Industrial wastewater often has high levels of salt, either due to seawater or e.g. sodium chloride (NaCl) usage in the processing. Previous work indicated that aerobic granular sludge (AGS) is differently affected by seawater or saline water at similar osmotic strength. Here we investigate in more detail the impact of NaCl concentrations and seawater on the granulation and conversion processes for AGS wastewater treatment. Glycerol was used as the carbon source since it is regularly present in industrial wastewaters, and to allow the evaluation of microbial interactions that better reflect real conditions. Long-term experiments were performed to evaluate and compare the effect of salinity on granulation, anaerobic conversions, phosphate removal, and the microbial community. Smooth and stable granules as well as enhanced biological phosphorus removal (EBPR) were achieved up to 20 g/L NaCl or when using seawater. However, at NaCl levels comparable to seawater strength (30 g/L) incomplete anaerobic glycerol uptake and aerobic phosphate uptake were observed, the effluent turbidity increased, and filamentous granules began to appear. The latter is likely due to the direct aerobic growth on the leftover substrate after the anaerobic feeding period. In all reactor conditions, except the reactor with 30 g/L NaCl, Accumulibacter was the dominant microorganism. In the reactor with 30 g/L NaCl, the relative abundance of Accumulibacter decreased to ≤1 % and an increase in the genus was observed. Throughout all reactor conditions, and , both actinobacteria, were present which were likely responsible for the anaerobic conversion of glycerol into volatile fatty acids. None of the glycerol metabolizing proteins were detected in . Accumulibacter which supports previous findings that glycerol can not be directly utilized by . Accumulibacter. The proteome profile of the dominant taxa was analysed and the results are further discussed. The exposure of salt-adapted biomass to hypo-osmotic conditions led to significant trehalose and PO-P release which can be related to the osmoregulation of the cells. Overall, this study provides insights into the effect of salt on the operation and stability of the EBPR and AGS processes. The findings suggest that maintaining a balanced cation ratio is likely to be more important for the operational stability of EBPR and AGS systems than absolute salt concentrations.

中文翻译：

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盐度对好氧颗粒污泥甘油转化及生物除磷的影响


工业废水通常含有大量盐分，原因可能是海水或废水等。氯化钠（NaCl）在加工中的使用。先前的工作表明，好氧颗粒污泥（AGS）在渗透强度相似的情况下受到海水或盐水的不同影响。在这里，我们更详细地研究了 NaCl 浓度和海水对 AGS 废水处理的造粒和转化过程的影响。甘油被用作碳源，因为它经常存在于工业废水中，并且可以评估更好地反映真实条件的微生物相互作用。进行长期实验来评估和比较盐度对造粒、厌氧转化、磷酸盐去除和微生物群落的影响。氯化钠浓度高达 20 g/L 或使用海水时，可实现光滑稳定的颗粒以及增强的生物除磷 (EBPR)。然而，在与海水浓度（30克/升）相当的氯化钠水平下，观察到厌氧甘油吸收和需氧磷酸盐吸收不完全，出水浊度增加，并且开始出现丝状颗粒。后者可能是由于厌氧饲喂期后剩余基质上的直接需氧生长所致。在所有反应器条件下，除了 30 g/L NaCl 的反应器外，Accumulibacter 是优势微生物。在含有 30 g/L NaCl 的反应器中，Accumulibacter 的相对丰度下降至 ≤1%，并且观察到该属有所增加。在所有反应器条件中， 和 ，两种放线菌都存在，这可能是甘油厌氧转化为挥发性脂肪酸的原因。中未检测到甘油代谢蛋白。 Accumulibacter 支持先前的发现，即甘油不能直接被利用。累积杆菌。分析了优势类群的蛋白质组谱并进一步讨论了结果。将适应盐的生物质暴露于低渗透压条件下会导致大量海藻糖和 PO-P 释放，这可能与细胞的渗透压调节有关。总体而言，本研究深入了解了盐对 EBPR 和 AGS 工艺的运行和稳定性的影响。研究结果表明，对于 EBPR 和 AGS 系统的运行稳定性而言，保持平衡的阳离子比例可能比绝对盐浓度更重要。