Presence of pharmaceutically active compounds (PACs) as emerging contaminants in water is a major concern. Recent reports have confirmed the presence of PACs in natural and wastewater systems, which have caused several problems indicating the urgent need for their removal. The current review evaluates the role of chemically modified biosorbents in the removal of PACs in water. Reported biosorbents include plant and animal solid waste, microorganisms and bio-composite. Bio-composites exhibited better prospects when compared with other biosorbents. Types of chemical treatment reported include acid, alkaline, solvent extraction, metal salt impregnation and surface grafting, with alkaline treatment exhibiting better results when compared with other treatments. The biosorption processes mostly obeyed the pseudo-second-order model and the Langmuir isotherm model in a process described mainly by ionic interaction. Desorption and regeneration capacity are very important in selecting an appropriate biosorbent for the biosorption process. Depending on the type of biosorbent, the cost of water treatment per million liters of water was estimated as US $10–US $200, which presents biosorption as a cheap process compared to other known water treatment processes. However, there is a need to conduct large-scale studies on the biosorption process for removing PACs in water.

The need for a reliable and sustainable energy source, stability in energy price and solution to environmental challenges of fossil fuel has led to searching for an alternative energy source to fossil fuel. Several alternative sources have been developed over time, but they are limited in one form or another. However, biofuel such as bioethanol has been identified as a superb alternative with superior properties to fossil fuel. One major challenge with biofuel is the high production cost resulting from feedstock, which may also serve as a food source. In order to address this challenge, research is focused on searching for cheap and sustainable feedstock for biofuel production. Currently, attention is on lignocellulosic waste as feedstock with a keen interest in developing the most appropriate technique for processing it to bioethanol, especially in developing countries, which is the focus of this review. This review involves converting lignocellulosic waste to bioethanol and the pretreatment steps involved as well as its challenges, prospect and economic aspect. Among the pretreatment steps reported, biological treatment remains outstanding but with a few challenges which can be managed. Biofuel has come to stay in developing countries with lots of opportunities that favours its production cost. Although the high cost of enzyme production has been identified as a challenge to the economic viability of lignocellulosic bioethanol, there is hope that developing an efficient bio-system for simultaneous saccharification and fermentation (SSF) and consolidated biomass processing may help circumvent the challenge. In conclusion, the effective utilization of lignocellulosic waste in an efficient biocatalyst system can serve as an economically viable means to overcome the challenge posed by fossil fuel.

The detection of per- and polyfluoroalkyl substances (PFAS) in water presents a significant challenge for developing countries, requiring urgent attention. This review focuses on understanding the emergence of PFAS in drinking water, health concerns, and removal strategies for PFAS in water systems in developing countries. This review indicates the need for more studies to be conducted in many developing nations due to limited information on the environmental status and fate of PFAS. The health consequences of PFAS in water are enormous and cannot be overemphasized. Efforts are ongoing to legislate a national standard for PFAS in drinking water. Currently, there are few known mitigation efforts from African countries, in contrast to several developing nations in Asia. Therefore, there is an urgent need to develop economically viable techniques that could be integrated into large-scale operations to remove PFAS from water systems in the region. However, despite the success achieved with removing long-chain PFAS from water, more studies are required on strategies for eliminating short-chain moieties in water.