Marion completed her PhD in the area of environmental sciences at the University of Geneva (Switzerland) in February 2008, under the supervision of Prof. J. Dominik and Dr B. Ferrari. Her doctoral research focused on freshwater macrophytes and their interaction with trace metals, in particular, the optimised methodology of exposure in order to describe their biological accessibility (bioavailability), uptake and toxicity. On completing her PhD, she then gained a Swiss National Science Foundation Postdoctoral Fellowship to continue her research here at the Water Research Centre.

Research Interests

Marion’s research focuses on understanding the complex interplay between chemical and biological mechanisms under various pollution conditions in marine and freshwater ecosystems. Her research investigates the relationship between the water environment and the biology of photosynthetic organisms.

She is currently focussing on the implication of nutrients (nitrogen, phosphorus) and metals (iron, copper, zinc) in the formation of harmful algal blooms (HAB) and the mechanism of ichthyoxicity through reactive oxygen species (ROS) generation. The three Australian algal species selected for this studie are: Chattonella marina, Gymnodinium catenatum and Karlodinium veneficum.

Her research objectives are contributing to the ARC project (Impact of ROS on the toxicity of marine algae) and involve strong collaborative relationships with external people:

i)     The culturing of potentially HAB species; forming microalgae under nutrient replete or deplete conditions including the organisation of field trips with Dr C. Hassler from the University of Technology, Sydney.

ii)    Assessment of ROS production from harmful algal species; using the advanced methodologies of, and collaborating with, Dr A. Rose from Southern Cross University, Lismore.

iii)   Developing a method to assess the toxicity of these microalgae to fish gill cells, in close collaboration with Prof G. Hallegraeff and his PhD student J. Dorantes from the University of Tasmania.

Publications

Minouflet M, Hassler C, Rose A, Waite TD, in prep., Formation of harmful algal blooms in marine natural waters in NSW: Nutrient requirements and assessment of their toxicity.

Minouflet M, Ferrari B, Dominik J, in prep., Metals bioaccumulation and their effects in aquatic macrophytes: a review.

Minouflet M, Ferrari B, Dominik J, in prep., Influence of the metal contamination design on the bioavailability assessment in aquatic macrophytes: recommendations.

Minouflet M, Ferrari B, Dominik J, in prep., Metals bioaccumulation and their effects on performance index of PSII in Elodea nuttallii.

Minouflet M, 2008, Thèse de doctorat de l’Université de Genève, Journal Terre et Environnement, 298 p.

Minouflet M, Ayrault S, Badot PM, Cotelle S, Ferard JF, 2005, Assessment of the genotoxicity of 137Cs radiation using Vicia-micronucleus, Tradescantia-micronucleus and Tradescantia-stamen-hair mutation bioassays, Journal of Environmental Radioactivity, 81(2-3), 143-153.

Vignati DAL, Dworak T, Ferrari B, Koukal B, Loizeau JL, Minouflet M, Camusso MI, Polesello S, Dominik J, 2005, Assessment of the geochemical role of colloids and their impact on contaminant toxicity in freshwater: An example from the Lambro-Po system (Italy) Environmental Science and Technology, 39(2), 489-497.

Chris is undertaking a PhD in Environmental Engineering titled “The transformation and implication of reactive oxygen species in natural aquatic systems” which is exploring the mechanisms of production of reactive oxygen species (ROS) in natural environments by both biololgically mediated and abiotic processes and also the significance of these processes to natural systems, with a specific emphasis to the importance of some algae. Chris’ undergraduate qualifications include a B.E. (Environmental) and B.Sc. (Chemistry) obtained from UNSW in 2008.

Research Interests     

·   The development and application of chemiluminescent methods for quantitative determination of reactive oxygen species in complicated matrices with particular emphasis to the use of such methods in the presence of algae.

·   Utilisation of computational kinetic modelling as a tool to obtain a more quantitative understanding of fundamental processes occurring in complex, interrelated systems.

·   Examination of processes leading to production of reactive oxygen species, particularly hydroxyl radical and singlet state dioxygen, under conditions representative of natural environments with particular emphasis on the interplay between pure chemical processes and processes mediated by an organism such as an alga.

·   Examination of the fate of hydroxyl radicals in natural systems, what are the key reactions and how do these transformations impact the final reactivity of the major species formed? What are the consequences and significance of these processes?

Publications

Miller C. J., Rose A. L. and Waite T. D. (2009) Impact of natural organic matter on H₂O₂-mediated oxidation of Fe(II) in a simulated freshwater system. Geochim. Cosmochim. Acta 73, 2758-2768.

Yongjia Xin obtained his Master of Engineering Science (in water and wastewater treatment) at the University of New South Wales in 2008, and worked at WLK Engineering LTD before PhD study. Earlier in 2006, Yongjia completed bachelor’s Degree of Engineering (in water supply and sewerage work) from Jinan University, China. His PhD research area is related to membrane fouling control, and he is currenly working on scale formation and its prevention in Indigenous community water supplies.

Research interests

·        Nature and extent of the problem of scaling in water supply systems

·        The most appropriate approach to minimize scaling

·        Measuring properties of the scale

Project Team: Andrew Kinsela, in collaboration with Mike Melville (UNSW - Biological, Earth & Environmental Sciences), Ian White and Ben Macdonald (ANU), and cane farmer Robert Quirk. Funding was provided for this project by the Sugarcane Research and Development Corporation with support from Tweed Shire Council.

Annual acid drainage discharges from coastal acid sulfate soils (ASS), in NSW alone, have been estimated to be at least equivalent to 75,000 tonnes of sulfuric acid and contain high concentrations of sulfide oxidation- and acid leaching-products, particularly aluminium and iron, resulting in fish kills and other environmental and infrastructure damage (White et al., 1997). Constructed wetlands, which have been successfully used in the treatment of acid rock drainage, offer one possible broad-acre management option for reducing the concentration of dissolved metals, protonic acidity and downstream ecological risks for the treatment of these ASS discharges. As such, the principal objectives of this collaborative project were to:

1.   Construct a wetland to reduce drainage discharges of sediment, nutrients, acidity, and dissolved metals.

2.   Examine the potential incorporation of the technology in Australian sugar industry best practice guidelines for treating discharge water. 

Wetland outlet pipe returning the treated water to the farm drainage network

A bunded 1.44 ha freshwater wetland was constructed at McLeods Creek on the NSW far north coast of the Tweed River floodplain. It was designed to treat ~10% of the drainage from a 100 ha hydraulically-isolated floodplain area under sugarcane cultivation. The wetland was laser-levelled into 6 terraced bays with an overall hydraulic gradient of 0.13%. Water retention time varied between 19 and 82 days, dependent on the prevailing evapotranspiration rate (Quirk et al., 2009). The wetland was designed to treat the most highly acidic groundwater-dominated recession phase of drainage with large concentrations of dissolved aluminium, iron and manganese. Common couch grass (Cynodon dactylon) and Eleocharis reeds were established in the wetland by natural recruitment.

The underlying principles underpinning the effectiveness of the wetland were that generally oxic conditions were expected to prevail close to the inlet of the wetland due to pumping from the inlet drain which would favour the precipitation of iron oxyhydroxides and the release of additional protons.

Fe²⁺ + 1.5 H₂O + 0.25 O₂ –> FeOOH_(s) + 2 H⁺

As water proceeds through the wetland it is expected that the wetland is essentially titrating the discharge with organic matter, so that redox potentials and DO levels should fall eventually resulting in the reduction of sulfate to sulfide, the reduction of FeOOH to Fe2+, the consumption of protonic acidity and the  precipitation of iron sulfides.

4 FeOOH_(s) + 4 SO₄^2- + 9 CH₂O + 8 H⁺ –> FeS_(s) + 9 CO₂ + 15 H₂O

The rise in pH following the consumption of protonic acidity leads to the precipitation of aluminium and other dissolved metals. As well, it implies that the large amount of carbon dioxide produced by the oxidation of organic matter should be present as bicarbonate.

Formation of iron oxide flocs in the wetland sediment

The wetland was clearly successful in treating acid drainage, improving water quality by increasing the pH up to 3 units, as well as decreasing the total actual- and total potential acidity. The wetland also achieved large reductions in metal loads (including aluminium). However, owing to climatic variations, even in high rainfall environments (> 1600mm), maintaining an adequate freshwater level in the wetland proved difficult. In dry periods, drain water is too saline (> 8mS/cm) to be applied to the wetland which results in the drying of sediments and oxidation of deposited sulfides and caused enhanced acidification. 

Neutralisation of discharge water pH as it moves through the wetland

Despite the improvement in drainage water quality, such constructed wetlands, requiring up to 20% of the available cane farm, are impracticable in the treatment of sugarcane ASS discharges. However, lessons which can be applied to in-drain management have been learned. One example is the benefit of vegetative growth in (particularly shallower) drainage channels. This vegetation, which is often seen as deleterious to flow regimes, would provide minimal obstruction during high-runoff events, whilst adding some of the environmental benefits observed from our wetland study.

Further Reading

Quirk R, Melville M, Kinsela A, Reynolds J, Zwemer T, Hancock M, Macdonald B & White I (2009) Treatment of drainage from acidic canelands using a constructed wetland. Sugar Tech 11(1), 73-76.

White I, Melville MD, Wilson BP Sammut J (1997) Reducing acid discharge from estuarine wetlands in eastern Australia. Wetlands Ecology and Management 5: 55-72.

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Tian obtained her Masters Degree in Environmental Engineering (specialising in environmental monitoring and instrument analysis) at Sichuan University, China, in 2004. Subsequent to this she worked as a research associate at the National Institute of Measurement and Testing Technology, Chengdu, before beginning her PhD at UNSW in February 2009. Her thesis relates to the application of zero valent silver nanoparticles in water disinfection.

Research Interests

·     Examination of the biocidal effects of zero valent silver (Ag⁰) nanoparticle suspensions exhibiting different morphological and physical characteristics.

·     Determination of the antibacterial mechanism of Ag⁰.

·     To investigate the possible methods of integrating the bactericidal effects of Ag⁰ into current water treatment procedures.

Publications

TAN He-ping, FANG Zheng, MA Tian, ZENG Lingping, 2008. “A Method for Quick Determination of Formaldehyde in Indoor Air”, Acta Metrologica Sinica, Vol.29, No.2, p.182-185.

TAN He-ping, SUN Deng-feng, SHI Xie-fei, MA Tian, FANG Zheng, DAN De-zhong, 2007.  “IVHOCs Determination by Whole Sampling Gas Chromatography”, Industrial Measurement, Vol.17, No.2, p.8-12.

MA Tian, FANG Zheng, GUAN Sheng, DAN De-zhong, TAN He-ping, 2007. “Study on method of quick determination of indoor VOC using VOC detector”, China Measurement Technology, Vol.33, No.1, p.29-33.

TAN He-ping, SUN Deng-feng, FANG Zheng, MA Tian, 2007. “Preparation of 16 hazardous VOCs standard mixture”, China Measurement Technology, Vol.33, No.1, p.1-4.

TAN He-Ping, SUN Deng-Feng, SHI Xie-fei, MA Tian, 2006. “Formaldehyde in indoor air determined by canister sampling-GC/MS method”, China Measurement Technology, Vol.32, No.6, p.1-4.

SUN Deng-feng, FANG Zheng, MA Tian, TAN He-ping, 2006. “Study on Measurement and Testing Properties of Formaldehyde Detector”, China Measurement Technology, Vol.32, No.6, p.26-28,38.

He-ping Tan, Tian Ma*, Zheng Fang, Deng-feng Sun, 2006.  “Study on the limit standard for indoor hazardous volatile organic gas”, China Measurement Technology, Vol.32, No.5, p.8-15. (* corresponding author)

He-ping Tan, Tian Ma, Deng-feng Sun, Zhen-wei Xie, Zheng Fang, De-zhong Dan, 2006.  “Study on the Technique for Quick Determination and Whole Sampling of VOC in Indoor Air”, China Measurement Technology, Vol.32, No.1, p.1-4.

Tian Ma, Yu-jie Wang, Dian Hao, Sheng Guan, De-zhong Dan, Bin Wang, 2003.  “Ecological Monitoring and Its Development in China”, Sichuan Environment, Vol.22, No.2, p.19-24, 34.

Dian Hao, Sheng Guan, Tian Ma, Yu-jie Wang, Dong Yuan, De-zhong Dan, 2002.  “Study on Acidity Determination by Automatic Coulometric Titration”, Chemical Sensors, Vo.22, No.3, p.27-32.

Fouling Control in Hybrid Membranes

Project Team: David Waite in collaboration with Xiaomao Wang (University of Hong Kong), Xianghua Wen & Xia Huang (Tsinghua University)

The submerged hollow fibre membrane bioreactor (SHFMBR) is one of the most rapidly growing technologies for wastewater treatment and reuse. However, the major factor constraining SHFMBR performance and its application is that of fouling. Most published literature suggests that extracellular polymeric substances (EPS) in the mixed liquor are responsible for membrane fouling in SHFMBR under bubbling and controlled flux conditions. One approach to reducing the impact of EPS is to add an agent such as iron oxide or activated carbon which will adsorb the EPS and prevent it fouling the membrane. While the use of such hybrid submerged hollow fibre membrane bioreactor systems is attractive, very little investigation of the hydraulic behaviour of the composite (adsorbent/EPS/bacteria) fouling layer has been undertaken nor have operating conditions been optimised.

This collaborative project specifically aims to;

1)    improve our understanding of the factors controlling membrane fouling in hybrid SHFMBR systems for wastewater treatment through complementary theoretical and experimental studies in which interrelationships between membrane fouling, extracellular polymeric substance (EPS) properties and biological and physicochemical process parameters will be established;

2)    investigate and model the structure and transport characteristics of the composite layer formed on the membrane surface through rigorous simulation and advanced image morphological processing and, in so doing, develop a rigorous approach to describe the relationship between structure parameters and transport mechanism within the composite layer; and

3)    apply the above findings to optimization of design and operation of membrane processes in large scale hybrid SHFMBR systems.

Collaboration with our Chinese partners on the project facilitated the establishment of a laboratory-scale SHFMBR system here at UNSW. Data from these well-defined operating and system conditions was then collated for the development of advanced modelling studies, which was subsequently applied to the larger-scale SHFMBR in Tsinghua University.

Further Reading

Wang X. & Waite T.D. (2008) Gel layer formation and hollow fiber membrane filterability of polysaccharide dispersions. Journal of Membrane Science 322; 204-213.

Wang X. & Waite T.D. (2008) Impact of gel layer formation on colloid retention in membrane filtration processes. Journal of Membrane Science 325; 486-494.

Waite T.D. & Santiwong S.R. (2006) Membrane fouling in water treatment: effect of solution composition on resistance and compressibility of gel-forming filter cakes. Water Science and Technology: Water Supply 6; 157-164.

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Reactivity and Fate of Silver Nanoparticles

Project Team: Adele Jones, An Ninh Pham, Shikha Garg & David Waite

Silver has been widely used as a bactericide in the biomedical, biological and pharmaceutical industries.  Although the effect of silver nanoparticles on microorganisms has been widely studied, to date the toxic mechanism has only been inferred, with identification of the actual toxic species involved largely unknown. The bactericidal properties of elemental silver (Ag^o) appear to be enhanced when present as nanosized particles, and the supposition that reactive oxygen species are the key antimicrobial agents in nanoparticulate silver provides the focus of this research.  

While the potential uses for Ag^o and Ag^o/TiO₂ composites in disinfection and detoxification of waters appears exciting, too little information on either the reaction mechanism or on the optimal conditions of use is available to render this a viable technology at present. Indeed, whilst indirect evidence regarding the formation of reactive oxygen species by nanoparticulate silver exists, an identification of the actual toxic species involved remains unidentified.

The aim of our current efforts is this area are therefore to investigate i) the mechanism underlying the bactericidal abilities of Ag^o and Ag^o composites (including Ag^o/TiO₂, and ii) the optimal conditions of use of Ag^o and Ag^o composites for the disinfection of waters and wastewaters be implemented. The following key aspects of this study include:

1.  Preparation and characterisation of nanosized zerovalent silver (Ag^o) particles

2.  Examination of production of reactive oxygen species by Ag^o particles

3.  Examination of the bactericidal properties of Ag^o particles

4.  Review of composite assemblages that enhance Ag^o activity (including Ag^o/TiO₂ composites)

5.  Preparation and characterisation of preferred Ag^o composites

6.  Examination of the bactericidal properties of Ag^o composites under dark and light conditions

7.  Examination of contaminant degradation by Ag^o and Ag^o composites under dark and light conditions

Further Reading

Ratte, H. T. 1999. Bioaccumulation and toxicity of silver compounds: A review. Environmental Toxicology and Chemistry, 18, 89-108.

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Before beginning his PhD at UNSW in March 2009, Cuong obtained his Masters of Engineering from the National University of Singapore with a thesis examining the behaviour of heavy metals in Singaporean marine waters. During this time, Cuong worked on several different projects looking at the speciation and modelling of heavy metal and micro-nutrient pollutants in sediments and run-off waters. Prior to this Cuong was awarded a Bachelor of Engineering with 1st class honours in wastewater treatment systems from the Ho Chi Minh City University of Technology. Cuong’s PhD research area relates to iron transformation dynamics on uptake kinetics of Microcystis and Anabaena species in Sydney water supply reservoirs.

Research Interests 

·   Iron transformation dynamics in freshwater algae

·   Marine water quality management relating to heavy metal contamination

Publications

Journal Papers

Dang The CUONG, Subramanian KARUPPIAH, Jeffrey Philip OBBARD. Distribution of Heavy Metals in the Dissolved and Suspended Phase of the Sea-Surface Microlayer, Seawater Column and in Sediments of Singapore’s Coastal Environment. Environmental Monitoring and Assessment 138 (2008): 255-272.

Dang The CUONG, Jeffrey Philip OBBARD. Metal Speciation in Coastal Marine Sediments from Singapore using a Modified BCR-Sequential Extraction Procedure. Applied Geochemistry 21 (2006): 1335-1346.

Dang The CUONG, Stéphane BAYEN, Oliver WURL, Subramanian KARUPPIAH, Kelvin Kae Shing WONG, N. SIVASOTHI, Jeffrey Philip OBBARD. Heavy metal contamination in mangrove habitats of Singapore. Marine Pollution Bulletin, 50 (2005): 1713-1744.

Conference Papers

Dang The CUONG, Jeffrey Philip OBBARD. Phosphorus Fractionation in Marine Sediments, Singapore Using a Fractionation Extraction Procedure. The 23rd Annual International Conference on Soils, Sediments and Water, USA (October 15-18th, 2007).

Dang The CUONG, Jeffrey Philip OBBARD. Fractionation of Heavy Metals in Marine Sediments of Singapore Using the Modified BCR-Sequential Extraction Procedure – The 5th International Conference on Marine Pollution and Eco-toxicology, Hong Kong, (June 4-6th, 2007).

Dang The CUONG, Jeffrey Philip OBBARD. Heavy Metals in the Seawater Column and Sediments in the Coastal Environment of Singapore – The 3rd HAS-NUS Annual Scientific Seminar, Singapore (May 11th, 2005).

Dang The CUONG, Stéphane BAYEN, Oliver WURL, Subramanian KARUPPIAH, Kelvin Kae Shing WONG, N. SIVASOTHI, Jeffrey Philip OBBARD. Heavy Metal Contamination in Mangrove Habitats of Singapore – The 4th Asia Pacific Symposium on Environmental Geochemistry (APSEG4) – Perth, Australia (January 16th – 20th, 2005).

Daniel completed a Bachelor of Engineering (Environmental Engineering) with first class honours and a Bachelor of Arts (Japanese) at the University of Western Australia in 2009. He started his PhD project, Molecular scale mechanisms that contribute to the fate of uranium during iron oxide crystallization in July 2009 at the University of NSW.

·  The fate of uranium during iron oxide crystallization : Is it possible that uranium may be immobilized in this process? What is the effect of additional ubiquitous environmental species in this process, e.g. silicate?

·  The use of synchrotron radiation to determine crystal structure

·  Mineral transformations in acid sulfate soils

Publications

Boland DD, RN Collins, AM Jones, TE Payne and TD Waite (2009) Investigating the fate of U(VI) during the Fe(II)-catalysed transformation of Fe(III) minerals with X-ray absorption spectroscopy.  Proceedings of 16th AINSE Conference on Nuclear and Complementary Techniques of Analysis, Lucas Heights, Australia, November 2009 (accepted 09/2009).