Chemical and Environmental Engineering, School of Engineering, RMIT University, Melbourne, VIC 3000, Australia; ARC Training Centre for the Transformation of Australia's Biosolids Resources, RMIT University, Bundoora, VIC 3083, Australia.
South East Water Corporation, Frankston, VIC 3199, Australia.
Waste Manag. 2023 Mar 15;159:146-153. doi: 10.1016/j.wasman.2023.01.037. Epub 2023 Feb 8.
Anaerobic digestion is a popular unit operation in wastewater treatment to degrade organic contaminants, thereby generating biogas (methane-rich gas stream). Catalytic decomposition of the biogas could be a promising upcycling approach to produce renewable hydrogen and sequester carbon in the form of carbon nanomaterials (CNMs). Biosolids are solid waste generated during the wastewater treatment process, which can be valorised to biochar via pyrolysis. This work demonstrates the use of biosolids-derived biochar compared with ilmenite as catalysts for biogas decomposition to hydrogen and CNMs. Depending on the reaction time, biosolids-derived biochar achieved a CH and CO conversion of 50-70 % and 70-90 % at 900 °C with a weight hourly space velocity (WHSV) of 1.2 Lgh. The high conversion rate was attributed to the formation of amorphous carbon on the biochar surface, where the carbon deposits acted as catalysts and substrates for the further decomposition of CH and CO. Morphological characterisation of biochar after biogas decomposition revealed the formation of high-quality carbon nanospheres (200-500 nm) and carbon nanofibres (10-100 nm) on its surface. XRD pattern and Raman spectroscopy also signified the presence of graphitic structures with I/I ratio of 1.19, a reduction from 1.33 in the pristine biochar. Finally, the produced CNM-loaded biochar was tested for PFAS adsorption from contaminated wastewater. A removal efficiency of 79 % was observed for CNM-coated biochar which was 10-60 % higher than using biochar and ilmenite alone. This work demonstrated an integrated approach for upcycling waste streams generated in wastewater treatment facilities.
厌氧消化是一种在废水处理中常用的单元操作，可降解有机污染物，从而产生沼气（富含甲烷的气流）。沼气的催化分解可能是一种很有前途的升级方法，可以生产可再生氢气，并以碳纳米材料 (CNM) 的形式固碳。生物固体是废水处理过程中产生的固体废物，可以通过热解转化为生物炭。这项工作展示了使用生物固体衍生的生物炭与钛铁矿作为催化剂，将沼气分解为氢气和 CNM。根据反应时间的不同，生物固体衍生的生物炭在 900°C 下的 CH 和 CO 转化率分别为 50-70%和 70-90%，重量时空间速度 (WHSV) 为 1.2 Lgh。高转化率归因于生物炭表面无定形碳的形成，其中碳沉积物充当 CH 和 CO 进一步分解的催化剂和底物。在沼气分解后对生物炭的形貌特征进行了研究，发现其表面形成了高质量的碳纳米球（200-500nm）和碳纳米纤维（10-100nm）。XRD 图谱和拉曼光谱也表明存在具有 I/I 比为 1.19 的石墨结构，这与原始生物炭中的 1.33 相比有所降低。最后，测试了负载 CNM 的生物炭对受污染废水中 PFAS 的吸附性能。观察到 CNM 涂层生物炭的去除效率为 79%，比单独使用生物炭和钛铁矿高 10-60%。这项工作展示了一种综合方法，用于升级废水处理设施中产生的废物流。
