The AlgaeWatch Online Fluorometer Used by the Santa Clara Valley Water District
Application(s)
In Vivo Chlorophyll aIntroduction
The AlgaeWatch Online Fluorometer provides a continual indication of the algal biomass in water, thus allowing for the early detection of algal blooms, detection of nuisance species, and a measure of daily and seasonal fluctuations in the algal community. The Santa Clara Valley Water District (SCVWD) has been using the AlgaeWatch system since 2005 and presently owns multiple instruments installed at various reservoirs and treatment plants. Grab samples from the facilities are taken periodically and sent to the in-house laboratory for algal speciation and algal count measurements. The AlgaeWatch used at the Penitencia Water Treatment Plant (PWTP) measures the relative Chlorophyll a content of the pre-treated water which is received mainly from the Sacramento-San Joaquin Delta via the South Bay Aqueduct (SBA). This facility can treat up to 40 million gallons of water per day and measures other water quality parameters such as turbidity and pH at the pre-treatment sampling point.
Results
The PWTP is a conventional water treatment plant with coagulation, flocculation, sedimentation, ozonation, and filtration processes. Pre-treated water is first injected with coagulant chemicals and then mixed with flocculator paddles to turn undesirable particles in the water into bigger denser flocs; which settles away in the sedimentation basins. In the final stage, filters composed of granular activated carbon and sand remove the remaining particles in the 'settled' water. A high chlorophyll a measurement by the AlgaeWatch can be an indication that an algal bloom is occurring along the SBA. As a result, the filters may be taking on an increased load during an algal bloom and have to be washed more often.
Contact
- Author: Lotina Nishijima & Karla Guevarra
- Website: http://www.valleywater.org