Review: Clay-Modified Electrodes in Heterogeneous Electro-Fenton Process for Degradation of Organic Compounds: The Potential of Structural Fe(III) as Catalytic Sites

Advanced oxidation processes are considered as a promising technology for the removal of persistent organic pollutants from industrial wastewaters. In particular, the heterogeneous electro-Fenton (HEF) process has several advantages such as allowing the working pH to be circumneutral or alkaline, recovering and reusing the catalyst and avoiding the release of iron in the environment as a secondary pollutant. Among different iron-containing catalysts, studies using clay-modified electrodes in HEF process are the focus in this review. Fe(III)/Fe(II) within the lattice of clay minerals can possibly serve as catalytic sites in HEF process. The description of the preparation and application of clay-modified electrodes in the degradation of model pollutants in HEF process is detailed in the review. The absence of mediators responsible for transferring electrons to structural Fe(III) and regenerating catalytic Fe(II) was considered as a milestone in the field. A comprehensive review of studies investigating the use of electron transfer mediators as well as the mechanism behind electron transfer from and to the clay mineral structure was assembled in order to uncover other milestones to be addressed in this study area.

Adsorbents for Removal of Hazardous Metals from waste water and natural water samples: A Review

Wide ranges of low cost adsorbents were used to remove hazardous metal in aqueous solution and wastewater. The low cost adsorbents were usually collected from agricultural waste, seafood waste, food waste, industrial by-product and soil. These adsorbents are readily available in a copious amount. Some of the natural adsorbents appeared as good heavy metal removal, while some were not and require further modifications and improvements to enhance the adsorption capacity. Currently, heavy metals exist in most of the industrial wastewaters and water supplies are among the most severe environmental contaminants. Numerous research works have been conducted in this field, this review includes few potential solution containing papers.

Chemically Enhanced Biodegradation of High Organic Matter in Wastewater – Confectionary Plant Effluents

The study explored the merit of chemically enhanced biodegradation of high organic matter as a sustainable treatment scheme for industrial wastewaters. For this purpose, an integrated, chemically enhanced activated sludge configuration was tested for confectionary effluents with a COD level of around 10.000 mg L-1. In this configuration, chemical settling acted as a polishing step, which removed 50% of the total COD load, including 10% of colloidal COD in the soluble COD range. The sequential batch reactor, selected as the final biological treatment step, was able to remove the remaining biodegradable COD completely. The study primarily demonstrated the merit of in-plant pollution footprint assessment and wastewater characterization with significant COD fractions as necessary prerequisites for the management and final biodegradation of industrial wastewaters with high organic matter content.

Effect of High-Speed Railways on City Industrial Sewage Discharge

Industrial wastewaters threatening the sustainability of society have increasingly become a key social issue across the globe. Consequently, countermeasures have been suggested across a broad range of research fields and policy cycles in both industrialized and industrializing countries. Thus, identifying factors that drive reductions in industrial wastewater discharge is a key task in the water research and policymaking fields. In contrast to previous studies that have focused on reducing industrial wastewater discharge through techniques, policy, management, and other tools, the aim of this study was to investigate the effect of transport infrastructure development, particularly high-speed railways (HSR), on industrial sewage discharge. Given the rapid development of high-speed railways in China and the country’s severe water pollution, China was our research context, and our sample was 298 prefecture-level Chinese cities during the period 1999–2018. The empirical results show that cities with high-speed railways have greater reductions in industrial wastewaters, and that these effects are weakened in cities with a more developed economy and information environment. The results are consistent when using different methods to test their robustness, such as time-varying difference-in-difference (DID), instrumental variables, and placebo tests. These findings offer useful guidance for practitioners and policymakers in the management of water resources and the development of transport infrastructure in cities. These results contribute to the literature in the field of water management and to the assessment of the broader effect of high-speed railways.