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Advanced oxidation processes (AOPs) have led the way in the treatment of aqueous waste and are rapidly becoming the chosen technology for many applications. In this paper, COD reduction of textile industry wastewater by electro-Fenton (EF) oxidation, was studied at batch experimental conditions. The wastewater samples with a COD of 590 mg l^-1 in average were taken from the outlet of an equalization tank of a textile industry in the Marmara Region in Turkey. The wastewater samples were treated in a batch reactor equipped with two iron electrodes. The EF tests were conducted at different H₂O₂ doses such as 313, 626, 940, and 1253 mg l^-1 and constant electrical power of 24 W and pH of 3. For each EF test electricity consumption was determined based on per unit of COD mass removed
(kW kg^-1). The COD removal increased with decreasing H₂O₂ dose. The highest treatment efficiency was attained at 313 mg l^-1 of H₂O₂, by which more than 85% of COD was removed within 10 min of reaction time. These results indicate that the EF process can be considered as an alternative method for textile wastewater treatment. 

Hydrogen peroxide consumption is known to be one of the key parameters of the photo-Fenton process responsible for its high operating costs. The purpose of this study was to find out whether adding dissolved oxygen to the reaction medium in a continuous stream of pure oxygen or air with different H₂O₂ dosage strategies could improve the Dorfman mechanism, generating secondary oxidation species that could boost mineralization, and consequently, diminish H₂O₂ consumption. Experiments confirmed less efficient COD elimination. Additional DO slightly increased H₂O₂ consumption, as it initiated a series of reactions generating hydroxyl radical scavengers and H₂O₂ self-decomposition slowing down the reaction. At the same time, the study highlighted that automatic H₂O₂ dosing based on DO setpoints would be a highly attractive control option, however, more detailed studies on the initial amount of hydrogen peroxide and dosing rates must be undertaken.

Cu₂O photocatalyst is synthesized by solvothermal method. Morphology and structure of Cu₂O photocatalyst are analyzed by SEM, XRD and N₂ sorption technique. The catalytic performances and reaction kinetics of Cu₂O photocatalyst for the degradation of methylene blue (MB) are investigated. The toxicity effect of Cu₂O photocatalyst on yeast Saccharomyces cerevisiae is also studied. The results show pure Cu₂O photocatalyst with truncated octahedron morphology is obtained and demonstrates good potential on degradation of MB. The degree of MB degradation is improved significantly in the presence of H₂O₂, and the optimum H₂O₂ concentration is 1.3 wt%. The degradation rate constant decreases as the initial MB concentration increases, and the degradation reaction can be represented by pseudo-first-order kinetics model. Cu₂O photocatalyst shows a good reusability and slight limited growth rate of Saccharomyces cerevisiae, suggesting it can serve as an effective and recyclable photocatalyst.

Removal of Fe(II) and Mn(II) ions from aqueous solution by fungal biosorbent Aspergillus sp. TU-GM14immobilized on Detarium microcarpum matrix was investigated in this study. Effects of biosorption parameters pH, biosorbent concentration, bead size and equilibrium time on Fe(II) and Mn(II) ions sorption were also determined. Equilibrium was attained within in 3 hours while optimum Fe(II) and Mn(II) ions removal was observed at pH 6, 8 mm bead size, 2 g l^-1 spore load respectively. Adsorption capacity was described using Langmuir, Freundlich and BET isotherm models. The experimental data fitted best to the Freundlich model (R² 0.992 and 0.996 for Mn(II) and Fe(II) respectively). Favourable surface sorption process was described by Langmuir isotherm for both metals (Q_max 34 and 14 mg g^-1 for Mn(II) and Fe(II) ions) while the BET isotherm constant, B, described high metals sorption beyond the biosorbent surface in a multi-layer sorption process (4.8 and 9.0 for Mn(II) and Fe(II)  respectively). Results of the study showed that Aspergillus sp. TU-GM14 biosorbent can remove large quantities of Fe(II) and Mn(II) ions from solution in both surface and multi-layer sorption process with Detarium microcarpum acting as a cheap immobilization matrix.