Monitoring strategies for direct reuse of reclaimed water
In areas of the arid Western United States where water is a scarce resource, many communities are turning to
engineered wastewater reuse to meet water demand. Reclaimed water can be used for irrigation, groundwater
recharge, potable water supply, industrial reuse and other non-potable municipal uses. Reuse of reclaimed water
carries an overarching concern for achieving adequate water quality and mitigating potential risks from microbial
or chemical contaminants. Water reuse treatment systems are designed with multiple barriers to mitigate
potential risks. Barriers can include redundant process treatment operations as well as preventative source water
protection, which mitigates risk at the source.
Reuse plant monitoring plays a key role in ensuring effluent water quality by identifying changes in influent water
quality so downstream treatment processes can adjust and optimize to real- time information. Monitoring
strategies depend on reclaimed water end-use. Real-time monitoring of water quality is an important tool for
ensuring product water quality. Treatment objectives may be focused on specific contaminants (e.g., pathogens
and micropollutants) or bulk water properties (e.g., potential for scaling or fouling of systems). Many
contaminants of concern cannot be measured in real-time. Real-time monitoring strategies rely on surrogates
that are defined as related substitute measurements to determine the performance of individual unit processes or
operations in removing targeted water constituents. Examples include pH, turbidity, UV absorbance, fluorescence,
conductivity and chlorine residual. In 2010, the surrogate analysis approach was endorsed by the California State
Water Resources Control Board.
The objective of this scoping proposal is to identify the current use of real-time surrogates to monitor and control
water reuse treatment systems and determine knowledge gaps for future research projects.
Need and Benefit
Monitoring strategies for water reuse applications is a very timely and relevant topic. With groundwater resources
being depleted in many western areas, many communities have turned to water reuse systems to meet water
demand (both potable and non-potable). Most research has focused on the development of treatment
technologies, and few studies have focused on operational monitoring of advanced treatment processes. A 2012
report by the National Research Council identified monitoring as a future research priority to identify better
indicators and surrogates that can be used to monitor process performance in reuse scenarios and develop online
real-time monitoring techniques for their measurement.
Reviewing recent publications on the topic revealed that most of the focus has been on developing treatment
technologies for water reuse rather than operational treatment strategies. The most recent monitoring related
studies by the Water Research Foundation were between 1998-2000. A contemporary investigation including
technological advances over the last 15 years is needed. Recent WateReuse Research Foundation reports regarding
online monitoring have focused primarily on monitoring microbial contaminants. This approach neglects
non-microbial treatment objectives that may be of interest for specific end-use applications. Therefore, a
comprehensive understanding of monitoring strategies for different treatment objectives is needed to identify
opportunities for future improvement.
Contact the Principal Investigator for information about partners.
Bureau of Reclamation Review
The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.
Monitoring strategies for direct reuse of reclaimed water (final, PDF,
By Julie Korak
Publication completed on September 30, 2016