It is no secret where this small town’s water comes from
Cloudcroft, N.M.’s 1,000 residents began considering wastewater reuse a few years ago when a drought forced the high-elevation community to haul in 20,000 gallons of water daily during the peak summer tourism season. The village received $600,000 in 2004 from the state’s $10 million initiative to promote innovative water conservation and used it to help fund a $2 million water reuse system. The resulting system uses three types of membrane technology to treat the community’s wastewater and potable water before it is distributed to residents.
Livingston Associates, of Alamogordo, N.M., designed the project, which converted the original wastewater treatment plant to a membrane bioreactor (MBR) process. The MBR system produces a high-quality effluent that is disinfected with chloramines and pumped uphill to a water storage tank, where it stays 30 days for natural treatment by diffusion and sunlight. From there, some of the water is diverted for irrigation, and each day, 100,000 gallons flow 2.5 miles downhill to the water treatment plant.
The water treatment plant contains a reverse osmosis (RO) system, which filters the water with high-rejection, low-pressure, thin-film composite membranes. Permeate from the RO system is disinfected with peroxide and ultraviolet light, and discharged into a 1-million-gallon covered reservoir. From there, the water flows into a 750,000-gallon covered reservoir, where it is blended with spring and ground waters. The purified wastewater constitutes up to 50 percent of the drinking water supply.
Finally, the blended water passes through ultrafiltration membranes and granular activated carbon, then is disinfected using sodium hypochlorite before entering the distribution system and residents’ homes. Essentially, Cloudcroft implemented a system that shortens the distance — and traces an obvious path — from the wastewater treatment discharge point to the intake point of the potable water treatment system.
Read the main story, “A new frontier,” to learn more about how membranes are playing a critical role in helping communities stretch the water supplies.