Sewage sludge as carbon source for polyhydroxyalkanoates: a holistic approach at pilot scale level

Chlorine-free Extractions of Mixed-Culture Polyhydroxyalkanoates Produced from Fermented Sewage Sludge at Pilot Scale

“…The PHA-rich biomass production (described in previous works , ) was obtained through a three stage process consisting in (i) a first anaerobic fermentation in a 380 L reactor for the production of volatile fatty acids (VFAs), used as feedstock; (ii) a biomass selection into PHA-accumulating consortium (enriched-MMC) in a second 100 L aerobic sequencing batch reactor (SBR) and (iii) a PHA accumulation in a third 70–90 L fed-batch aerobic reactor. At the end of the accumulation stage, the biomass was stabilized with sulfuric acid (pH 2), in order to preserve the PHA content and properties, centrifuged, and stored at 4 °C until the downstream processing.…”

“…At the end of the accumulation stage, the biomass was stabilized with sulfuric acid (pH 2), in order to preserve the PHA content and properties, centrifuged, and stored at 4 °C until the downstream processing. The original biomass contained 62 wt % of PHA with respect of total dry solids, consisting in a P­(3HB- co -3HV) copolymer with a 3HV content of 12.9 wt % …”

“…35,36 ■ RESULTS AND DISCUSSION PHA Extraction and Recovery. Table 1 summarizes the results of the different performed extraction experiments together with those described in other studies, 4,5,10,18,19,33,37 where conditions similar to those used in the present study were employed. To ensure consistency, the same biomass harvest was used for all PHA extractions and characterizations reported in both the present study and in ref 10.…”

“…The MMCs allow reduction of the production costs of PHAs because sterile conditions are not required. In addition, a variety of cheap carbon sources can be used as substrates, including organic fraction of municipal solid waste (OFMSW), mixture of OFMSW and waste activated sludge (WAS), , and thickened sewage sludge. , As a confirmation of this, the conversion of wastewater and different available organic feedstocks by MMC represents key elements for the implementation of a three-step process through the integration of MMC-PHA production into a wastewater treatment plant (WWPT) . Although the use of organic fermentable substrates allows to reduce the upstream costs, the production of MMC-PHA is still at the pilot scale only and the downstream process is a crucial stage due to the impact on the economic sustainability .…”

Prospective LCA to provide environmental guidance for developing waste-to-PHA biorefineries

“…This choice was made following the guidelines on the LCA of alternative feedstock for plastics production (Nessi et al, 2021). Given the actual TRL, i.e., from 5 to 6, the temporal boundaries were established for 2030, when market level maturity is expected to be reached (Lorini et al, 2022).…”