Steven Pratt

Silica-polyamide nanofriction in electrolyte solutions: Insights into scaling of RO membranes

Publisher: Elsevier BV

Date: 02-2020

DOI: 10.1016/J.COLSURFA.2019.124206

‘Active’ filters for upgrading phosphorus removal from pond systems

Publisher: IWA Publishing

Date: 06-2005

DOI: 10.2166/WST.2005.0441

Abstract: This paper investigates limestone and iron slag filters as an upgrade option for phosphorus removal from wastewater treatment ponds. A review of ‘active’ filter technology and the results from laboratory and field research using packed columns of the different media is presented. It is shown that both limestone and iron slag can remove phosphorus but highlights that different types of limestone give markedly different performance. Filter performance appears to be improved by increasing temperature and by the presence of algae, presumably because of its tendency to elevate pH. Performance is related to hydraulic retention time (HRT), but this relationship is not linear, particularly at low HRTs. Importantly for future research, the results from field-testing with pond effluent show significant differences compared to those obtained when using a synthetic feed in the laboratory. For the iron slag filter, higher performance was observed in the field (72% in field vs. 27% in laboratory, at a 12 hour-HRT), while the opposite was observed for the limestone (64% in laboratory vs. 18% in field, at a 12-hour HRT).

Composites of Wood and Biodegradable Thermoplastics: A Review

Publisher: Informa UK Limited

Date: 02-11-2017

DOI: 10.1080/15583724.2017.1380039

Cycling of iodine by microalgae: Iodine uptake and release by a microalgae biofilm in a groundwater holding pond

Publisher: Elsevier BV

Date: 09-2016

DOI: 10.1016/J.ECOLENG.2016.05.001

The morphology of crystallisation of PHBV/PHBV copolymer blends

Publisher: Elsevier BV

Date: 03-2019

DOI: 10.1016/J.EURPOLYMJ.2018.12.022

Enhanced methane production from algal digestion using free nitrous acid pre-treatment

Publisher: Elsevier BV

Date: 04-2016

DOI: 10.1016/J.RENENE.2015.11.054

Rapid quantification of intracellular PHA using infrared spectroscopy: An application in mixed cultures

Publisher: Elsevier BV

Date: 11-2010

DOI: 10.1016/J.JBIOTEC.2010.09.939

Abstract: Fourier transform infrared (FT-IR) spectroscopy is proposed for a method for rapid quantification of polyhydroxyalkanoates (PHA) in mixed culture bacterial systems. Spectra from 122 s les from a wide range of PHA production systems were studied. The spectra were collected in a library that was used to calibrate a partial least squares (PLS) model linking FT-IR spectra with PHA content in the biomass. The library of spectra contained s les with a range of total PHA content (0.03-0.58 w/w) as well as varying compositions (poly-(3-hydroxyvalerate) (3HV) content of 0-63% in Cmol basis). A robust PLS model was developed using calibration data from a erse range of systems and PHA content. Coupling this model with FT-IR spectra has been shown to be applicable for predicting PHA content in mixed culture production systems. The method was used to reliably determine PHA content in biomass from a new, independent PHA production system with a standard error of prediction (RMSEP) value of 0.023 w/w, despite the complexity of the matrices. This method reduces the analytical time for PHA quantification down to under 30 min (5 min handling time was achieved when FT-IR equipment was immediately available), and eliminates hazardous waste by-products. The work has demonstrated a level of accuracy and reproducibility in quantifying PHA in mixed culture systems similar to that obtained from the GC analytical technique. Further work is required to enable the use of the method to analyze crystallinity related factors that may be useful towards quantifying poly-(3-hydroxybutyrate) and poly-(3-hydroxyvalerate) (3HB/3HV) composition. The method has been shown to be suitable for rapid quantification in large scale applications and in its present form is reliable for routine process monitoring.

Enhanced triacylglyceride extraction from microalgae using free nitrous acid pre-treatment

Publisher: Elsevier BV

Date: 09-2015

DOI: 10.1016/J.APENERGY.2015.04.045

The chemomechanical properties of microbial polyhydroxyalkanoates

Publisher: Elsevier BV

Date: 03-2013

DOI: 10.1016/J.PROGPOLYMSCI.2012.06.003

Thermal properties and crystallization behavior of fractionated blocky and random polyhydroxyalkanoate copolymers from mixed microbial cultures

Publisher: Wiley

Date: 07-05-2014

DOI: 10.1002/APP.40836

Silica fouling during groundwater RO treatment: The effect of colloids’ radius of curvature on dissolution and polymerisation

Publisher: Elsevier BV

Date: 2020

DOI: 10.1016/J.WATRES.2019.115135

Abstract: Silica fouling during groundwater reverse osmosis (RO) treatment can have a significant impact on filtration performance. To better understand this phenomenon, the equilibrium kinetics of amorphous colloidal silica were studied at conditions relevant to RO of silica-rich alkaline groundwater. The impact of particle size was investigated using synthetic monodisperse silica nanoparticles. Bench scale experiments were conducted by monitoring dissolved silica concentration of aqueous suspensions of colloids of 100 and 300 nm diameter and pH 8.5 to 9.5. The equilibrium data was determined from existing established rate law equations. This study concluded that surface energy has a major impact on silica dissolution rate constant, particularly for colloidal silica. Observations of Ostwald ripening in bidisperse silica dispersions further confirmed these results, which indicate that dissolution and redeposition is responsible for the problematic silica fouling behaviour during RO treatment. 2D modelling based on inferred equilibrium data allows visualization of scale layer growth in agreement with cross-sectional scanning electron micrographs of autopsied membranes.

Phosphorus removal by an ‘active’ slag filter–a decade of full scale experience

Publisher: Elsevier BV

Date: 2006

DOI: 10.1016/J.WATRES.2005.11.002

Abstract: Active filters, which facilitate phosphorus (P) removal via precipitation and/or adsorption, offer a promising 'appropriate technology' for upgrading small wastewater treatment systems. Research on active filters for P removal using steel slag material has been conducted in laboratories across the world, however, field experiments have been limited and long-term data is practically non-existent. This paper presents a decade of experience on P removal by active slag filters at a full-scale treatment plant. During 1993-1994 the filter removed 77% of the total phosphorus (TP), and over the first 5 years of the filter's operation it reduced the mean effluent TP concentration to 2.3 mgl(-1). However during the sixth year of operation P removal was significantly reduced. Over the 11 years of monitoring, 22.4 tonnes of TP was removed by the filter, 19.7 tonnes of this in the first 5-year period. It was determined that the slag material maintained its maximum removal potential until reaching a P-retention ratio of 1.23 kg TP per tonne of slag. This paper provides the first long-term field data for slag filters, and shows that they can provide P removal for a half a decade before filter replacement/rejuvenation is required.

Hydrocarbon hydrogen carriers for catalytic transfer hydrogenation of guaiacol

Publisher: Elsevier BV

Date: 10-2020

DOI: 10.1016/J.IJHYDENE.2020.07.136

Chemical techniques for pretreating and regenerating active slag filters for improved phosphorus removal

Publisher: Informa UK Limited

Date: 07-2011

DOI: 10.1080/09593330.2010.525749

Abstract: Active slag filters are an emerging technology for removing phosphorus (P) from wastewaters. Recent research revealed that adsorption onto Fe oxides/oxyhydroxides at near-neutral pH and oxidizing Eh is the key mechanism of P removal by melter slag filters. Currently, filter lifespan is limited by available adsorption sites. This study examined whether the performance and longevity of active filters could be improved via chemical treatment to create additional reactive sites as well as regenerate exhausted ones. Fresh original melter slag as well as slag from an exhausted full-scale filter was tested. Chemical reagents that could manipulate the pH/Eh of the slag granule surfaces and potentially activate them for further P removal were used, namely hydrochloric acid (HCI), sodium hydroxide (NaOH) and sodium dithionite (Na2S2O4). Waste stabilization pond effluent was then applied to the treated slag to assess the effectiveness of the treatments at improving P removal. Fresh slag treated with Na2S204 and HCl, respectively, retained 1.9 and 1.4 times more P from the effluent than the untreated fresh slag. These reagents were even more effective at regenerating the exhausted slag, increasing total retained P by a factor of 13 and six, respectively, compared with untreated slag. Sodium hydroxide was ineffective at increasing P removal. The higher P retention by the 'treated exhausted slag' compared with the 'treated fresh media' indicates that adsorption sites on melter slag filters become increasingly reactive with time. This research is the first study to provide evidence that P retention by active slag filters can be increased by both (1) chemical pre treatment and (2) chemical post-treatment once their P removal is exhausted, thereby potentially transforming them from a single use system to a more viable, reusable treatment technology.

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

Publisher: Elsevier BV

Date: 02-2019

DOI: 10.1016/J.DIB.2018.12.084

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

Publisher: Elsevier BV

Date: 11-2014

DOI: 10.1016/J.IJBIOMAC.2014.04.055

Abstract: 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 licon pyrosequencing. While organisms were common to both fractions, the relative abundances of species were found to be different between the two fractions. The average PHA content in one of the fractions was found to be higher (24wt%) than the other (16wt%) separation was considered to be in part driven by the density difference associated with PHA content, but also by other factors such as cell dimension and cellular morphology. But while differences in PHA content were observed, the PHA composition in both fractions was found to be approximately the same (43-44mol% HV), which shows that distinct groups of microbial populations within mixed cultures may generate PHA with similar average copolymer composition.

Techno-economic assessment of poly-3-hydroxybutyrate (PHB) production from methane - The case for thermophilic bioprocessing

Publisher: Elsevier BV

Date: 12-2016

DOI: 10.1016/J.JECE.2016.07.033

Enhanced biogas production using cow manure to stabilize co-digestion of whey and primary sludge

Publisher: Informa UK Limited

Date: 09-2013

DOI: 10.1080/09593330.2013.774032

Abstract: Increasing biogas production from municipal anaerobic digesters via additional loading with industrial/agricultural wastes offers a low-cost, sustainable energy generation option of significant untapped potential. In this work, bench-top reactors were used to mimic a full-scale primary sludge digester operating at an organic loading rate (OLR) of 2.4 kg COD/m3 d and a 20 d hydraulic retention time (HRT). Co-digestion of whey with primary sludge was sustained at a loading rate of 3.2 kg COD/m3 d (17 d HRT) and boosted gas production to 151% compared to primary sludge digestion alone. Addition of chemical alkalinity enabled co-digestion of whey with primary sludge to be maintained at an elevated OLR of 6.4 kg COD/m3 d (11 d HRT) with gas production increased to 208%. However, when the chemical addition was simply replaced by cow manure, stable operation was maintained at OLRs of 5.2-6.9 kg COD/m3 d (11-14 d HRT) with gas production boosted up to 268%.

Public attitudes towards bioplastics – knowledge, perception and end-of-life management

Publisher: Elsevier BV

Date: 12-2019

DOI: 10.1016/J.RESCONREC.2019.104479

Active slag filters: Rapid assessment of phosphorus removal efficiency from effluent as a function of retention time

Publisher: Informa UK Limited

Date: 2013

DOI: 10.1080/09593330.2012.689365

Abstract: There is increasing pressure to upgrade effluent ponds for phosphorus removal. Active slag filters offer a solution, but design information is limited. Hydraulic retention time (HRT) is a key factor in filter design because it controls filter treatment efficiency as well the filter substrate lifespan. This paper reports on a rapid method of continual looping of effluent through a filter column to obtain a relationship between HRT and phosphorus removal efficiency. Phosphorus removal declined logarithmically with respect to retention time. While the mechanisms that yield this relationship involve complex mass transfer and adsorption of phosphorus to Fe oxyhydroxide sites, in general terms, the adsorption rate is proportional to the adsorbate effluent concentration. Waste stabilization pond effluent treated by the slag achieved phosphorus removal efficiencies over 90% at extended HRTs greater than 70 hours, while 80% removal was obtainable in 30 hours. Higher phosphorus removal was achieved for slag treating real effluent compared with synthetic phosphate solution. This can be explained by: (1) different starting phosphorus concentrations in the synthetic phosphate solution and real effluent and (2) the presence of constituents in real effluent that can enhance phosphorus removal, such as oxidized iron compounds, cations, algae and humic complexes. This new technique, which proved capable of replicating treatment efficiencies obtained from long-term column studies, offers rapid assessment of phosphorus removal efficiency as a function of retention time and thus will enable design engineers to size active filters on the basis of achieving the required phosphorus removal standards.

Erratum to “The chemomechanical properties of microbial polyhydroxyalkanoates” [Prog. Polym. Sci. 38 (2013) 536–583]

Publisher: Elsevier BV

Date: 02-2014

DOI: 10.1016/J.PROGPOLYMSCI.2013.06.007

Mixed culture polyhydroxyalkanoate-rich biomass assessment and quality control using thermogravimetric measurement methods

Publisher: Elsevier BV

Date: 10-2017

DOI: 10.1016/J.POLYMDEGRADSTAB.2017.07.029

The contribution of bacteria to algal growth by carbon cycling

Publisher: Wiley

Date: 23-12-2015

DOI: 10.1002/BIT.25475

Abstract: Algal mass production in open systems is often limited by the availability of inorganic carbon substrate. In this paper, we evaluate how bacterial driven carbon cycling mitigates carbon limitation in open algal culture systems. The contribution of bacteria to carbon cycling was determined by quantifying algae growth with and without supplementation of bacteria. It was found that adding heterotrophic bacteria to an open algal culture dramatically enhanced algae productivity. Increases in algal productivity due to supplementation of bacteria of 4.8 and 3.4 times were observed in two batch tests operating at two different pH values over 7 days. A kinetic model is proposed which describes carbon limited algal growth, and how the limitation could be overcome by bacterial activity to re-mineralize photosynthetic end products.

Luxury uptake of phosphorus by microalgae in full-scale waste stabilisation ponds

Publisher: IWA Publishing

Date: 02-2011

DOI: 10.2166/WST.2011.116

Abstract: Biological phosphorus removal was studied in two full-scale waste stabilisation ponds (WSP). Luxury uptake by microalgae was confirmed to occur and in one pond the biomass contained almost four times the phosphorus required by microalgae for normal metabolism. However, the phosphorus content within the biomass was variable. This finding means that assumptions made in prior publications on modelling of phosphorus removal in WSP are questionable. While fluctuations in microalgal growth causes variation in many water quality parameters, this further variation in luxury uptake explains the high degree of variability in phosphorus removal commonly reported in the literature. To achieve effective biological phosphorus removal high levels of both luxury uptake and microalgal concentration are needed. The findings of this work show that while high levels of these parameters did occur at times in the WSP monitored, they did not occur simultaneously. This is explained because accumulated phosphorus is subsequently consumed during rapid growth of biomass resulting in a high biomass concentration with a low phosphorus content. Previous laboratory research has allowed a number of key considerations to be proposed to optimise both luxury uptake and biomass concentration. Now that is has been shown that high levels of biomass concentration and luxury uptake can occur in the field it may be possible to redesign WSP to optimise these parameters.

The chemomechanical properties of microbial polyhydroxyalkanoates

Publisher: Elsevier BV

Date: 02-2014

DOI: 10.1016/J.PROGPOLYMSCI.2013.06.008

Production of volatile fatty acids by fermentation of waste activated sludge pre-treated in full-scale thermal hydrolysis plants

Publisher: Elsevier BV

Date: 02-2011

DOI: 10.1016/J.BIORTECH.2010.10.054

Abstract: This work focuses on fermentation of pre-treated waste activated sludge (WAS) to generate volatile fatty acids (VFAs). Pre-treatment by high-pressure thermal hydrolysis (HPTH) was shown to aid WAS fermentation. Compared to fermentation of raw WAS, pre-treatment enabled a 2-5x increase in VFA yield (gVFA(COD)gTCOD(-1)) and 4-6x increase in VFA production rate (gVFA(COD) L(-1) d(-1)). Three sludges, pre-treated in full-scale HPTH plants, were fermented. One was from a plant processing a mix of primary sludge and WAS and the other two from plants processing solely WAS. The HPTH plants solubilised suspended matter, evidenced by a 20-30% decrease in suspended solids and an increase of soluble COD : total COD from 0.04 to 0.4. Fermentation of the three sludges yielded similar VFA concentrations (15-20gVFA(COD) L(-1)). The yields were largely independent of retention time (1 d-6 d) and temperature (42°C, 55°C). Also, the product spectrum depended mostly on the composition of the sludge rather than on operating conditions.

Assessment of physical techniques to regenerate active slag filters removing phosphorus from wastewater

Publisher: Elsevier BV

Date: 02-2009

DOI: 10.1016/J.WATRES.2008.10.020

Abstract: Active slag filters are an emerging technology for removing phosphorus (P) from wastewater. Currently, the lifespan of these filters is limited by their available reactive sites. An increasing number of researchers suggest that drying active filters can renew their P removal capacity, although there has only been one research paper that has achieved regeneration. Hence, this study investigated techniques to regenerate the P removal efficiency of exhausted melter slag filter media which had successfully treated effluent for 5 years in the field before becoming inactive. Several techniques were performed to expose fresh surface sites on the slag, including: (1) drying (2) agitation and (3) crushing of the slag granules. Crushing resulted in the best regeneration of P removal efficiency by the slag, however, after just 2 months the renewed P removal efficiency of the crushed slag fell back to a similar level to that exhibited by exhausted slag. Furthermore, none of the other physical methods caused long-term rejuvenation of the exhausted slag to remove P from effluent. Scanning electron microscopy revealed that none of the regeneration techniques exposed substantial new phosphorus adsorption sites on the slag granules. These findings therefore challenge the validity of the existing dogma that active slag filters can be effectively regenerated by simple physical treatments, indicating further research is required to optimise active filter performance.

Effects of Redox Potential and pH Changes on Phosphorus Retention by Melter Slag Filters Treating Wastewater

Publisher: American Chemical Society (ACS)

Date: 17-08-2007

DOI: 10.1021/ES070914M

Abstract: The release of phosphorus (P) and iron (Fe) from a melter slag filter in solutions of varying Eh and pH was examined. The filter had been removing P from waste stabilization pond effluent for several years. The study revealed that the highest P (95% of total P) and Fe (25% of total Fe) release from the slag occurred in the solution with the lowest Eh (-400 mV, relative to the standard hydrogen electrode, SHE) and lowest pH (4.9). Solutions with high pH (9.1) also proved favorable for P release (20 to 40% of total P) from the slag, at both reducing (-400 mV) and oxidizing (+300 mV) Eh. By contrast, solutions with pH 4.9 and 6.7 and oxidizing Eh (+300 mV) liberated the lowest P and Fe contents into the aqueous phase (<1% for both elements). The findings showed that Eh and pH are important parameters affecting P release from slag filters. At low Eh and low pH, P is released due to the dissolution of Fe oxides/oxyhydroxides, as supported by scanning electron microscopy (SEM)/energy dispersive spectrometry (EDS). At high pH, P is desorbed from negatively charged Fe oxide/oxyhydroxide surfaces. The results of this investigation are pertinentto the design and operation of melter slag filters that treat all forms of P-rich waters, such as wastewater, stormwater, and farm runoff. The study demonstrated that P retention by melter slag filters is optimal in water bodies characterized by near-neutral pH and oxidizing Eh because these conditions favor P adsorption onto Fe oxides/oxyhydroxides.

Microbial community analysis during continuous fermentation of thermally hydrolysed waste activated sludge

Publisher: IWA Publishing

Date: 2012

DOI: 10.2166/WST.2011.705

Abstract: Acidogenic fermentation of thermally hydrolysed waste activated sludge was carried out at laboratory scale in two reactors operated under different hydraulic retention times (HRT). Process performance was assessed in terms of volatile fatty acid (VFA) composition and yield. The ersity of the microbial population was investigated by constructing a 16S rRNA gene library and subsequent phylogenetic analysis of clones. Fluorescence in situ hybridization (FISH) was used to assess the relative abundance of different bacterial groups. Bacteroidetes and Firmicutes were the dominant taxonomic groups representing 93% of the total sequences obtained in the reactor with 4 d HRT. A similar VFA yield (0.4–0.5 g VFACOD g SCOD−1) was obtained for the HRTs tested (1–4 d), indicating that extended retention times were not useful. Within Firmicutes, Clostridia was the major group detected in the clone sequences. These had close affiliation to Sporanaerobacter acetigenes, suggesting organisms of this group were important for hydrolysis of the protein fraction of the substrate. However, FISH analysis failed to detect the major portion of the bacteria, and this is most likely due to the lack of appropriate probes. This work emphasizes the ersity of fermentative communities, and indicates that more work is needed to identify and detect the important members.

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

Publisher: MDPI AG

Date: 07-03-2017

DOI: 10.3390/BIOENGINEERING4010020

Mechanical and physical stability of polyhydroxyalkanoate (PHA)-based wood plastic composites (WPCs) under natural weathering

Publisher: Elsevier BV

Date: 02-2019

DOI: 10.1016/J.POLYMERTESTING.2018.11.028

High pressure thermal hydrolysis as pre-treatment to increase the methane yield during anaerobic digestion of microalgae

Publisher: Elsevier BV

Date: 03-2013

DOI: 10.1016/J.BIORTECH.2012.12.125

Abstract: Anaerobic digestion of algal biomass will be an essential component of algal biofuel production systems, yet the methane yield from digestion of algae is typically much lower than the theoretical potential. In this work, high pressure thermal hydrolysis (HPTH) is shown to enhance methane yield during algae digestion. HPTH pre-treatment was applied to both raw algae and algal residue resulting from lipid extraction. HPTH and even the lipid extraction process itself increased methane yield, by 81% and 33% respectively in combination they increased yield by 110% over that of the raw algae (18L CH4 gVS(-1) substrate). HPTH had little effect on the rate of anaerobic digestion, however lipid extraction enhanced it by 33% over that for raw algae (0.21day(-1)). Digestion resulted in solubilisation of nitrogen (and phosphorous to a lesser degree) in all cases, showing that there is potential for nutrient recycling for algal growth.

Impact of osmotic shock pre-treatment on microalgae lipid extraction and subsequent methane production

Publisher: Elsevier BV

Date: 09-2019

DOI: 10.1016/J.BITEB.2019.100214

Understanding the effect of copolymer content on the processability and mechanical properties of polyhydroxyalkanoate (PHA)/wood composites

Publisher: Elsevier BV

Date: 09-2019

DOI: 10.1016/J.COMPOSITESA.2019.05.005

Factors Influencing Luxury Uptake of Phosphorus by Microalgae in Waste Stabilization Ponds

Publisher: American Chemical Society (ACS)

Date: 02-07-2008

DOI: 10.1021/ES703118S

Abstract: Phosphorus removal in waste stabilization ponds (WSP) is highly variable, but the reasons for this are not well understood. Luxury uptake of phosphorus by microalgae has been studied in natural systems such as lakes but not under the conditions found in WSP. This work reports on the effects of phosphate concentration, light intensity, and temperature on luxury uptake of phosphorus by WSP microalgae in continuous culture bioreactors. Increasing temperature had a statistically significant "positive effect" on intracellular acid-insoluble polyphosphate concentration. It is likely that elevated temperature increased the rate of polyphosphate accumulation, but because the biomass was not starved of phosphate, the stored acid-insoluble polyphosphate was not utilized. Increasing light intensity had no effect on acid-insoluble polyphosphate but had a "negative effect" on the acid-soluble polyphosphate. A possible explanation for this is that the faster growth rate at high light intensity results in this form of polyphosphate being utilized by the cells for synthesis of cellular constituents at a rate that exceeds replenishment. The variability in the phosphorus content of the microalgal biomass shows that with this new understanding ofthe luxury uptake mechanism there is the potential to optimize WSP for biological phosphorus removal.

Development of a novel electrochemical system for oxygen control (ESOC) to examine dissolved oxygen inhibition on algal activity

Publisher: Wiley

Date: 07-2013

DOI: 10.1002/BIT.24905

Abstract: The development of an Electrochemical System for Oxygen Control (ESOC) for examining algal photosynthetic activity as a function of dissolved oxygen (DO) is outlined. The main innovation of the tool is coulombic titration in order to balance the electrochemical reduction of oxygen with the oxygen input to achieve a steady DO set-point. ESOC allows quantification of algal oxygen production whilst simultaneously maintaining a desired DO concentration. The tool was validated abiotically by comparison with a mass transfer approach for quantifying oxygenation. It was then applied to quantify oxygen inhibition of algal activity. Five experiments, using an enriched culture of Scenedesmus sp. as the inoculum, are presented. For each experiment, ESOC was used to quantify algal activity at a series of DO set-points. In all experiments substantial oxygen inhibition was observed at DO >30 mgO2 L-1. Inhibition was shown to fit a Hill inhibition model, with a common Hill coefficient of 0.22±0.07 L mg-1 and common log10 CI50 of 27.2±0.7 mg L-1. This is the first time that the oxygen inhibition kinetic parameters have been quantified under controlled DO conditions.

Insights into the biodegradation of PHA / wood composites: Micro- and macroscopic changes

Publisher: Elsevier BV

Date: 09-2019

DOI: 10.1016/J.SUSMAT.2019.E00099

Designing for effective controlled release in agricultural products: new insights into the complex nature of the polymer–active agent relationship and implications for use

Publisher: Wiley

Date: 22-06-2020

DOI: 10.1002/JSFA.10531

Rate of nitrate production during a two-stage nitrification batch reaction

Publisher: IWA Publishing

Date: 11-2004

DOI: 10.2166/WST.2004.0615

Abstract: The two steps of nitrification, namely the oxidation of ammonia to nitrite and nitrite to nitrate, often need to be considered separately in process studies. It has been assumed that these two reactions can be described by single Monod models. In this paper, the suitability of the single Monod model for describing nitrite oxidation to nitrate is discussed. The measured rate of nitrate production during a batch reaction is presented. For the system studied it was found that nitrate production actually increased after the completion of ammonia oxidation. It is suggested that the reason for the increase was a combination of: (i) likely competition for oxygen when both substrates were present, and (ii) a decrease in ammonia inhibition of nitrite oxidisers with the removal of ammonia. The result is that a single Monod expression (based on nitrite as the substrate) could not be used to describe nitrate production. In these types of systems the consequence of oxygen limitation and substrate inhibition should also be considered.

Development of membrane inlet mass spectrometry for examination of fermentation processes

Publisher: Elsevier BV

Date: 15-12-2010

DOI: 10.1016/J.TALANTA.2010.09.034

Abstract: Membrane inlet mass spectrometry (MIMS) is useful for on-line monitoring of fermentation processes. However, readings are affected by the complex and dynamic matrix in which biological processes occur, making MIMS calibration a challenge. In this work, two calibration strategies were evaluated for measurement of typical products of acidogenic fermentation, i.e., ethanol, H(2), and CO(2) in the liquid phase, and H(2) and CO(2) in the gas phase: (1) "standard calibration", which was performed independent of fermentation experiments with sterile standards in water with a N(2) headspace, and (2) "in-process calibration" whereby fermentation was monitored concurrent with off-line analysis. Fermentation was operated in batch and continuous modes. In-process calibration was shown to be most effective for measurements of H(2) and CO(2) in both gas and liquid phases standard calibration gave erroneous results. In the gas phase, this was due to a lower sensitivity during experiments compared to the independent standard calibration, believed to be caused by formation of a liquid film on the surface of the probe. In the liquid phase, moving from the standard calibration environment to the fermentation caused the linear relationship between the H(2) concentration and MIMS signal to change in intercept, and the relationship for CO(2) to change in slope, possibly due to dissolved ions, and related non-ideality. For ethanol, standard calibration results were fairly consistent with in-process calibration results. The main limitation with in-process calibration is the potential for a lack of variability in target concentration. This could be addressed by spiking the targeted compound at the end of the experiment. Regardless, MIMS is an ideal instrument for analysing fermentation experiments, due to its ability to measure targeted compounds semi-continuously, and due to a lack of drift over long periods.

Mechanical performance and long-term indoor stability of polyhydroxyalkanoate (PHA)-based wood plastic composites (WPCs) modified by non-reactive additives

Publisher: Elsevier BV

Date: 2018

DOI: 10.1016/J.EURPOLYMJ.2017.11.041

Microaerophilic conditions support elevated mixed culture polyhydroxyalkanoate (PHA) yields, but result in decreased PHA production rates

Publisher: IWA Publishing

Date: 2012

DOI: 10.2166/WST.2012.086

Abstract: For commercial polyhydroxyalkanoate (PHA) production the objective is to maximise the fraction of feedstock that ends up as polymer, and minimise biomass growth. In this paper, oxygen limitation was applied to achieve this. Intracellular PHA content in mixed cultures in batch systems operated with low and high DO was compared. It is shown that in microaerophilic conditions a higher fraction of substrate is accumulated as PHA in comparison to high DO conditions, evidenced by elevated intracellular PHA content: in the order of 50% higher in the early stages of accumulation. However, the accumulation capacity is not affected by DO. The PHA content in biomass in both the low and high DO systems reached approximately 35%. The time taken for the PHA content in the low DO system to reach capacity was three times longer than in the high DO system.

Gas controlled hydrogen fermentation

Publisher: Elsevier BV

Date: 04-2012

DOI: 10.1016/J.BIORTECH.2012.01.122

Abstract: Acidogenic fermentation is an anaerobic process of double purpose, while treating organic residues it produces chemical compounds, such as hydrogen, ethanol and organic acids. Therefore, acidogenic fermentation arises as an attractive biotechnology process towards the biorefinery concept. Moreover, this process does not need sterile operating conditions and works under a wide range of pH. Changes of operating conditions produce metabolic shifts, inducing variability on acidogenic product yield. To induce those changes, experiments, based on reactor headspace N(2)-flushing (gas phase), were designed. A major result was the hydrogen yield increase from 1 to 3.25±0.4 ( [Formula: see text] ) at pH 4.5 and N(2)-flushing of 58.4 (L·d(-1)). This yield is close to the theoretical acidogenic value (4 [Formula: see text] ). The mechanisms that explain this increase on hydrogen yield shifts are related to the thermodynamics of three metabolic reactions: lactate hydrogenase, NADH hydrogenase and homoacetogenesis, which are affected by the low hydrogen partial pressures.

Composting of waste algae: A review

Publisher: Elsevier BV

Date: 07-2014

DOI: 10.1016/J.WASMAN.2014.01.019

Abstract: Although composting has been successfully used at pilot scale to manage waste algae removed from eutrophied water environments and the compost product applied as a fertiliser, clear guidelines are not available for full scale algae composting. The review reports on the application of composting to stabilize waste algae, which to date has mainly been macro-algae, and identifies the peculiarities of algae as a composting feedstock, these being: relatively low carbon to nitrogen (C/N) ratio, which can result in nitrogen loss as NH3 and even N2O high moisture content and low porosity, which together make aeration challenging potentially high salinity, which can have adverse consequence for composting and potentially have high metals and toxin content, which can affect application of the product as a fertiliser. To overcome the challenges that these peculiarities impose co-compost materials can be employed.

Value-added bioplastics from services of wastewater treatment

Publisher: IWA Publishing

Date: 09-2015

DOI: 10.2166/WPT.2015.063

Abstract: Pilot and prototyping scale investigations were undertaken in order to evaluate the technical feasibility of producing value-added biopolymers (polyhydroxyalkanoates (PHAs)) as a by-product to essential services of wastewater treatment and environmental protection. A commonly asked question concerns PHA quality that may be expected from surplus biomass produced during biological treatment for water quality improvement. This paper summarizes the findings from a collection of investigations. Alongside the summarized technical efforts, attention has been paid to the social and economic networks. Such networks are needed in order to nurture circular economies that would drive value chains in renewable resource processing from contaminated water amelioration into renewable value-added bioplastic products and services. We find commercial promise in the polymer quality and in the process technical feasibility. The next challenge ahead does not reside so much any more in fundamental research and development of the technology but, rather, in social-economic steps that will be necessary to realize first demonstration scale polymer production activities. It is a material supply that will stimulate niche business opportunities that can grow and stimulate technology pull with benefit of real life material product market combinations.

Crystallisation and fractionation of selected polyhydroxyalkanoates produced from mixed cultures

Publisher: Elsevier BV

Date: 06-2014

DOI: 10.1016/J.NBT.2013.05.005

Abstract: Poly[R-3-hydroxybutyrate-co-(R-3-hydroxyvalerate)] (PHBV) copolymers were produced from mixed cultures of biomass (activated sludge) fed with acetic acid (HAc) and propionic acid (HPr). Feeding was performed in such a way as to produce materials with a wide range of monomer compositions and microstructures. Solvent-cast thin films of these materials have recently been shown to exhibit a narrow range of mechanical properties similar to those of the homopolymer poly(R-3-hydroxybutyrate) (PHB) [1]. In this work, more detailed analyses of the thermal and crystallisation properties of these mixed-culture polyesters have revealed that they like comprise complex blends with broad compositional distribution of random and/or blocky copolymers of very different 3-hydroxyvalerate (3HV) contents and melting temperatures and thus have very different respective crystallisation kinetics. This blend complexity was confirmed by solvent fractionation of selected s les. The findings support the hypothesis that overall mechanical properties of these complex copolymer blend materials will be strongly influenced by the more rapidly crystallising components that form the matrix within which the slower crystallising components exist as microdomains. New opportunities in the material development of PHAs are likely to be found in establishing and exploiting such structure-function relationships.

Mechanical Stability of Polyhydroxyalkanoate (PHA)-Based Wood Plastic Composites (WPCs)

Publisher: Springer Science and Business Media LLC

Date: 18-03-2020

DOI: 10.1007/S10924-020-01697-9

Biodegradation in a soil environment of activated sludge derived polyhydroxyalkanoate (PHBV)

Publisher: Elsevier BV

Date: 11-2012

DOI: 10.1016/J.POLYMDEGRADSTAB.2012.07.035

Understanding the Mobilization of a Nitrification Inhibitor from Novel Slow Release Pellets, Fabricated through Extrusion Processing with PHBV Biopolymer

Publisher: American Chemical Society (ACS)

Date: 06-02-2019

DOI: 10.1021/ACS.JAFC.8B05709

Abstract: Dicyandiamide (DCD) has been studied as a stabilizer for nitrogen fertilizers for over 50 years. Its efficacy is limited at elevated temperatures, but this could be addressed by encapsulation to delay exposure. Here, poly(3-hydroxybutyrate- co-3-hydroxyvalerate) (PHBV) was investigated as a biodegradable matrix for the encapsulation of DCD. Cylindrical ∼3 mm × 3 mm pellets were fabricated through extrusion processing with 23 wt % DCD. Release kinetics were monitored in water, sand, and both active and γ-irradiated agricultural clay loam soils. Raman maps showed a wide particle size distribution of DCD crystals and indicated that Hitachi's classic moving front theory did not hold for this formulation. The inhibitor release kinetics were mediated by four distinct mechanisms: (i) initial rapid dissolution of surface DCD, (ii) channeling of water through voids and pores in the PHBV matrix, (iii) gradual diffusion of water and DCD through layers of PHBV, and (iv) biodegradation of the PHBV matrix. After ∼6 months, 45-100% release occurred, depending on the release media. PHBV is shown to be an effective, biodegradable matrix for the long-term slow release of nitrification inhibitors.

Modeling aerobic carbon oxidation and storage by integrating respirometric, titrimetric, and off-gas CO2 measurements

Publisher: Wiley

Date: 2004

DOI: 10.1002/BIT.20199

Abstract: A method for detailed investigation of aerobic carbon degradation processes by microorganisms is presented. The method relies on an integrated use of the respirometric, titrimetric, and off-gas CO(2) measurements. The oxygen uptake rate (OUR), hydrogen ion production rate (HPR), and the carbon dioxide transfer rate (CTR) resulting from the biological as well as physicochemical processes, coupled with a metabolic model characterizing both the growth and carbon storage processes, enables the comprehensive study of the carbon degradation processes. The method allows the formation of carbon storage products and the biomass growth rates to be estimated without requiring any off-line biomass or liquid-phase measurements, although the practical identifiability of the system could be improved with additional measurements. Furthermore, the combined yield for biomass growth and carbon storage is identifiable, along with the affinity constant with respect to the carbon substrate. However, the in idual yields for growth and carbon storage are not identifiable without further knowledge about the metabolic pathways employed by the microorganisms in the carbon conversion. This is true even when more process variables are measured. The method is applied to the aerobic carbon substrate degradation by a full-scale sludge using acetate as an ex le carbon source. The sludge was able to quickly take up the substrate and store it as poly-beta-hydroxybutyrate (PHB). The PHB formation rate was a few times faster than the biomass growth rate, which was confirmed by off-line liquid- and solid-phase analysis. The estimated combined yield for biomass growth and carbon storage compared closely to that determined from the theoretical yields reported in literature based on thermodynamics. This suggests that the theoretical yields may be used as default parameters for modeling purposes.

Comparative effects of biomass pre-treatments for direct and indirect transesterification to enhance microalgal lipid recovery

Publisher: Frontiers Media SA

Date: 04-12-2014

DOI: 10.3389/FENRG.2014.00057

Extrusion of wood fibre reinforced poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) biocomposites: Statistical analysis of the effect of processing conditions on mechanical performance

Publisher: Elsevier BV

Date: 2019

DOI: 10.1016/J.POLYMDEGRADSTAB.2018.10.015

The effect of methane and odd-chain fatty acids on 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) synthesis by a Methylosinus-dominated mixed culture

Publisher: Springer Science and Business Media LLC

Date: 12-2019

DOI: 10.1186/S40643-019-0285-1

Abstract: A methanotrophic community was enriched in a semi-continuous reactor under non-aseptic conditions with methane and ammonia as carbon and nitrogen source. After a year of operation, Methylosinus sp., accounted for 80% relative abundance of the total sequences identified from potential polyhydroxyalkanoates (PHAs) producers, dominated the methane-fed enrichment. Prior to induction of PHA accumulation, cells harvested from the parent reactor contained low level of PHA at 4.0 ± 0.3 wt%. The cells were later incubated in the absence of ammonia with various combinations of methane, propionic acid, and valeric acid to induce biosynthesis of poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate- co -3-hydroxyvalerate) (PHBV). Previous studies reported that methanotrophic utilization of odd-chain fatty acids for the production of PHAs requires reducing power from methane oxidation. However, our findings demonstrated that the PHB-containing methanotrophic enrichment does not require methane availability to generate 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV)—when odd-chain fatty acids are presented. The enrichment yielded up to 14 wt% PHA with various mole fractions of 3HV monomer depending on the availability of methane and odd-fatty acids. Overall, the addition of valeric acid resulted in a higher PHA content and a higher 3HV fraction. The highest 3HV fraction (up to 65 mol%) was obtained from the methane–valeric acid experiment, which is higher than those previously reported for PHA-producing methanotrophic mixed microbial cultures.

Improving titrimetric techniques by modelling pH change in activated sludge systems

Publisher: IWA Publishing

Date: 06-2003

DOI: 10.2166/WST.2003.0613

Abstract: Existing titrimetric techniques rely on a well defined hydrogen ion production rate. In particular, they are only suitable in circumstances in which constant background pH influencing reactions take place. This is rarely the case due to the presence of the carbonate acid/base system. In this paper, a model, which describes the influence of the nitrification process on pH and accounts for the action of the carbonate system, is presented. The validity of the model is tested by comparison of model predictions for the important state variables with that of experimental data from a batch oxidation of ammonium nitrogen. The two cases studied are the responses of an endogenously respiring nitrifying sludge to: an ammonium chloride pulse and a pulse of both bicarbonate and ammonium chloride. The results are most encouraging as the dynamic HPR response is mirrored by the model simulation. Furthermore, using the model for data interpretation, the initial nitrogen substrate levels are recovered. It is shown that this could not have been achieved in either case using existing titrimetric techniques.

Stabilisation of microalgae: Iodine mobilisation under aerobic and anaerobic conditions

Publisher: Elsevier BV

Date: 10-2015

DOI: 10.1016/J.BIORTECH.2015.06.063

Abstract: Mobilisation of iodine during microalgae stabilisation was investigated, with the view of assessing the potential of stabilised microalgae as an iodine-rich fertiliser. An iodine-rich waste microalgae (0.35 ± 0.05 mg I g(-1) VS(added)) was stabilised under aerobic and anaerobic conditions. Iodine mobilisation was linearly correlated with carbon emission, indicating iodine was in the form of organoiodine. Comparison between iodine and nitrogen mobilisation relative to carbon emission indicated that these elements were, at least in part, housed separately within the cells. After stabilisation, there were 0.22 ± 0.05 and 0.19 ± 0.01 mg g(-1) VS(added) iodine remaining in the solid in the aerobic and anaerobic processed material respectively, meaning 38 ± 5.0% (aerobic) and 50 ± 8.6% (anaerobic) of the iodine were mobilised, and consequently lost from the material. The iodine content of the stabilised material is comparable to the iodine content of some seaweed fertilisers, and potentially satisfies an efficient I-fertilisation dose.

Production of polyhydroxyalkanoates in open, mixed cultures from a waste sludge stream containing high levels of soluble organics, nitrogen and phosphorus

Publisher: Elsevier BV

Date: 10-2010

DOI: 10.1016/J.WATRES.2010.06.043

Abstract: In this study, the production of polyhydroxyalkanoates (PHAs) from waste activated sludge (WAS) was evaluated. PHAs were produced from fermented WAS pretreated via high-pressure thermal hydrolysis, a stream characterised by high levels of nutrients (approximately 3.5 g N L(-1) and 0.5 g P L(-1)) and soluble organics. PHA-storing organisms were successfully enriched at high organic loading rates (6 g COD(sol) L(-1) d(-1)) under aerobic dynamic feeding in sequencing batch reactors at a sludge retention time of 6 d with a short feast length less than 20% of the cycle, and a maximum substrate concentration during feast of 1 g COD(VFA) L(-1). The biomass enrichment, characterised by a decrease in species evenness based on Lorenz curves, provided a biomass that accumulated 25% PHA on a dry-biomass basis with yields on VFA of 0.4 Cmol Cmol(-1) in batch tests. The PHA consisted of ∼70 mol% 3-hydroxybutyrate and ∼30 mol% 3-hydroxyvalerate, and presented high thermal stability (T(d) = 283-287 °C) and a molecular mass ranging from 0.7 to 1.0 × 10(6) g mol(-1). Overall PHA storage was comparable to that achieved with other complex substrates however, lower PHA storage rates (0.04-0.05 Cmol PHA(-1) Cmol X(-1) h(-1)) and productivities (3-4 Cmol PHA L(-1) h(-1)) were probably associated with a biomass-growth and high-respiration response induced by high levels of non-VFA organics (40-50% of COD(sol) in feed) and nutrients. PHA production is feasible from pretreated WAS, but the enrichment and accumulation process require further optimisation. A milder WAS pretreatment yielding lower levels of non-VFA organics and readily available nutrients may be more amenable for improved performance.

Phosphorus recovery from wastewater through microbial processes

Publisher: Elsevier BV

Date: 12-2012

DOI: 10.1016/J.COPBIO.2012.08.001

Abstract: Waste streams offer a compelling opportunity to recover phosphorus (P). 15-20% of world demand for phosphate rock could theoretically be satisfied by recovering phosphorus from domestic waste streams alone. For very dilute streams (<10 mg PL(-1)), including domestic wastewater, it is necessary to concentrate phosphorus in order to make recovery and reuse feasible. This review discusses enhanced biological phosphorus removal (EBPR) as a key technology to achieve this. EBPR relies on polyphosphate accumulating organisms (PAOs) to take up phosphorus from waste streams, so concentrating phosphorus in biomass. The P-rich biosolids can be either directly applied to land, or solubilized and phosphorus recovered as a mineral product. Direct application is effective, but the product is bulky and carries contaminant risks that need to be managed. Phosphorus release can be achieved using either thermochemical or biochemical methods, while recovery is generally by precipitation as struvite. We conclude that while EBPR technology is mature, the subsequent phosphorus release and recovery technologies need additional development.

Modelling microalgal activity as a function of inorganic carbon concentration: Accounting for the impact of pH on the bicarbonate system

Publisher: Springer Science and Business Media LLC

Date: 19-10-2014

DOI: 10.1007/S10811-013-0146-9

Biodegradability of plastics: Discussion papers. A joint collaboration between Corrs Chambers Westgarth and The University of Queensland

Publisher: The University of Queensland

Date: 07-2023

DOI: 10.14264/20D45A9

Inhibition by fatty acids during fermentation of pre-treated waste activated sludge

Publisher: Elsevier BV

Date: 05-2012

DOI: 10.1016/J.JBIOTEC.2012.02.001

Abstract: Fermentation of waste activated sludge produces volatile fatty acids (VFAs), which can be used as the carbon sources for numerous biological processes. However, product inhibition can limit extent of fermentation to VFAs. In this study, product inhibition during fermentation of waste activated sludge pre-treated by a thermal hydrolysis process (THP-WAS) was investigated. Product inhibition was confirmed as spiking reactors with high levels of a mix of VFAs prevented fermentation taking place. Various inhibition models were trialled and it was found that a threshold model (based on thermodynamics) provided the best fit between model and data. This is the first time that threshold type inhibition has been shown for a mixed substrate, mixed population system. Batch fermentations carried out with THP-WAS of different dilutions were used to evaluate the impact of different organic loadings. The threshold VFA concentration for the systems studied was determined to be 17±1gCOD(VFA)L(-1). Inhibition was shown to be due to the presence of a combination of VFAs containing 2-6 carbon atoms each. When evaluated in idually, by spiking in idual VFAs, all VFAs except for acetate had the same impact at this threshold acetate being approximately 50% as inhibitory as the other organic acids (COD basis). Based on this, a weighted model could be proposed to better represent the data. Strategies to improve overall yield could be increased production of acetate, or dilution to below the inhibitory level.

Individual and combined effect of salinity and nitrite on freshwater Anammox bacteria (FAB)

Publisher: Elsevier BV

Date: 02-2020

DOI: 10.1016/J.WATRES.2019.114931

Abstract: Anaerobic ammonium oxidation (Anammox) based technology has potential for nitrogen removal from wastewater with high salinity, but both salt and nitrite (a substrate for Anammox) have negative effect on microbial activity. In order to achieve Anammox in saline wastewater treatment, it is essential to understand the combined effect of these two components. In this study, the in idual and combined effect of salinity and nitrite on fixed film freshwater Anammox bacteria (FAB, mainly belonging to the Ca. Brocadia genus), enriched on carriers from a 1500 L pilot scale one-stage (PN/Anammox) moving bed bioreactor (MBBR), were systematically investigated by 57 pre-designed batch tests. The combined inhibition of nitrite and salinity was determined by comparing with additive and independent inhibition models. With salinity only, the specific Anammox activity (SAA) decreased with increasing salinity: 14.6 mS/cm (about 9.1 g NaCl/L) of salinity caused 50% inhibition (IC

Biogas production coupled to repeat microalgae cultivation using a closed nutrient loop

Publisher: Elsevier BV

Date: 09-2018

DOI: 10.1016/J.BIORTECH.2018.05.039

Abstract: Anaerobic digestion is an established technology to produce renewable energy as methane-rich biogas for which microalgae are a suitable substrate. Besides biogas production, anaerobic digestion of microalgae generates an effluent rich in nutrients, so-called digestate, that can be used as a growth medium for microalgal cultures, with the potential for a closed nutrient loop and sustainable bioenergy facility. In this study, the methane potential and nutrient mobilization of the microalga Scenedemus dimorphus was evaluated under continuous conditions. The suitability of using the digestate as culture medium was also evaluated. The results show that S. dimorphus is a suitable substrate for anaerobic digestion with an average methane yield of 199 mL g

Salinity effect on freshwater Anammox bacteria: Ionic stress and ion composition

Publisher: Elsevier BV

Date: 2021

DOI: 10.1016/J.WATRES.2020.116432

Facilitating access to the algal economy: Mapping waste resources to identify suitable locations for algal farms in Queensland

Publisher: Elsevier BV

Date: 05-2014

DOI: 10.1016/J.RESCONREC.2014.01.008

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

Publisher: Elsevier BV

Date: 06-2014

DOI: 10.1016/J.NBT.2013.10.005

Abstract: 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. Two types of materials were tested: two mixed culture PHAs extracted from biomass produced in laboratory and pilot scale after an acidic pre-treatment, and two commercially available materials derived from pure culture production systems. Thermal degradation studies were carried out in a laboratory scale extruder with conical twin screws connected to a NIR spectrometer by a fibre optic to allow in situ monitoring. Multivariate data analysis methods were applied for assessing thermal degradation kinetics and predicted the degree of degradation as measured by (1)H NMR (proton nuclear magnetic resonance spectroscopy). The pre-treated mixed culture PHAs were found to be more thermally stable when compared with the commercial pure culture PHAs as demonstrated by NIR, (1)H NMR and GPC (gel permeation chromatography).

Wood-PHA Composites: Mapping Opportunities

Publisher: MDPI AG

Date: 07-07-2018

DOI: 10.3390/POLYM10070751

Phosphorus Removal Mechanisms in Active Slag Filters Treating Waste Stabilization Pond Effluent

Publisher: American Chemical Society (ACS)

Date: 04-04-2007

DOI: 10.1021/ES062496B

Abstract: Phosphorus (P) removal mechanisms from waste stabilization pond effluent by a melter slag filter were investigated. The studied filter had treated pond effluent for a decade, but lost its P removal efficiency after 5 years. The P distribution in the slag was examined by scanning electron microscopy (SEM), electron dispersive spectrometry (EDS), X-ray fluorescence (XRF), X-ray diffraction (XRD), and chemical fractionation. The results showed the slag to be covered by a film comprising metal oxides/oxyhydroxides, organic resin, and Fe-phosphate precipitates. The slag porous matrix beneath this film hosted lower P concentrations and consisted of metal oxides/oxyhydroxides and calcmagnesium silicates. The study revealed the following mechanisms for P removal from effluent by the melter slag: (1) P adsorption onto metal oxides/oxyhydroxides which are ubiquitous throughout the porous slag matrix and its surface film (2) P precipitation, mainly as Fe-phosphates (determined by SEM/EDS) on the surface film, derived from the release of metal ions into the solution phase and (3) P sequestration by an amorphous organic resin that comprises a substantial proportion of the surface film, which was deduced by SEM/EDS and XRF. Results of chemical extractions performed on the slag demonstrated that 1 M HCl, which has been used to determine Ca-associated P in previous studies, is an unreliable Ca-P marker. By contrast, the citrate-dithionite reagent was shown to be a good indicator of Fe/Al-associated P and revealed that adsorption onto metal oxides/oxyhydroxides, in the porous matrix as well as its surface film, is the most significant P removal mechanism achieved by the slag filter.

Impact of operating history on mixed culture fermentation microbial ecology and product mixture

Publisher: IWA Publishing

Date: 08-2011

DOI: 10.2166/WST.2011.699

Abstract: Mixed culture fermentation is an alternative to pure culture fermentation for production of biofuels and valuable products. A glucose-fed, continuous reactor was operated cyclically to a central pH of 5.5 from a number of precedent pHs, from 4.5 to 7.5. At each pH, stable chemical production was reached after 2 retention times and was held for least 2 further retention times prior to the next change. Bacterial groups were identified by phylogenetic analysis of 16S rRNA gene clones. Bacterial community dynamics were monitored by terminal-restriction fragment length polymorphism. More ethanol was produced at high pH, and more butyrate at lower pH. At pH 5.5, the product spectrum was not measurably influenced by precedent pH but showed seemingly random changes. The impact of precedent pH on community structure was more systematic, with clear indications that when the pH was returned to 5.5, the bacterial group that was dominant at the precedent pH remained at high abundance. This result is important, since it indicates a decoupling between microbial function (as indicated by product spectrum), and community structure. More work is needed to determine the longevity of this hysteresis effect. There was evidence that groups retained their ability to re-emerge even after times of low abundance.

Phosphate release from waste stabilisation pond sludge: significance and fate of polyphosphate

Publisher: IWA Publishing

Date: 04-2011

DOI: 10.2166/WST.2011.336

Abstract: Net phosphorus removal from waste stabilisation pond (WSP) systems is governed by the rate of phosphorus incorporation into the sludge layer and the rate of phosphorus release from this sludge back to the overlying wastewater. Luxury uptake of phosphorus by microalgae has been shown to occur under WSP conditions in the laboratory however, the significance of this mechanism and the fate of polyphosphate contained in the settled solids have not previously been investigated. In this work the analysis of sludge s les from three WSP showed that up to 71% of the total phosphorus in the sludge was in the form of polyphosphate. This indicates that polyphosphate accumulation could potentially be an important mechanism for phosphorus sequestration in WSP and challenges the common view that chemical precipitation is the predominant phosphorus removal mechanism in these systems. The release of phosphate from WSP sludge s les was monitored in the laboratory. The s les from two different pond systems had release rates in the order of 4.3 μgP/gTSS.d. However, the third s le which was collected during an algal bloom had a release rate of 12.4 μgP/gTSS.d. Phosphate release from fresh microalgal sludge grown under laboratory conditions was also studied and was shown to have a release rate of 160 μgP/gTSS.d. Analysis of polyphosphate during the experiments on laboratory grown microalgal sludge showed that polyphosphate was indeed degraded resulting in phosphate release. Interestingly, after the initial release phase phosphorus was assimilated by the biomass and some polyphosphate was reformed. It is likely that this is due to bacterial growth in the sludge.

Downstream processing of reverse osmosis brine: Characterisation of potential scaling compounds

Publisher: Elsevier BV

Date: 09-2015

DOI: 10.1016/J.WATRES.2015.05.004

Abstract: Reverse osmosis (RO) brine produced at a full-scale coal seam gas (CSG) water treatment facility was characterized with spectroscopic and other analytical techniques. A number of potential scalants including silica, calcium, magnesium, sulphates and carbonates, all of which were present in dissolved and non-dissolved forms, were characterized. The presence of spherical particles with a size range of 10-1000 nm and aggregates of 1-10 microns was confirmed by transmission electron microscopy (TEM). Those particulates contained the following metals in decreasing order: K, Si, Sr, Ca, B, Ba, Mg, P, and S. Characterization showed that nearly one-third of the total silicon in the brine was present in the particulates. Further, analysis of the RO brine suggested supersaturation and precipitation of metal carbonates and sulphates during the RO process should take place and could be responsible for subsequently capturing silica in the solid phase. However, the precipitation of crystalline carbonates and sulphates are complex. X-ray diffraction analysis did not confirm the presence of common calcium carbonates or sulphates but instead showed the presence of a suite of complex minerals, to which amorphous silica and/or silica rich compounds could have adhered. A filtration study showed that majority of the siliceous particles were less than 220 nm in size, but could still be potentially captured using a low molecular weight ultrafiltration membrane.

Online titrimetric and off-gas analysis for examining nitrification processes in wastewater treatment

Publisher: Elsevier BV

Date: 06-2003

DOI: 10.1016/S0043-1354(03)00022-8

The Role of Biodegradable Plastic in Solving Plastic Solid Waste Accumulation

Publisher: Elsevier

Date: 2019

DOI: 10.1016/B978-0-12-813140-4.00019-4

Advanced Microscopy of Inorganic Colloids Sampled From Consecutive Stages of RO Filtration

Publisher: Elsevier BV

Date: 03-2017

DOI: 10.1016/J.COLCOM.2017.01.002

Enhanced lipid extraction from algae using free nitrous acid pretreatment

Publisher: Elsevier BV

Date: 05-2014

DOI: 10.1016/J.BIORTECH.2014.01.133

Abstract: Lipid extraction has been identified as a major bottleneck for large-scale algal biodiesel production. In this work free nitrous acid (FNA) is presented as an effective and low cost pretreatment to enhance lipid recovery from algae. Two batch tests, with a range of FNA additions, were conducted to disrupt algal cells prior to lipid extraction by organic solvents. Total accessible lipid content was quantified by the Bligh and Dyer method, and was found to increase with pretreatment time (up to 48 h) and FNA concentration (up to 2.19 mg HNO2-N/L). Hexane extraction was used to study industrially accessible lipids. The mass transfer coefficient (k) for lipid extraction using hexane from algae treated with 2.19 mg HNO2-N/L FNA was found to be dramatically higher than for extraction from untreated algae. Consistent with extraction results, cell disruption analysis indicated the disruption of the cell membrane barrier.

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

Publisher: Elsevier BV

Date: 2016

DOI: 10.1016/J.NBT.2015.07.007

Abstract: The use of mixed microbial cultures for the production of polyhydroxyalkanoates (PHAs) is emerging as a viable technology. In this study, 16S rRNA gene licon 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. The population was observed to cycle through an increase in Zoogloea followed by a return to a community composition similar to the initial one (highly enriched in Flavisolibacter). It was found that the PHA accumulation capacity of the community was robust to population flux during enrichment and even PHA accumulation, with final polymer composition dependent on the overall proportion of acetic to propionic acids in the feed. This community adaptation suggests that mixed culture PHA production is a robust process.

Development and examination of a granular nitrogen-fixing wastewater treatment system

Publisher: Elsevier BV

Date: 05-2007

DOI: 10.1016/J.PROCBIO.2007.02.009

Towards a luxury uptake process via microalgae – Defining the polyphosphate dynamics

Publisher: Elsevier BV

Date: 09-2009

DOI: 10.1016/J.WATRES.2009.06.011

Abstract: Microalgae in waste stabilization ponds (WSP) have been shown to accumulate polyphosphate. This luxury uptake of phosphorus is influenced by the wastewater phosphate concentration, light intensity and temperature, but the dynamics of how these factors affect luxury uptake with respect to time are not understood. With improved understanding of the dynamics of this mechanism and how it could be manipulated, a phosphorus removal process utilizing luxury uptake by microalgae might be developed. In this work, luxury uptake was investigated by chemical extraction of the acid-soluble and acid-insoluble fractions of polyphosphate in the microalgae. The results showed that the initial accumulation and subsequent utilization of both acid-soluble polyphosphate (ASP) and acid-insoluble polyphosphate (AISP) is a function of the wastewater phosphate concentration. It was found that light intensity influenced both the accumulation and utilization of ASP. The temperature influenced the accumulation of AISP. AISP is believed to be a form of phosphorus storage and ASP is involved in metabolism however, the results of this work show that ASP can also act as a short term form of phosphorus storage. To optimize luxury uptake by microalgae a 'luxury uptake pond' is proposed where the conditions the microalgae are exposed to can be manipulated. This 'luxury uptake pond' would be designed to expose the microalgae to a high phosphate concentration and high light intensity for a short period of time in order to achieve optimal polyphosphate accumulation. Subsequent harvesting would then remove the phosphorus rich microalgae from the system.

Integrated biodiesel and biogas production from microalgae: Towards a sustainable closed loop through nutrient recycling

Publisher: Elsevier BV

Date: 02-2018

DOI: 10.1016/J.RSER.2017.09.091

Algal growth and community structure in a mixed-culture system using coal seam gas water as the water source

Publisher: Informa UK Limited

Date: 03-2013

DOI: 10.1080/09593330.2012.715676

Abstract: Coal seam gas (CSG) is being touted as a transition fuel as the world moves towards low-carbon economies. However, the development of CSG reserves will generate enormous volumes of saline water. In this work, we investigate the potential of using this saline water to support mass algae production. Water and brine from a CSG water treatment facility (1.6 and 11.6 g total dissolved solids per litre (TDS L(-1)) respectively) were inoculated with algal biomass from freshwater and seawater environments and supplemented with nutrients in open, fed-batch reactors. Significant algal growth was recorded, with maximum specific growth rates in CSG water and CSG brine of 0.20 +/- 0.05 d(-1) and 0.26 +/- 0.04 d(-1) respectively. These maximum specific growth rates were equal to or greater than specific growth rates in deionized water and seawater diluted to the same salinity. However, algal growth lag time in CSG brine was between 7 and 9 times longer than in other waters. Microscopy and terminal-restriction fragment length polymorphism (T-RFLP) were used to monitor community structure in the reactors. The same few algal species dominated all of the reactors, except for the CSG brine reactor at day 15. This result indicates that conditions in CSG brine select for different species of algae compared to seawater of the same salinity and other waters tested. The findings suggest that mass algae production in CSG water is feasible but algae community composition may be a function of CSG water chemistry. This has implications for the downstream use of algae.

Modelling biological processes under anaerobic conditions through integrating titrimetric and off-gas measurements - Applied to EBPR systems

Publisher: Springer Berlin Heidelberg

Date: 2006

DOI: 10.1007/11758501_28

Mechanical properties of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)/wood flour composites: Effect of interface modifiers

Publisher: Wiley

Date: 27-08-2018

DOI: 10.1002/APP.46828

Public attitudes towards plastics

Publisher: Elsevier BV

Date: 08-2019

DOI: 10.1016/J.RESCONREC.2019.05.005

Thermophilic production of poly(3-hydroxybutyrate-co-3-hydrovalerate) by a mixed methane-utilizing culture

Publisher: Elsevier BV

Date: 11-2019

DOI: 10.1016/J.NBT.2019.06.008

Abstract: The production of polyhydroxyalkanoates (PHAs) from methane is limited to mesophiles and thus suffers from high energy requirements for cooling. To address this issue, the use of thermophilic processes is gaining interest, as this strategy may deliver improved economic feasibility for PHA production. This study reports the first thermophilic PHA-producing culture grown on methane at 55 °C in fill-and-draw batch reactors. Harvested cells were incubated with various combinations of methane, propionic acid and valeric acid to assess their capacity for the synthesis of poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). Only PHB was produced when fed with methane alone. The addition of odd-carbon-number fatty acids resulted in higher PHA content with 3 HV fractions in the range of 15-99 mol%, depending on the types of fatty acids added. Acetic acid addition enhanced the synthesis of 3HB monomer, but not of 3 HV. On increasing the temperature to 58 °C, PHA productivity was not significantly affected.

Waste activated sludge as biomass for production of commercial-grade polyhydroxyalkanoate (PHA)

Publisher: Springer Science and Business Media LLC

Date: 14-10-2013

DOI: 10.1007/S12649-012-9165-Z

Development of a novel titration and off-gas analysis (TOGA) sensor for study of biological processes in wastewater treatment systems

Publisher: Wiley

Date: 18-12-2003

DOI: 10.1002/BIT.10490

Abstract: The development of the new TOGA (titration and off-gas analysis) sensor for the detailed study of biological processes in wastewater treatment systems is outlined. The main innovation of the sensor is the amalgamation of titrimetric and off-gas measurement techniques. The resulting measured signals are: hydrogen ion production rate (HPR), oxygen transfer rate (OTR), nitrogen transfer rate (NTR), and carbon dioxide transfer rate (CTR). While OTR and NTR are applicable to aerobic and anoxic conditions, respectively, HPR and CTR are useful signals under all of the conditions found in biological wastewater treatment systems, namely, aerobic, anoxic and anaerobic. The sensor is therefore a powerful tool for studying the key biological processes under all these conditions. A major benefit from the integration of the titrimetric and off-gas analysis methods is that the acid/base buffering systems, in particular the bicarbonate system, are properly accounted for. Experimental data resulting from the TOGA sensor in aerobic, anoxic, and anaerobic conditions demonstrates the strength of the new sensor. In the aerobic environment, carbon oxidation (using acetate as an ex le carbon source) and nitrification are studied. Both the carbon and ammonia removal rates measured by the sensor compare very well with those obtained from off-line chemical analysis. Further, the aerobic acetate removal process is examined at a fundamental level using the metabolic pathway and stoichiometry established in the literature, whereby the rate of formation of storage products is identified. Under anoxic conditions, the denitrification process is monitored and, again, the measured rate of nitrogen gas transfer (NTR) matches well with the removal of the oxidised nitrogen compounds (measured chemically). In the anaerobic environment, the enhanced biological phosphorus process was investigated. In this case, the measured sensor signals (HPR and CTR) resulting from acetate uptake were used to determine the ratio of the rates of carbon dioxide production by competing groups of microorganisms, which consequently is a measure of the activity of these organisms. The sensor involves the use of expensive equipment such as a mass spectrometer and requires special gases to operate, thus incurring significant capital and operational costs. This makes the sensor more an advanced laboratory tool than an on-line sensor.

Enhanced biological phosphorus removal for high-strength wastewater with a low rbCOD:P ratio

Publisher: Elsevier BV

Date: 03-2008

DOI: 10.1016/J.BIORTECH.2007.02.013

Abstract: In order to assess the feasibility of enhanced biological phosphorus removal (EBPR) for dairy processing wastewater, which in New Zealand have rbCOD:P ratios that can be as low as 13:1, a sequencing batch reactor treating a synthetic wastewater with a COD(VFA) of 800 mg/l (representing a dissolved air flotation (DAF) treated, pre-fermented dairy wastewater with a raw COD of 3000 mg/l) was operated at COD:P ratios of 25:1, 15:1 and 10:1. Full (>99%) phosphate removal was achieved for COD:P loadings of 25:1 and 15:1. The trial using 10:1 COD:P loading showed less consistency but still achieved 82% phosphate removal. Based on further analysis of the final trial this study proposes that the minimum COD:P loading for complete phosphate removal is 13:1 indicating that EBPR could indeed be feasible for effective treatment of dairy processing wastewaters. With regard to the type of COD consumed, propionate was found to be favoured over acetate as a substrate. Further research into increasing the propionate content of pre-fermented dairy wastewaters is suggested.

University Of Queensland

Location: Australia

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Next Generation Bioplastics: Production Of Polyhydroxyalkanoate (PHA) Bioplastics From Organic Waste

Start Date: 2009

End Date: 2012

Funder: Australian Research Council

Adsorption On Activated Alumina: Mitigating Fouling Of Water Treatment Processes Caused By Deposition Of Silica, Organics And Hardness Ions

Start Date: 2012

End Date: 2014

Funder: Australian Research Council

Efficient CO And CO2 Conversion To Biopolymers Using Phototrophic Bacteria

Start Date: 2019

End Date: 2021

Funder: Australian Research Council

Tough Bio-derived And Biodegradable Wood Plastic Composites

Start Date: 2017

End Date: 2019

Funder: Australian Research Council

Stabilisation Of Algal Biomass Harvested From Coal Seam Gas Associated Water To Generate A Renewable, High Nutrient Resource

Start Date: 2012

End Date: 2014

Funder: Australian Research Council

Intracellular Manufacturing: High Performance Biomaterials From Methane

Start Date: 2015

End Date: 2017

Funder: Australian Research Council

Bioderived And Biodegradable Wood Plastic Composites From Wastes

Start Date: 2014

End Date: 2017

Funder: Australian Research Council

Mitigation Of Silica Nanoparticle Scaling In Water Treatment

Start Date: 2016

End Date: 2018

Funder: Australian Research Council

Linkage Projects - Grant ID: LP120100664

Start Date: 11-2012

End Date: 12-2016

Amount: $166,953.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0990917

Start Date: 06-2010

End Date: 12-2013

Amount: $525,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP200101144

Start Date: 02-2020

End Date: 12-2023

Amount: $330,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP160101294

Start Date: 09-2017

End Date: 09-2023

Amount: $450,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP200200965

Start Date: 09-2021

End Date: 09-2024

Amount: $366,516.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP140100596

Start Date: 12-2014

End Date: 12-2017

Amount: $343,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP150103060

Start Date: 2015

End Date: 12-2018

Amount: $414,300.00

Funder: Australian Research Council

Industrial Transformation Training Centres - Grant ID: IC210100023

Start Date: 07-2022

End Date: 07-2027

Amount: $4,943,949.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP120100670

Start Date: 11-2012

End Date: 11-2015

Amount: $118,700.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP190102979

Start Date: 02-2019

End Date: 12-2023

Amount: $408,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP160101763

Start Date: 12-2017

End Date: 03-2021

Amount: $173,000.00

Funder: Australian Research Council