Use of Fractionation Procedures and Extensive Chemical Analysis for Toxicity Identification of a Chemical Plant Effluent

Abstract

As a part of a National Pollutant Discharge Elimination System (NPDES) biomonitoring program a series of toxicity tests was conducted with process water from a chemical plant using Ceriodaphniu dubia and Pimephales promelas. There were marked differences among the two tested species. The acute (LC50) values from 96-h static toxicity tests with Pimephulespromelas were always lower (higher toxicity) than the values obtained from the invertebrate tests. The concentration of ammonia in the effluent, particularly its un-ionized form (250 mg NH,-N/L, which represents 0.7 mg NH,-N/L), was above the threshold concentration for most freshwater species and therefore was the primary suspect of the toxicity present in the effluent.Prior to initiation of the toxicity identification evaluation (TIE) program, chemical analyses that included measurements of inorganic and organic parameters were conducted with the effluent. During the TIE fractionation, a portion of the sample was purged with nitrogen to remove volatile organics, and a second portion of the sample was pressure-filtered through a 0.45-1.lm filter. Because toxicity equal to the whole sample was found in these fractions, a portion of the inorganic fraction was subfractionated into zeolite, clinoptilolite, activated carbon, pH-adjustment, aeration, and cation fractions. The results of these tests confirmed that ammonia played a role in the sample's toxicity. However, when ammonia was removed from the effluent sample, toxicity was still present. Next organic chemicals were fractionated as suspected sources of toxicity. At first, organics were removed from the effluent by passing the filtered sample over an XAD-resin column. Because a portion of the reconstituted organic fraction was toxic, the organic fraction was subfractionated further by extracting with dichloromethane at pH > 11, pH < 2, and pH 7.1. The dichloromethane extracts were toxic, whereas the aqueous portions were not toxic. The neutral extract, which was more toxic than the basic and acidic extract, was further fractionated by using HPLC. Seventeen HPLC fractions were isolated and tested for toxicity to determine which constituent(s) were responsible for the observed whole effluent toxicity.

Toxicity identification evaluations of produced‐water effluents

“…Most applications of the TIE approach in the NPDES program have been directed to refinery wastewater effluents [10][11][12][13][14] and municipal wastewater effluents [15][16][17]. Research has also been conducted on specific aspects of toxicological causes in effluents, such as major cation and anion toxicity relationships in low-salinity effluents [18], trace metal chelation relationships [19], effects of brine addition [20], influence of pH on ammonia [21,22], and sensitivities of toxicity test species [23].…”

Development of procedures for identifying pesticide toxicity in ambient waters: Carbofuran, diazinon, chlorpyrifos

“…Concomitantly, increased attention has focused on methods of identifying the causes of toxicity so that appropriate control measures can be taken. These methods use a variety of approaches to separate toxic samples into different fractions and/or eliminate toxicity due to specific chemical classes [2][3][4][5][6][7][8]. Once the toxicity has been isolated, chemical analyses are used to further identify suspected toxicants.…”

Assessing the toxicity of chemically fractionated Hamilton Harbour (Lake Ontario) sediment using selected aquatic organisms

“…Although other researchers used benzene and MetOH, followed by a DCM rinse (Fabacher et al 1988;West et al 1988), the most commonly used extracting solvent has been DCM (Jop et al 1991;Middaugh et al 1991;Mueller et al 1991;Pollard & Hrudey 1992;Maguire et al 1993).…”