Browsing by Author "Cooper, Mick"

Now showing 1 - 5 of 5
  • Thumbnail Image
    ItemOpen Access
    Efficient arsenic removal by a bifunctional heterogeneous catalyst through simultaneous hydrogen peroxide (H2O2) catalytic oxidation and adsorption
    (Elsevier, 2021-10-09) Su, Jing; Lyu, Tao; Cooper, Mick; Mortimer, Robert J. G.; Pan, Gang
    Arsenic (As) is a toxic contaminant in surface waters and groundwater. Oxidation of arsenite (As(III)) to less toxic arsenate (As(V)) by hydrogen peroxide (H2O2) is desirable for enhancing the immobilisation of Arsenic (As). However, this As(III) oxidation process is constrained by the strong pH dependence and the generated As(V) must also be removed for complete As remediation. This study developed and evaluated a novel heterogeneous catalytic system using manganese-doped Lanthanum oxycarbonate (MnL) to catalyse the oxidation of As(III) by H2O2 and simultaneously adsorb the generated As(V). The presence of MnL enhanced the removal rate of As(III) by 35 times compared with systems utilising H2O2 alone. Additionally, this superior performance was observed over a wide pH range (5–9), which demonstrated this approach could bypass the well-known pH restriction on oxidation by H2O2. Mechanistic studies revealed that the long-lived superoxide radicals (·O2−/·OOH), present on the particle surfaces and derived from the dissociation of the Lewis acid-base adduct (La–OOH*), were the dominant active species for As(III) oxidation. Mn atoms with low valence states played a crucial role in As(III) oxidation through the provision of extra active sites to facilitate radical production. The La and Mn sites in MnL could rapidly immobilize the generated As(V) by forming precipitates, resulting in a final As removal efficiency of 99% even after three cycles of reutilisation. Overall, this study demonstrates the viability of the proposed novel multi-functional catalyst for efficient As remediation from aqueous environments.
  • Thumbnail Image
    ItemOpen Access
    Hydrothermal carbonization of microalgae for phosphorus recycling from wastewater to crop-soil systems as slow-release fertilizers
    (Elsevier, 2020-10-12) Chu, Qingnan; Lyu, Tao; Xue, Lihong; Yang, Linzhang; Feng, Yanfang; Sha, Zhimin; Yue, Bin; Mortimer, Robert J. G.; Cooper, Mick; Pan, Gang
    Due to the finite stocks of phosphate rock and low phosphorus (P) use efficiency (PUE) of traditional mineral P fertilizers, more sustainable alternatives are desirable. One possibility is to culture microalgae in wastewater to recover the P and then convert the microalgae biomass into slow-release fertilizers through hydrothermal carbonization (HTC). Therefore, this study aimed to recycle P from wastewater to agricultural field using microalgae and HTC technology. Chlorella vulgaris (CV) and Microcystis sp. (MS) were cultured in poultry farm wastewater with an initial concentration of 41.3 mg P kg-1. MS removed 88.4% P from the wastewater, which was superior to CV. CV- and MS-derived hydrochars were produced at 200 or 260°C, in solutions using deionized water or 1wt% citric acid. The MS-derived hydrochar using 1 wt% citric acid solution at 260 °C (MSHCA260) recovered the highest amount of P (91.5%) after HTC. The charring promoted the transformation of soluble and exchangeable P into moderately available P (Fe/Al-bound P), and using citric acid solution as feedwater increased the P recovery rate and formation of Fe/Al-bound P. With the abundant moderately available P pool, hydrochar amendment released P more slowly and enhanced the soil P availability more persistently than chemical fertilizer did, which helped to improve PUE. In a wheat-cultivation pot experiment, MSHCA260 treatment improved wheat PUE by 34.4% and yield by 21.6% more than chemical fertilizer did. These results provide a novel sustainable strategy for recycling P from wastewater to crop-soil systems, substituting the mineral P fertilizer, and improving plant PUE.
  • Thumbnail Image
    ItemOpen Access
    Mitigating antibiotic pollution using cyanobacteria: removal efficiency, pathways and metabolism
    (Elsevier, 2020-12-08) Pan, Minmin; Lyu, Tao; Zhan, Lumeng; Matamoros, Victor; Angelidaki, Irini; Cooper, Mick; Pan, Gang
    The occurrence of pharmaceuticals and personal care products (PPCPs) in wastewater poses huge environmental threats, even at trace concentrations, and novel approaches are urged due to the inefficiencies of conventional wastewater treatment plants, especially when processing contaminants at high concentrations. Meanwhile, another widespread problem in the aquatic domain is the occurrence of harmful algal blooms (HABs) which cause serious damage to the ecosystem, but have rarely been investigated for possible valorization. This study investigated the possibilities, mechanisms, and effects of toxin release of using a harmful cyanobacterial species, Microcystis aeruginosa (M. aeruginosa), in order to remove the widely used drug, tetracycline, at high concentration. The results were compared with the performance obtained by the use of the hitherto generally-selected chlorophyte alga Chlorella pyrenoidosa (C. pyrenoidosa) for tetracycline concentrations of 10-100 mg L−1. M. aeruginosa exhibited a much more effective and rapid tetracycline removal (over 98.0% removal in 2 days) than did C. pyrenoidosa (36.7%-93.9% in 2 days). A comprehensive kinetic investigation into probable removal pathways indicated that, theoretically, bio-remediation dominated the process by M. aeruginosa (71.6%), while only accounting for 20.5% by C. pyrenoidosa. Both microalgae promoted the hydrolysis of tetracycline under conditions of increased pH and inhibited abiotic photolytic reactions by the shading effect to the water column, when compared with control experiments. Although identical degradation by-products were identified from treatments by both microalgal species, distinct by-products were also confirmed, unique to each treatment. Moreover, the growth of M. aeruginosa biomass exhibited strong tolerance to tetracycline exposure and released significantly lower levels of microcystin-LR, compared with the control systems. This study supports the possibility of reusing HABs species for the effective remediation of antibiotics at high concentrations. We have further suggested possible mechanisms for remediation and demonstrated control of toxin release.
  • Thumbnail Image
    ItemOpen Access
    Reducing arsenic toxicity using the interfacial oxygen nanobubble technology for sediment remediation
    (Elsevier, 2021-09-11) Tang, Ying; Zhang, Meiyi; Zhang, Jing; Lyu, Tao; Cooper, Mick; Pan, Gang
    The arsenic (As)-bearing eutrophic waters may suffer from the dual conditions of harmful algal blooms and release of As, driven by algal-induced hypoxia/anoxia. Here, we investigate the use of interfacial oxygen (O2) nanobubble technology to combat the hypoxia and control As exposure in simulated mesocosm experiments. It was observed that remediation of algal-induced hypoxia at the sediment-water interfaces (SWI) by application of O2 nanobubbles reduced the level of dissolved As from 23.2 μg L−1 to <10 μg L−1 and stimulated the conversion of As(III) to the less toxic As(V) (65–75%) and methylated As (10–15%) species. More than half of the oxidation and all the methylation of As(III) resulted from the manipulation by O2 nanobubbles of microbes responsible for As(III) oxidation and methylation. Hydroxyl radicals were generated during the oxidation of reductive substances at the SWI in darkness, and should be dominant contributors to As(III) abiotic oxidation. X-ray absorption near-edge structure (XANES) spectroscopic analysis demonstrated that surface sediments changed from being sources to acting as sinks of As, due to the formation of Fe-(hydr)oxide. Overall, this study suggests that interfacial O2 nanobubble technology could be a potential method for remediation of sediment As pollution through the manipulation of O2-related microbial and geochemical reactions
  • Thumbnail Image
    ItemOpen Access
    Utilization of coal fly ash waste for effective recapture of phosphorus from waters
    (Elsevier, 2021-10-01) Xu, Rui; Lyu, Tao; Wang, Lijing; Yuan, Yuting; Zhang, Meiyi; Cooper, Mick; Mortimer, Robert J. G.; Yang, Queping; Pan, Gang
    Reutilization of the waste by-products from industrial and agricultural activities is crucially important towards attainment of environmental sustainability and the ‘circular economy’. In this study, we have developed and evaluated a sustainably-sourced adsorbent from coal fly ash, which was modified by a small amount of lanthanum (La-FA), for the recapture of phosphorous (P) from both synthetic and real natural waters. The prepared La-FA adsorbent possessed typical characteristic diffraction peaks similar to zeolite type Na–P1, and the BET surface area of La-FA was measured to be 10.9 times higher than that of the original FA. Investigation of P adsorption capability indicated that the maximum adsorption (10.8 mg P g−1) was 6.14 times higher than that (1.8 mg P g−1) of the original fly ash material. The ζ potentials measurement and P K-edge X-ray Absorption Near Edge Structure (XANES) spectra demonstrated that P was bonded on La-FA surfaces via an adsorption mechanism. After applying the proposed adsorbent to real lake water with La/P molar ratios in the range from 0.5:1 to 3:1, the La-FA adsorbent showed the highest phosphate removal ability with a La/P molar ratio 1:1, and the P adsorption was similar to that performance with the synthetic solution. Moreover, the La-FA absorbent produced a negligible effect on the concentrations of total dissolved nitrogen (TDN), NH4+-N and NO3−-N in water. This study thus provides a potential material for effective P recapture and details of its operation.