Transformative Catalysis Purifies Municipal Wastewater of Micropollutants

Abstract

We describe the use of TAML/peroxide to reduce micropollutants (MPs) in Tucson, AZ, secondary municipal wastewater. The laboratory studies establish simple-to-apply MP abatements rivaling ozone in technical performance. The approach rests on the latest-generation TAML catalyst, 2, currently the highest-technical performance H2O2 activator across both chemistry and biology. Thirty-eight MPs were examined with five 2/H2O2 treatments (50 nM 2 with 22.4 ppm H2O2, 100 nM 2 with 11.2 ppm H2O2, 100 nM 2 with 22.4 ppm H2O2, 200 nM 2 with 11.2 ppm H2O2, and 200 nM 2 with 22.4 ppm H2O2) and four ozone treatments (2, 4, 6, and 8 ppm). Satisfactory analytical data were returned for 25 MPs that were monitored kinetically (LC-MS/MS) from 6 min to 6 h. For all 2/H2O2 conditions, decreases in MP concentration had either ceased at 30 min or showed marginal improvements at 1 h remaining constant to 6 h. The highest-performance 2/H2O2 system (200 nM 2 with 22.4 ppm H2O2) outperformed 2 ppm ozone virtually across the board, delivering micropollutant percent reductions (MPPRs) of 26−98% corresponding to performance advantage ratios over 2 ppm ozone of ∼0.9− 8. These data indicate that 2 (1 kg at 70 nM) and H2O2 (53.55 kg at 11.2 ppm) would treat the daily wastewater output of 150,000 Europeans [150 L day−1 (population equivalent)−1, 22,500 tons total] in a manner comparable to that of a common ozone administration of 3 ppm, establishing a new approach worthy of further optimization for municipal wastewater MP treatment.