Combined use of physical-photoeletrochemical processes to remove substances which are responsible for taste and odor in drinking water

Abstract

One of the major problems on water treatment plants is the presence of substances that are responsible for earthy and musty taste and odors (G&O) in drinking water, which is the cause of most consumer complaints and considered indicators of drinking water quality. The main substances responsible for this off-flavour are geosmin (GSM) and 2-methylisoborneol (2-MIB), produced by blue algae (cyanobacteria) and actinomycetes. In Brazil, the first correlation of GSM and 2-MIB results in waters was published in 2005, which showed significant results from the detection of these compounds in drinking water. Data collected by SABESP between 2014 and 2016 and compared with the years 2002 and 2004 showed a significant drop in the average values of GSM and 2-MIB, this drop being due to the presence of an algaecide application protocol (pesticides used in the elimination of blue or cyanobacteria) in aquatic systems. However, the presence and detection of these compounds is still evident (in concentrations of the order of 6-10 ng L-1), requiring optimized technologies that aim to meet the drinking standards required by the Ministry of Health (MS), since the methods conventional treatment methods used in water treatment plants (coagulation, sedimentation and filtration) are considered inefficient in removing these two compounds. In this context, this project proposes the combined use of a physical-photoelectrochemical process to remove substances that add flavor and odor to drinking water, in order to obtain a low-cost, efficient and easy-to-operate large-scale treatment system. For this, separate optimization studies will be carried out on a pilot scale of the following processes: adsorption using activated carbon from yeast residue biomass, filtering membranes and photoelectrochemical process using nanostructured electrodes activated by visible light, and in the combined form: adsorption followed by photoelectrochemical process and filter membranes followed by a photoelectrochemical process. Estimation of the costs of implementing the most efficient process in water treatment plants will be carried out based on the kinetic and operational parameters obtained in the pilot scale tests. (AU)