Salmonella serotype in ammonia MIC tests. The toxicity of VFAs was much greater than that of ammonia, and an antagonistic effect was found between VFAs and ammonia on Salmonella inactivation. Apart from the toxicity of free VFAs and free ammonia, the inhibitory effects of pH alone, ionized VFAs and ammonium were also observed.
KW - Ammonia
KW - Dry co-digestion
KW - Minimum inhibitory concentration
KW - Modified Weibull distribution
KW - Salmonella inactivation
KW - Volatile fatty acids
UR - http://www.scopus.com/inward/record.url?scp=85055491737&partnerID=8YFLogxK
U2 - 10.1016/j.wasman.2018.10.037
DO - 10.1016/j.wasman.2018.10.037
M3 - Article
C2 - 30509585
AN - SCOPUS:85055491737
SN - 0956-053X
VL - 82
SP - 231
EP - 240
JO - Waste Management
JF - Waste Management
ER -