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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)

September 2012

Pub No. NWRI-2012-05

Download Report (580-KB PDF, 60 Pages)





Report Description


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

water supplies.


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:



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

panel meeting.


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:


Click here to read the panel biographies.





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