WRRC Researchers Participate in Recent HWEA Wastewater Conference
Dr. Roger Fujioka made a presentation about his work investigating sunlight inactivation of sewage-borne microorganisms in receiving waters. Dr. Fujioka pointed out that viruses, the microorganisms most likely to cause illness in swimmers, are much less susceptible to sunlight inactivation than are sewage indicator bacteria such as the fecal coliforms, E. coli, and enterococci. He proposed the use of bacteriophage (bacterial viruses) as a feasible and reliable indicator of sewage contamination of environmental waters as they respond in a similar fashion to environmental stresses as do human viruses. Dr. Fujioka said that it is difficult to rely on the inactivation of sewage-borne microorganisms due to the great variations in insolation over time and place, but noted that sunlight's purifying effects should be taken into account when assessing the risk of water-borne disease transmission.
WRRC Researcher Dr. Roger Babcock also presented a paper at the conference. Dr. Babcock talked about the work he is doing to assess the fate of pharmaceutical residuals in wastewater. With the increasing national emphasis on wastewater reclamation and agricultural reuse there is potential for the transport of pharmaceutical residuals in the effluent to drinking water aquifers. This is obviously a matter of serious concern in Hawaii where such a large proportion of our drinking water comes from aquifers underlying agricultural lands. To date Dr. Babcock's work has included efforts to measure pharmaceuticals in groundwater from different sources around Oahu, wastewater influents and effluents, and reclaimed waters, and to quantify relationships between wastewater treatment techniques and pharmaceutical removal efficiencies. The research also includes laboratory studies to determine the fate and transport of pharmaceuticals percolating through packed soil columns and field test plots. In addition to these tests lysimeter percolate samples are also being taken at field sites in central Oahu, where reclaimed wastewater is being applied to several test plots.
Dr. Victor Moreland spoke about research he has been conducting into the efficacy of ultraviolet disinfection of primary sewage effluent. He identified a four step process for assessing the applicability of UV disinfection for wastewater. These steps are characterization of the effluent water quality, bench scale evaluation (collimated beam dose-response curves), pilot-scale evaluation (pilot dose-response curves), and full-scale evaluation (dose-response curves and microbial monitoring). Other information that Dr. Moreland identified as necessary in the evaluation process includes: the best lamp type for the particular application, the type of automatic cleaning system to be used, whether fats, oils, and greases will coat the lamp sleeves, the velocity of wastewater through the reactor, and lamp and/or lamp sleeve configuration changes that can reduce the low UVT water quality impacts on the reactor.
Ms. Gayatri Vithanage, a graduate student research assistant with WRRC, won the $150 prize for the best student poster. Her poster title was: "Assessment of Sewage Pollution in Hawaii's Streams Based on Concentrations of FRNA Coliphage." Ms. Vithanage's research focuses on the use of non-standard indicators for sewage in environmental waters. Specifically she has been exploring whether the Environmental Protection Agency's approved fecal indicators (fecal coliform, E. coli, and enterococci) are naturally present in high concentrations in Kauai's streams as they have been found to be on Oahu, and whether the use of Clostridium perfringens and FRNA coliphage (bacterial viruses) can provide more reliable data when streams are contaminated with sewage.
Another WRRC research assistant, Mr. Sumon Kanpirom was awarded an HWEA Scholarship at the conference.