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This review highlights the methodologies for sampling, sample preparation, and identification of microplastics found in wastewater treatment plants. The presence and deposition of microplastics in the environment lead to serious environmental and ecological concerns. The role of wastewater treatment plants in spreading microplastics to the environment poses additional threats that need to be treated. Thus, the key challenges remain in understanding the fate and occurrence of microplastics in the wastewater treatment plant and the ability to detect them at each stage of the treatment. This review, therefore, helps to understand the fate and occurence of microplastics in the wastewater treatment plant. Besides, it is organized to present an overall discussion of the available microplastics detection techniques from sampling to identification. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Nanoparticles are defined as a group of particles having sizes between 1 and 100 nm and characterized by some specific physicochemical properties such as surface area, surface charge, degree of agglomeration, particle morphology and surface coating. Nanoparticles have been widely used in different fields resulting in their intentional or unintentional release into the aquatic environment. This work focused on reviewing the main sources of nanoparticles in the aquatic environment, their interactions and transformation processes. This review also summarizes all the possible toxicity forms and the factors affecting nanoparticles toxicity in the aquatic environment.

Shale gas is an alternative natural source of energy resulting from the anaerobic degradation of organics within shale formations. However, shale gas exploration is accompanied by shale gas wastewater production constituting a new source of pollution threatening the environment. Electro-Fenton process (EF) is used for the first time in this study as a new method for shale gas wastewater treatment where the optimum operating parameters of the the responses including COD, color, total phenol removal efficiencies and waste sludge volume were determined using a response surface methodology (RSM). Based on the analysis of variance (ANOVA), the coefficient of determination (R 2 ) was calculated and found to be above 0.94 for all the responses. The maximum removal efficiencies were found to be around 87.35%, 89.15%, and 91.75% for COD, color, and total phenol removal under the optimum conditions, respectively. The operational cost of the EF process applied to shale gas wastewater for COD removal at optimum conditions was determined to be 4.13 €/m 3 . The results indicated that the electro-Fenton seems to be an efficient treatment method for shale gas wastewater.