Removal of Recalcitrant Compounds from Winery Wastewater by Electrochemical Oxidation

Abstract

The electro-oxidation of recalcitrant compounds, phthalic acid, tyrosol, and catechin was studied in simulated and real winery wastewater samples using a boron-doped diamond (BDD) anode. In the simulated samples, catechin, although presenting a higher removal rate than that of phthalic acid and tyrosol, attained lower combustion efficiency, indicating that this compound is readily converted into other products rather than being completely oxidized. On the other hand, phthalic acid was easily mineralized. Regarding the electro-oxidation assays performed with the spiked winery wastewater, recalcitrant compounds and overall organic load removal rates increased with applied current density (j), but the removal efficiency of recalcitrant compounds decreased with the increase in j, and the specific energy consumption was significantly raised. The increase in treatment time showed to be a feasible solution for the WW treatment at lower j. After 14 h treatment at 300 A m−2, phthalic acid, tyrosol, and catechin removals above 99.9% were achieved, with a chemical oxygen demand removal of 98.3%. Moreover, the biodegradability index was increased to 0.99, and toxicity towards Daphnia magna was reduced 1.3-fold, showing that the electro-oxidation process using a BDD anode is a feasible solution for the treatment of winery wastewaters, including phthalic acid, tyrosol, and catechin degradation.

Reuse of Pretreated Agro-Industrial Wastewaters for Hydroponic Production of Lettuce

“…When considering AIWW treatment options, two determining factors must be considered: the AIWW composition and characteristics and the intended quality of the treated effluent. Several different treatment technologies have been applied to AIWWs, such as physicochemical and biological processes, constructed wetlands, advanced oxidation processes, including electrochemical processes, and membrane technologies [1,[3][4][5]. Among the different processes described in the literature for AIWW treatment, immediate onestep lime precipitation (IOSLP) is presented as a simple and economic process that can be used to obtain, in a fast and efficient way, a clarified and disinfected effluent, rich in nutrients and with very low content in heavy metals, apparently capable of being reutilized for agricultural purposes [6].…”