A study on the removal of humic acid using advanced oxidation processes

Humic acid ( HA) removal using advanced oxidation processes (AOPs) was investigated, particularly UVA/H2O2 and photo Fenton-like process (UVA/Fe(III)/ H2O2). Changes in the UV254 absorbance, dissolved organic carbon (DOC), apparent molecular weight (AMW) distribution, and the Trihalomethane formation potential (THMFP) of the organics were monitored. UVA/Fe( III)/H2O2 based process was found to be effective in removing more than 80% DOC and 90% UV254 absorbance. Differences in the reduction profiles of AMW distributions for UVA/ Fe( III)/ H2O2 based process and UVA/ H2O2 process were observed, with the latter showing preferential removal of a certain molecular weight range. Selected samples were then fractionated into four components: very hydrophobic acids (VHA), slightly hydrophobic acids (SHA), hydrophilic charged (CHA), and hydrophilic neutral (NEU). The HA used is found to consist mostly of VHA fraction that is very susceptible to AOP treatments. The results illustrate that the degradation process occurred via the fragmentation of VHA fraction to form SHA, CHA, and NEU fractions.