Indirect Potable Reuse and Aquifer Injection of Reclaimed Water

摘要

Drinking water aquifers in coastal areas around the nation are increasingly stressed due topopulation expansion, drought and saltwater intrusion. Advanced technologies exist which couldprovide a large supply of pure water from reclaimed water sources. Membrane technology in theform of microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), electrodialysis (ED) and/orreverse osmosis (RO) has become an increasingly affordable alternative to conventional watertreatment processes.PB Water, a division of Parsons Brinckerhoff Quade & Douglas, Inc. has been researchingthe use of membrane technology and ultraviolet light disinfection at an advanced reclaimed waterfacility in Orlando, Florida. Early indications are that 100% of the water quality goals for thetreatment 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 inoperation from January to April 2000. Bench-scale studies included innovative fractionation of thereclaimed water under typical plant conditions.It has been demonstrated that a treatment train, which utilizes membrane elementsfollowed by ultraviolet radiation (UV), provides multiple effective barriers to known waterpollutants. UF alone can provide log 4 removal of pathogens. This membrane technology wouldeasily remove viruses, cryptosporidium, and giardia. NF alone can provide log 6 removal ofparticles with a molecular weight greater than 200 Daltons. Many heavy metals fall into this sizerange, as do most endocrine disruptors. While no standard methods are available to test forendocrine disruptors, it is believed that this method of removal will be effective for the two largestdisruptor groups: pesticides and human hormones. In addition, ultrafiltration combined withnutrient specific electrodialysis or reverse osmosis effectively removes nutrients that must becontrolled for release of reclaimed water into the environment. In most cases, reclaimed watertreated by these methods of disinfection is purer than surface water and/or some groundwatersupplies.Bench scale results will be used to design a pilot scale system to be operated for aminimum extended period of twelve months as required by Florida law. Results will be used tocharacterize membrane fouling and estimate replacement costs of the full-scale project. Withknowledge gained from the pilot scale apparatus, a full-scale system could be developed and puton-line, continuing central Florida's tradition of innovative water reclamation practices.