Effects of 2-Sulfonatofatty Acid Methyl Ester (α-SFMe) on Aquatic Organisms and Activated Sludge

Effects of 2-sulfonatofatty acid methyl ester (α-SFMe) on aquatic organisms and activated sludge were studied. Acute fish toxicity was determined using Japanese killifish (Oryzias latipes) with individual homologues of α-SFMe (C12, C14 or C16 alkyl chain length) and C14/C16-mixed α-SFMe, according to JIS K 0102 “Testing Methods for Industrial Wastewater-Acute Toxicity Test with Fish”. The 96 h lethal concentration fifty (LC50) values for C16-, C14- and C12-α-SFMe were 1.3, 24 and 298 mg/L, respectively, thus indicating the fish toxicity of α-SFMe to decrease with decreasing alkyl chain length. The 96 h LC50 of mixed α-SFMe was 2.4 mg/L, this being essentially the same as that of alkylbenzene sulfonate (LAS) or α-olefinsulfonate (AOS). The effect of α-SFMe on fish mortality during biodegradation was also determined. Biodegradation was shown to bring about significant reduction in toxicity. The effects of α-SFMe on oxidative performance of activated sludge were examined by the Japanese MITI test by measuring oxygen consumption of mixed liquor containing glucose and glutamic acid. Oxygen consumption was not affected at a significantly higher concentration (50 mg/L) of α-SFMe in the test liquor. The effects of α-SFMe on anaerobic digestion of excess sludge were studied by measuring the volume and components of gas produced in the digester. The volume of generated gas and components were not affected even at an extremely higher concentration of mixed α-SFMe (12 mg/g dry sludge) in the anaerobic digester.