Treatment of microfiber alkali weight-reduction wastewater with high salt concentration by Fenton oxidation and bacterial degradation

Alkali weight-reduction is a necessary process to remove the sea component (polyesters) by alkali for 'sea-island' microfiber manufacture, in which large amounts of wastewater with high content of Na2SO4, ethylene glycol (EG) and terephthalic acid (TPA) were produced, thus making the traditional activated sludge method being invalid for wastewater treatment. To address this issue, a combination method was employed to treat the wastewater, i.e. the wastewater was treated by Fenton oxidation then followed by bioaugmentation process, simultaneously, the degradation characteristics of combined method were investigated in detail. In the first stage, the wastewater was treated by optimised Fenton's reagent, some stable compounds were found to degrade into metastable molecules; In the second stage, a new halotolerant bacteria, which could efficiently degrade EG, was isolated from the soil and added into the activated sludge to further degrade the oxidized wastewater. The results indicated that wastewater was treated by this combination method, the chemical oxygen demand (COD) and total organic carbon (TOC) decreased from 9070 and 4656.9 mgO(2)/L to 150 and 13.05 mgO(2)/L, showing an obvious positive effect. Moreover, the two-dimensional fractal dimension (D-2f) of activated sludge was also found to be enhanced, again demonstrating the positive effect among bacteria, activated sludge and chemical reaction.