Context and gap: Biofilm formation on a biocarrier surface is a complex process which is not only determined by characteristics of supporting media but also affected by the type of microorganisms, initial inoculum concentration, and extracellular polymers production. Polyurethane (PU) is one of the suitable biocarrier which was cheap, high availability, accessible, non-biodegradable, non-toxic, and environmentally friendly.
Aim: This study aimed to observe the effect of microbial attachment and growth during biofilm formation of syntrophic consortium (propionate-enriched microorganisms) on PU foam.
Method: Two reactors were operated without (R1) and with carbon source (sodium propionate) addition (R2) to investigate the effect of attachment and growth of syntrophic consortium on PU foam as a biofilm.
Findings: Without carbon source addition, the performance of R1 was still good along with its operation period (60 days) according to the conditions of pH value (7.22-7.93) and total volatile acid to alkalinity (T/A) ratio ( < 0.1). On the other hand, R2 showed remarkable results in terms of accumulated biomass on PU, methanogenic activities, and morphology. The maximum biomass amount on PU of R2 was 1.47 g VSS at day 30 followed by increases in acetoclastic (ACM) and hydrogenotrophic methanogens (HTM) activities as approximately 0.005 and 0.012 g COD-CH4/PU cube/d, respectively, as shown in Fig. 1. SEM results showed the presence of 'EPS-like polymer' among microbial attachment on PU which probably strengthens the biofilm structure in this reactor (Fig. 1). Archaea and Eubacteria communities were randomly distributed and their attachments on PU surface mostly occurred on the corners of PU matrices.
Utilization: Providing a carbon source during the biofilm formation of syntroph microbial groups resulted in higher methanogenic activities and longer biomass attachment on PU. The biofilm structure in R2 was also probably strengthened by the 'EPS-like' polymer produced during the microbial growth.
