There are still a dozen or so cooling towers on campus, and ISTC staff are meeting with related building representatives later this month to review the options for reducing water consumption in these towers.
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Reduce Cooling Tower and Chiller Plant Water Use (In Progress)
The 2015 iCAP, chapter 5, objective 2 is "Improve the water efficiency of cooling towers by limiting the amount discharged to sewer to less than 20% of water intake for chiller plant towers, and less than 33% for stand-alone building towers, by FY20." The results of the Illinois Sustainable Technology Center’s True Cost of Water Study yielded five action items and two pilot studies. These action items and pilot studies were to generate ideas for improving water use efficiency. The first goal of the study, to benchmark water use in cooling towers, was fulfilled in the study’s initial research.
The initial five action items and two pilot studies are as followed:
1. Install Trasar 3D monitoring at the Oak Street Chiller Plant (OSCP) and Vet Med Chiller Plant.
2. Initiate engineering design and feasibility study of sulfuric acid dosing to increase Cycle of Concentration (COC) at chiller plants.
3. Explore optimization of Abbott Cooling Tower and RO as a whole system.
4. Monitor the feed water going into the RO at Abbott to allow for independent determination of the RO efficiency.
5. Monitor any existing Cooling Tower blowdown meters to compare operation with the observed chemistry.
1. Initiate piloting of Nanofiltration of Oak Street Sub-soil drainage water as make-up for cooling tower.
2. Conduct pilot investigation of non-chemical water treatment (especially VRTX) technologies for stand-alone towers.
The first action item, the installation of the Trasar 3D monitoring at OSCP, has already been completed. The 3D Trasar technology is installed on the cooling towers at Abbott, as well as the boilers at Abbott. The link for the information on the 3D Trasar for boilers is http://www.nalco.com/services/3d-trasar-boilers.htm.
The second action item has been taken out of consideration due to a safety issue.
The third to fifth action items have been initiated and should be investigated for implementation in the future.
For the pilot studies, the first one about applying nanofiltration of drainage water is studied and needs funding to be implemented. For the second one about the non-chemical water treatment technologies, after some research about the onsite VRTX technology, Illinois Sustainable Technology Center (ISTC) has proved it inefficient. A new technology called Zero Blowdown Cooling Towers, which uses water softening to prevent scaling and silica to prevent corrosion, removes blowdown water loss and has proven to be highly efficient with a COC of about 50 (usual number is 1.2-2.5). An EPA building in research park has already applied this technology, saving energy and water usage. The campus is looking for a cooling tower location to implement this new technology.