Effects of the operational parameters on carbon recovery and water flux in ultrafiltration using fractional factorial design

The distribution of molecular weight of natural organic matter on the effect of operational efficiency for water treatment units is very important, like coagulation, the biological activated carbon, and chlorination. This work discusses the following three topics: (1) The properties of humic acid were compared using fluorescent spectrometry and optical spectrometry; (2) the variations of carbon recovery and the water flux in the membrane filter after repeated rinsing with a 0.1 M sodium hydroxide and 10 ppm NaOCl mixed cleaner and reuse; and (3) the effect of operational parameters, such as the concentration of humic acid, the operating pressure, the mixer speed, and the fractional reduction in retentate volume, on the membrane filter during the fractionating of organic matter in a stirred cell using Statistica 7 software with fractional factorial design. Humic acid yields both fluorescent peaks of both 240/440 nm and 450/510 nm. Fluorescent organic matter with an emission wavelength of 510 nm can be removed using a 5 kDa polyethersulfone membrane filter with rinsing for 90 min. Rinsing with a mixed cleaner reduced both carbon recovery and water flux, but especially the latter. NaOCl solution included in the mixer cleaner should be considered not only because of its ability to destroy organic matter but also because it might transform the properties of the cleaning membrane surface. With respect to the absolute magnitude of the effect of the four factors on the water flux ratio, the humic acid concentration affected the carbon recovery more than the other three factors. The humic acid concentration is negatively correlated with carbon recovery. The operating pressure more strongly affects the water flux than do any of the other parameters. Furthermore, the operational pressure was positively correlated with the water flux.