NWRI Independent Advisory Panel Report
BDOC as a Performance Measure for Organics Removal in Groundwater Recharge of Recycled Water
Prepared for the California Department of Public Health (CDPH)
Pub No. NWRI-2012-05
The focus of the 2012 report, “BDOC as a Performance
Measure for Organics Removal in Groundwater Recharge
of Recycled Water,” was on the suitability of using one
water quality monitoring tool over another.
Recycled water can be used for groundwater recharge,
which is the process of refilling aquifers used as drinking
Since the 1970s, California has specified in its groundwater recharge criteria that total organic carbon (TOC) – or, the amount of carbon in an organic compound – can be used to measure the concentration of organic matter in water to determine the effectiveness of organics removal during the water purification process.
TOC is considered a surrogate for unregulated organic chemicals of wastewater origin; therefore, the less TOC found in the product water, the better the quality of that water.
However, the use of TOC as an indicator of water quality has some limitations. For instance, drinking water and wastewater both contain TOC, so communities that already have high concentrations of TOC in their potable groundwater supplies might be unable to meet TOC removal requirements for groundwater recharge with recycled water.
Biodegradable dissolved organic carbon (BDOC) has been identified as a possible alternative to TOC for groundwater recharge projects that include the artificial percolation process of surface water spreading (that is, recycled water is spread on land as surface water and moves downward to refill the aquifer).
The use of BDOC as a water-quality indicator involves measuring organic matter that is consumed or altered by naturally-occurring bacteria underground.
A seven-member panel of experts evaluated the suitability of BDOC as an alternative to TOC. The Panel was led by Dr.-Ing. Jörg Drewes, professor at the Colorado School of Mines and Director of Research for the NSF Engineering Research Center ReNUWIt. Drewes specializes in water reuse treatment technologies and is a member of the National Research Council Committee on Water Reuse as an Approach for Meeting Future Water Supply Needs.
In their report, the panel evaluated the use of TOC to assess the performance of groundwater recharge facilities and BDOC as a monitoring alternative. They prepared sections on:
- History of TOC as a performance measure.
- Water quality changes during groundwater recharge using various chemical parameters.
- Two alternative options involving the use of BDOC in place of TOC.
Among their final recommendations, the panel encouraged the State to “consider BDOC as an alternative performance measure to assess the efficiency of surface spreading operations.” If properly validated, BDOC can be “a much superior measure of health protection than estimates of wastewater TOC.”
Panel members met at CDPH facilities in Sacramento, California, in 2012.
About the Panel
In preparation of the NWRI Independent Advisory
Panel meeting in March 2012, the panel members discussed the panel charge and scope of work
during a kick-off conference call in January 2012.
A report was prepared by the Panel Chair to
summarize background information regarding
previous research on the concept of using
BDOC as a treatment performance measure
of biological activity. The panel members
reviewed this background report prior to the
A one-day meeting of the NWRI panel was held on March 21, 2012, at CDPH’s facilities in Sacramento, California. Representatives from CDPH participated at the meeting.
A follow-up conference call was conducted on September 12, 2012, between the Panel Chair and representatives from CDPH and NWRI to discuss the preparation of the final report.
Member of the panel include:
- Chair: Professor Dr.-Ing. Jörg Drewes, Colorado School of Mines (Golden, CO)
- Richard Bull, Ph.D., MoBull Consulting (Richland, WA)
- James Crook, Ph.D., P.E., Environmental Engineering Consultant (Boston, MA)
- Jean-François Debroux, Ph.D., Kennedy/Jenks Consultants (San Francisco, CA)
- Professor Peter Fox, Ph.D., Arizona State University (Tempe, AZ)
- Professor Shane Snyder, Ph.D., University of Arizona (Tucson, AZ)
- Dennis Williams, Ph.D., P.G., CHG, GEOSCIENCE Support Services, Inc. (Claremont, CA)
- Learn more about Recycled Water Regulations and Guidance on the CDPH website.
- View other NWRI Panel Reports for CDPH.
- Learn more about the NWRI Panel Process.
- View NWRI Panel Reports for other agencies.
- View other reports on the topic of water reuse.