Photocatalytical visbreaking of wastewater produced from polymer flooding in oilfields

Wastewater produced from polymer flooding in oilfields features a high viscosity and oily content because of a residue of high concentration of polyacrylamide (PAM). It is more difficulty efficiently to treat than that from water flooding by a conventional treatment system including gravitational settling and filtration. In this paper, initially by analyzing emulsification action and role of PAM in the wastewater, a process of photocatalytical visbreaking was proposed and investigated by taking aim at viscosity breaking and degradation of PAM in favor of further treatments. The experimental results show that viscosity of wastewater produced from polymer flooding is greatly decreased to the same level as that of distilled water under illumination of 5–10 min using photocatalytic degradation over TiO2 powders. The rate of PAM photogradation is above 90% within illumination of 90 min. The efficient breaking of viscosity favors treatments to feed the conventional system used in the water flooding with low viscosity of wastewater.