WRF, LA County Public Works Win ASCE Sustainability Project Award

Nov. 10, 2014
Project 4470 validates the efficiency of biological denitrification in groundwater recovery

The Metropolitan Los Angeles Branch of the American Society of Civil Engineers (ASCE) recognized the Water Research Foundation (WRF) and Los Angeles County Public Works—Waterworks (LACPW) as recipients of the 2014 Outstanding Sustainability Project of the Year award. The award was presented at a ceremony held Nov. 1, 2014 in Los Angeles and recognizes projects that advance the field of civil engineering and provide an exemplary display of ASCE values.

The winning project, Minimizing Waste Backwash Water From a Biological Denitrification Treatment System (#4470), was jointly funded by WRF and LACPW. The projects focuses on measuring the effectiveness of biological denitrification (BDN) for removing potential co-contaminants from groundwater, specifically hexavalent chromium (Cr(VI)), and exploring the viability of recovering waste backwash water through a BDN treatment system.

“We are honored by this award and want to thank ASCE for the recognition, and also LA County Public Works and our research partners at Water Quality & Treatment Solutions Inc. for collaborating with us on such an important project,” said Rob Renner, executive director of WRF. “We are focused on funding research that delivers valuable insights and information to the water community and this work in exploring BDN is just another wonderful example of what these types of projects can uncover.”

WRF and LACPW collaborated to examine BDN further in anticipation of a California Department of Public Health (CDPH) maximum contaminant level (MCL) for Cr(VI). Earlier this year, CDPH approved a new Cr(VI) MCL of 0.010 mg/L.

Bench-scale testing was first performed to assess the prevalence of indigenous denitrifying bacteria in the groundwater supply of select areas. This step was followed by pilot testing, which was conducted at County well 37-01 in Acton, California due to the well’s historically consistent nitrate levels averaging roughly 8.5 mg/L.

The study found that BDN is in fact effective in removing Cr(VI) from groundwater sources. After two weeks of operation, the BDN process met the study’s water quality goals for nitrate and nitrite at its full hydraulic capacity. Additionally, BDN and media filtration processes were successfully operated with washwater recovery throughout the pilot study, resulting in water recoveries exceeding 99%.

The findings of Project #4470 increase the water sector’s knowledge about the use of BDN for groundwater treatment. The results not only validate the technology’s efficiency, reliability and robustness, but show that the BDN treatment process provides effective removal of Cr(VI) when present as a co-contaminant. In light of the new California MCL of 0.010 mg/L for Cr(VI), the demonstration of another effective Cr(VI) treatment technology, in addition to ion exchange and the typical reduction/coagulation/filtration treatment, is an important step forward for drinking water providers with groundwater supplies in which both nitrate and Cr(VI) are present.

“Water resource agencies throughout Southern California have invested heavily in local water supply infrastructure and stormwater capture facilities to increase use of the region’s groundwater resources,” said Gail Farber, LA County Public Works director. “This study opens the door to even more possibilities for increasing the reliability of the region’s water portfolio.”

The study was led by Water Quality & Treatment Solutions Inc., located in Los Angeles. The principal investigators for this project were Issam Najm, Nancy Patania Brown, Brian Gallagher, Eric Seo and Karl Gramith.

Source: Water Research Foundation

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