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Port Adelaide, Australia

Chong M.N.,University of Adelaide | Zhu H.Y.,Queensland University of Technology | Jin B.,University of Adelaide | Jin B.,SA Water Corporation
Chemical Engineering Journal | Year: 2010

In this study, a new generation H-titanate nanofiber catalyst (TNC) with long fibril morphology and surface covered anatase titanium dioxide (TiO2) crystals of 10-20 nm was used as the photocatalyst for improved photoactivity, mass transfer resistance and downstream separation. The combined Taguchi method and response surface analysis (RSA) were employed to evaluate the effects of key operational factors of TNC loading, pH, aeration rate and initial Congo Red (CR) concentration on the performances of TNC in an annular slurry photoreactor (ASP). The average CR photocatalytic degradation rate (mg dm-3 min-1) was estimated and applied as the response outputs of the L9 (3)4 Taguchi orthogonal array. Results from the RSA interpretations revealed that pH, initial CR concentration and aeration rate were the significant factors, while TNC loading appears to be the least significant factor. On contrary, positive interactions of TNC loading were observed when being coupled with pH and aeration rate. Other interactions of the operation factors were also determined using statistical analysis. A natural logarithmic modified regression equation was developed from multiple regression analysis for response surface modelling. This model predicted that the average photocatalytic degradation rate of CR was 0.1576 mg dm3 min-1 under the optimal conditions. A subsequent verification experiment showed a photocatalytic degradation rate of 0.1563 ± 0.0282 mg dm-3 min-1, which is in good agreement with the model predicted value. This proved the applicability of the developed model as a reliable design and modelling tool for scaling up the photocatalytic reactor process. © 2009 Elsevier B.V. All rights reserved.

Laera G.,CNR Water Research Institute | Chong M.N.,CSIRO | Chong M.N.,University of Adelaide | Jin B.,University of Adelaide | And 2 more authors.
Bioresource Technology | Year: 2011

This paper aims to demonstrate that integrating biological process and photocatalytic oxidation in a system operated in recycling mode can be a promising technology to treat pharmaceutical wastewater characterized by simultaneous presence of biodegradable and refractory/inhibitory compounds. A lab-scale system integrating a membrane bioreactor (MBR) and a TiO2 slurry photoreactor was fed on simulated wastewater containing 10mg/L of the refractory drug Carbamazepine (CBZ). Majority of chemical oxygen demand (COD) was removed by the MBR, while the photocatalytic oxidation was capable to degrade CBZ. CBZ degradation kinetics and its impacts on the biological process were studied. The adoption of a recycling ratio of 4:1 resulted in removal of up to 95% of CBZ. Effluent COD reduction, sludge yield increase and respirometric tests suggested that the oxidation products were mostly biodegradable and not inhibiting the microbial activity. These results evidenced the advantages of the proposed approach for treating pharmaceutical wastewater and similar industrial effluents. © 2011 Elsevier Ltd.

Vimonses V.,University of Adelaide | Chong M.N.,University of Adelaide | Jin B.,University of Adelaide | Jin B.,SA Water Corporation
Microporous and Mesoporous Materials | Year: 2010

In this study, a microporous layer photocatalyst of titania nanocrystallites heterocoagulated with structurally modified kaolin (TiO2-K) was synthesised via a modified sol-gel method. Physical properties (particle size, morphology, stability and settleability) and photodegradation capacity of the TiO2-K catalyst subject to its synthesis, regeneration and use for water treatment were studied. The modified kaolin, as a support for the titania nanocrystallites had a delaminated sandwich silica structure that minimises chemical intercalation within the nanocomposite structure. Microscopic examination revealed that the TiO2 nanocrystallites were uniformly deposited on the kaolin external surface, resulting in a high degree of photon activation. Compared to the commercial TiO2 P25, the TiO2-K demonstrated a superior photocatalytic degradation capacity to remove an anionic Congo red dye. Its removal efficiency and photo-reaction performance were improved when the TiO2-K was regenerated by a thermal treatment. The TiO2-K particles can be easily separated from the water system for further reuse. This unique nanocomposite photocatalyst shows promising technical advantages for a continuous industrial process of water treatment. © 2010 Elsevier Inc.

Cai G.,University of Adelaide | Jin B.,University of Adelaide | Monis P.,SA Water Corporation | Saint C.,University of South Australia
Biotechnology and Bioengineering | Year: 2013

Clostridium butyricum, a well known H2 producing bacterium, produces lactate, butyrate, acetate, ethanol, and CO2 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 H2 yield. Herein, this study aimed to establish a genetic and metabolic approach for enhancing H2 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. © 2012 Wiley Periodicals, Inc.

Ho L.,SA Water Corporation | Ho L.,University of Adelaide | Lambling P.,School of Chemistry, Physics and Electronics, Lyon | Bustamante H.,Sydney Water | And 2 more authors.
Water Research | Year: 2011

Cylindrospermopsin (CYN) and microcystin are two potent toxins that can be produced by cyanobacteria in drinking water supplies. This study investigated the application of powdered activated carbon (PAC) for the removal of these toxins under conditions that could be experienced in a water treatment plant. Two different PACs were evaluated for their ability to remove CYN and four microcystin variants from various drinking water supplies. The removal of natural organic material by the PACs was also determined by measuring the levels of dissolved organic carbon and UV absorbance (at 254 nm). The PACs effectively removed CYN and the microcystins from each of the waters studied, with one of the PACs shown to be more effective, possibly due to its smaller particle diameter. No difference in removal of the toxins was observed using PAC contact times of 30, 45 and 60 min. Furthermore, the effect of water quality on the removal of the toxins was minimal. The microcystin variants were adsorbed in the order: MCRR > MCYR > MCLR > MCLA. CYN was found to be adsorbed similarly to MCRR. © 2011 Elsevier Ltd.

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