EVALUATION OF CLINOPTILOLITE ZEOLITE FOR REMOVAL OF LEAD FROM DOMESTIC DRINKING WATER

THE DESIREABLE PHYSICAL CHARACTERISTICS OF LEAD ARE RESPONSIBLE FOR ITS WIDESPREAD USE IN WATER DISTRIBUTION SYSTEMS PLUMBING SYTEMS, EVEN THOUGH VERY LOW LEVELS OF LEAD MAY POSE A SIGNIFICANT HEALTH HAZARD AND CAUSE LEARNINGDISABILITIES IN CHILDREN. THOUGH MUNICIPAL WATER SUPPLIES GENERALLY HAVE VERY LOW LEAD LEVELS, THEY FREQUENTLY BECOME CONTAMINATED WITH LEAD FROM THE DISTRIBUTION SYSTEM AND/OR DOMESTIC PLUMBING. PROPOSED ENVIRONMENTAL PROTECTION AGENCY REGULATIONS WILL REDUCE THE PROBLEM THROUGH CORROSION CONTROL, BUT NOT ENTIRELY CURE IT. CLINOPTILOLITE ZEOLITE, A NAUTRALLY OCCURRING MINERAL WITH A HIGH ION-EXCHANGE CAPACITY, CAN SELECTIVELY REMOVE LEAD FROM WATER. CURRENT RESEARCH AT THE U.S. BUREAU OF MINES AND THE IDAHO NATIONAL ENGINEERING LABORATORY SHOWS THAT ION-EXCHANGE COLUMNS CONTAINING CLINOPTILOLITE CAN REDUCE LEAD LEVELS TO WELL BELOW THE DRINKING WATER STANDARD FROM RELATIVELY HIGH INITIAL CONCENTRATIONS. THIS, AND OTHER RESEARCH, INDICATES THAT CLINOPTILOLITE ZEOLITE MAY PROVIDE AN EFFECTIVE MEDIA FOR USE IN FILTERS TO TREAT DRINKING WATER. HOWEVER, DETAILED DATA ARE NEEDED TO DEVELOP EFFECTIVE, LOW-COST FILTERS USING CLINOPTILOLITE FOR LEAD REMOVAL. MOST IMPORTANTLY, THIS STUDY WILL ADDRESS QUESTIONS SUCH AS THE CONTACT TIME NEEDED FOR LEAD REMOVAL, THE EFFECTIVE CAPACITY AT RELATIVELY HIGH FLOW RATES, AND PARAMETERS SUCH AS THE OPTIMUM PARTICLE SIZE TO MAXIMIZE EFFICIENCY WHILE MAINTAINING GOOD FLOW CHARACTERISTICS.