Fly ash is a waste products in the power generation industry, however, it is a resource in the coal use industry that has yet to be fully utilized and exploited. As a result, thermal power providers are exploring for ways to repurpose fly ash. Currently, the cement industry is considering using them as a raw ingredient for concrete manufacturing. Fly ash from coal-fired power plants could be used as a by-product, and its usage in agricultural and engineering recycling materials is being investigated. Fly ash conversion to zeolite and MCM-21 has also been extensively researched. Fly ash can be used as a low-cost adsorbent for gas and water treatment. Fly ash was used as an effective materials for adsorption of specific pollutants from water and wastewater. The findings are promising in terms of removing organics, particularly dyes, from domestic and industrial wastewater. The applications of fly ash in wastewater treatment for the elimination of various organic pollutants will be described in this book. This book will be a guide for environmental chemist and chemical engineers working in the utilization of solid waste for the remediation of water pollutants.