Matrix influence on the treatment of emerging pollutants by advanced oxidation processes

Abstract

The shortage of fresh water in the world is a growing problem that, added to the high anthropogenic contamination of this resource, makes the advance in new technologies and developments of water recovery a priority need. Advanced oxidation processes (AOPs) can be an useful technique for the wastewaters treatment. Some AOPs need light and have used lamps of low or medium pressure as a source of UV radiation. The short life-time, high energy consumption and the presence of mercury in its components make it necessary to think of an alternative for these conventional lamps. Nowadays, studies have been carried out that suggest the source of LED light as a viable alternative, owing to LEDs have a low energy consumption, a long life-time and are mercury free. Besides the efficiency of the results of the oxidation of emerging pollutants through the photo-Fenton process, this process is used in this study but with LEDs (λ = 365-370 nm) for the treatment of the propranolol drug. On the other hand, an important aspect in the AOPs is the influence of the water matrix because it can significantly interfere with the process. For this reason, this project has experienced with four effluent waters from the secondary treatments from two different WWTPs. The treatments are: secondary with nutrient elimination, without elimination of nutrients, Integrated Fixed-film Activated Sludge (IFAS) and Membrane Bioreactor (MBR). However, ultrapure water has also been tested to make comparisons with the other matrices. All experiments have been carried out by setting a 2L batch reactor, 8W total power lamp and pH of 2.8. The ratio in ppm of Fe(II)/H2O2 used was 0.07 and the concentration of propranolol 50 ppm. Finally, it has been shown that with the Milli-Q water matrix, a 100% degradation is obtained at the end of the experiment in both BLB and LED. Regarding the WWTP matrices, the propranolol highest degradation corresponds to MBR with a result of 95.28% in BLB and AEN with 52.91% inLED. In contrast, IFAS showed degradations of 70.25% and 32.91% in BLB and LED respectively, being the matrix with the lowest degradation of the pollutant.