Wetsus, European Centre Of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA, Leeuwarden, The Netherlands E-mail:
Department Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands.
Water Sci Technol. 2022 Mar;85(6):1920-1935. doi: 10.2166/wst.2022.057.
In a wastewater treatment plant (WWTP), several sludge streams exist and the composition of their liquid phase varies with time and place. For evaluating the potential for formation of precipitates and equilibria for weak acids/bases, the ionic strength and chemical composition need to be known. This information is often not available in literature, and even neglected in chemical model-based research. Based on a literature review, we proposed three ranges of concentration (low, typical and high) for the major constituents of the liquid phase of the different streams in a WWTP. The study also discusses the reasons for the concentration evolution, and the exceptional cases, to allow readers to consider the right range depending on their situation. The ionic strength of the different streams and the contribution of its constituents were calculated based on the ionic composition. The major contributors to the ionic strength for the wastewater-based streams (influent, effluent and mixed sludge) were Na, Cl, Mg and Ca, representing 50-70% of the ionic strength. For digestate, NH and HCO accounted for 65-75% of the ionic strength. Even though the ionic strength is recognized to impact several important wastewater treatment processes, its utilization in literature is not always adequate, which is discussed in this study.
在废水处理厂 (WWTP) 中，存在多个污泥流，其液相的组成随时间和地点而变化。为了评估形成沉淀物的潜力和弱酸/弱碱的平衡，需要知道离子强度和化学成分。这些信息在文献中通常不可用，甚至在基于化学模型的研究中也被忽视。基于文献综述，我们为 WWTP 中不同流的液相的主要成分提出了三个浓度范围（低、典型和高）。该研究还讨论了浓度演变的原因和特殊情况，以使读者能够根据自己的情况考虑正确的范围。根据离子组成计算了不同流的离子强度及其组成部分的贡献。废水基流（进水、出水和混合污泥）的主要离子强度贡献者为 Na、Cl、Mg 和 Ca，占离子强度的 50-70%。对于消化物，NH 和 HCO 占离子强度的 65-75%。尽管离子强度被认为会影响几个重要的废水处理过程，但在文献中其利用并不总是充分的，本研究对此进行了讨论。
