“This review paper summarizes and critically evaluates the most important findings and innovations worldwide on the use of various low-cost materials for the treatment of contaminated wastewater due to heavy metals.” ~S. Babel

Our paper is highly cited due to the overwhelming interest among environmental researchers in adsorption processes using low-cost adsorbents for removal of heavy metals from contaminated water. Our paper focused on the usage of various low-cost adsorbents compared with commercial activated carbon for water pollution control. It provides an overview of different types of adsorbents which could be used for removal of toxic metals which find their way into the environment and contaminate our bodies of water. Last, but not least, it significantly formulates a new body of knowledge in the field of water pollution control.

This review paper summarizes and critically evaluates the most important findings and innovations worldwide on the use of various low-cost materials for the treatment of contaminated wastewater due to heavy metals. Most of these materials are wastes from some activities (industrial, agricultural operations) which can be modified and used as an adsorbent. It suggests how these adsorbents can be applied to advance research in the field of water pollution control.

Our paper exhaustively reviews and assesses the technical feasibility and engineering applicability of a wide range of miscellaneous low-cost adsorbents that have been used worldwide for the removal of heavy metals. These heavy metals are highly toxic, and tend to bioaccumulate in the food chain as they are not biodegradable. This paper presents various natural materials as well as certain waste products from industrial or agricultural operation, which can be used as low-cost adsorbents. It is important to note that conversion of waste, representing an unused resource, into activated carbon, which can be used as an adsorbent in water purification, would add considerable economic value, helping the industrial sector to reduce the cost of waste disposal, and most importantly, provide a potentially inexpensive alternative to costly commercial activated carbon. It also provides a comparative overview of all low-cost adsorbents in terms of their removal performance, adsorption capacity, and cost effectiveness.

If low-cost adsorbents are found highly efficient for heavy metal removal, not only the industries, but living organisms and their surrounding environment will also benefit from this removal of potential toxicity due to heavy metal. Thus, the use of low-cost adsorbents may contribute to the sustainable development of the surrounding environment.

We became involved in this research (water pollution control) at a time when several episodes of toxicity from heavy metals had been reported worldwide—most especially in developing countries, due to their rapid industrialization. Industries in developing countries may simply illegally discharge wastewater containing toxic heavy metals, such as chromium, cadmium, and copper, into receiving water bodies. Undoubtedly, the existence of such contaminants in receiving water bodies causes many adverse effects, not only for organisms that live in the water, but also for people who are exposed to these water-borne contaminants. Consequently, there is an urgent need to protect surrounding rivers, streams, and lakes from potential toxicity due to heavy metals. Also, environmental protection and the improvement of water quality are of vital importance within our global society today, as water is indeed the lifeblood of our planet. Everyone uses water and is concerned about its quality and availability. Once contaminated, it is very difficult and expensive to purify contaminated water. To provide our children with clean water and a cleaner environment, it is necessary to promote a sustainable environment as early as possible through the use of water pollution controls.