Deng Shihai, Wang Qi, Cai Qinqing, Ong Say Leong, Hu Jiangyong
Sembcorp-NUS Corporate Laboratory, Sembcorp-NUS Corporate Laboratory c/o FoE, National University of Singapore, Block E1A, #04-01, 1 Engineering Drive 2, Singapore 117576, Singapore; Department of Civil and Environmental Engineering, Faculty of Engineering, National University of Singapore, Block E1A, #07-01, 1 Engineering Drive 2, Singapore 117576, Singapore.
Department of Civil and Environmental Engineering, Faculty of Engineering, National University of Singapore, Block E1A, #07-01, 1 Engineering Drive 2, Singapore 117576, Singapore.
Water Res. 2022 Feb 1;209:117943. doi: 10.1016/j.watres.2021.117943. Epub 2021 Dec 7.
Micro-scale ZVI@GAC-based iron-carbon galvanic-cells (ZVI@GACs) were prepared with the Ca-Si-H/Ca-H formation process and first applied to initiate radical generation and coagulation processes in MBR for treating bio-refractory industrial wastewater (IWW). Batch tests revealed the HO production (0.19-0.28 mg/L) and •OH generation (p-CBA decay, k = 0.040 min) in ZVI@GACs-dosed system (packing volume of 5%) under aeration. Adoption of ZVI@GACs into aerobic activated sludge process (ZVI@GACs/AS) enhanced TOC degradation (k) and phenolic compounds (PHENs) destruction (k). ZVI@GACs/AS at ZVI@GACs packing volume of 5%, 10% and 20% improved k from 0.11 h (bare AS) to 0.17, 0.21 and 23 h and k from 0.24 h to 0.36, 0.49 and 0.57 h, respectively. The oxygen uptake rate (OUR) and 15-min acute bio-toxicity demonstrated that the bio-toxicity of IWW was reduced and the activity of biomass was enhanced in the ZVI@GACs/AS system. In MBR, ZVI@GACs at packing volume of 10% enhanced COD and PHENs removal by 14% and 22%, respectively. Membrane fouling cycle was prolonged by 71%. The accumulations of EPS-proteins, EPS-polysaccharides, SMP-proteins and SMP-polysaccharides were reduced by 6%, 67%, 27% and 60%, respectively. Fourier transform infrared spectroscopy (FTIR) confirmed the oxidation of SMP-polysaccharides in ZVI@GACs-MBR. The iron ions released from ZVI@GACs showed inhibition on the secretion of SMP-/EPS-proteins. Floc particle size distribution (PSD) and X-ray diffraction (XRD) spectrum confirmed that the coagulation effects of Fe(OH) and FeOOH triggered by Fe increased the sludge floc size and contributed to membrane fouling mitigation. Genus Enterococcus was enriched in MBR with the destruction of PHENs by the ZVI@GACs-initiated radical generation process. The findings of this study confirmed successful development and adoption of ZVI@GACs into MBR for bio-refractory IWW treatment. It also provided an in-depth understanding on the mechanisms of ZVI@GACs-MBR system.
基于微尺度零价铁负载颗粒活性炭（ZVI@GAC）的铁碳原电池（ZVI@GACs）通过钙硅氢/氢化钙形成工艺制备而成，并首次应用于膜生物反应器（MBR）中引发自由基生成和混凝过程，以处理生物难降解工业废水（IWW）。批次试验表明，在曝气条件下，投加ZVI@GACs的系统（填充体积为5%）中产生了羟基自由基（HO，0.19 - 0.28mg/L）和·OH（对氯苯甲酸降解，k = 0.040min⁻¹）。将ZVI@GACs应用于好氧活性污泥工艺（ZVI@GACs/AS）中提高了总有机碳（TOC）降解率（k）和酚类化合物（PHENs）去除率（k）。ZVI@GACs填充体积为5%、10%和20%的ZVI@GACs/AS系统分别将k从0.11h⁻¹（纯活性污泥）提高到0.17、0.21和0.23h⁻¹，将k从0.24h⁻¹提高到0.36、0.49和0.57h⁻¹。氧摄取率（OUR）和15分钟急性生物毒性试验表明，ZVI@GACs/AS系统降低了IWW的生物毒性并提高了生物质的活性。在MBR中，填充体积为10%的ZVI@GACs分别使化学需氧量（COD）和PHENs的去除率提高了14%和22%。膜污染周期延长了71%。胞外聚合物蛋白质（EPS - proteins）、胞外聚合物多糖（EPS - polysaccharides）、溶解性微生物产物蛋白质（SMP - proteins）和溶解性微生物产物多糖（SMP - polysaccharides）的积累分别减少了6%、67%、27%和60%。傅里叶变换红外光谱（FTIR）证实了ZVI@GACs - MBR中SMP - polysaccharides的氧化。ZVI@GACs释放的铁离子对SMP - /EPS - proteins的分泌有抑制作用。絮体粒径分布（PSD）和X射线衍射（XRD）光谱证实，由铁引发的氢氧化铁（Fe(OH)）和氢氧化氧铁（FeOOH）的混凝作用增加了污泥絮体尺寸，有助于减轻膜污染。通过ZVI@GACs引发的自由基生成过程破坏PHENs，肠球菌属在MBR中得到富集。本研究结果证实了ZVI@GACs在MBR中成功开发并应用于生物难降解IWW处理。它还对ZVI@GACs - MBR系统的机制提供了深入理解。
