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Publications (9)17.83 Total impact

  • Jing Sun, Shihu Hu, Keshab Raj Sharma, Beatrice Keller-Lehmann, Zhiguo Yuan
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    ABSTRACT: Volatile organic sulfur compounds (VOSCs) are important sources of unpleasant odor in wastewater systems. However, the study of VOSCs is usually hindered by their complicated measurement method and highly reactive nature. In this work, a static headspace method utilising gas chromatography (GC) with a sulfur chemiluminescence detector (SCD) was developed to quantitatively analyze VOSCs in wastewater matrices. The method has low detection limits and requires no pre-concentration treatment. Three typical VOSCs, namely methanethiol (MT), dimethyl sulfide (DMS) and dimethyl disulfide (DMDS), were chosen as examples for this study. The calibration curves of all three compounds covering a wide range from 0.5 ppb to 500 ppb showed good linearity (R(2) > 0.999). The method detection limits (MDL) were 0.08, 0.12 and 0.21 ppb for MT, DMS and DMDS, respectively. The reproducibility (relative standard deviation) was approximately 2%. The recovery ratio of MT, DMS and DMDS in spiked wastewater samples were 83 ± 4%, 103 ± 4% and 102 ± 3%, respectively. Sample preservation tests showed that VOSCs in wastewater samples could be preserved in vials without headspace under acidified conditions (pH ∼1.1) for at least 24 h without significant changes (<1.8 ppb). The analysis of real wastewater samples from both a laboratory-scale sewer system and a full-scale sewer pipe demonstrated the suitability of this method for routine wastewater VOSC measurement.
    Water Research 11/2013; · 4.66 Impact Factor
  • G. Sudarjanto, J Keller, B. Keller-lehmann
    01/2011;
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    Gatut Sudarjanto, Beatrice Keller-Lehmann, Jurg Keller
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    ABSTRACT: The integrated chemical-biological degradation combining advanced oxidation by UV/H(2)O(2) followed by aerobic biodegradation was used to degrade C.I. Reactive Azo Red 195A, commonly used in the textile industry in Australia. An experimental design based on the response surface method was applied to evaluate the interactive effects of influencing factors (UV irradiation time, initial hydrogen peroxide dosage and recirculation ratio of the system) on decolourisation efficiency and optimizing the operating conditions of the treatment process. The effects were determined by the measurement of dye concentration and soluble chemical oxygen demand (S-COD). The results showed that the dye and S-COD removal were affected by all factors individually and interactively. Maximal colour degradation performance was predicted, and experimentally validated, with no recirculation, 30 min UV irradiation and 500 mgH(2)O(2)/L. The model predictions for colour removal, based on a three-factor/five-level Box-Wilson central composite design and the response surface method analysis, were found to be very close to additional experimental results obtained under near optimal conditions. This demonstrates the benefits of this approach in achieving good predictions while minimising the number of experiments required.
    Journal of Hazardous Materials 12/2006; 138(1):160-8. · 4.33 Impact Factor
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    B. Keller-lehmann, S. Corrie, R Ravn, Z. Yuan, J Keller
    01/2006;
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    ABSTRACT: Poly-beta-hydroxyalkanoate (PHA) is a polymer commonly used in carbon and energy storage for many different bacterial cells. Polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs), store PHA anaerobically through metabolism of carbon substrates such as acetate and propionate. Although poly-beta-hydroxybutyrate (PHB) and poly-beta-hydroxyvalerate (PHV) are commonly quantified using a previously developed gas chromatography (GC) method, poly-beta-hydroxy-2-methylvalerate (PH2MV) is seldom quantified despite the fact that it has been shown to be a key PHA fraction produced when PAOs or GAOs metabolise propionate. This paper presents two GC-based methods modified for extraction and quantification of PHB, PHV and PH2MV from enhanced biological phosphorus removal (EBPR) systems. For the extraction of PHB and PHV from acetate fed PAO and GAO cultures, a 3% sulfuric acid concentration and a 2-20 h digestion time is recommended, while a 10% sulfuric acid solution digested for 20h is recommended for PHV and PH2MV analysis from propionate fed EBPR systems.
    Journal of Chromatography A 05/2005; 1070(1-2):131-6. · 4.61 Impact Factor
  • Gatut Sudarjanto, Beatrice Keller-Lehmann, Jurg Keller
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    ABSTRACT: The homogeneous advanced oxidation process of UV/H2O2 was utilized to decolourize CI Reactive Red 195A (RR195A) as one of the most used dyes in the textile industry in Queensland. The UV radiation source was a low-pressure mercury arc lamp (60W emitting at 253.7nm). In this study, the effects of initial hydrogen peroxide (H2O2) dosage, dye concentration, pH and temperature were examined to find out the optimum operating conditions of the treatment process. Complete decolourization was achieved in the relatively short time of 20-30 minutes irradiation. Faster decolourization was achieved at low pH and high temperature. The removal rate increased with increasing initial concentration of H2O2 up to an optimum value. The decolourization reaction was found to follow at least initially first order kinetics with respect to the dye concentration. However, even after near complete removal of the active dye from the solution, approximately 60% of the COD was still remaining, indicating only partial breakdown of the dye molecule. In general, the result indicates that the UV/H2O2 technology proved to have good potential for removing dyestuff from wastewater but further treatment might be necessary to achieve complete mineralization of the organic intermediates.
    Journal of Water and Environment Technology 01/2005;
  • Barry Chiswell, Beatrice Keller-Lehmann
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    ABSTRACT: The concentrations of aqueous chlorite and chlorate in mixtures can be determined by the decolorization of Indigo Carmine at 610 nm in the presence of FeII. The reactions are stoichiometric and therefore a good correlation between the absorbance and the concentration is found. The linear range for measurements of chlorite is 0–0.51 mg l–1 and that of chlorate is 0–0.78 mg l–1. The detection limits for chlorite and chlorate are 0.036 and 0.008 mg l–1, respectively. The presence of chlorine interferes with the determinations.
    The Analyst 01/1993; 118(11). · 4.23 Impact Factor
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    ABSTRACT: Thesis (doctoral)--Eidgenössische Technische Hochschule Zürich, 1990.
  • G. Sudarjanto, J Keller, B. Keller-lehmann