Search results for "polyhydroxyalkanoate"
showing 10 items of 19 documents
Membrane Fouling Mitigation in MBR via the Feast–Famine Strategy to Enhance PHA Production by Activated Sludge
2022
Fouling is considered one of the main drawbacks of membrane bioreactor (MBR) technology. Among the main fouling agents, extracellular polymeric substances (EPS) are considered one of the most impactful since they cause the decrease of sludge filterability and decline of membrane flux in the long term. The present study investigated a biological strategy to reduce the membrane-fouling tendency in MBR systems. This consisted of seeding the reactor with activated sludge enriched in microorganisms with polyhydroxyalkanoate (PHA) storage ability and by imposing proper operating conditions to drive the carbon toward intracellular (PHA) rather than extracellular (EPS) accumulation. For that purpos…
Development of a Higee bioreactor (HBR) for production of polyhydroxyalkanoate: Hydrodynamics, gas–liquid mass transfer and fermentation studies
2010
Abstract This study addresses the hydrodynamics and mass transfer characterisation of a Higee bioreactor (HBR) for application to polyhydroxyalkanoate (PHA) production from Pseudomonas putida KT2442 fermentation. The motivation for this work is to address the potential oxygen transfer limitations which can severely impede the progress of this aerobic fermentation process and reduce PHA productivity in conventional bioreactors. It is shown that a maximum of 2.5 transfer units can be achieved in an oxygen-stripping operation where the presence of packing, higher rotor speeds, higher air flowrates and lower liquid flowrates all have a positive influence on the number of transfer units (NTU). W…
Antiviral properties of silver nanoparticles against norovirus surrogates and their efficacy in coated polyhydroxyalkanoates systems
2017
Silver nanoparticles (AgNP) have strong broad-spectrum antimicrobial activity and gained increased attention for the development of AgNP based products, including medical and food applications. Initially, the efficacy of AgNP and silver nitrate (AgNO3) was evaluated for inactivating norovirus surrogates, the feline calicivirus (FCV) and the murine norovirus (MNV). These norovirus surrogates were exposed to AgNO3 and AgNP solutions for 24 h at 25 °C and then analyzed by cell-culture assays. Both AgNP and silver ions significantly decreased FCV and MNV infectivity in a dose-dependent manner between concentrations of 2.1 and 21 mg/L. Furthermore, poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (…
Draft genome sequence of Pseudomonas mediterranea strain CFBP 5447T, a producer of filmable medium-chain-length polyhydroxyalkanoates
2014
ABSTRACT Pseudomonas mediterranea strain CFBP 5447 T is a phytopathogenic bacterium isolated from tomato plants affected by pith necrosis disease. Moreover, its ability to produce medium-chain-length polyhydroxyalkanoates (mcl-PHAs) in culture from different carbon sources and valuable microbial products, such as cyclic lipopeptides, has been well documented. Here, we report the first draft genome sequence of this species.
Effect of organic loading rate on the production of Polyhydroxyalkanoates from sewage sludge
2023
The aim of this work was to study the effect of organic loading rate on the production of Polyhydroxyalkanoates (PHA) from sewage sludge. Synthesis of PHA using sewage sludge as platform was achieved in this work. Three pilot-scale selection-sequencing batch reactors (S-SBR) were used for obtaining a culture able to accumulate PHA following a strategy of aerobic dynamic feeding (ADF) at different volumetric organic-loading-rate (vOLR): 1.3, 1.8 and 0.8 g COD L-1 d-1 for S-SBR 1, S-SBR 2 and S-SBR 3, respectively. Decreasing the vOLR enhanced the general performance of the process as for organic matter removal (from 99.2% ± 0.3% in S-SBR-3 to 92 ± 2 in S-SBR-2) while the opposite trend was r…
Biopolymer Recovery from Aerobic Granular Sludge and Conventional Flocculent Sludge in Treating Industrial Wastewater: Preliminary Analysis of Differ…
2022
The recovery of biopolymers from sewage sludge could be a crucial step in implementing circular economy principles in wastewater treatment plants (WWTP). In this frame, the present study was aimed at evaluating the simultaneous production of polyhydroxyalkanoates (PHA) and extracellular polymeric substances (EPS) obtainable from the treatment of agro-industrial wastewater. Two biological enrichment systems, aerobic granular sludge (AGS) and a conventional activated sludge operating as a sequencing batch reactor (SBR), were monitored for 204 and 186 days, respectively. The maximum biopolymers accumulation capacity was close to 0.60 mgPHA-EPS gVSS−1 in the AGS when operating at 3 kgCODm…
Processing and Properties of Biopolymer/Polyhydroxyalkanoates Blends
2011
In this paper, the processability and the performance of a biodegradable polymer, Mater-Bi, and of its blends with either a sample of poly (hydroxy alkanoates) (PHA) or with bacterial biomass containing PHAs were compared. Adding PHA or directly the biomass containing it allows improving the processability of the matrix. Moreover, the mechanical behaviour of the systems was compared considering two different preparation methods, namely compression and injection moulding. The injection moulded samples show poorer mechanical performances than those of the compression moulded systems. The impact strength significantly improves when PHA is added while it reduces when bacterial biomass is used i…
Modelling the metabolic shift of polyphosphate-accumulating organisms
2014
Enhanced biological phosphorus removal (EBPR) is one of the most important methods of phosphorus removal in municipal wastewater treatment plants, having been described by different modelling approaches. In this process, the PAOs (polyphosphate accumulating organisms) and GAOs (glycogen accumulating organisms) compete for volatile fatty acids uptake under anaerobic conditions. Recent studies have revealed that the metabolic pathways used by PAOs in order to obtain the energy and the reducing power needed for polyhydroxyalkanoates synthesis could change depending on the amount of polyphosphate stored in the cells. The model presented in this paper extends beyond previously developed metaboli…
Resource or waste? A perspective of plastics degradation in soil with a focus on end-of-life options.
2018
‘Capable-of-being-shaped’ synthetic compounds are prevailing today over horn, bone, leather, wood, stone, metal, glass, or ceramic in products that were previously left to natural materials. Plastic is, in fact, economical, simple, adaptable, and waterproof. Also, it is durable and resilient to natural degradation (although microbial species capable of degrading plastics do exist). In becoming a waste, plastic accumulation adversely affects ecosystems. The majority of plastic debris pollutes waters, accumulating in oceans. And, the behaviour and the quantity of plastic, which has become waste, are rather well documented in the water, in fact. This review collects existing information on pla…