2011-081 - Laserfiche WebLink

Home Browse Search

Scope : The PC South Algal Turf Scrubber(D Pilot was implemented with the intent of determining the applicability of the technology to meet targeted performance goals and identifying critical performance parameters to be applied to a proposed full scale Algal Turf Scrubber® system to be designed to provide 1 ) reduction and recovery of nutrients from the South Canal within Indian River County , as managed by the Indian River Farms Water Control District ( IRFWCD) and 2 ) elimination of biological toxicity associated with a Reverse Osmosis ( RO ) Concentrate . The operational protocol originally delineated for the pilot was to dilute the RO Concentrate with the water from the South Canal at a proportion of about 10 % RO concentrate . The pilot investigation was initiated on 1 / 17/2011 . Laboratory data to date provides indication that the system at the stated dilution does render the blended water non -toxic , and is effective in removing and recovering both nitrogen and phosphorus at rates within expected ranges . To this extent , the system appears applicable and appropriate for meeting the project intent at a 10 % RO Concentrate , 90 % Canal water blend Based upon reviews by the County staff and HydroMentia of historical flow patterns within the South Canal in the vicinity of the proposed full scale facility , it was determined that flows within the canal would not always be sufficient to ensure the 90 % dilution of the RO Concentrate , which is projected to have a constant flow rate of about 1 MGD . Consequently , it was decided that based upon the worst case low flow conditions within the canal of 1 MGD , that the most conservative dilution would be 1 : 1 , or 50 % RO Concentrate and 50 % Canal water . To accommodate this design feature , it was decided that the pilot system should be adjusted to receive a 1 : 1 blend , and assessed accordingly both in terms of nutrient removal and toxicity . Because the shift in the influent blend will result in a significant increase in conductivity (salinity) , it will be necessary to change the bioassay protocol from freshwater species (fathead minnows and daphnia ) to marine/estuarine species ( mysid shrimp and menidia minnows ) . To adequately assess the toxicity of this new blend , six additional bioassay tests will be required , using these marine/estuarine species . Three of these will be acute tests , which if found non toxic , will be followed by three chronic tests . Following about 12 weeks of operation under the new blend conditions , the system will be again returned to the 10 % RO Concentrate blend , and planned chronic bioassay testing of the freshwater species will be completed . This revised program will not only allow assessment of the efficacy of the technology under these two conditions , but will permit assessment of performance during the transitional period associated with changes in blends , during which time the algal turf community will undergo ecological adjustments .