For decades, water utilities have relied on giant tanks filled with ion-exchange resin beads to remove perchlorate, a harmful industrial pollutant, from drinking water. The system works by attracting negatively charged perchlorate ions to positively charged resin beads, allowing purified water to fl ow out of the tanks. But the process leaves behind a difficult problem: resin beads loaded with perchlorate that must be regenerated or disposed of as hazardous waste. ...read more read less