Paracetamol biodegradation by activated sludge and photocatalysis and its removal by a micelle–clay complex, activated charcoal, and reverse osmosis membranes

Abstract

<p>Kinetic studies on the stability of the pain killer paracetamol in Al-Quds activated sludge demonstrated that paracetamol underwent biodegradation within less than one month to furnish <i>p</i>-aminophenol in high yields. Characterizations of bacteria contained in Al-Quds sludge were accomplished. It was found that <i>Pseudomonas aeruginosa</i> is the bacterium most responsible for the biodegradation of paracetamol to <i>p</i>-aminophenol and hydroquinone. Batch adsorptions of paracetamol and its biodegradation product (<i>p</i>-aminophenol) by activated charcoal and a composite micelle (octadecyltrimethylammonium)–clay (montmorillonite) were determined at 25°C. Adsorption was adequately described by a Langmuir isotherm, and indicated better efficiency of removal by the micelle–clay complex. The ability of bench top reverse osmosis (RO) plant as well as advanced membrane pilot plant to remove paracetamol was also studied at different water matrixes to test the effect of organic matter composition. The results showed that at least 90% rejection was obtained by both plants. In addition, removal of paracetamol from RO brine was investigated by using photocatalytic processes; optimal conditions were found to be acidic or basic pH, in which paracetamol degraded in less than 5 min. Toxicity studies indicated that the effluent and brine were not toxic except for using extra low energy membrane which displayed a half maximal inhibitory concentration (IC-50) value of 80%.</p