The presence of heavy metals such as Cr(VI) in the aquatic environment and their harmful effects on living organisms has emerged as one of the most serious environmental concerns world-wide. This book reports the technical feasibility of coconut shell waste, a low cost material from local agricultural waste, as well as zeolite, an inexpensive natural material for treatment of Cr(VI)-contaminated wastewater. The book contains insightful and novel ideas on how solid waste, an unused resource available in large quantities from local coconut industries, is able to be chemically modified in such a way that it could be further used as a low cost material adsorbent to remove toxic Cr(VI) from contaminated wastewater, thus improving environmental protection in the aquatic environment.