Removal of organic carbon from wastepaper pulp effluent by lab-scale solar photo-Fenton process

The bleaching wastewater effluent from a pulp and paper mill (located in Tianjin, China) was treated with solar photo-Fenton process in a lab-scale reactor (22cm×15cm thermostatic dish). The mill used wastepaper as raw material and the effluent contained 332mgL−1 of total organic carbon (TOC) and 1286mgL−1 of COD. The treatment involved a constant intensity of irradiation (0.2kW/m2) with a solar simulator of 250W xenon lamp and various conditions of pH, temperature, and initial concentrations of H2O2 and Fe(II). The better treatment conditions were searched for in the ranges of initial Fe(II) concentration from 31 to 310mgL−1 (initial pH 3.0, 30°C), initial H2O2 concentration from 0.5 to 3Dth (1Dth=1883mgL−1 for TOC mineralization) (initial pH 3.0, 30°C), initial pH from 2.0 to 6.0 (1 and 2Dth, 10:1 of H2O2/Fe(II), 30°C), and temperature from 30 to 50°C (1Dth, 10:1 of H2O2/Fe(II), initial pH 2.8). TOC removal generally showed the initial fast increase stage within the first sampling time of 15min, followed by the gradual increase stage in the remaining sampling time of 180min experimental time course. The highest percentage of TOC removal in the first stage was about 60% when the initial pH was either 2.8 (H2O2 =1Dth, ratio=10:1, temperature=30–50°C) or 3.5 (H2O2 =2Dth, ratio=10:1, temperature=30°C). Also under the latter condition, the value reached 82% at 120min and was projected to reach 94% at 180min. According to the positive effect of temperature increase on TOC removal observed in this experiment, further increase above these maximum values is possible if the temperature of the above condition were increased from 30 to 40°C or 50°C. Furthermore, under most of the treatment conditions, the TOC removal reached or was projected to reach over 60% toward the end of the experiments. The result indicated that the solar photo-Fenton process has a potential to effectively remove TOC from the wastepaper pulp effluent on a large scale. [Copyright &y& Elsevier]