(60c) The Effect of Advanced Oxidation on Physicochemical Properties of Natural Organic Matter (NOM) in Water

Natural organic matters (NOM) present in all surface, ground waters and terrestrial ecosystems. Due to their complex nature, microbial degradation of NOM is not sufficient to completely mineralize them under natural conditions. The presence of NOM in water effect on water quality by causing color, taste and odor problems. NOM are the precursor for formation of disinfection by product (DBPs) which are suspected as the carcinogenic compounds. Therefore, NOMs need to be removed from drinking water. The major limiting factors for using membrane technology for removal of NOM from water is that NOM fouls the membrane surface and decreases process efficiency and membrane lifetime. UV-based advanced oxidation processes (UV-AOPs) have been shown as effective methods for the removal of organic materials in water. In this work, a batch photoreactor with a 450-W UV lamp with high-pressure mercury vapor was used to evaluate the UV/H₂O₂ oxidation process for the removal of humic acids from water. We found 88% decrease in total organic carbon (TOC) also 95% decrease in concentration of humic acid as representative NOM from solution by using UV/H₂O₂. Also, UV/H₂O₂ treatment changed the physicochemical properties of humic acid (HA) aggregates by reducing the super-micrometer size range (>1μm) aggregates to a bimodal distribution of two sub-micrometer size ranges <1μm (10â??100 nm and 100â??1000 nm) and increased the zeta potential of HA solution due to the production of new functional groups. Furthermore, sequential using of AOPs / membrane filtration enhanced membrane filtration performance. We found membrane flux decline at 120 min improved from 21% up to 80% and increased the Flux Recovery Ratio (FRR%) from 58% to 80% for the cross flow polysulfone (PSF) ultrafiltration membrane. At the end, the removal of humic acid (HA) was compared by other photocatalytic processes including UV/TiO₂.