Bioplastic recovery from wastewater: A new protocol for polyhydroxyalkanoates (PHA) extraction from mixed microbial cultures

Abstract

A new protocol for polyhydroxyalkanoates (PHA) extraction from mixed microbial cultures (MMCs) is proposed. PHA-accumulating capacity of the MMC was selected in a sequencing batch reactor (SBR) fed with a synthetic effluent emulating a fermented oil mill wastewater (OMW). The highest recovery yield and purity (74 ± 8% and 100 ± 5%, respectively) was obtained when using NH 4 -Laurate for which operating conditions of the extraction process such as temperature, concentration and contact time were optimized. Best conditions for PHA extraction from MMC turned to be: i) a pre-treatment with NaClO at 85°C with 1 h of contact time, followed by ii) a treatment with lauric acid in a ratio acid lauric to biomass of 2:1 and 3 h of contact time.

Polyhydroxyalkanoate (PHA) purification through dilute aqueous ammonia digestion at elevated temperatures

“…Most of the studies up to now, have only tested NH 3 digestion in a screening phase, and discarded the method due to lower initial PHA purity and recovery compared to other alkalis (such as NaOH, KOH or NH 3 -laurate). 13,[17][18][19] Nonetheless, the whole picture of the results obtained here and reported previously, suggests that NH 3 digestion efficiency largely depends on the digestion conditions (and possibly on the PHA accumulating culture), and that adjustment of the parameters can lead to relatively pure PHA and high PHA recovery.…”

“…Higher PHA purity and recovery were also observed at elevated temperatures using NH 3 -laurate digestion in MMC. 19 These differences might imply that the efficiency of dilute aqueous NH 3 digestion depends on the PHA accumulating culture.…”

“…Some studies included NH 3 in initial screenings, which generally resulted in lower PHA recoveries and purities compared to other alkalis (such as NaOH and KOH), after which NH 3 was excluded from further experiments. 13,[17][18][19] To the extent of our knowledge, only two studies have reported the molar mass of PHA after NH 3 digestion. 15,20 Up to date, there has not been a comprehensive evaluation of the potential of NH 3 digestion as a PHA purification method.…”

Design and optimization of poly(hydroxyalkanoate)s production plants using alternative substrates

“…PHAs are biomaterials that can be intracellularly produced from renewable sources by microorganisms. They are natural biopolymers, non-toxic and completely biodegradable polyesters whose physical and thermal properties resemble synthetic thermoplastics such as polyethylene, polypropylene and polystyrene (Mannina et al, 2019).…”

Biotechnological valorization of algal biomass: an overview

“…Day-to-day increment in the single-use fossil derived plastics has led the world to face a mountain of nonbiodegradable plastics which are causing ecological imbalance and environmental pollution [72][73][74]. Alternatively, the use of microbial-derived biodegradable plastics could overcome the dilemmas we have encountered with non-degradable plastics while encouraging the biomanufacturing sector as well [ [77].…”