Wastewater treatment anionic surfactants

The primary application of these alcohols is the manufacture of anionic or nonionic surfactants for personal cleansing products, most of which end up in your wastewater treatment plants and rivers. Microorganisms don t chew up branch-chain surfactants as well as they do the straight ones. It used to be, for example that the surfactant based on the sodium salt of dodecyl benzene sulfonate, a 12-carbon branch chained anionic surfactant, was found to be slowing, down water treatment processes. Dodecyl alcohol as a raw material for these surfactants has been largely replaced by laurel alcohol, a 12-carbon straight-chain, linear alcohol. If you look at the bottle next time you shampoo your hair and rinse, you ll see sulfonates based on laurel alcohol listed, but none based on dodecyl. 

AES are typically measured in environmental matrices by nonspecific colorimetric analyses (MBAS) that collectively measure LAS, AS, and naturally occurring anionic surfactants. Alternatively, a specific gas chromatographic method for AES, developed by Neubecker (55), was employed to measure AES concentrations in influent and effluent from STPs and river water. Total AES measured in influent wastewater to a STP was 1.88 mg/L. AES removal of 94-100% was measured during actual sewage treatment by activated sludge the resulting effluent concentration was 0.06 mg/L. Total AES levels in river water were less than 0.01 mg/L. AES accounted for 6-13% of MBAS measured in natural water. 

In this context also, the electrochemical oxidation was proposed as effective process of wastewater treatment. Among surfactants, sodium dodecyl benzenesulfonate is generally assumed to represent anionic surfactants, whereas hexadecyltrimethy-lammonium chloride is assumed as representing the cationic class. 

Oxidation of sulphuric solutions of anionic surfactants was considered by Panizza and co-workers (Panizza et al. 2005) which compared the performance of ternary Ti-Ru-Sn oxide and BDD electrodes during oxidative treatment of synthetic and real wastewater containing sodium dodecyl benzenesulfonate. The authors demonstrated that the anionic surfactant was mineralised at active Ti-Ru-Sn electrodes only when a certain amount of chlorides were added to the solution. The process mainly occurred in homogeneous reaction by means of the oxidant species originated by chlorides, since it was not influenced by the stirring velocity of the solution. 

Solubilization in polymer-surfactant aggregates adsorbed at the solid—liquid interface has been recently presented by Esumi et al. as a promising tool in wastewater treatment research [46]. Their study concerns the adsolubilization of 2-naphtol into PVP-anionic surfactants adsorbed at the alumina-water interface. Two surfactants were used SDS and Aerosol OT. 

Adachi A., M. Kamide, R. Kawafume, N. Miki, and T. Kobuyashi (1990). Removal-efficiency of anionic and nonionic surfactants from chemical wastewater by a treatment plant using activated carbon adsorption and coagulation precipitation processes. Environmental Technology 11 133-141. 

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