Department of Earth and Environmental Sciences (DISAT), Università degli Studi di Milano-Bicocca, P.zza della Scienza 1, 20126, Milano, Italy.
Environ Sci Pollut Res Int. 2023 Jan;30(3):6730-6745. doi: 10.1007/s11356-022-22506-x. Epub 2022 Aug 25.
The integration of microalgae-bacteria consortia within existing wastewater treatment plants as alternative biological treatment could be an interesting option to improve the sustainability of these facilities. However, the fate of the produced biomass is decisive to make that option economically attractive. The present study aimed to valorize the microalgae grown at a pilot scale and used for the treatment of the centrate from municipal sewage sludge, producing microalgal-based iron nanoparticles (ME-nFe), by hydrothermal carbonization. The final product had high carbon content, strong sorbent power, and reducing properties, due to the presence of zerovalent iron. Different synthesis conditions were tested, comparing iron (III) nitrate nonahydrate (Fe (NO)·9HO) and ammonium iron (III) sulfate dodecahydrate (NH Fe (SO)·12 HO) as iron sources, four different Fe/C molar ratios (0.02, 0.05, 0.1, 0.2), and three process temperatures (180, 200, 225 °C). Based on the characterization of all the prototypes, the best one (having a specific area of 110 mg) was chosen and tested for the removal of selected heavy metals by Jar tests. The removal of copper, zinc, cadmium, and nickel from the treated effluent from the wastewater treatment plant was 99.6%, 97.8%, 96.4%, and 80.3%, respectively, also for very low starting concentrations (1 mg L). The removal of total chromium, on the contrary, was only 12.4%. Thanks to the magnetic properties, the same batch of ME-nFe was recovered and used effectively for three consecutive Jar tests.
将微藻-细菌共生体整合到现有的废水处理厂中作为替代生物处理方法，可以是提高这些设施可持续性的一个有趣选择。然而，产生的生物质的命运对于使该选择在经济上具有吸引力是决定性的。本研究旨在通过水热碳化来利用在中试规模下生长并用于处理城市污水污泥浓缩物的微藻，生产基于微藻的铁纳米颗粒（ME-nFe）。由于存在零价铁，最终产品具有高碳含量、强吸附能力和还原性能。测试了不同的合成条件，比较了硝酸铁九水合物（Fe(NO)·9HO）和硫酸铁铵十二水合物（NHFe(SO)·12HO）作为铁源、四种不同的 Fe/C 摩尔比（0.02、0.05、0.1、0.2）和三个工艺温度（180、200、225°C）。基于所有原型的表征，选择了最好的一个（比表面积为 110 mg），并通过Jar 试验测试其对选定重金属的去除效果。从污水处理厂处理后的废水中去除铜、锌、镉和镍的去除率分别为 99.6%、97.8%、96.4%和 80.3%，起始浓度也非常低（1 mg L）。相比之下，总铬的去除率仅为 12.4%。由于具有磁性，同一批 ME-nFe 被回收并有效地用于三个连续的 Jar 试验。
