Spatial distribution of major bacterial species and different volatile fatty acids in a two-phase anaerobic biofilm reactor with PVA gel beads as bio-carrier

Abstract

Conventional completely mixed anaerobic treatment systems limit the chances of the different species of bacteria to spatially group together according to their mutual cooperation and as a result, show a lower efficiency and vulnerability towards shock situations. It is interesting to know about the stratification of the different bacterial species participating in the degradation process and the intermediates that they produce. In this study, we established and optimized a two-phase anaerobic packed bed biofilm reactor system (AnPBR) with porous PVA gel beads used as bio-carriers and ran the reactor system in a steady state to observe the VFAs produced along with the microbial diversity of the predominant species at different stages of the reactor system. We observed that acetate and butyrate were the predominant intermediate VFAs while concentrations of other VFAs such that propionic acid were low. Acetobacterium and Clostridium were found to be the most abundant bacterial species in acidogenic reactor while methanogenic reactor was highly enriched with Methanobacterium and Methanosarcina. Apart from the above, syntrophic populations such as Syntrophobactor wolinii were also observed to be dominant in both the reactors – especially towards the end of acidogenic reactor and the initial part of the methanogenic reactor.

Keywords:

• 16s rDNA
• anaerobic biofilm reactor
• anaerobic wastewater treatment
• microbial diversity
• PVA gel beads
• two-phase anaerobic reactor

Acknowledgements

The authors are thankful to Mr. Vipin rose, Head of operations, Kuraray India Private Ltd, for providing us with the PVA-gel beads. Authors are also indebted to Aldee water Pvt. Ltd., Ahmedabad, for their valuable help during the work. One of the authors, Pandey S., received financial support in the form of fellowship from the Ministry of Human Resource and Development (MHRD), Government of India.