Adsorption has become a competitive method in the field of wastewater and air treatment. Adsorption kinetics is one of the main factors that must be understood before the applicability of any adsorbent. In every adsorption process, linear or nonlinear analysis of the kinetics is applied. The goodness of fit index (coefficient of correlation or sum of squares) is applied to access the best model. The usage of linear or non-linear from of the adsorption kinetics has an impact on the distribution of error function. Almost in every adsorption study, linear forms have been used to conclude the best kinetic model that influence the adsorption mechanismwhich might be an error. Therefore, this review highlights the mistakes in the usage of linear and non-linear models. The applicability of the adsorption kinetics in wastewater treatment is also illuminated.

The prevalence of cyanobacteria is increasing in freshwaters due to climate change, eutrophication, and their ability to adapt and thrive in changing environmental conditions. In response to various environmental pressures, they produce toxins known as cyanotoxins, which impair water quality significantly. Prolonged human exposure to cyanotoxins, such as microcystins, cylindrospermopsin, saxitoxins, and anatoxin through drinking water can cause severe health effects. Conventional water treatment processes are not effective in removing these cyanotoxins in water and advanced water treatment processes are often used instead. Among the advanced water treatment methods, adsorption is advantageous compared to other methods because of its affordability and design simplicity for cyanotoxins removal. This article provides a current review of recent developments in cyanotoxin removal using both conventional and modified adsorbents. Given the different cyanotoxins removal capacities and cost of conventional and modified adsorbents, a future outlook, as well as suggestions are provided to achieve optimal cyanotoxin removal through adsorption.

Municipal solid waste is a problem to developed and developing cities in the world. If municipal solid waste is not managed well, it can be a source of numerous contaminants to water, air, and soil. Although landfill is at the bottom in terms of priorities of municipal solid waste management techniques, its applicability cannot be neglected in developing economies. Landfill site selection is a hard puzzle comprised of political, social, economic, and environmental factors. Makkah, Saudi Arabia, is targeting 30 million pilgrims by 2030, putting the city in a difficult circumstance: More pilgrims, more municipal solid waste. The current dump site, Kakia, is expected to be full by 2020; thus, there is a need to locate a new landfill site. In 20 years, Makkah is expected to produce 44 million tonnes of municipal solid waste, which requires approximately a 7.5 m × 5,874,000 square meter landfill capacity. In this study, a geographic information system, analytical hierarchy process, vertical electrical sounding, and ground-penetrating radar are applied to select the best new landfill site for Makkah. By combining these techniques, there are three suitable site locations: (39°36 ́38.45 ́ ́E: 21°18 ́26.46 ́ ́N), (39°37 ́54.07 ́ ́E: 21°19 ́35.25 ́ ́N), and (39°44 ́04.45 ́ ́E: 21°13 ́08.93 ́ ́N). These sites have a considerable depth to water table of 12 m. Therefore, the city of Makkah should use these findings to establish a sanitary landfill.

The use of adsorption using nanomaterials has become a very competitive method for removal of hazardous materials from wastewater. With increasing consumption of fossil fuels and development of energy storage systems, the levels of vanadium pollution are expected to increase. Utilizing natural shale and coal waste as adsorbents, batch adsorption, isotherms, and kinetics of vanadium was studied. The adsorption characteristics of shale and coal waste were studied using Fourier Transform Infrared spectroscope and Scanning Electron Microscopy. The effect of pH, the amount of adsorbent, vanadium concentration, temperature, and contact time between adsorbate and adsorbents were also studied to obtain optimum conditions for maximum adsorption of vanadium. The Fourier Transform Infrared results show little distortion in the vibration of bands, and hence the surface properties remain unchanged for both sorbents after adsorption. The adsorption kinetics are best described by pseudo-second order, while Langmuir model fits the adsorption isotherm for both adsorbents. Maximum sorption capacity is 67.57 mg/g for shale while that of coal is 59.88 mg/g at 298 K and pH 3. For both adsorbents, the adsorption process is spontaneous, endothermic, and chemisorption in nature. Both adsorbents can effectively be recycled twice.

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