Feasibility of Photocatalytic Oxidation for Wastewater Clean-Up and Reuse

摘要

A feasibility study has been conducted on a new treatment technology for the destruction of pollutant compounds in wastewater. The process uses solar energy to drive an oxidation which is photocatalyzed at the surface of a semiconductor powder. The process is being investigated particularly for water clean-up prior to industrial resuse, because of its non-energy-intensive nature. Five compounds (chloroform, dimethylamine, methanol, phenol, and ammonia) were used as model substrates, and removal at several pH values, using three different semiconductors (TiO2, ZnO, and Fe2O3) was investigated in the laboratory, using a xenon lamp to simulate solar radiation. While Fe2O3 was found to be ineffective, both ZnO and TiO2 catalyzed the removal of all compounds. Ammonia was not very effectively destroyed, but all four organic compounds experienced 30-50% removal in six hours at intensities slightly above that of normal solar radiation. Favorable cases were confirmed using sunlight. Quantum efficiencies for both sets of experiments were 13-20% for TiO2 and 4-7% using ZnO. Estimated treatment cost for a 1 mgd stream using laboratory conditions ranged from $0.18-$0.72 per thousand gallons, depending on the values of engineering parameters which were not investigated in this feasibility study.