The electro-Fenton process (EFP) has been known as an effective process with highly outstanding oxidation power. In this study, the real pharmaceutical wastewater was successfully mineralized via EFP by using boron-doped diamond (BDD) anode and carbon-fiber brush cathode (CFB) with Fe2+/Fe3+/Co2+ cocatalysts. The effect of various parameters, including the electrode, ratio of cocatalysts, current density, pH, and O2 flow rate, was investigated. The TOC and COD removal efficiencies of 92% and 93%, respectively, were achieved. For the increase in biodegradability, BOD5/COD ratio increased from 0.1 to 0.69 after 2 h in the presence of Fe2+/Fe3+/Co2+ cocatalysts under optimal conditions in a batch experiment (current density of 17 mA cm−2, initial pH of 3, a Fe2+/Fe3+/Co2+ ratio of 1:1:2, O2 flow rate of 0.5 L min−1). In comparison, TOC and COD removal efficiencies were reached 81% and 85% after 10 h of reaction in a continuous-flow condition, respectively. The oxidation of pharmaceutical organic pollutants was mainly found by the electrochemically produced hydroxyl (OH) and sulfate (SO4−) radicals, followed by pseudo-first-order kinetics. Hence, EFP demonstrated the feasibility of potential technology for the treatment of real pharmaceutical wastewater. 

Fe2+, Fe3+, Co2+ as highly efficient cocatalysts in the homogeneous electro-Fenton process for enhanced treatment of real pharmaceutical wastewater

Successional dynamics of microbial communities in response to concentration perturbation in constructed wetland system.

Efficient hydrogen generation from the NaBH4 methanolysis by waste material: banana peel

Removal of ofloxacin from wastewater by chloride electrolyte electro-oxidation: Analysis of the role of active chlorine and operating costs

Electrochemical oxidation (EO) is a promising technology for water purification, but indirect environmental burdens may arise in association with consumption of materials and energy during electrode preparation and process operation. This study evaluated the life cycle environmental impacts of emerging EO technology from laboratory scale to industrial scale using prospective life cycle assessment (LCA) on a quantitative basis. Environmental impacts of EO technology were assessed at laboratory scale by comparing three representative anode materials (SnO2, PbO2, and boron-doped diamond) and other two typical processes (adsorption and Fenton method), which verified the competitiveness of the EO process and identified the key factors to environmental hotspots. Thereafter, LCA of scale-up EO was performed to offer guidance for practical application, and the life cycle inventory was compiled upon thermodynamic and kinetic simulations, empirical calculation rules, and similar technical information. Results demonstrated EO to be effective for destructing recalcitrant organic pollutants, but visible direct benefits might be outweighed by increased indirect environmental burdens associated with the preparation of anode materials, use of electrolytes, and energy consumption during the operation stage at both laboratory scale and larger scale. This necessitated attention to overall life cycle profiles by taking into account reactor design, anode materials, electrolyte and flow pattern, and decentralized location with a large share of renewable power station and rigorous contamination control strategies for wastewater treatment plants.

Prospective Life Cycle Assessment for the Electrochemical Oxidation Wastewater Treatment Process: From Laboratory to Industrial Scale.

Despite numerous efforts to treat wastewater with sulfonamides, their mineralization has rarely been achieved, resulting in the generation of more toxic by-products. In this study, greater than 75% mineralization of sulfamerazine (SMR) was achieved following 4 h of electrochemical oxidation. Remarkably, the Microtox® toxicity test confirmed the elimination of by-products with higher toxicity. The electrochemical treatment process was carried out using a dynamic oxygen-vacancy-mediated TiO2 anode (TiO2-OV@Ti-F), which comprised oxygen-deficient Ti4O7 coated on titanium-foam (Ti-F) via thermal spraying, allowing simultaneous high reactivity and mass transfer. SMR degradation followed a pseudo-first-order kinetics model, where the rate constant (kapp = 1.64 × 10−2 min−1) for the rotary TiO2-OV@Ti-F configuration was 1.98-fold greater than that of the static one (kapp = 8.30 × 10−3 min−1). This highlights the superiority of the rotary TiO2-OV@Ti-F anode for SMR decay. The high oxidation capabilities arose from: (i) the synergetic effect between the rotating system and the Ti4O7 coating; (ii) the enhanced mass transfer coefficient (3.49 × 10−5 m s−1) in the rotating configuration, as well as the increase in SMR degradation via direct oxidation, due to a low hole injection energy, as supported by density functional theory calculations; and (iii) boosted ˙OH formation achieved via removing the gas bubbles attached to the anode, along with lower adsorption energies for H2O and ˙OH. The results revealed that rotary TiO2-OV@Ti-F is a promising alternative for antibiotic wastewater treatment owing to its high organic mineralization and low level of energy consumption (0.29 kW per h per gTOC).

Jyh-Ping Hsu

Papers

A dynamic anode boosting sulfamerazine mineralization via electrochemical oxidation