AWWA SOURCES55669

Drinking water aquifers in coastal areas around the nation are increasingly stressed due to population expansion, drought and saltwater intrusion. Advanced technologies exist which could provide a large supply of pure water from reclaimed water sources. Membrane technology in the form of microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), electrodialysis (ED) and/or reverse osmosis (RO) has become an increasingly affordable alternative to conventional water treatment processes. This paper discusses how PB Water, a division of Parsons Brinckerhoff Quade & Douglas, Inc., has been researching the use of membrane technology and ultraviolet light disinfection at an advanced reclaimed water facility in Orlando, Florida. Early indications are that 100% of the water quality goals for the treatment of reclaimed water can be achieved by a combination of UF and/or NF followed by UV. Based on preliminary findings, a bench-scale process plant has been devised and was in operation from January to April 2000. Bench-scale studies included innovative fractionation of the reclaimed water under typical plant conditions. It has been demonstrated that a treatment train, which utilizes membrane elements followed by ultraviolet radiation (UV), provides multiple effective barriers to known water pollutants. UF alone can provide log 4 removal of pathogens. This membrane technology would easily remove viruses, cryptosporidium, and giardia. NF alone can provide log 6 removal of particles with a molecular weight greater than 200 Daltons. Many heavy metals fall into this size range, as do most endocrine disruptors. While no standard methods are available to test for endocrine disruptors, it is believed that this method of removal will be effective for the two largest disruptor groups: pesticides and human hormones. In addition, ultrafiltration combined with nutrient specific electrodialysis or reverse osmosis effectively removes nutrients that must be controlled for release of reclaimed water into the environment. In most cases, reclaimed water treated by these methods of disinfection is purer than surface water and/or some groundwater supplies. Bench scale results will be used to design a pilot scale system to be operated for a minimum extended period of twelve months as required by Florida law. Results will be used to characterize membrane fouling and estimate replacement costs of the full-scale project. With knowledge gained from the pilot scale apparatus, a full-scale system could be developed and put on-line, continuing central Florida's tradition of innovative water reclamation practices. Includes 6 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

01/01/2002

Number of Pages:

14

File Size:

1 file , 370 KB