The influence of organic carbon concentration on atrazine removal by UF membranes

The primary objective of the study described in the present paper was to investigate the problem of how the concentration of organic matter (expressed as dissolved organic carbon, DOC) contributes to the efficiency of separating atrazine form aqueous solutions by ultrafiltration. Another objective was to examine how the type of organic matter (humic substances HS, tannic acid TA) may affect the efficiency of atrazine separation. A series of experiments was carried out with model solutions containing atrazine (1000 mg/m3), humic substances (10, 20, 50 g/m3) or tannic acid (5, 10, 15, 20 g/m3) at a neutral pH. The ultrafiltration process involved a DS-GE polysulfone/polyamide membrane (Osmonics) and a transmembrane pressure of 0.1 and 0.3 MPa. The highest atrazine rejection coefficient (80%) was achieved at the organic matter concentration, DOC = 8.1 g C/m3.

1. The efficiency of atrazine separation from aqueous solutions in the ultrafiltration process is noticeably affected by two factors: dissolved (or total) organic carbon (DOC or TOC) concentration and type of organic matter. 2. The effect of atrazine removal was found to be much better when humic substances were present in the treated solution. The increase of TOC concentration by 9.5 gC/m3 for the organic compounds raised the atrazine rejection up to 79.6% and 47.0% for humic substances and tannic acid, respectively (for DSGE membrane and pressure difference 0.1 MPa).