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The performance and economic cost of the removal of phenol with TiO2 photocatalysis, photo‐Fenton reactions, biological aerated filter (BAF), and constructed wetland (CW) reactors has been studied. The BAF achieved complete removal with a maximum phenol concentration of 200 mg·L−1. The BAF‐CW combination provided a phenol‐free effluent with a maximum phenol concentration of 650 mg·L−1. In both cases, a complete detoxification of the treated water was achieved at the concentrations studied. The efficiency of TiO2 photocatalysis was limited to concentrations below 50 mg L−1 to minimize removal reduction and toxicity of the intermediates. Photo‐Fenton was more efficient, but also more expensive because of the high cost of H2O2. The photo‐Fenton‐BAF combination is proposed to be the most suitable one.

Abstract:A hybrid constructed wetland mesocosm has been used for the treatment of raw urban wastewater. The first stage was a mulch-based, subsurface, horizontal flow constructed wetland (HF). The HF achieved good removals of COD (61%; 54 g/m 2 ·day) and Total Suspended Solids (84%; 29 g/m 2 ·day). The second stage was composed of vertical flow constructed wetlands (VF) that were employed to study the effect of substrate (gravel vs. mulch), feeding mode (continuous vs. intermittent) and the number of stages (1 vs. 2) on performance. High hydraulic and organic surface loadings (513-583 L/m 2 ·day and 103-118 g/m 2 ·day of COD) were applied to the reactors. The mulch was more efficient than gravel for all the parameters analyzed. The continuous feeding allowed a 3 to 6-fold reduction of the surface area required.

A B S T R A C TThis work studies the elimination, mineralization and detoxification through Fenton-based processes of wastewaters contaminated with the fungicide imazalil as a result of the postharvest treatment of bananas. Fe(II) and H 2 O 2 concentrations were optimized for degradation of the corresponding imazalil concentrations. The activity of the imazalil degradation process was studied in deionized water and in simulated and real agroindustrial wastewaters. Results show that the water matrix had no detrimental effect on wastewater treatment when using the Fenton technique, but optimal iron content had to be increased when applying the photo-Fenton process. Even so, the optimal iron and H 2 O 2 contents required for the photo-Fenton reaction were 6 times and 50% lower, respectively, than for the Fenton procedure. Solar pilot plant tests confirmed the detoxification of two agro-industrial wastewater effluents containing imazalil.