Visualization of Polyhydroxyalkanoate Accumulated in Waste Activated Sludge.

Polyhydroxyalkanoates (PHAs) can be produced with municipal waste activated sludge from biological wastewater treatment processes. Methods of selective fluorescent staining with confocal laser scanning microscopy (CLSM) were developed and optimized to evaluate the distribution of PHA storage activity in this mixed culture activated sludge microbial communities. Selective staining methods were applied to a municipal activated sludge during pilot scale PHA accumulation in replicate experiments.

Influence of environmental conditions on accumulated polyhydroxybutyrate in municipal activated sludge.

Poly(3-hydroxybutyrate) (PHB) was accumulated in full-scale municipal waste activated sludge at pilot scale. After accumulation, the fate of the PHB-rich biomass was evaluated over two weeks as a function of initial pH (5.5, 7.

Calcium enhances polyhydroxyalkanoate production and promotes selective growth of the polyhydroxyalkanoate-storing biomass in municipal activated sludge.

Activated sludge from municipal wastewater treatment processes can be used directly for the production of biodegradable polyesters from the family of polyhydroxyalkanoates (PHAs). However, municipal activated sludge typically cannot accumulate PHAs to very high levels and often low yields of polymer produced on substrate are observed. In the present work, it was found that the presence of calcium promotes selective growth and enrichment of the PHA-storing biomass fraction and significantly improved both PHA contents and yields.

Process conditions affect properties and outcomes of polyhydroxyalkanoate accumulation in municipal activated sludge.

The developments of mixed culture polyhydroxyalkanoate production has been directed to maximize the biomass PHA content with limited attention to polymer quality. Direct comparison of PHA accumulation literature is challenging, and even regularly contradicting in reported results, due to underlying differences that are not well expressed. A study was undertaken to systematically compare the commonly reported process conditions for PHA accumulation by full-scale municipal activated sludge.

Exploring the Limits of Polyhydroxyalkanoate Production by Municipal Activated Sludge.

Municipal activated sludge can be used for polyhydroxyalkanoate (PHA) production, when supplied with volatile fatty acids. In this work, standardized PHA accumulation assays were performed with different activated sludge to determine (1) the maximum biomass PHA content, (2) the degree of enrichment (or volume-to-volume ratio of PHA-accumulating bacteria with respect to the total biomass), and (3) the average PHA content in the PHA-storing biomass fraction. The maximum attained biomass PHA content with different activated sludge ranged from 0.

Quantification of polyhydroxyalkanoate accumulated in waste activated sludge.

Polyhydroxyalkanoate accumulation experiments at pilot scale were performed with fullscale municipal waste activated sludge. Development of biomass PHA content was quantified by thermogravimetric analysis. Over 48 h the biomass reached up to 0.

Modelling Mixed Microbial Culture Polyhydroxyalkanoate Accumulation Bioprocess towards Novel Methods for Polymer Production Using Dilute Volatile Fatty Acid Rich Feedstocks.

Volatile fatty acid (VFA) rich streams from fermentation of organic residuals and wastewater are suitable feedstocks for mixed microbial culture (MMC) Polyhydroxyalkanoate (PHA) production. However, many such streams have low total VFA concentration (1-10 gCOD/L). PHA accumulation requires a flow-through bioprocess if the VFAs are not concentrated.

Simultaneous nitrification and denitrification in microbial community-based polyhydroxyalkanoate production.

Microbial community-based polyhydroxyalkanoate (PHA) production has been demonstrated repeatedly at pilot scale. Ammonium, normally present in waste streams, might be oxidized by nitrifying bacteria resulting in additional aeration energy demand. The use of low dissolved oxygen (DO) concentrations allowed to reduce nitrifying rates by up to 70% compared to non-oxygen limiting conditions.

Scaling-up microbial community-based polyhydroxyalkanoate production: status and challenges.

Conversion of organic waste and wastewater to polyhydroxyalkanoates (PHAs) offers a potential to recover valuable resources from organic waste. Microbial community-based PHA production systems have been successfully applied in the last decade at lab- and pilot-scales, with a total of 19 pilot installations reported in the scientific literature. In this review, research at pilot-scale on microbial community-based PHA production is categorized and subsequently analyzed with focus on feedstocks, enrichment strategies, yields of PHA on substrate, biomass PHA content and polymer characterization.

Wood-PHA Composites: Mapping Opportunities.

Polyhydroxyalkanoate (PHA) biopolymers are emerging as attractive new sustainable polymers due to their true biodegradability and highly tuneable mechanical properties. However, despite significant investments, commercialisation barriers are hindering the capacity growth of PHA. In this work, we investigated the market potential for wood plastic composites (WPCs) based on PHAs.

Consistent production of high quality PHA using activated sludge harvested from full scale municipal wastewater treatment - PHARIO.

Production of polyhydroxyalkanoate (PHA) biopolymers by mixed microbial cultures concurrent to wastewater treatment is a valorization route for residual organic material. This development has been at pilot scale since 2011 using industrial and municipal organic residuals. Previous experience was the basis for a PHA production demonstration project: PHARIO.

Experimental data for extrusion processing and tensile properties of poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) polymer and wood fibre reinforced PHBV biocomposites.

This article features a large database on different extrusion processing conditions and the resulting tensile properties of poly(hydroxybutyrate--hydroxyvalerate) (PHBV) and wood fibre reinforced biocomposites. The data presented here corresponds to a comprehensive design of experiments conducted separately for both neat PHBV polymer and wood-PHBV composites, in which the effects of temperature profile, screw speed, feeding rate, feeding method, screw configuration, and wood contents (wood-PHBV composites only) of 10, 20, 30, and 40 wt% wood content were examined. For each processing condition, 5 specimens were tested under uniaxial tensile loading.

Application of dissolved oxygen (DO) level control for polyhydroxyalkanoate (PHA) accumulation with concurrent nitrification in surplus municipal activated sludge.

Mixed microbial cultures are a viable means for polyhydroxyalkanoate (PHA) production, which can produce polymers of commercial quality with high yields. Various PHA co-polymer blends can be produced by surplus full-scale municipal activated sludge fed with fermented waste feedstocks. In biological nutrient removal, ammonia is converted to nitrate by ammonia and nitrite oxidizing bacteria (AOBs and NOBs) through nitrification and removed as nitrogen gas through denitrification.

The Evolution of Polymer Composition during PHA Accumulation: The Significance of Reducing Equivalents.

This paper presents a systematic investigation into monomer development during mixed culture Polyhydroxyalkanoates (PHA) accumulation involving concurrent active biomass growth and polymer storage. A series of mixed culture PHA accumulation experiments, using several different substrate-feeding strategies, was carried out. The feedstock comprised volatile fatty acids, which were applied as single carbon sources, as mixtures, or in series, using a fed-batch feed-on-demand controlled bioprocess.

A process for polyhydroxyalkanoate (PHA) production from municipal wastewater treatment with biological carbon and nitrogen removal demonstrated at pilot-scale.

A process was developed for biological treatment of municipal wastewater for carbon and nitrogen removal while producing added-value polyhydroxyalkanoates (PHAs). The process comprised steps for pre-denitrification, nitrification and post-denitrification and included integrated fixed-film activated sludge (IFAS) with biofilm carrier media to support nitrification. In a pilot-scale demonstration (500-800L), wastewater treatment performance, in line with European standards, were achieved for total chemical oxygen demand (83% removal) and total nitrogen (80% removal) while producing a biomass that was able to accumulate up to 49% PHA of volatile suspended solids with acetic acid or fermented organic residues as substrates.

Carbon recovery from wastewater through bioconversion into biodegradable polymers.

Polyhydroxyalkanoates (PHA) are biodegradable polyesters that can be produced in bioprocesses from renewable resources in contrast to fossil-based bio-recalcitrant polymers. Research efforts have been directed towards establishing technical feasibility in the use of mixed microbial cultures (MMC) for PHA production using residuals as feedstock, mainly consisting of industrial process effluent waters and wastewaters. In this context, PHA production can be integrated with waste and wastewater biological treatment, with concurrent benefits of resource recovery and sludge minimization.

Fluxes in PHA-storing microbial communities during enrichment and biopolymer accumulation processes.

The use of mixed microbial cultures for the production of polyhydroxyalkanoates (PHAs) is emerging as a viable technology. In this study, 16S rRNA gene amplicon pyrosequencing was used to analyse fluctuations in populations over a 63-day period within a PHA-storing mixed microbial community enriched on fermented whey permeate. This community was dominated by the genera Flavisolibacter and Zoogloea as well as an unidentified organism belonging to the phylum Bacteroidetes.

Polyhydroxyalkanoate (PHA) storage within a mixed-culture biomass with simultaneous growth as a function of accumulation substrate nitrogen and phosphorus levels.

The response of a mixed-microbial-culture (MMC) biomass for PHA accumulation was evaluated over a range of relative nitrogen (N) and phosphorus (P) availabilities with respect to the supply of either complex (fermented whey permeate - FWP) or simpler (acetic acid) organic feedstocks. Fed-batch feed-on-demand PHA accumulation experiments were conducted where the feed N/COD and P/COD ratios were varied ranging from conditions of nutrient starvation to excess. A feast-famine enrichment (activated sludge) biomass, produced in a pilot-scale aerobic sequencing batch reactor on FWP and with a long history of stable PHA accumulation performance, was used for all the experiments as reference material.

Integrated production of polyhydroxyalkanoates (PHAs) with municipal wastewater and sludge treatment at pilot scale.

A pilot-scale process was operated over 22 months at the Brussels North Wastewater Treatment Plant (WWTP) in order to evaluate polyhydroxyalkanoate (PHA) production integration with services of municipal wastewater and sludge management. Activated sludge was produced with PHA accumulation potential (PAP) by applying feast-famine selection while treating the readily biodegradable COD from influent wastewater (average removals of 70% COD, 60% CODsol, 24% nitrogen, and 46% phosphorus). The biomass PAP was evaluated to be in excess of 0.

Sludge minimization in municipal wastewater treatment by polyhydroxyalkanoate (PHA) production.

An innovative approach has been recently proposed in order to link polyhydroxyalkanoates (PHA) production with sludge minimization in municipal wastewater treatment, where (1) a sequencing batch reactor (SBR) is used for the simultaneous municipal wastewater treatment and the selection/enrichment of biomass with storage ability and (2) the acidogenic fermentation of the primary sludge is used to produce a stream rich in volatile fatty acids (VFAs) as the carbon source for the following PHA accumulation stage. The reliability of the proposed process has been evaluated at lab scale by using substrate synthetic mixtures for both stages, simulating a low-strength municipal wastewater and the effluent from primary sludge fermentation, respectively. Six SBR runs were performed under the same operating conditions, each time starting from a new activated sludge inoculum.

Fractionation of microbial populations in a PHA accumulating mixed culture and associated PHA content and composition.

The uniformity of PHA composition and content across groups of organisms in mixed cultures was considered. An activated sludge microbial community, with an average PHA content of 20wt%, was fractioned by Percoll assisted buoyant density separation. The microbial community in the two principal fractions was characterised using amplicon pyrosequencing.

Polyhydroxyalkanoate (PHA) production from sludge and municipal wastewater treatment.

Polyhydroxyalkanoates (PHAs) are biodegradable polyesters with comparable properties to some petroleum-based polyolefins. PHA production can be achieved in open, mixed microbial cultures and thereby coupled to wastewater and solid residual treatment. In this context, waste organic matter is utilised as a carbon source in activated sludge biological treatment for biopolymer synthesis.

Integration of biopolymer production with process water treatment at a sugar factory.

The present investigation has focused on generating a surplus denitrifying biomass with high polyhydroxyalkanoate (PHA) producing potential while maintaining water treatment performance in biological nitrogen removal. The motivation for the study was to examine integration of PHA production into the water treatment and residuals management needs at the Suiker Unie sugar beet factory in Groningen, the Netherlands. At the factory, process waters are treated in nitrifying-denitrifying sequencing batch reactors (SBRs) to remove nitrogen found in condensate.

In-line monitoring of thermal degradation of PHA during melt-processing by Near-Infrared spectroscopy.

Polyhydroxyalkanoate (PHA) biopolymer processing is often challenged by low thermal stability, meaning that the temperatures and time for which these polymers can be processed is restrictive. Considering the sensitivity of PHA to processing conditions, there is a demand for in-line monitoring of the material behaviour in the melt. This paper investigates the application of Near-Infrared (NIR) spectroscopy for monitoring the thermal degradation of PHAs during melt-processing.

Methodological issues in life cycle assessment of mixed-culture polyhydroxyalkanoate production utilising waste as feedstock.

Assessing the environmental performance of emerging technologies using life cycle assessment (LCA) can be challenging due to a lack of data in relation to technologies, application areas or other life cycle considerations, or a lack of LCA methodology that address the specific concerns. Nevertheless, LCA can be a valuable tool in the environmental optimisation in the technology development phase. One emerging technology is the mixed-culture production of polyhydroxyalkanoates (PHAs).