By: Larry Schimmoller, CH2M Global Technology Leader for Water Reuse

Larry Schimmoller will present his paper, “Potable Reuse for Inland Applications: Pilot Testing Results from a New Potable Reuse Treatment Scheme,” co-authored by Jeff Biggs, Tucson Water, at this year’s American Water Works Association Annual Conference and Exposition (ACE), on Monday, June 20, at 2:30 p.m. Get our full list of #ACE16 presenters!

Tucson, Arizona boasts a diversity of cultures, architecture and peoples; and is one of the Mega-Trend cities of the 21st century. To meet the water supply needs of the greater Tucson Metropolitan area, the City of Tucson and Tucson Water are exploring potable reuse as a means to diversify and expand their water portfolio. In support of this effort, CH2M and the City conducted a pilot test of an innovative and sustainable potable reuse treatment scheme, which offers significant benefits to other utilities considering potable reuse as a viable option to addressing water supply needs.

When considering potable reuse, water quality is a big factor. Critical treated water quality considerations for many successful potable reuse programs include partial reduction of total dissolved solids (TDS), multiple barriers for trace organics and pathogens and reduction of total organic carbon (TOC) to control the formation of disinfection byproducts (DBPs) during distribution. Equally critical is cost-effective and environmentally sustainable management of waste streams generated, including concentrated salt. The proposed treatment scheme implemented in Tucson addresses these concerns using short-term soil aquifer treatment (SAT), slip-stream nanofiltration (NF), ozone oxidation and biologically active carbon (BAC) filtration. Implementation of these proven technologies in this innovative and integrated manner provides a sustainable potable reuse scheme that has potential application at other inland states with limited concentrate disposal options.

Tucson scheme’s major benefits, include:

  • Short-Term SAT: SAT has been shown to provide excellent removal of organics, pathogens and nitrogen compounds, thereby providing a robust first barrier in the potable reuse treatment scheme.
  • Nanofiltration: Reverse osmosis (RO) has traditionally been used in potable reuse schemes, but it is energy intensive and produces a concentrate that is difficult to dispose of. NF provides excellent removal of pathogens, organics and divalent ions, and could be used to meet specific TDS goals at significantly lower energy consumption than RO, while producing a lower-salinity concentrate that has more disposal options.
  • Ozone and BAC Filtration: The recent use of ozone for oxidation of trace organics and inactivation of pathogens in secondary effluent has shown excellent results. In addition, BAC filtration provided downstream of ozone will assimilate and remove a significant portion of the transformed organics by both biological and adsorptive mechanisms.

We’re seeing success with Tucson’s pilot scheme. Significant samples at multiple locations within the pilot have shown excellent water quality with respect to pathogens, TOC, TDS, nitrogen, nitrosamines, fluorescence and numerous trace organics. The operational performance of the treatment processes has also been extensively monitored, and the results, such as GAC regeneration frequency, demonstrate the scheme’s strong performance.

To learn more about the sustainability of the proposed scheme as compared to other potable reuse schemes, as well as the full-scale applicability to other utilities, contact me or connect with me at #ACE16.

Larry Schimmoller is CH2M’s global technology leader for water reuse, based in Denver, Colorado. He specializes in advanced water treatment processes, such as membrane technologies, advanced disinfection and oxidation, activated carbon, as well as planning, managing and delivering water reuse projects. Larry serves on the WateReuse Research Foundation’s Research Advisory Committee (RAC) where he provides research guidance for the water reuse industry. He has also served as principal investigator on several water reuse research projects for the Foundation to test alternative technologies for potable reuse and investigate the sustainability of various treatment processes through a triple bottom line analysis. Larry received a bachelor’s degree in civil engineering from Clarkson University and a master’s degree in environmental engineering from the University of Illinois at Urbana-Champaign.