Wastewater treatment cationic surfactants

Few data have been published on cationic surfactants in aquatic sediments. Levels from 3 to 67 mg kg-1 were determined in sediment samples from Rapid Creek [54] and 6-69 mg kg-1 concentrations were found in sediment samples from Japan [4]. DTD MAC was reported in digested sewage sludge at levels ranging from 0.15 to 5.87 gkg-1 [22]. Also, cationic surfactants were determined in urban coastal environments and they were reported as markers [18,55]. In our work, concentrations of BAC ranged from 23 to 206 p,gkg 1 in sediment samples from different rivers near to wastewater treatment plants,... 

Cationic surfactants are used widely as fabric softeners, anti-static agents, antiseptic components and as the main ingredients in rinse conditioner products. However, there is little data on their occurrence in wastewater and removal during wastewater treatment. The concentrations of some cationic surfactants and their biodegradation intermediates, found in WWTP influents and effluents, are listed in Table 6.1.3. 

In general, the main pollution problems associated with surfactants can be summarized as (1) foaming in river and wastewater treatment plants [314,326, 344,348,349,356,357], (2) transformation to bioactive metabolites (i.e., poly-ethoxylated alkylphenols, estrogenic compounds) under aerobic and anaerobic conditions [315,356], and (3) formation of certain cationics which are toxic to microorganisms at high concentrations [356,357]. 

Initial and residual cationic surfactant concentrations in a water or wastewater treatment system can be determined by titration methods, colorimetric methods, or UV method [69-71, 77-79,81]. Additional references for cationic surfactant removal are available elsewhere [44,45,51,65,66]. 

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. 

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