Major Ion Toxicity in Effluents: A Review With Permitting Recommendations

Abstract

Effluent toxicity testing methods have been well defined, but for the most part, these methods do not attempt to segregate the effects of active ionic concentrations and ion imbalances upon test and species performances. The role of various total dissolved solids in effluents on regulatory compliance has emerged during the last few years and has caused confusion in technical assessment and in permitting and compliance issues. This paper assesses the issue of ionic strength and ion imbalance, provides a brief summary of applicable data, presents several case studies demonstrating successful tools to address toxicity resulting from salinity and ion imbalance, and provides recommendations for regulatory and compliance options to manage discharges with salinity/ion imbalance issues. Effluent toxicity resulting from inorganic ion imbalance and the ion concentration of the effluent is pervasive in permitted discharge from many industrial process and municipal discharges where process streams are concentrated, adjusted, or modified. This paper discusses procedures that use weight-of-evidence approaches to identify ion imbalance toxicity, including direct measurement, predictive toxicity models for freshwater, exchange resins, mock effluents, and ion imbalance toxicity with tolerant/ susceptible text species. Cost-effective waste treatment control options for a facility whose effluent is toxic because of total dissolved solids (TDS) or because of specific ion(s) are scarce at best. Depending on the discharge situation, TDS toxicity may not be viewed with the same level of concern as other, more traditional, toxicants. These discharge situations often do not require the conservative safety factors required by other toxicants. Selection of the alternative regulatory solutions discussed in this paper may be beneficial, especially because they do not require potentially expensive or high-energy-using treatment options that may be ineffective control options. The information presented is intended to provide a better understanding of the role of ion imbalance in aquatic toxicity testing and to provide various recommendations that should be considered in addressing these issues.

Reusing wastewater to cope with water scarcity: Economic, social and environmental considerations for decision-making

“…Pedrero et al (2010) discussed the most common water quality problems when reusing water for agricultural irrigation. These are: specific ion toxicity (plants take up certain ions like sodium, chloride, and boron) (Goodfellow et al, 2000); soil permeability caused by sodium that alters soil structure, the water infiltration rate and soil aeration (Menneer et al, 2001); nutrients, but only when there might be an imbalance between the uptake and the provision (Minhas and Yadav, 2015); microbiological content (pathogens, residual drugs, organic compounds, endocrine disruptor compounds and active residues of personal care products) (Shargil et al, 2015); miscellaneous problems (clogging problems in the irrigation system or excessive residual chlorine) (Elbana et al, 2012). An important parameter to decide on the economic feasibility of a reuse plan in agriculture is salinity, as this is not reduced by regular treatments, but requires environmental and economic costly solutions such as reverse osmosis (Haruvy, 1997;Ghyselbrecht et al, 2012).…”

Effects of environmentally relevant mixtures of major ions on a freshwater mussel

“…Elevated major ion concentrations in freshwaters can induce osmotic stress in freshwater organisms (McCulloch et al, 1993). The toxicity of major ions to freshwater organisms depends upon both the concentration and the ionic composition (Goodfellow et al, 2000;Mount et al, 1997;Soucek and Kennedy, 2005).…”

Bioenergetic effects of sodium sulfate on the freshwater crustacean, Ceriodaphnia dubia

“…While a wealth of literature exists on the physiological effects observed in organisms exposed to changes in salinity when sodium and chloride are the dominant ions, i.e., seawater (e.g., Aarset and Aunaas 1990;Arné r and Koivisto 1993;Cowgill and Milazzo 1990;Guerin and Stickle 1992;Richmond and Woodin 1999), only recently has toxicity of effluents dominated by other ''major ions'' (particularly sodium and sulfate) in freshwater systems received increasing attention (Goodfellow et al 2000). Common sources of effluents with elevated total dissolved solids (TDS), which in freshwater is essentially the sum of the concentrations of all common ions, include reverse osmosis systems, pH modifications of waste water, agricultural runoff, gas and oil production, and coal or metal mining operations (Goodfellow et al 2000).…”

“…Common sources of effluents with elevated total dissolved solids (TDS), which in freshwater is essentially the sum of the concentrations of all common ions, include reverse osmosis systems, pH modifications of waste water, agricultural runoff, gas and oil production, and coal or metal mining operations (Goodfellow et al 2000). Sodium and sulfate are two of the most common dominant ions in effluents associated with the coal industry, and the fact that toxicity of TDS in general and sodium sulfate in particular is dependent on characteristics like hardness, number of major cations, and chloride concentration of a water or effluent has been well established (e.g., Kennedy et al 2005;Mount et al 1997;Soucek and Kennedy 2005).…”