NBOT Project Log

Friday, September 17, 2021.  Yesterday the Lab team collected the weekly bacteria samples.  Sadly, the results from the upstream stations (station TPJ and CALC) did not show results we were hoping for with this project.  Both sites were again in the several thousands – well above our target concentration of less than 500 MPN/100mL.  The results should be available in the data visualization (below) after 6 pm.  The Lab and Green Water Solutions staff also conducted a test of the equipment at the 3rd NBOT equipment site using the closed, 275 gallon tank that also showed very effective treatment in less than 15 minutes.  This closed system tank testing provided validation that the NBOT machines were functioning as designed.  The 60-day commitment of NBOT treatment ends on Monday.  Also on Monday, the Lab Staff will conduct another round of comprehensive water quality and sediment sampling and analysis to measure conditions immediately following the 60-day treatment phase of the project.  In the coming weeks we will compile and review all of the analysis results. We will also do computations to try and understand why we did not get the anticipated results. At this point it seems the most logical factors are the tidal flushing and the “crop” of bacteria living in the sediments and debris were just too much for the 6 NBOT units to overcome.  But we will fully evaluate the data and all potential scenarios in our final report.  Our sincere thanks goes out to the residents in the area for their patience and support of this project, particularly the residents that allowed us to deploy the equipment on their property, and their neighbors, that tolerated the noise.

Friday, September 10, 2021.  The bacteria testing this week showed similar bacteria concentrations at the upstream stations (Station TPJ and CALC) and notably lower concentrations in the downstream portion of Jones Creek (Stations 71 and 75).  These latest results should be posted to the data visualization tool this evening. This week we also conducted another round of testing using the 275 gallon closed system using the NBOT system at the downstream treatment site that, again, demonstrated highly effective treatment bringing bacteria concentrations from roughly 750 MPN/100mL to less than 10 MPN/100mL in 15 minutes of treatment. We also downloaded the instrument data from Sims Creek and that comparison data is in the Instrumentation visualization below. The NBOT equipment continues to run in hopes of the ozone concentration possibly reaching a threshold that provides substantial treatment at the upstream Jones Creek stations.  We are tentatively scheduled to conduct another round bacteria testing next Wednesday or Thursday.

Friday, September 3, 2021.  The Jones Creek water quality instrument was retrieved yesterday and the data is posted to the Instrumentation visualization tool below.  The chlorophyll results, a measure of algae in the water, is one of the parameters that we have been watching carefully as other NBOT projects have demonstrated effective treatment.  Unfortunately, the instrumentation data indicates that many of the chlorophyll values remain well above the water quality target of 15 ug/L.  We will retrieve and post the instrumentation data from the reference site in Sims Creek next Tuesday or Wednesday.  The weekly water quality sampling for bacteria, collected yesterday at the regular monitoring sites and adjacent to the NBOT systems show bacteria concentrations lower than last week, but nowhere near the sub-500 MPN/100mL concentrations we were seeking.  Next week’s sampling is scheduled for Wednesday 9/8.  We are working with the Green Water Solutions Team to conduct closed-system tests using the 275 gallon tank for all of the NBOT systems to demonstrate that each unit is performing as designed. We continue to hope that the concentration of ozone nanobubbles will reach the threshold within the creek to provide measurable treatment of the bacteria. However, the tidal flushing may be greater than we estimated and/or the concentration of organic material is so great that the ozone is overwhelmed.  Unfortunately, a hydrodynamic model to fully understand the flow characteristics of the creek requires extensive survey data, flow measurements and modeling work that is very complex and expensive.  But this information would be valuable to help guide restoration work into the future.  The 60-day commitment of NBOT equipment ends on Sunday, September 19th.

Monday, August 30, 2021.  The water quality samples collected last Thursday (8/26) showed increased bacteria concentrations at our regular monitoring sites, particularly the Caloosahatchee Bridge (CALC at 10,462) and Footbridge (TPJ at 19,683).  Undoubtedly, this was influenced by the 1.4 inches of rain on Wednesday night.  In addition to the regular sample sites, the Lab Team collected samples at the NBOT equipment discharge area and those bacteria concentrations were lower at 2,035 (downstream of CALC) and 9,208 (upstream of TPJ).  The results from last Wednesday’s test on the alternate configuration using the closed 275 gallon system also showed very effective treatment of Jones Creek water.  These two small, closed-system tests helped to verify the equipment is working as designed.  Collectively, the work to date has led us to our current hypothesis that the treatment is not as effective as anticipated because of 1) higher than expected ozone losses due to tidal flushing, and 2) the high amount of organic material in the creek that may be consuming the ozone so quickly that the six NBOT units cannot provide the ozone concentrations needed to provide widespread treatment.  Based on the bacteria results from last week that suggest measurable treatment near the equipment, we are hopeful that we will have less rain/flushing this week and perhaps see the area of treatment expand in the creek.  This Thursday the Lab Team will collect another round of samples for bacteria testing, and retrieve the water quality instrument for data download, maintenance and calibration. We will try to have these results posted by late Friday.

Wednesday, August 25, 2021.  The closed system test treating water from Jones Creek in a 275 gallon tank verified the NBOT equipment is working as designed.  The bacteria results demonstrated very effective treatment with bacteria concentrations at 1,455  and 1,616 MPN/100 mL before treatment to less than 50 in the first 15 minutes of operation. Today we conducted another closed system test of the alternate configuration of the NBOT system and observed very similar results in the field. The bacteria results for the second test will be available late tomorrow (Thursday).  It is worth noting that we filled the tank with water in the vicinity of the second, operating NBOT system and the bacteria results, while roughly 1,500, are are lower than we have measured in a long time.  So, perhaps we are starting to see some bacteria treatment in the Creek.  The Lab Team will sample the regular monitoring sites tomorrow and we will post those results late Friday or early Saturday.

Tuesday, August 24, 2021.  The bacteria samples collected last Thursday did not show the treatment we are all seeking (results below).  Today we loaded the water quality data from the datasonde instruments that measure several parameters every 15 minutes.  While we have not yet thoroughly reviewed this data, there are some interesting trends in a few of the parameters including the turbidity (a measure of the clarity of the water) and chlorophyll (a measure of algae).  This data can be viewed in the visualization tool below.  Today we are conducting a separate experiment to evaluate the bacteria treatment of Jones Creek water in a closed, 275 gallon tank.  Once the tank is filled, we will put the intake and discharge lines in the tank simulating a small, closed (non-tidal) system and then test the water for bacteria at a specific time interval – every 15 minutes the first hour, every 30 minutes for hours 2 and 3.  This experiment should provide insights into some of the variables affecting the treatment in Jones Creek such as contact time needed to treat these bacteria, the effectiveness of the ozone in the heat, etc.  We will have the bacteria results late tomorrow (Wednesday).

Wednesday, August 18, 2021.  The Green Water Solutions Team continues to make adjustments to their equipment to try and improve treatment of the high bacteria concentrations.  On Sunday we shut down the NBOT equipment at the site near the Caloosahatchee Ave bridge and moved that equipment about 300 yards to the east.  Treatment for that site resumed this evening.  One hypothesis is it may take more time to effectively treat the bacteria because of several factors including: 1) the loss of ozone to the extensive organic material, 2) the loss of ozone to constant tidal flushing, and/or 3) increased contact time needed for the ozone to kill the bacteria. Today, the Lab Team collected another set of bacteria samples from each of the water quality stations and those results will be posted late tomorrow or early Friday.

Wednesday, August 11, 2021.  The Green Water Solutions Team has been hard at work making modifications to their equipment and increasing the capacity of ozone treatment.  Tomorrow we will collect and test water samples for bacteria 1) directly from the equipment under the new configurations, and 2) sample the regular monitoring sites in Jones and Sims Creeks.  We will have those results late Friday.

Friday, August 6, 2021.  The results from yesterday’s testing did not show the treatment effect we hoped for.  Over the weekend the Green Water Team will continue to diagnose the issues to improve the treatment effectiveness.

Thursday, August 5, 2021.  The Green Water Team has reconfigured their equipment to provide additional filtering and simplify cleaning of the diffusers.  It appears performance is improved.  The Lab Team collected water samples from the equipment to test the effectiveness of the bacteria treatment under the new configuration.  We will have results from this testing tomorrow afternoon.

Tuesday, August 3, 2021.  NBOT treatment continues while experiencing challenges brought about by the shallow water during low tide and debris clogging the equipment.  The results from the bacteria sampling on Monday are not showing the significant reductions in bacteria concentrations we are all hoping for.  The Green Water Team is continuing to explore and test methods to improve the treatment process in this challenging environment.

Friday, July 30, 2021.  NBOT treatment continues.  Yesterday, the Lab Team downloaded the data from the water quality instruments in Jones and Sims Creeks.  These instruments measure key water quality parameters every 15 minutes.  Below is a new data visualization tool to explore these data; note there are multiple pages of figures.  There is some interesting variation in the turbidity and chlorophyll measurements that corresponds to the treatment start, but also the notable rainfall the first few days of treatment. It will be interesting to evaluate these data as the treatment continues. On Monday, the Lab Team will collect another round of bacteria samples at the monitoring sites, and collect some additional samples near the diffusers to evaluate the treatment effect.

Wednesday, July 28, 2021.  The bacteria results from the samples collected on Monday continue to show high bacteria concentrations at the sites in upper Jones Creek (CALC and TPJ).  The Green Water Team is making adjustments to the depth and angle of the NBOT diffuser heads to try and reduce the chances of sediment mobilization and increase ozone diffusion in the water column.  The sediments contain high concentrations of bacteria and could be a factor in these observations.

Monday, July 26, 2021.  NBOT Treatment continued over the weekend with minimal down time.  We collected the Day 5 post-treatment water quality and sediment samples late this afternoon.  Because the samples were collected late in the day, the bacteria results will likely be posted Wednesday morning.  We fixed the issue with the automatic update for the data visualization tools that failed to refresh over the weekend, and added a Table view of the results on page 2 of the visualization tool. The bacteria concentrations measured at the sites in upper Jones Creek on Thursday and Friday were still high following some heavy rains on Wednesday and Thursday.  We look forward to seeing the results from the samples collected today.

Friday, July 23, 2021.  The 24- and 48-hours post treatment water quality samples have been collected and results will be coming in as the analysis is completed. The analysis of Enterococci bacteria, the analyte we are most interested in, takes 24 hrs to incubate so results are posted soon after.  It looks like bacteria concentrations increased 24 hrs after treatment began, but we have had some heavy rain events that are likely affecting the results.  Today we modified the data visualization tools to help differentiate the treatment area in Jones Creek (green lines) and our reference area Sims Creek (blue lines), and to provide reference lines for the treatment start date and enterococci target of 500 MPN/100mL.  We will sample another round of water quality and sediments on Monday.

Wednesday, July 21, 2021.  Big milestone!  Midday today, the Green Water Solutions Team began the NBOT treatment.  Treatment at the Caloosahatchee site may need to temporarily shut down at low tide because of very limited water depths.  We are seeking potential alternative deployment sites along the east-west canal off Sioux St and Mohawk St.  If you are a homeowner in this area and might be willing to provide access for the this 60 day project, please contact bud.howard@lrecd.org.  Another round of comprehensive water quality monitoring occurs tomorrow following 24 hrs of treatment.

Tuesday, July 20, 2021.  The Lab Team successfully completed the comprehensive water quality and sediment sampling event.  We will post the results as they are released from the laboratories through the NBOT Water Quality Data Explorer below.  Remember you can click on the double arrow icon in the lower right of the graphics window to view full screen.  The data is refreshed at 5:30pm and 10am daily.

Monday, July 19, 2021.  The Green Water Solutions Team is setting up the NBOT equipment preparing for treatment to begin on Wednesday, July 21.  The Lab Team is preparing for their big water quality and sediment sampling event on Tuesday to document the pre-treatment conditions.