Enrichment of Plasticicumulans acidivorans at pilot-scale for PHA production on industrial wastewater

Combining the enrichment and accumulation step in non-axenic PHA production: Cultivation of Plasticicumulans acidivorans at high volume exchange ratios

“…Once a stable culture is obtained, the SBR will be operated as a biomass production step and the excess sludge used in step 3: maximization of the PHA content of the biomass in a (nitrogen-limited) fed-batch reactor (Johnson et al, 2009a). Biomass with PHA contents of 70-80 wt% has thus been produced from fermented waste streams like molasses and paper or food industry effluents (Albuquerque et al, 2010;Jiang et al, 2012;Tamis et al, 2014). The highest PHA contents reported for microbial enrichment cultures are around 90 wt% and were obtained using sole acetate or lactate as substrate (Jiang et al, 2011b;Johnson et al, 2009a).…”

“…Moreover, fermented organic waste streams -containing also compounds that are less suitable for PHA production -will ultimately be used as substrate. This will lead to the co-enrichment of non-PHA-storing bacteria and thereby to a reduction of the culture's PHA content (Jiang et al, 2012;Tamis et al, 2014).…”

Survival of the fastest: Selective removal of the side population for enhanced PHA production in a mixed substrate enrichment

“…Research on PHA-production from wastewater has shown that slowly degradable organic carbon may contribute to a significant fraction of the wastewater COD and is degraded at a much lower rate in comparison to methanol (q VFA /q non-VFA-COD > 10) (Bengtsson et al, 2008;Jiang et al, 2012;Tamis et al, 2014a). This suggests that settling after the feast phase may significantly enhance the productivity of the process for industrial wastewater, but one should realize that post-treatment of the supernatant is required before discharge to surface waters.…”

“…Nonetheless, when using real wastewater the experimental results indicated that PHA production is primarily associated with the VFA fraction of the wastewater (Coats et al, 2007;Bengtsson et al, 2008;Beccari et al, 2009;Albuquerque et al, 2010;Morgan-Sagastume et al, 2010;Jiang et al, 2012;Tamis et al, 2014a;Morgan-Sagastume et al, 2014, 2015Korkakaki et al, 2016). This correlation is based on the fact that the VFA carbon fraction serves as a PHA precursor and efficiently enriches for a PHA accumulating community.…”

Anaerobic digestion without biogas?

“…Studies with wastewater achieved lower PHA contents of 0.75 gPHA gVSS -1 using fermented molasses (Albuquerque et al 2010) and 0.77 gPHA gVSS -1 using fermented paper mill wastewater (Jiang et al 2012). Recent pilot-scale experiments showed a comparable PHA content of 0.70 ± 0.05 gPHA gVSS -1 (Tamis et al 2014). Solids in the fermented wastewater and possible nonstoring side-populations can influence the production rates of the system and should therefore be minimized.…”