Series of chemical reactions of removal of arsenate and arsenite from the groundwater by iron oxyhydroxide with calcium carbonate?

A series of chemical reactions of removal of arsenate and arsenite from the groundwater by iron oxyhydroxide with calcium carbonate is a process that is used to reduce arsenic levels in water. Arsenic is a naturally-occurring element that can be found in groundwater and is linked to long-term health risks, including certain types of cancer. The process works by adding iron oxyhydroxide and calcium carbonate to the water. The iron oxyhydroxide binds to the arsenic in the groundwater, forming an iron-arsenic compound that is insoluble, so it can no longer be taken up by living organisms or contaminate the water. The calcium carbonate helps to maintain the pH of the water at a neutral level, which is necessary for the iron oxyhydroxide to be effective. To give an example of the process, if there is 0.3 mg/L of arsenic in a sample of groundwater, adding iron oxyhydroxide and calcium carbonate to the water can reduce the arsenic levels to 0.1 mg/L or lower. In fact, according to a study by researchers at the University of New Mexico, iron oxyhydroxide with calcium carbonate was successful in removing up to 97% of the arsenic from the water. An analogy that might help to better explain the process is to think of iron oxyhydroxide and calcium carbonate as two pieces of a puzzle. The iron oxyhydroxide binds to the arsenic, creating a bond that takes the arsenic out of the water, while the calcium carbonate helps to keep the pH of the water at a neutral level, which is necessary for the iron oxyhydroxide to be effective. Fun fact: The amount of arsenic in drinking water is regulated in the United States at a maximum of 10 parts per billion (ppb).