Pandhal Jagroop, Siswanto Anggun, Kuvshinov Dmitriy, Zimmerman William B, Lawton Linda, Edwards Christine
Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, United Kingdom.
Vocational School, Diponegoro University, Semarang, Indonesia.
Front Microbiol. 2018 Apr 5;9:678. doi: 10.3389/fmicb.2018.00678. eCollection 2018.
There has been a steady rise in the incidences of algal blooms globally, and worryingly, there is increasing evidence that changes in the global climate are leading to a shift toward cyanobacterial blooms. Many cyanobacterial genera are harmful, producing several potent toxins, including microcystins, for which there are over 90 described analogues. There are a wide range of negative effects associated with these toxins including gastroenteritis, cytotoxicity, hepatotoxicity and neurotoxicity. Although a variety of oxidation based treatment methods have been described, ozonation and advanced oxidation are acknowledged as most effective as they readily oxidise microcystins to non-toxic degradation products. However, most ozonation technologies have challenges for scale up including high costs and sub-optimum efficiencies, hence, a low cost and scalable ozonation technology is needed. Here we designed a low temperature plasma dielectric barrier discharge (DBD) reactor with an incorporated fluidic oscillator for microbubble delivery of ozone. Both technologies have the potential to drastically reduce the costs of ozonation at scale. Mass spectrometry analysis revealed very rapid (<2 min) destruction of two pure microcystins (MC-LR and MC-RR), together with removal of by-products even at low flow rate 1 L min where bubble size was 0.56-0.6 mm and the ozone concentration within the liquid was 20 ppm. Toxicity levels were calculated through protein phosphatase inhibition assays and indicated loss of toxicity as well as confirming the by-products were also non-toxic. Finally, treatment of whole cells showed that even at these very low ozone levels, cells can be killed and toxins (MC-LR and Desmethyl MC-LR) removed. Little change was observed in the first 20 min of treatment followed by rapid increase in extracellular toxins, indicating cell lysis, with most significant release at the higher 3 L min flow rate compared to 1 L min. This lab-scale investigation demonstrates the potential of the novel plasma micro reactor with applications for treatment of harmful algal blooms and cyanotoxins.
全球范围内藻华事件的发生率一直在稳步上升，令人担忧的是，越来越多的证据表明全球气候变化正导致藻华向蓝藻水华转变。许多蓝藻属是有害的，会产生多种强效毒素，包括微囊藻毒素，已描述的微囊藻毒素类似物有90多种。这些毒素会产生广泛的负面影响，包括肠胃炎、细胞毒性、肝毒性和神经毒性。尽管已经描述了多种基于氧化的处理方法，但臭氧化和高级氧化被认为是最有效的，因为它们能轻易地将微囊藻毒素氧化为无毒的降解产物。然而，大多数臭氧化技术在扩大规模方面存在挑战，包括成本高和效率不理想，因此，需要一种低成本且可扩展的臭氧化技术。在这里，我们设计了一种低温等离子体介质阻挡放电（DBD）反应器，并集成了用于微气泡输送臭氧的流体振荡器。这两种技术都有潜力在大规模应用中大幅降低臭氧化成本。质谱分析表明，两种纯微囊藻毒素（MC-LR和MC-RR）在极短时间内（<2分钟）被破坏，即使在低流速1 L/min（气泡大小为0.56 - 0.6毫米，液体中臭氧浓度为20 ppm）的情况下，副产物也能被去除。通过蛋白质磷酸酶抑制试验计算毒性水平，结果表明毒性消失，同时也证实了副产物也是无毒的。最后，对整个细胞的处理表明，即使在这些极低的臭氧水平下，细胞也能被杀死，毒素（MC-LR和去甲基MC-LR）也能被去除。在处理的前20分钟内观察到变化不大，随后细胞外毒素迅速增加，表明细胞裂解，与1 L/min相比，在3 L/min的较高流速下释放最为显著。这项实验室规模的研究证明了新型等离子体微反应器在处理有害藻华和蓝藻毒素方面的应用潜力。
