Commercial Laundry Water Characterisation

Abstract

Surfactants are the major active ingredients of laundry detergents. Therefore, special attention should be focused on the treatment and disposal of laundry wastewater. The aim of this study was to characterise the wastewater from a commercial laundry over 30 days. Physicochemical analyses were performed, monitoring the content of nitrogen, phosphate, heavy metals, linear alkylbenzene sulphonate (LAS), volatile organic acids and alcohols. The pH was approximately 5.6 and the COD approximately 4800 mg · L － 1 . The average concentrations of sulphate, sulphide, N-ammoniacal organic nitrogen compounds and heavy metals were below the maximum limit, in accordance with local and national environmental legislation, and the average total suspended solids was 0.08 g · L － 1 . Among the metals analysed, iron was observed with the highest concentrations (0.037 mg · L － 1 and 0.72 mg · L － 1 ). Phosphate was detected in 93% of samples (94.65 mg · L － 1 average). LAS was detected in all samples (12.24 mg · L － 1 to 1023.7 mg · L － 1 ). Thirty-three different xenobiotic organic compounds were identified in the laundry wastewater with the qualitative screening. The major groups of the compounds were fragrances, preservatives, solvents and some surfactants. Although the characterisation indicated low values for many parameters, this does not eliminate the need for specific treatment before its disposal at the sewage system .