Grand Challenges in Chemical Treatment of Hazardous Pollutants

The tremendous growth in industrialization and urbanization has resulted in generation of large amount of wastewater as well as hazardous waste (Chai et al., 2021; Titchou et al., 2021). Heterogenous solid waste usually ends up in landfills which undergoes various physicochemical change (Xiong et al., 2019; Patel et al., 2021)The nature and composition of hazardous waste varies depending on the source materials. Leachate from landfill sites has the potential to affect the water quality if it further enters into water streams via rainwater/stormwater (Bishop et al., 1986; Gautam et al., 2019). Accumulation of hazardous pollutants result in soil, water and air pollution (Quesada et al., 2019; Alemany et al., 2021; Dionne andWalker, 2021; Nikolaeva et al., 2021; Yadav et al., 2021; Łyszczarz et al., 2021). Heavy metals are widely used in different industries and due to their inefficient removal, they can directly or indirectly gain entry into water bodies. Metals are non-biodegradable and can easily accumulate in the environment (Gholizadeh and Hu, 2021; Xu et al., 2021). Different industries like textile, cosmetics, tannery, food and beverages release toxic bio-recalcitrant hazardous pollutants in the environment (Choina et al., 2013;Muszyński et al., 2019; Quesada et al., 2019; Keskin et al., 2021). The presence of both organic and inorganic pollutants in water bodies can harmfully affect the aquatic environment. Additionally, highly acidic or alkaline wastewater can also pose detrimental effects on aquatic environment. Further, various organic pollutants like pharmaceuticals, EDCs, refractory organic and dyes can generate more toxic species due to degradation or interaction with other available pollutant species (Tijani et al., 2013). Sometimes, degraded byproducts are even more toxic in comparison to their parent compound (Yin et al., 2017). The presence of emerging contaminants (ECs) in the environment is of great concern due to their harmful impacts on one hand and great challenges in existing water treatment technologies in terms of their removal efficiency on the other hand (Ahmed et al., 2021; Zamri et al., 2021). Consumption of polluted water can result in a great threat to living beings hence the wastewater needs to be properly treated before being discharged into the water bodies (Gitis and Hankins, 2018; Hussein and Jasim, 2021). It is noteworthy that due to water scarcity and environmental pollution by emission of pollutants, there is a continual rising global concern regarding the treatment of wastewater in order to make it available for reuse (Hussein and Jasim, 2021; Patel et al., 2021). Due to inefficient traditional treatment technologies, varieties of pollutants reach into the environment which directly and/or indirectly affects flora and fauna. Removal of lower concentrations of pollutants is more challenging and varied concentrations of emerging pollutants can be detected in the municipal sludge and effluents of municipal wastewater treatment plants. Hazardous waste and wastewater can be treated by physical, chemical, thermal, biological as well as physico-chemical methods. Conventional technologies like physico-chemical and biological treatment methods are mainly used for the treatment of wastewater and hazardous solid waste. Edited and reviewed By: Xitao Liu, Beijing Normal University, Beijing, China