Publications by authors named "Christopher Saint"

51 Publications

Stormwater monitoring using on-line UV-Vis spectroscopy.

Environ Sci Pollut Res Int 2021 Oct 31. Epub 2021 Oct 31.

Scarce Resources and Circular Economy (ScaRCE), UniSA STEM, University of South Australia, Adelaide, SA, 5095, Australia.

Stormwater runoff contains a myriad of pollutants, including faecal microbes, and can pose a threat to urban water supplies, impacting both economic development and public health. Therefore, it is a necessity to implement a real-time hazard detection system that can collect a substantial amount of data, assisting water authorities to develop preventive strategies to ensure the control of hazards entering drinking water sources. An on-line UV-Vis spectrophotometer was applied in the field to collect real-time continuous data for various water quality parameters (nitrate, DOC, turbidity and total suspended solids) during three storm events in Mannum, Adelaide, Australia. This study demonstrated that the trends for on-line and comparative laboratory-analysed samples were complimentary through the events. Nitrate and DOC showed a negative correlation with water level, while turbidity and total suspended solids indicated a positive correlation with water level during the high rainfall intensity. The correlations among nitrate, DOC, turbidity, total suspended solids and water level are the opposite during low rainfall intensity. Nitrate, one of the main pollutants in stormwater, was investigated and used as a surrogate parameter for microbial detection. However, the microbiological data (Escherichia coli) from captured storm events showed poor correlations to nitrate and other typical on-line parameters in this study. This is possibly explained by the nature of the stormwater catchment outside of rain events, where the sources of bacteria and nutrients may be physically separated until mixed during surface runoff as a result of rainfall. In addition, the poor correlations among the microbiological data and on-line parameters could be due to the different sources of bacteria and nutrients that were transported to the stormwater drain where sampling and measurement were conducted.
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http://dx.doi.org/10.1007/s11356-021-17056-7DOI Listing
October 2021

Carbon sequestration value of biosolids applied to soil: A global meta-analysis.

J Environ Manage 2021 Apr 30;284:112008. Epub 2021 Jan 30.

Department of Agronomy, Throckmorton Plant Sciences Center, Kansas State University, Manhattan, KS, 66506-5501, United States.

Biosolids produced at wastewater treatment facilities are extensively used in agricultural land and degraded mine sites to improve soil health and soil organic carbon (SOC) stocks. Many studies have reported increases in SOC due to application of biosolids to such sites. However, lack of a comprehensive quantification on overall trends and changes of magnitude in SOC remains. Here, we performed a meta-analysis to identify drivers with a relationship with SOC stocks. A meta-regression of 297 treatments found four variables with a relationship with SOC stocks: cumulative biosolids carbon (C) input rate, time after application, soil depth and type of biosolids. The cumulative biosolids C input rate was the most influencing driver. The highest mean difference for SOC% of 3.3 was observed at 0-15 cm soil depth for a cumulative C input of 100 Mg ha at one year after biosolids application. Although years after biosolids application demonstrated a negative relationship with SOC stocks, mineralization of C in biosolids-applied soils is slow, as indicated with the SOC% decrease from 4.6 to 2.8 at 0-15 cm soil depth over five years of 100 Mg ha biosolids C input. Soil depth illustrated a strong negative effect with SOC stocks decreasing by 2.7% at 0-15 cm soil depth at a cumulative biosolids C input of 100 Mg ha over a year. Overall, our model estimated an effect of 2.8 SOC% change, indicating the application of biosolids as a viable strategy for soil C sequestration on a global scale.
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http://dx.doi.org/10.1016/j.jenvman.2021.112008DOI Listing
April 2021

Aquatic Phytotoxicity to Lemna minor of Three Commonly Used Drugs of Addiction in Australia.

Bull Environ Contam Toxicol 2019 Nov 3;103(5):710-716. Epub 2019 Sep 3.

Natural and Built Environments Research Centre, School of Natural and Built Environments, University of South Australia, Mawson Lakes, SA, 5095, Australia.

The manufacturing and consumption of drugs of addiction has increased globally and their widespread occurrence in the environment is an emerging concern. This study evaluated the phytotoxicity of three compounds: methamphetamine, codeine and morphine; commonly reported in Australian urban water, to the aquatic plant Lemna minor under controlled conditions. L. minor was sensitive to lower drug concentrations when administered in multi-compound mixtures (100-500 µg L) than when applied individually (range 600-2500 µg L), while no adverse effects were observed at environmentally-relevant concentrations (1-5 µg L) detected in wastewater effluent. In conclusion, the results show that the concentrations of these compounds discharged into the environment are unlikely to pose adverse phytotoxic effects. These three compounds are known to be the most stable of their group under such conditions indicating that with this respect it is safe to use recycled water for existing regulated reclaimed purposes including agricultural or parklands irrigation or replenishing surface and groundwater. However, more research on the analysis of methamphetamines and opiates in municipal effluents is needed to reassure the likely environmental hazard of these neuroactive drug classes to aquatic organisms. Given the ever-growing production and aquatic disposal of discharge wastewater globally, this study provides timely and valuable insights into the likely drug-related impacts of effluent disposal on aquatic plants in receiving environments.
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http://dx.doi.org/10.1007/s00128-019-02708-9DOI Listing
November 2019

Transformation pathway and toxicity assessment of malathion in aqueous solution during UV photolysis and photocatalysis.

Chemosphere 2019 Nov 12;234:204-214. Epub 2019 Jun 12.

Natural and Built Environments Research Centre, University of South Australia, Mawson Lakes Campus, SA, 5095, Australia.

In drinking water treatment, complete mineralization of organophosphorus pesticides (OPPs) by UV-based advanced oxidation processes (UV AOPs) is rarely achieved. The formation of intermediate oxidation byproducts would likely have some profound effects on toxicity of the reaction solutions. This study investigated the intermediate oxidation byproducts, transformation pathway and toxicity of malathion solutions during the treatment processes of UV alone, UV/HO, UV/TiO and UV/Fenton. The main intermediate oxidation byproducts were derived using ultra-performance liquid chromatography - electrospray - time-of-flight mass spectrometry. Thereby the transformation pathway for each of these treatment processes was proposed. The results indicate that in UV photolysis, the transformation pathway of malathion proceeded initially via cleavage of the phosphorus-sulfur bonds while in photocatalysis, the desulfurization from a PS bond to a PO bond was the primary degradation pathway. Interestingly, only in the UV/TiO process a small fraction of malathion was found decomposed via a demethylation reaction. At the same time, a toxicity assessment of the treated solutions was conducted by both luminescence inhibition of Vibrio fischeri and inhibition of acetylcholinesterase (AChE). It was found that after UV AOP treatment, the toxicity of the malathion aqueous solution increased sharply. In contrast, no increase in toxicity was observed for the malathion aqueous solution after UV alone treatment. This study demonstrates that the high removal efficiency achieved by OPPs does not imply that detoxification of the water solution has been achieved. On the contrary, the toxicity of the treated solutions by OPPs may be increased significantly depending on the selected treatment processes.
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http://dx.doi.org/10.1016/j.chemosphere.2019.06.058DOI Listing
November 2019

Label-Free Bacterial Toxin Detection in Water Supplies Using Porous Silicon Nanochannel Sensors.

ACS Sens 2019 06 17;4(6):1515-1523. Epub 2019 Jun 17.

Future Industries Institute , University of South Australia , Mawson Lakes , South Australia 5095 , Australia.

Lipopolysaccharides (LPS) are the major component of the outer membrane of all Gram-negative bacteria and some cyanobacteria and are released during growth and cell death. LPS pose a potential health risk in water, causing acute respiratory illnesses, inhalation fever, and gastrointestinal disorders. The need for rapid and accurate detection of LPS has become a major priority to facilitate more timely and efficacious intervention and, hence, avoid unsafe water distribution. In this context, a porous silicon membrane (pSiM)-based electrochemical biosensor was developed for direct and sensitive detection of LPS. pSiM, featuring arrays of nanochannels, was modified with polymyxin B (PmB), an antimicrobial peptide with strong affinity to LPS. Detection of LPS was based on measuring the changes in the diffusion through the nanochannels of an electroactive species added in solution, caused by the nanochannel blockage upon LPS binding to PmB. Results showed a limit of detection of 1.8 ng/mL, and a linear response up to 10,000 ng/mL spiked in buffer. Selectivity of the sensor toward potential interfering species in water supplies was also assessed. Sensor performance was then evaluated in water samples from a water treatment plant (WTP), and detection of LPS well below the levels encountered in episodes of water contamination and in humidifiers was demonstrated. The same platform was also tested for bacterial detection including Pseudomonas aeruginosa and Escherichia coli spiked in water samples from a WTP. Considering its performance characteristics, this platform represents a promising screening tool to identify the presence of LPS in water supplies and provide early warning of contamination events.
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http://dx.doi.org/10.1021/acssensors.8b01670DOI Listing
June 2019

Removal of emerging drugs of addiction by wastewater treatment and water recycling processes and impacts on effluent-associated environmental risk.

Sci Total Environ 2019 Aug 7;680:13-22. Epub 2019 May 7.

Natural and Built Environments Research Centre, School of Natural and Built Environments, University of South Australia, Mawson Lakes, SA 5095, Australia; Future Industries Institute, University of South Australia, Mawson Lakes, SA 5095, Australia; Division of Information Technology, Engineering and the Environment, University of South Australia, Mawson Lakes, SA 5095, Australia. Electronic address:

Drugs of addiction, have been recognized as potential contaminants of concern to the environment. Effluent wastewater discharge is a major source of contamination to aquatic receiving environments. A year-long monitoring program was undertaken in Australia to characterise the fate of four emerging drugs of addiction: methamphetamine; MDMA; pharmaceutical opioids: codeine and morphine and a metabolite: benzoylecgonine in four wastewater treatment plants operating with different secondary treatment technologies: conventional activated sludge (CAS), membrane bioreactors (MBR), integrated fixed-film AS (IFAS) and sequencing batch reactor (SBR). The effect of subsequent tertiary treatment (coagulation/flocculation) on the removal efficiency was also assessed. Drugs were detected in influent and effluent samples (mean concentration ranged from 43-4777 and 17-1721 ng/L, respectively). Treated effluents had noticeably lower levels compared to raw influents. Removal efficiency of compounds depended on the secondary treatment employed, with IFAS and MBR performing the best with significant removal of compounds (≈90%) followed by CAS (54-96%) and lastly SBR (42-83%). Despite the low levels of drugs measured after the secondary treatment, near complete removal after tertiary treatment (≈99%) was recorded, which demonstrated the effectiveness of using the coagulation/flocculation process as an effective step for enhancing the removal efficiency. The levels of drugs were at a low level in the effluents released into the environment and used for recycling and all posed a low environmental risk in urban water courses based on the risk assessment. The information given here provides new and useful information to the water industry and regulators on the efficiency of drug removal in a range of wastewater treatment configurations.
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http://dx.doi.org/10.1016/j.scitotenv.2019.05.068DOI Listing
August 2019

Assessment of chromium hyper-accumulative behaviour using biochemical analytical techniques of greenhouse cultivated Sonchus asper on tannery waste dump site soils.

Environ Sci Pollut Res Int 2018 Sep 14;25(27):26992-26999. Epub 2018 Jul 14.

Natural and Built Environments Research Centre, Division of Information Technology, Engineering and the Environment, University of South Australia, Adelaide, SA, 5095, Australia.

Keeping the sources of pollution such as chromium (Cr) under a safe limit is a daunting challenge due to the negative impact of heavy metal bioaccumulation in vegetation and the concomitant human health exposure. We took a closer look at Sonchus asper by cultivating in the green house. It resulted in 80% germination when cultivated over nine different soils collected from the tannery dump site. The biochemical analytical techniques such as mass spectrometry indicated significant bioaccumulation of Cr in the plant tissue. As per the ICP-MS analysis, this annual herb resulted in the accumulation of 601 mg kg of total Cr with 212 mg kg in its shoot from soil samples containing up to 41 mg kg of hexavalent Cr. The energy dispersive X-ray (EDX) spectroscopy of S. asper revealed a higher level of S element indicating a sulfate-Cr binding relation. Elevated content of Cr in soil (73,721 ± 65 mg kg) caused biochemical changes in the shoot of S. asper as indicated by the disappearance of Fourier transform infrared spectroscopy (FTIR) bands at 935 and 872 cm and further revealing aliphatic -CH appearing as anti-symmetry ν(CH) and symmetric vibration ν(CH) at the band of 2920 and 2850 cm, respectively.
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http://dx.doi.org/10.1007/s11356-018-2740-5DOI Listing
September 2018

Electrochemical Biosensing of Algal Toxins in Water: The Current State-of-the-Art.

ACS Sens 2018 07 18;3(7):1233-1245. Epub 2018 Jul 18.

Research Centre for Water Environment Technology, Department of Urban Engineering , The University of Tokyo , Tokyo 113-0033 , Japan.

Due to increasing stringency of water legislation and extreme consequences that failure to detect some contaminants in water can involve, there has been a strong interest in developing electrochemical biosensors for algal toxin detection during the past decade, evidenced by literature increasing from 2 journal papers pre-2009 to 24 between 2009 and 2018. In this context, this review has summarized recent progress of successful algal toxin detection in water using electrochemical biosensing techniques. Satisfactory detection recoveries using real environmental water samples and good sensor repeatability and reproducibility have been achieved, along with some excellent limit-of-detection (LOD) reported. Recent electrochemical biosensor literature in algal toxin detection is compared and discussed to cover three major design components: (1) biorecognition elements, (2) electrochemical read-out techniques, and (3) sensor electrodes and signal amplification strategy. The recent development of electrochemical biosensors has provided one more step further toward quick in situ detection of algal toxins in the contamination point of the water source. In the end, we have also critically reviewed the current challenges and research opportunities regarding electrochemical biosensors for algal toxin detection that need to be addressed before they attain commercial viability.
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http://dx.doi.org/10.1021/acssensors.8b00359DOI Listing
July 2018

Occurrence, removal and environmental risk of markers of five drugs of abuse in urban wastewater systems in South Australia.

Environ Sci Pollut Res Int 2019 Nov 9;26(33):33816-33826. Epub 2018 Jun 9.

Natural and Built Environments Research Centre, School of Natural and Built Environments, University of South Australia, Mawson Lakes, SA, 5095, Australia.

The occurrence and fate of five drugs of abuse in raw influent and treated effluent wastewater were investigated over a period of 1 year in the Adelaide region of South Australia. Four wastewater treatment plants were chosen for this study and monitored for five drugs which included cocaine in the form of its metabolite benzoylecgonine (BE), methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA) and two opioids (codeine and morphine) during the period April 2016 to February 2017. Alongside concentrations in raw sewage, the levels of drugs in the treated effluent were assessed and removal efficiencies were calculated. Drug concentrations were measured by mixed-mode solid phase extraction and liquid chromatography coupled to a quadrupole mass spectrometer. Drug concentrations detected in the raw wastewater ranged from 7 to 6510 ng/L and < LOD to 4264 ng/L in treated effluent samples. Drug removal rates varied seasonally and spatially. The mass loads of drugs discharged into the environment were in descending order: codeine > methamphetamine > morphine > MDMA > BE. Results showed that all the targeted drugs were on average incompletely removed by wastewater treatment, with removal performance highest for morphine (94%) and lowest for MDMA (58%). A screening-level environmental risk assessment was subsequently performed for the drugs based on effluent wastewater concentrations. Based on calculated risk quotients, overall environmental risk for these compounds appears low, with codeine and methamphetamine likely to pose the greatest potential risk to receiving environments. Given the recognised limitations of current ecotoxicological models and risk assessment methods for these and other pharmaceutical drugs, the potential for environmental impacts associated with the continuous discharge of these compounds in wastewater effluents should not be overlooked.
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http://dx.doi.org/10.1007/s11356-018-2464-6DOI Listing
November 2019

Nanostructured Electrochemical Biosensors for Label-Free Detection of Water- and Food-Borne Pathogens.

ACS Appl Mater Interfaces 2018 Feb 12;10(7):6055-6072. Epub 2018 Feb 12.

Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia.

The emergence of nanostructured materials has opened new horizons in the development of next generation biosensors. Being able to control the design of the electrode interface at the nanoscale combined with the intrinsic characteristics of the nanomaterials engenders novel biosensing platforms with improved capabilities. The purpose of this review is to provide a comprehensive and critical overview of the latest trends in emerging nanostructured electrochemical biosensors. A detailed description and discussion of recent approaches to construct label-free electrochemical nanostructured electrodes is given with special focus on pathogen detection for environmental monitoring and food safety. This includes the use of nanoscale materials such as nanotubes, nanowires, nanoparticles, and nanosheets as well as porous nanostructured materials including nanoporous anodic alumina, mesoporous silica, porous silicon, and polystyrene nanochannels. These platforms may pave the way toward the development of point-of-care portable electronic devices for applications ranging from environmental analysis to biomedical diagnostics.
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http://dx.doi.org/10.1021/acsami.7b13943DOI Listing
February 2018

Analysis of chromium status in the revegetated flora of a tannery waste site and microcosm studies using earthworm E. fetida.

Environ Sci Pollut Res Int 2018 Feb 3;25(6):5063-5070. Epub 2017 Nov 3.

Natural and Built Environments Research Centre, Division of Information Technology, Engineering and the Environment, University of South Australia, Adelaide, SA, 5095, Australia.

Chromium from tannery waste dump site causes significant environmental pollution affecting surrounding flora and fauna. The primary aims of this study were to survey vegetation, investigate the degree of soil pollution occurring near tannery waste dump site and make a systematic evaluation of soil contamination based on the chromium levels found in plants and earthworms from the impacted areas. This paper presents the pollution load of toxic heavy metals, and especially chromium, in 10 soil samples and 12 species of plants. Soil samples were analysed for heavy metals by using ICP-MS/ICP-OES method. Results indicated that Cr in soils exceeded soil quality guideline limits (SQGL). The total chromium present in the above ground parts of plants ranged from 1.7 mg kg in Casuarina sp. to 1007 mg kg in Sonchus asper. The Cr bioaccumulation in Eisenia fetida from tannery waste soil ranged from 5 to 194 mg kg. The high enrichment factor of Cr in S. asper and bioaccumulation factor in earthworms indicate that there is a steady increase of toxic chromium risk in this area, which could be correlated with the past dumping activity. Emphasis needs to be put on control measures of pollution and remediation techniques in such areas to achieve an ecologically sustainable industrialisation.
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http://dx.doi.org/10.1007/s11356-017-0543-8DOI Listing
February 2018

The impact of biosolids application on organic carbon and carbon dioxide fluxes in soil.

Chemosphere 2017 Dec 20;189:565-573. Epub 2017 Sep 20.

Office of the Dean, Faculty of Applied Sciences, University of Sri Jayewardenepura, Nugegoda, 10250, Sri Lanka.

A field study was conducted on two texturally different soils to determine the influences of biosolids application on selected soil chemical properties and carbon dioxide fluxes. Two sites, located in Manildra (clay loam) and Grenfell (sandy loam), in Australia, were treated at a single level of 70 Mg ha biosolids. Soil samples were analyzed for SOC fractions, including total organic carbon (TOC), labile, and non-labile carbon contents. The natural abundances of soil δC and δN were measured as isotopic tracers to fingerprint carbon derived from biosolids. An automated soil respirometer was used to measure in-situ diurnal CO fluxes, soil moisture, and temperature. Application of biosolids increased the surface (0-15 cm) soil TOC by > 45% at both sites, which was attributed to the direct contribution from residual carbon in the biosolids and also from the increased biomass production. At both sites application of biosolids increased the non-labile carbon fraction that is stable against microbial decomposition, which indicated the soil carbon sequestration potential of biosolids. Soils amended with biosolids showed depleted δC, and enriched δN indicating the accumulation of biosolids residual carbon in soils. The in-situ respirometer data demonstrated enhanced CO fluxes at the sites treated with biosolids, indicating limited carbon sequestration potential. However, addition of biosolids on both the clay loam and sandy loam soils found to be effective in building SOC than reducing it. Soil temperature and CO fluxes, indicating that temperature was more important for microbial degradation of carbon in biosolids than soil moisture.
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http://dx.doi.org/10.1016/j.chemosphere.2017.09.090DOI Listing
December 2017

Occurrence of illicit drugs in water and wastewater and their removal during wastewater treatment.

Water Res 2017 11 26;124:713-727. Epub 2017 Jul 26.

Natural and Built Environments Research Centre, School of Natural and Built Environments, University of South Australia, Mawson Lakes, SA 5095, Australia; Future Industries Institute, University of South Australia, Mawson Lakes, SA 5095, Australia. Electronic address:

This review critically evaluates the types and concentrations of key illicit drugs (cocaine, amphetamines, cannabinoids, opioids and their metabolites) found in wastewater, surface water and drinking water sources worldwide and what is known on the effectiveness of wastewater treatment in removing such compounds. It is also important to amass information on the trends in specific drug use as well as the sources of such compounds that enter the environment and we review current international knowledge on this. There are regional differences in the types and quantities of illicit drug consumption and this is reflected in the quantities detected in water. Generally, the levels of illicit drugs in wastewater effluents are lower than in raw influent, indicating that the majority of compounds can be at least partially removed by conventional treatment processes such as activated sludge or trickling filters. However, the literature also indicates that it is too simplistic to assume non-detection equates to drug removal and/or mitigation of associated risks, as there is evidence that some compounds may avoid detection via inadequate sampling and/or analysis protocols, or through conversion to transformation products. Partitioning of drugs from the water to the solids fraction (sludge/biosolids) may also simply shift the potential risk burden to a different environmental compartment and the review found no information on drug stability and persistence in biosolids. Generally speaking, activated sludge-type processes appear to offer better removal efficacy across a range of substances, but the lack of detail in many studies makes it difficult to comment on the most effective process configurations and operations. There is also a paucity of information on the removal effectiveness of alternative treatment processes. Research is also required on natural removal processes in both water and sediments that may over time facilitate further removal of these compounds in receiving environments.
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http://dx.doi.org/10.1016/j.watres.2017.07.068DOI Listing
November 2017

A Novel Fabrication Approach for Multifunctional Graphene-based Thin Film Nano-composite Membranes with Enhanced Desalination and Antibacterial Characteristics.

Sci Rep 2017 08 8;7(1):7490. Epub 2017 Aug 8.

Future Industries Institute, University of South Australia, Adelaide, SA, 5095, Australia.

A practical fabrication technique is presented to tackle the trade-off between the water flux and salt rejection of thin film composite (TFC) reverse osmosis (RO) membranes through controlled creation of a thinner active selective polyamide (PA) layer. The new thin film nano-composite (TFNC) RO membranes were synthesized with multifunctional poly tannic acid-functionalized graphene oxide nanosheets (pTA-f-GO) embedded in its PA thin active layer, which is produced through interfacial polymerization. The incorporation of pTA-f-GOL into the fabricated TFNC membranes resulted in a thinner PA layer with lower roughness and higher hydrophilicity compared to pristine membrane. These properties enhanced both the membrane water flux (improved by 40%) and salt rejection (increased by 8%) of the TFNC membrane. Furthermore, the incorporation of biocidal pTA-f-GO nanosheets into the PA active layer contributed to improving the antibacterial properties by 80%, compared to pristine membrane. The fabrication of the pTA-f-GO nanosheets embedded in the PA layer presented in this study is a very practical, scalable and generic process that can potentially be applied in different types of separation membranes resulting in less energy consumption, increased cost-efficiency and improved performance.
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http://dx.doi.org/10.1038/s41598-017-07531-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5548761PMC
August 2017

Removal of glyphosate and aminomethylphosphonic acid from synthetic water by nanofiltration.

Environ Technol 2018 Jun 19;39(11):1384-1392. Epub 2017 Jun 19.

b Natural and Built Environments Research Centre, School of Natural and Built Environments , University of South Australia , Adelaide , South Australia , Australia.

The removal of glyphosate and aminomethylphosphonic acid (AMPA) with synthetic water was carried out on a lab-scale nanofiltration unit using two membranes, NFX and NFW. The presence of humic acid and some inorganic matters (CaCl and NaCl) was tested in the experiment. The results demonstrate that NFX exhibits better separation performance than NFW. The herbicide filtration is found to have little effect on the permeate flux as compared to transmembrane pressure. Intermediate concentrations of NaCl act positively on foulant separation, and an increment of 3.3-5.4 percentage points in foulant rejection is obtained with the addition of 100 mg/L of NaCl. In Contrast, CaCl has negative effect on foulant separation during nanofiltration. Humic acid alone shows little influence on the rejection performance, whereas it is slightly improved in the coexistence of humic acid and CaCl. The nanofiltration technology proves to be a good approach to treat the problem of pesticide micropollution in a one-step process. This work clearly shows that the composition of the water matrices may influence the efficiency of the nanofiltration process in terms of the separation of the micropollutants.
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http://dx.doi.org/10.1080/09593330.2017.1329356DOI Listing
June 2018

Impact of prechlorination on organophosphorus pesticides during drinking water treatment: Removal and transformation to toxic oxon byproducts.

Water Res 2016 Nov 26;105:1-10. Epub 2016 Aug 26.

Natural & Built Environments Research Centre, University of South Australia, Mawson Lakes Campus, SA, 5095, Australia.

Prechlorination is commonly used to minimize operational problems associated with biological growth as well as taste and odor control during drinking water treatment. However, prechlorination can also oxidise micropollutants into intermediate byproducts. This could impose profound effects on the safety of the finished water if the transformed byproducts are more toxic and less removable. This study investigated the effect of prechlorination on decomposition and subsequent removal of the four organophosphorus pesticides (OPPs): chlorpyrifos, diazinon, malathion and tolclofos-methyl using a simulated conventional water treatment process of powdered activated carbon assisted coagulation-sedimentation-filtration (PAC-CSF) and postchlorination. It was found that, following prechlorination, not only did the percentage of OPPs oxidation vary significantly, but also the concentration of transformed oxons, which are more toxic than their parent compounds, increased as the major identified oxidation byproducts in water. Removal of these oxons proved to be more difficult by the PAC-CSF than their parent OPPs, because they are more water soluble and more hydrophilic. Both the OPP oxidation and oxon formation increased with chlorine dose during prechlorination. Meanwhile, the continuing chlorination of OPPs by residual free chlorine during PAC-CSF further complicated the pesticide removal processes, generally resulting in a gradually increased formation of oxons. Moreover, in the final treatment stage of postchlorination, the more chlorine-reactive pesticides, malathion and diazinon, were completely oxidised and the formation of corresponding oxons was increased with the prechlorine dose. In contrast, a certain amount of the less chlorine-reactive pesticide tolclofos-methyl still remained in solution after postchlorination, accompanied by an increased formation of tolclofos-methyl oxon with prechlorine dose. Since the oxons are resistant to further oxidation and less adsorbable during the PAC-CSF process, the gross removal of these pesticides and their oxons decreased with increase of the prechlorine dose. This led to an accumulation of the more toxic oxons in the finished water, especially at higher chlorine doses during prechlorination. The significance of this work is the demonstration that, under circumstances where prechlorination is used and source water contains traces of OPPs, alternative practices should be prioritized to avoid the potential risks involved in consumption of the treated water.
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http://dx.doi.org/10.1016/j.watres.2016.08.052DOI Listing
November 2016

Remediation of metalliferous mines, revegetation challenges and emerging prospects in semi-arid and arid conditions.

Environ Sci Pollut Res Int 2016 Oct 19;23(20):20131-20150. Epub 2016 Aug 19.

Natural & Built Environments Research Centre, Division of Information Technology, Engineering and the Environment, University of South Australia, Adelaide, SA, 5095, Australia.

Understanding plant behaviour in polluted soils is critical for the sustainable remediation of metal-polluted sites including abandoned mines. Post-operational and abandoned metal mines particularly in semi-arid and arid zones are one of the major sources of pollution by soil erosion or plant hyperaccumulation bringing ecological impacts. We have selected from the literature 157 species belonging to 50 families to present a global overview of 'plants under action' against heavy metal pollution. Generally, all species of plants that are drought, salt and metal tolerant are candidates of interest to deal with harsh environmental conditions, particularly at semi-arid and arid mine sites. Pioneer metallophytes namely Atriplex nummularia, Atriplex semibaccata, Salsola kali, Phragmites australis and Medicago sativa, representing the taxonomic orders Caryophyllales, Poales and Fabales are evaluated in terms of phytoremediation in this review. Phytoremediation processes, microbial and algal bioremediation, the use and implication of tissue culture and biotechnology are critically examined. Overall, an integration of available remediation plant-based technologies, referred to here as 'integrated remediation technology,' is proposed to be one of the possible ways ahead to effectively address problems of toxic heavy metal pollution. Graphical abstract Integrated remediation technology (IRT) in metal-contaminated semi-arid and arid conditions. The hexagonal red line represents an IRT concept based on remediation decisions by combination of plants and microbial processes.
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http://dx.doi.org/10.1007/s11356-016-7372-zDOI Listing
October 2016

Single-Step Assembly of Multifunctional Poly(tannic acid)-Graphene Oxide Coating To Reduce Biofouling of Forward Osmosis Membranes.

ACS Appl Mater Interfaces 2016 Jul 29;8(27):17519-28. Epub 2016 Jun 29.

Future Industries Institute, University of South Australia , Adelaide, South Australia 5095, Australia.

Graphene oxide (GO) nanosheets have antibacterial properties that have been exploited as a biocidal agent used on desalination membrane surfaces in recent research. Nonetheless, improved strategies for efficient and stable attachment of GO nanosheets onto the membrane surface are still required for this idea to be commercially viable. To address this challenge, we adopted a novel, single-step surface modification approach using tannic acid cross-linked with polyethylene imine as a versatile platform to immobilize GO nanosheets to the surface of polyamide thin film composite forward osmosis (FO) membranes. An experimental design based on Taguchi's statistical method was applied to optimize the FO processing conditions in terms of water and reverse solute fluxes. Modified membranes were analyzed using water contact angle, adenosine triphosphate bioluminescence, total organic carbon, Fourier transform infrared spectroscopy, ζ potential, X-ray photoelectron spectroscopy, transmission electron microscopy, and atomic force microscopy. These results show that membranes were modified with a nanoscale (<10 nm), smooth, hydrophilic coating that, compared to pristine membranes, improved filtration and significantly mitigated biofouling by 33% due to its extraordinary, synergistic antibacterial properties (99.9%).
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http://dx.doi.org/10.1021/acsami.6b03719DOI Listing
July 2016

Porous silicon membrane-modified electrodes for label-free voltammetric detection of MS2 bacteriophage.

Biosens Bioelectron 2016 Jun 14;80:47-53. Epub 2016 Jan 14.

Future Industries Institute, Mawson Lakes, South Australia 5095, Australia. Electronic address:

A proof of concept for the label-free detection of bacteriophage MS2, a model indicator of microbiological contamination, is validated in this work as a porous silicon (pSi) membrane-based electrochemical biosensor. PSi membranes were used to afford nanochannel architectures. The sensing mechanism was based on the nanochannel blockage caused by MS2 binding to immobilized capture antibodies. This blockage was quantified by measuring the oxidation current of the electroactive species reaching the electrode surface, by means of differential pulse voltammetry (DPV). The immunosensor showed a limit of detection of 6 pfu/mL in buffer, allowing the detection of MS2 to levels commonly found in real-world applications, and proved to be unaffected by matrix effects when analyzing MS2 in reservoir water. This platform enables the straightforward, direct and sensitive detection of a broad range of target analytes and constitutes a promising approach towards the development of portable electronic point of sample analysis devices.
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http://dx.doi.org/10.1016/j.bios.2016.01.038DOI Listing
June 2016

Fine-Tuning the Surface of Forward Osmosis Membranes via Grafting Graphene Oxide: Performance Patterns and Biofouling Propensity.

ACS Appl Mater Interfaces 2015 Aug 6;7(32):18004-16. Epub 2015 Aug 6.

⊥Mawson Institute, University of South Australia, Adelaide, SA 5095, Australia.

Graphene oxide (GO) nanosheets were attached to the polyamide selective layer of thin film composite (TFC) forward osmosis (FO) membranes through a poly L-Lysine (PLL) intermediary using either layer-by-layer or hybrid (H) grafting strategies. Fourier transform infrared spectroscopy, zeta potential, and thermogravimetric analysis confirmed the successful attachment of GO/PLL, the surface modification enhancing both the hydrophilicity and smoothness of the membrane's surface demonstrated by water contact angle, atomic force microscopy, and transmission electron microscopy. The biofouling resistance of the FO membranes determined using an adenosine triphosphate bioluminescence test showed a 99% reduction in surviving bacteria for GO/PLL-H modified membranes compared to pristine membrane. This antibiofouling property of the GO/PLL-H modified membrane was reflected in reduced flux decline compared to all other samples when filtering brackish water under biofouling conditions. Further, the high density and tightly bound GO nanosheets using the hybrid modification reduced the reverse solute flux compared to the pristine, which reflects improved membrane selectivity. These results illustrate that the GO/PLL-H modification is a valuable addition to improve the performance of FO TFC membranes.
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http://dx.doi.org/10.1021/acsami.5b04818DOI Listing
August 2015

The role of methanol addition to water samples in reducing analyte adsorption and matrix effects in liquid chromatography-tandem mass spectrometry.

J Chromatogr A 2015 Apr 23;1389:76-84. Epub 2015 Feb 23.

Centre for Water Management and Reuse, School of Natural and Built Environments, University of South Australia, Mawson Lakes Campus, SA 5095, Australia.

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis coupled simply with water filtering before injection has proven to be a simple, economic and time-saving method for analyzing trace-level organic pollutants in aqueous environments. However, the linearity, precision and detection limits of such methods for late-eluting analytes were found to be much poorer than for early-eluting ones due to adsorption of the analytes in the operating system, such as sample vial, flow path and sample loop, creating problems in quantitative analysis. Addition of methanol (MeOH) into water samples as a modifier was shown to be effective in alleviating or even eliminating the negative effect on signal intensity for the late-eluting analytes and at the same time being able to reduce certain matrix effects for real water samples. Based on the maximum detection signal intensity obtained on desorption of the analytes with MeOH addition, the ratio of the detection signal intensity without addition of MeOH to the maximum intensity can be used to evaluate the effectiveness of methanol addition. Accordingly, the values of <50%, 50-80%, 80-120% could be used to indicate strong, medium and no effects, respectively. Based on this concept, an external matrix-matched calibration method with the addition of MeOH has been successfully established for analyzing fifteen pesticides with diverse physico-chemical properties in surface and groundwater with good linearity (r(2): 0.9929-0.9996), precision (intra-day relative standard deviation (RSD): 1.4-10.7%, inter-day RSD: 1.5-9.4%), accuracy (76.9-126.7%) and low limits of detection (0.003-0.028μg/L).
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http://dx.doi.org/10.1016/j.chroma.2015.02.044DOI Listing
April 2015

Electrochemical biosensors featuring oriented antibody immobilization via electrografted and self-assembled hydrazide chemistry.

Anal Chem 2014 Feb 13;86(3):1422-9. Epub 2014 Jan 13.

Mawson Institute, University of South Australia , Mawson Lakes, South Australia 5001, Australia.

Appropriate site-directed chemistry is essential to maximize the performance of immunosensors. We present two new functionalization strategies that preserve proper folding and binding potential of antibodies by forcing their oriented immobilization. Both strategies are based on the formation of hydrazone bonds between aldehyde groups on the Fc moieties of periodate-oxidized antibodies and hydrazide groups on functionalized gold electrodes. Those hydrazide groups are introduced by electrografting of diazonium salts or by self assembly of mono- and dithiolated hydrazide linkers, resulting in films with tailored functional groups and, thus, antibody distribution and spacing. Their barrier properties and permeability toward electroactive species are evaluated. To demonstrate the potential of these new functionalization strategies, detection of bacteriophage MS2 is performed through either a direct assay using electrochemical impedance spectroscopy (EIS) or through a sandwich assay using differential pulse voltammetry (DPV). Diazonium and monothiolated self-assembled monolayer-modified electrodes enable the detection of less than 1 plaque forming unit (pfu)/mL in a direct EIS assay. However, nonspecific adsorption renders measurements in river water samples difficult. In contrast, sandwich-assays on electrodes with electrografted diazonium salts and monothiolated self-assembled monolayers do not show significant matrix effects using river water samples, but the limits of detection are 10(8) times higher than those of the direct assay. Best results are achieved for immunosensors based on mixed monolayers of hydrazide and hydroxyl diothiolated linkers (15 pfu/mL). These new functionalization techniques are facile to implement. They afford the possibility to tune the surface composition and tailor the electrochemical properties of electrochemical sensors. These advantages should translate into broad interest in this type of surface chemistry for biosensor development.
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http://dx.doi.org/10.1021/ac401747jDOI Listing
February 2014

A genetic and metabolic approach to redirection of biochemical pathways of Clostridium butyricum for enhancing hydrogen production.

Biotechnol Bioeng 2013 Jan 18;110(1):338-42. Epub 2012 Jul 18.

School of Earth and Environmental Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia.

Clostridium butyricum, a well known H(2) producing bacterium, produces lactate, butyrate, acetate, ethanol, and CO(2) as its main by-products from glucose. The conversion of pyruvate to lactate, butyrate and ethanol involves oxidation of NADH. It was hypothesized that the NADH could be increased if the formation of these by-products could be eliminated, resulting in enhancing H(2) yield. Herein, this study aimed to establish a genetic and metabolic approach for enhancing H(2) yield via redirection of metabolic pathways of a C. butyricum strain. The ethanol formation pathway was blocked by disruption of aad (encoding aldehyde-alcohol dehydrogenase) using a ClosTron plasmid. Although elimination of ethanol formation alone did not increase hydrogen production, the resulting aad-deficient mutant showed approximately 20% enhanced performance in hydrogen production with the addition of sodium acetate. This work demonstrated the possibility of improving hydrogen yield by eliminating the unfavorable by-products ethanol and lactate.
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http://dx.doi.org/10.1002/bit.24596DOI Listing
January 2013

Removal of cyanobacterial metabolites through wastewater treatment plant filters.

Water Sci Technol 2012 ;65(7):1244-51

Australian Water Quality Centre, SA Water Corporation, Adelaide, Australia.

Wastewaters have the potential to proliferate excessive numbers of cyanobacteria due to high nutrient levels. This could translate to the production of metabolites, such as the saxitoxins, geosmin and 2-methylisoborneol (MIB), which can impair the quality of wastewater destined for re-use. Biological sand filtration was assessed for its ability to remove these metabolites from a wastewater. Results indicated that the sand filter was incapable of effectively removing the saxitoxins and in some instances, the effluent of the sand filter displayed greater toxicity than the influent. Conversely, the sand filter was able to effectively remove geosmin and MIB, with removal attributed to biodegradation. Granular activated carbon was employed as an alternative filter medium to remove the saxitoxins. Results showed similar removals to previous drinking water studies, where efficient removals were initially observed, followed by a decrease in the removal; a consequence of the presence of competing organics which reduced adsorption of the saxitoxins.
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http://dx.doi.org/10.2166/wst.2012.002DOI Listing
June 2012

EXPRESSION OF THE GEOSMIN SYNTHASE GENE IN THE CYANOBACTERIUM ANABAENA CIRCINALIS AWQC318(1).

J Phycol 2011 Dec 23;47(6):1338-43. Epub 2011 Sep 23.

Australian Water Quality Centre, South Australian Water Corporation, 250 Victoria Square, Adelaide, South Australia 5000, Australia Department of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia 5095, AustraliaSA Water Centre for Water Management and Reuse, University of South Australia, Mawson Lakes, South Australia 5095, Australia Australian Water Quality Centre, South Australian Water Corporation, 250 Victoria Square, Adelaide, South Australia 5000, Australia Department of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia 5095, Australia.

The occurrence of taste and odor episodes attributed to geosmin continues to trouble water utilities worldwide, and only recently have advances been made in our fundamental understanding of the biochemical and genetic mechanisms responsible for the production of geosmin in microorganisms. For the first time, we have examined the expression of the geosmin synthase gene and corresponding geosmin production by Anabaena circinalis Rabenh. ex Bornet et Flahault AWQC318 under conditions of continuous light illumination and the removal of light as a stimulus and demonstrate that the expression of geosmin synthase appears to be constitutive under these conditions. The decrease in geosmin synthase transcription post maximum cell numbers and stationary phase suggests that a decrease in isoprenoid synthesis may occur before a decrease in the transcription of ribosomal units as the process of cell death is initiated.
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http://dx.doi.org/10.1111/j.1529-8817.2011.01061.xDOI Listing
December 2011

Genetic manipulation of butyrate formation pathways in Clostridium butyricum.

J Biotechnol 2011 Sep 19;155(3):269-74. Epub 2011 Jul 19.

School of Earth and Environmental Sciences, The University of Adelaide, Adelaide, SA 5005, Australia.

Clostridium butyricum is one of the commonly used species for fermentative hydrogen production. While producing H₂, it can produce acids (lactic, acetic and butyric acids) and CO₂, as well as a small amount of ethanol. It has been proposed that elimination of competing pathways, such as the butyrate formation pathway, should increase H₂ yields in Clostridium species. However, the application of this strategy has been hindered by the unavailability of genetic tools for these organisms. In this study, we successfully transferred a plasmid (pMTL007) to C. butyricum by inter-specific conjugation with Escherichia coli and disrupted hbd, the gene encoding β-hydroxybutyryl-CoA dehydrogenase in C. butyricum. Fermentation data showed that inactivation of hbd in C. butyricum eliminated the butyrate formation pathway, resulting in a significant increase in ethanol production and an obvious decrease in H₂ yield compared with the wild type strain. However, under low partial pressure of H₂, the hbd-deficient strain showed increased H₂ production with the simultaneous decrease of ethanol production, indicating that H₂ production by C. butyricum may compete for NADH with the ethanol formation pathway. Together with the discovery of a potential bifurcating hydrogenase, this study extends our understanding of the mechanism of H₂ production by C. butyricum.
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http://dx.doi.org/10.1016/j.jbiotec.2011.07.004DOI Listing
September 2011

Assessing granular media filtration for the removal of chemical contaminants from wastewater.

Water Res 2011 May 8;45(11):3461-72. Epub 2011 Apr 8.

Australian Water Quality Centre, SA Water Corporation, 250 Victoria Square, Adelaide SA 5000, Australia.

Granular media filtration was evaluated for the removal of a suite of chemical contaminants that can be found in wastewater. Laboratory- and pilot-scale sand and granular activated carbon (GAC) filters were trialled for their ability to remove atrazine, estrone (E1), 17α-ethynylestradiol (EE2), N-nitrosodimethylamine (NDMA), N-nitrosomorpholine (NMOR) and N-nitrosodiethylamine (NDEA). In general, sand filtration was ineffective in removing the contaminants from a tertiary treated wastewater, with the exception of E1 and EE2, where efficient removals were observed after approximately 150 d. Batch degradation experiments confirmed that the removal of E1 was through biological activity, with a pseudo-first-order degradation rate constant of 7.4 × 10(-3) h(-1). GAC filtration was initially able to effectively remove all contaminants; although removals decreased over time due to competition with other organics present in the water. The only exception was atrazine where removal remained consistently high throughout the experiment. Previously unreported differences were observed in the adsorption of the three nitrosamines, with the ease of removal following the trend, NDEA > NMOR > NDMA, consistent with their hydrophobic character. In most instances the removals from the pilot-scale filters were generally in agreement with the laboratory-scale filter, suggesting that there is potential in using laboratory-scale filters as monitoring tools to evaluate the performance of pilot- and possibly full-scale sand and GAC filters at wastewater treatment plants.
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http://dx.doi.org/10.1016/j.watres.2011.04.005DOI Listing
May 2011

An adsorption-photocatalysis hybrid process using multi-functional-nanoporous materials for wastewater reclamation.

Water Res 2010 Oct 22;44(18):5385-97. Epub 2010 Jun 22.

School of Chemical Engineering, The University of Adelaide, Adelaide, SA 5005, Australia.

In this study, two of our recently developed laboratory scale wastewater treatment systems, fluidized-bed reactor (FBR) using formulated clay mixture absorbents (clay-FBR adsorption) and an annular slurry photoreactor (ASP) using TiO(2) impregnated kaolin catalysts (TiO(2)-K-ASP) were integrated as an adsorption-photocatalysis hybrid process to treat municipal wastewater as alternative secondary and tertiary treatment for wastewater reclamation. Primary effluent from sewage and secondary effluent from a membrane bioreactor treatment process were used to assess chemical removal capabilities of the FBR and ASP systems, and the hybrid process. The formulated clays-FBR system demonstrated the prevailing removal efficiency toward PO(4)(3-), NO(3)(-) and suspended solids. The TiO(2)-K-ASP showed superior degradation of dissolved organic content; while the presence of inorganic ions caused a detrimental effect on its performance. The integration of the adsorption and degradation system as a hybrid treatment process resulted in a synergetic enhancement for the chemical removal efficiency. Complete elimination of PO(4)(3-) content was obtained in the adsorption stage; while 30% and 65% NO(3)(-) removal were obtained from the hybrid treatment of the primary and secondary effluents, respectively. The corresponding COD reduction during the photodegradation was further investigated by the high-performance size exclusion chromatography technique, where it revealed the shift of apparent molecular weight of the dissolved organic contaminants toward the smaller region. This present study demonstrated that this adsorption-photocatalysis hybrid technology can be used as a feasible alternative treatment process for wastewater reclamation.
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http://dx.doi.org/10.1016/j.watres.2010.06.033DOI Listing
October 2010

Investigations into the biodegradation of microcystin-LR in wastewaters.

J Hazard Mater 2010 Aug 24;180(1-3):628-33. Epub 2010 Apr 24.

Australian Water Quality Centre, SA Water Corporation, Adelaide, SA 5000, Australia.

Microcystins are potent hepatotoxins that can be produced by cyanobacteria. These organisms can proliferate in wastewaters due to a number of factors including high concentrations of nutrients for growth. As treated wastewaters are now being considered as supplementary drinking water sources, in addition to their frequent use for irrigated agriculture, it is imperative that these wastewaters are free of toxins such as microcystins. This study investigated the potential for biodegradation of microcystin-LR (MCLR) in wastewaters through a biological sand filtration experiment and in static batch reactor experiments. MCLR was effectively removed at a range of concentrations and at various temperatures, with degradation attributed to the action of microorganisms indigenous to the wastewaters. No hepatotoxic by-products were detected following the degradation of MCLR as determined by a protein phosphatase inhibition assay. Using TaqMan polymerase chain reaction, the first gene involved in bacterial degradation of MCLR (mlrA) was detected and the responsible bacteria shown to increase with the amount of MCLR being degraded. This finding suggested that the degradation of MCLR was dependent upon the abundance of MCLR-degrading organisms present within the wastewater, and that MCLR may provide bacteria with a significant carbon source for proliferation; in turn increasing MCLR removal.
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http://dx.doi.org/10.1016/j.jhazmat.2010.04.081DOI Listing
August 2010

Development of an mlrA gene-directed TaqMan PCR assay for quantitative assessment of microcystin-degrading bacteria within water treatment plant sand filter biofilms.

Appl Environ Microbiol 2009 Aug 5;75(15):5167-9. Epub 2009 Jun 5.

Australian Water Quality Centre, South Australian Water Corporation, Adelaide, Australia.

We report for the first time a quantitative mlrA gene-directed TaqMan PCR assay for the rapid detection of microcystin-degrading bacteria. This was applied, in combination with 16S ribosomal DNA-directed quantitative PCR and denaturing gradient gel electrophoresis, to study virgin sand filter column biofilm development and to correlate mlrA gene abundance with microcystin removal efficiency.
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http://dx.doi.org/10.1128/AEM.00036-09DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2725489PMC
August 2009
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