Four new research reports related to desalination and water reuse were released on 28 December 2011 by the WateReuse Research Foundation (WRRF):

Attenuation of Emerging Contaminants in Streams Augmented with Recycled Water
This report presents the motivation and technical results of a combined field and laboratory study that was designed to assess attenuation of microconstituents in a creek augmented with recycled water. The study sought to supplement a planned stream augmentation pilot project in which the flow of Coyote Creek, a small, semiurban creek in San Jose, California, was to be augmented with local recycled water via release to the tributary Upper Silver Creek.

The report also provides a discussion of the rationale that led to project termination when results indicated the presence of potentially harmful contaminants in the recycled water.

Development of Surrogates to Determine the Efficacy of Groundwater Recharge Systems for the Removal of Trace Organic Chemicals
Dr Jörg E Drewes of the Colorado School of Mines was principal investigator and project manager for this project which sought to

  • to identify potential surrogates and indicators for the removal of wastewater-derived chemical contaminants in groundwater recharge projects employing soil-aquifer treatment after surface spreading and membrane treatment ahead of direct injection projects
  • to validate the ability of chosen surrogates and indicators to predict the removal of wastewater-derived contaminants in groundwater recharge projects
  • to develop recommendations for the water industry regarding suitable surrogates for groundwater recharge systems using reclaimed water.
  • Maximizing Recovery of Recycled Water for Groundwater Recharge Employing an Integrated Membrane System
    Dr Christopher Yu of Psomas was principal investigator and project manager for this tailored collaboration between the Water Replenishment District of Southern California and the WRRF. The study sought to determine whether a multistage, high-pressure membrane process, such as the one used at the Leo J Vander Lans Water Treatment Facility, could be operated at higher recovery and permeate flux, resulting in lower overall operating costs, without compromising product water quality.

    For this specific water reuse application, it was hypothesized that new-generation nanofiltration (NF) and low-pressure reverse-osmosis (RO) membranes could be operated at higher recovery and lower operating costs, while maintaining a product quality comparable to conventional RO membranes.

    This study provides data on NF membrane treatment of recycled water, which are critical for acceptance by the regulatory authorities. It is expected that this mode of operation will allow savings in operations for utilities seeking to treat recycled water without stringent TDS removal requirements. It could also offer a proven, cost-effective option to existing facilities that use two-stage RO.

    Characterization of US Seawaters and Development of Standardized Protocols for Evaluation of Foulants in Seawater Reverse Osmosis Desalination
    Principal investigator
 Dr Samer Adham, MWH, led this study, which developed a systematic approach to study organic fouling and determined the key foulants depositing on the membrane surface.

    Study objectives were to characterize seawater from various locations in the US, evaluate methods for characterizing clean and fouled membranes, identify organic foulants using bench-scale RO experiments, study the influence of membrane properties and algal bloom (red-tide events) on organic fouling, and compare fouling between bench-scale seawater reverse- osmosis (SWRO) operation and pilot-scale SWRO operation.

    Seawater from West Basin Municipal Water District, Carlsbad Desalination Project, Tampa Bay Desalination Plant and South Bay Power Plant was chosen as the feed water sources for this study. Membranes used in the study were DowFilmtec SW30HR, Hydranautics SWC4, and Saehan SR.

    To test the different seawaters for fouling propensity, a bench-scale RO unit was constructed at MWH in California and University of Illinois, Urbana-Champaign (UIUC). Experimental results and evaluation of methods for determining organic fouling in seawater are presented in detail in this study.

    The techniques and methods used in this study can be used prior to the operation of a pilot-scale process in order to access the nature of foulant material that would preferentially deposit on the membrane surface. The bench-scale experiments must be combined with the various analyses, characterizations, and autopsy techniques described in this study to obtain meaningful results.

    An understanding of the nature of foulant will facilitate cost-effective and optimal design/operation of pretreatment and the overall SWRO process.