Due to the continued deterioration of different bodies all over the world and especially in the Philippines, and because of people's negligence to our environment, it is a must to help our surroundings. This study aims to develop a key to treat mercury present in bodies of water through the use of calcined Anadara antiquata (Litob) shell. Considerably, river and lake water in nearby industries may contain mercuric discharges which are fatal for aquatic as well as human life. These discharges could accumulate in the stomach and remain non-digestible resulting in the formation of cancerous diseases. Long time exposure to mercury could cause serious damage to nerve, brain, kidney, lung irritation, skin rashes, vomiting, and diarrhea (Krishnan & Anirudhan, 2006; Ekinci, Budinova, Yardim, Petrov, Razvigorova, Minkova, 2002). Using cost-effective and environment-friendly catalysts is particularly useful for the production of heavy metal remover in waste water. The waste shells are usedas the catalyst for this process. The shells used in this study contain a compound known as calcium carbonate (CaCO3).