Fenton- and fenton-like AOPs for wastewater treatment:: From Laboratory-to-plant-scale application

Fenton- and Fenton- like AOPs systems have been utilized for the oxidative degradation of some chlorinated pollutants such as chloral hydrate or 1,1,1-trichloroethane, and for the treatment of real industrial wastewaters. Both ferrous sulfate (FeSO(4) center dot 7 H(2)O) and Mohr's salt (NH(4))(2)Fe(SO(4))(2)center dot 6 H(2)O have been used as Fe(2+)-ion sources. With Mohr's salt ( MS) the Fenton- and Fenton- like reaction has been successfully carried out under acidic ( pH 3) and neutral ( pH 7) reaction conditions. The new Fenton- like system utilizes zero-valent iron (Fe(o)) instead of ferrous sulfate has been applied for the 1,1,1-trichloroethane and chloral hydrate degradation. Similarly, the application of catechol- and hydroquinone- driven Fenton reaction for the degradation of chloral hydrate under acidic and neutral pH is a new Fenton- like AOPs approach. The photo-Fenton- like reactions such as Fe(3+)/h nu, Fe(2+)/H(2)O(2)/h nu, and ferrioxalate system have been also studied for the degradation of chloral hydrate. As an irradiation source a daily light or sun light have been used. In comparison with photoreactor experiments the best system was observed to be Fe(3+)/h nu. In some experiments the influence of standing time prolongation after Fenton reaction on the final degradation efficiency due to hydrolysis of intermediates such as phosgene (CCl(2)=O) has also been studied. The Fenton reaction was successfully utilized for the treatment of real industrial wastewaters, in two cases even in plant-scale applications.