Ionic strength of the liquid phase of different sludge streams in a wastewater treatment plant

Abstract

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 needs 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 3 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 was 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−, Mg2+ and Ca2+ representing 50–70% of the ionic strength. For digestate, and accounted for 65–75% of the ionic strength. Even though the ionic strength is recognised to impact several important wastewater treatment processes, its utilization in literature is not always adequate, which is discussed in this study.

Enhanced Arsenic Removal from Aqueous Solutions Via Magnesium Hydroxide Coated Iron Nanoparticles

“…Such results implied that the proposed nFe 0 @Mg(OH)2 can efficiently remove As(V) from aqueous solutions within a wide range of ionic strength. In terms of practicality, the investigated ionic strength range confirmed the possibility of employing nFe 0 @Mg(OH)2 in As(V) water treatment applications from either waste streams or groundwater [45,46].…”

Changes to Struvite Growth and Morphology as Impacted by Low Molecular Weight Organics

“…A simplified model solution of 0.1 M sodium chloride (NaCl) ,, mixed with LMW treatments was used as SWW, accounting for ionic strength commonly occurring in wastewaters and its effect on struvite growth ,, without interfering with experimental treatments by introducing competing precipitation reactions. The LMW functional groups of interest for SWW treatments were negatively charged carboxyl, positively charged amine, and nonpolar methyl (Figure ).…”

Characterizing Bacillus globigii as a Bacillus anthracis surrogate for wastewater treatment studies and bioaerosol emissions

“…The ionic strength of influent domestic wastewater is typically between 0.003 to 0.10 M (ref. 12 and 18) while the ionic strength of digestor recycle streams can be as high as 0.17 M. 18 Many municipal wastewater treatment plants also receive significant industrial discharges, which can have ionic strength levels that exceed 1 M. [36][37][38] Since ionic strength can impact the surface properties of Bacillus spores, future studies may investigate the effects of the higher ionic strength conditions (e.g. >1 M) present when a large volumetric fraction of the influent is received from industrial sources.…”

“…16,17 Therefore, experiments were carried out in deionized water (DI) and in phosphatebuffered solution (PBS) in order to evaluate the possible effects since the ionic strength of wastewaters may vary. 12,18 To help understand the results mechanistically, differences in BAS and BG aggregation were experimentally evaluated as a function of pH and ionic strength through optical microscopy and theoretical XDLVO analysis. Finding a safe surrogate for BAS is valuable; if large amounts of BAS were used in large scale pilot-or full-scale studies, it could pose a significant risk to wastewater treatment plant workers and the general public.…”