Detection and Mineralization of Organic Pollutants in Mesopotamian Marsh Water Using a Batch Bioreactor

Catalytic ozonation for water and wastewater treatment: Recent advances and perspective

Advances in catalytic oxidation of organic pollutants – Prospects for thorough mineralization by natural clay catalysts

Mineralization of organic pollutants by anodic oxidation using reactive electrochemical membrane synthesized from carbothermal reduction of TiO2.

Sonochemical oxidation of organic pollutants in an aqueous environment is considered to be a green process. This mode of degradation of organic pollutants in an aqueous environment is considered to render reputable outcomes in terms of minimal chemical utilization and no need of extreme physical conditions. Indiscriminate discharge of toxic organic pollutants in an aqueous environment by anthropogenic activities has posed major health implications for both human and aquatic lives. Hence, numerous research endeavours are in progress to improve the efficiency of degradation and mineralization of organic contaminants. Being an extensively used advanced oxidation process, ultrasonic irradiation can be utilized for complete mineralization of persistent organic pollutants by coupling/integrating it with homogeneous and heterogeneous photocatalytic processes. In this regard, scientists have reported on sonophotocatalysis as an effective strategy towards the degradation of many toxic environmental pollutants. The combined effect of sonolysis and photocatalysis has been proved to enhance the production of high reactive-free radicals in aqueous medium which aid in the complete mineralization of organic pollutants. In this manuscript, we provide an overview on the ultrasound-based hybrid technologies for the degradation of organic pollutants in an aqueous environment.

This review is devoted to oxidative water treatments, with emphasis on catalytic ozonation. The approach tackled herein resides in exposing a wide variety of oxidative treatments attempts as a basis for summarizing the main findings that allow envisaging improvements aiming towards total mineralization of organic pollutants. Comparison between specific operating conditions for specific pollutant-catalyst-oxidizing systems is quite difficult, and is not targeted in the present work. However, when deeply and judiciously analyzed, such a comparison allows demonstrating that, except for some works, most of these attempts seldom took into accounts basic requirements such as the parameter interactions, the role of cation mobility around a solid surface, if any, the multiple pollutant-catalyst-oxidizing species interactions and the significant contribution of adsorption, etc. Otherwise, how to explain that many experiments are still conducted with unsuitable catalysts under totally inadequate operating conditions? A better understanding of the essential requirements for a catalyst to achieve total mineralization of any organic molecules is the main objective of this work. The data summarized herein allow devoting a special interest to ozone, which is a powerful oxidizing agent and probably the most easily handleable, in spite of its low solubility in water. The use of catalysts is an ultimate strategy to improve the ozonation performance, by reducing the chemical oxygen demand (COD), even until total disappearance. However, solid catalysts, more particularly those developing high specific surface areas, such as silicates, aluminosilicates, zeolites, pseudozeolites, and clay minerals and derivatives are expected to display appreciable performances in ozonation. The latest findings show strong dependency of their catalytic activity on the chemical and physical characteristics of their surface, their concentration in the liquid media, the pH level of the reaction mixture and other parameters. The effects of these factors will be systematically examined in this review paper. The state-of-the-art in the catalytic ozonation of organic pollutants may be useful to understand the contribution of both surface and bulk ozonation reaction in the vicinity of the surface of a solid catalyst, and more particularly the role of the catalytic agent and its mobility near the solid surface. A rigorous data synthesis, made available in the present paper, allows understanding the ozone scavenging by the very species present in water, and correlating the highest effectiveness of ozone in the presence of optimum catalyst concentration at optimum pH. This supposes strong interactions between the main factors, which remain to be elucidated for each type of catalyst. The structure of this review makes emphasis on montmorillonite, which exhibits most of the required properties for effective ozonation catalysts. These are common features of natural clay minerals and zeolites, which appear as interesting candidates for large-scale water treatments, targeting complete mineralization of organic pollutants without generating persistent toxins.

A novel strategy of successive non-radical and radical process for enhancing the utilization efficiency of persulfate.

Interface engineered Ag-r-GO-CuFe2O4-Fe3O4 heterojunction an efficient photocatalyst for water treatment and toxicity study in Trifolium plants

Sorption and mineralization of organic pollutants during different stages of composting

Labneh Ambaris is a traditional Lebanese dairy product traditionally made using raw goat's milk in earthenware jars, but recently the use of artisanally pasteurized milk was introduced for safety reasons. In this study, 12 samples of labneh Ambaris were studied, six made using raw goat's milk and six others using artisanally pasteurized goat's milk. These samples were collected during fermentation and their microbial compositions were analyzed. The 16S V3-V4 and the ITS2 regions of the rDNA were sequenced by DNA metabarcoding analyses for the identification and comparison of bacterial and fungal communities, respectively. The samples had high microbial diversity but differences in samples microbiota were unrelated to whether or not milk was pasteurized. The samples were consequently clustered on the basis of their dominant bacterial or fungal species, regardless of the milk used. Concerning bacterial communities, samples were clustered into 3 groups, one with a higher abundance of Lactobacillus helveticus, another with Lactobacillus kefiranofaciens as the dominant bacterial species, and the third with Lentilactobacillus sp. as the most abundant species. Species belonging to the Enterobacteriaceae family were detected in higher abundance in all raw milk samples than in artisanally pasteurized milk samples. As for fungal communities, the samples were clustered into two groups, one dominated by Geotrichum candidum and the other by Pichia kudriavzevii.

Photochemical oxidative degradation studies of isoniazid in aqueous medium

An electro-Fenton (EF) based technology using activated carbon (AC) fiber as cathode and BDD as anode has been investigated for both regeneration of AC and mineralization of organic pollutants. The large specific surface area and low intraparticle diffusion resistance of AC tissue resulted in high maximum adsorption capacity of phenol (PH) (3.7 mmol g-1) and fast adsorption kinetics. Spent AC tissue was subsequently used as the cathode during the EF process. After 6 h of treatment at 300 mA, 70% of PH was removed from the AC surface. The effectiveness of the process is ascribed to (i) direct oxidation of adsorbed PH by generated hydroxyl radicals, (ii) continuous shift of adsorption equilibrium due to oxidation of organic compounds in the bulk, and (iii) local pH change leading to electrostatic repulsive interactions. Moreover, 91% of PH removed from AC was completely mineralized, thus avoiding adsorption of degradation byproducts and accumulation of toxic compounds such as benzoquinone. Morphological and chemical characteristics of AC were not affected due to the effect of cathodic polarization protection. AC tissue was successfully reused during 10 cycles of adsorption/regeneration with regeneration efficiency ranging from 65 to 78%, in accordance with the amount of PH removed from the AC surface.

Highly-efficient degradation of organic pollutants by oxalic acid modified sludge biochar: Mechanism and pathways

Recalcitrant compounds are a serious environmental and health problem mainly due to their toxicity and potential hazardous effects on living organisms, including human beings. Conventional wastewater treatments have not been able to remove pollutants from water efficiently; however, advanced oxidation processes (AOPs) are able to solve this environmental concern. One of the most recent AOP technology is photoelectrocatalysis (PEC), a process that combines electrochemical advanced oxidation and photocatalytic (PC) processes to avoid the recombination of photogenerated electron-hole pairs and the lifetime of photogenerated holes in order to promote an efficient degradation and mineralization of organic pollutants in aqueous medium. This chapter is divided in the following sections: (1) introduction (2) semiconductors and fundamentals of photoelectrocatalysis; (3) kinetic aspects of photoelectrocatalysis mechanism; (4) photocatalysts, (4.1) modified materials, (4.2) synthesis of the photoelectrodes; (5) electrophotocatalytic systems, (5.1) operational parameters; (6) applications in the degradation of pollutants, (6.1) organic pollutants, (6.2) inorganic contaminants, (6.3) industrial and municipal wastewater treatment; (7) conclusions and perspectives; and (8) references.

A separation-free polyacrylamide/bentonite/graphitic carbon nitride hydrogel with excellent performance in water treatment

In this work, UV/H2O2 treatment of actual pulp and paper mill wastewater (PPMW) was investigated. To determine optimal conditions, the effects of some experimental parameters (initial pH, initial H2O2 concentration, temperature, and organics load) on the UV/H2O2 process efficiency in terms of absorbance at 330 and 281 nm and chemical oxygen demand (COD) and total organic carbon (TOC) removals were studied. The results show that the UV/H2O2 system leads successfully to the almost-complete elimination of absorbance at 330 and 281 nm, COD, and TOC from an actual PPMW containing 270 mg of C L−1 under natural pH (pH 11.25) using 2.1 g of H2O2 L−1 at 28 °C. Under these optimal conditions, pseudo-first-order kinetics was determined for absorbance at 330 and 281 nm and COD decay with rate constants of 0.029, 0.02, and 0.008 min−1, respectively. Furthermore, the evolution with time of the H2O2 concentration exhibits two parts: a linear decrease to 300 min and then exponential change until the end of the treatment....