Removal of natural organic matter from Lake Terkos by EC process: Studying on removal mechanism by floc size and zeta potential measurement and characterization by HPSEC method

Abstract

The performance of electrocoagulation (EC) process via aluminium and iron plate anodes were evaluated for removal of aquatic natural organic matter (NOM). The effect of current density (j), operation time (t(EC)), initial pH (pH(i)), charge loading and electrode types were investigated. The NOM removal efficiencies were measured with respect to dissolved organic carbon (DOC), UV254/VIS436 and specific UV-absorbance (SUVA) with initial value 6.58 mg DOC/L, 0.1363 1/cm, 0.004 1/cm and 2.07 L/(m mg), respectively. The experimental results showed that the effective removal of NOM (63.7% for DOC, 79.7% for UV254 and 76.7% for VIS436 (color) was obtained by iron electrode at original pH(i) of lake water (7.74 +/- 0.02) at 60 min. The adsorption capacity, q(t), (mg DOC per g produced Al and Fe or coulomb) were calculated at a specific electrolysis time. At 6 mA/cm(2) of optimum current density, 8.2 mg of DOC was removed per g in-situ produced Fe at original pH(i) of water. In addition the zeta potential and floc size analysis' were used to explicate the removal mechanism of NOM. The results of the size exclusion chromatography showed that the affinity of EC process is higher for the aromatic fraction of NOM during electrolysis time.