Sustainable water use is an important goal of many companies and institutions, and significant progress has been realized in recent years that has saved millions of gallons of water while achieving the intended purposes of the systems, such as cooling towers, which use high volumes of water. Saving water has a positive impact on the environment as well as the bottom line.
The ability to justify a business case for applying efficient technologies can be difficult based on water savings alone. However, when the metrics include water, energy and chemical reductions, the business case for supporting a return on investment (ROI) in less than 24 months is possible.
Pilot installations have been developed to demonstrate electronic water conditioning technologies, which resulted in larger scale program rollouts in order to capture and replicate long term savings of water, energy, chemicals and maintenance at facilities throughout the enterprise.
Robust Water Efficiency Tools
A successful program that systematically identified significant water and associated cost savings across the U.S. was jointly developed by AT&T and The Environmental Defense Fund (EDF). The result of a year-long program identified 14-40% water savings in cooling systems at AT&T facilities and led to the development of a full suite of water efficiency tools and resources during the pilot project that was generously shared at no cost to other companies and organizations.
Current Water Management Practices Offer Limited Gains
Cooling towers remove heat from water by evaporating a small portion of the water that is recirculated through the unit. Maintaining water quality is essential for optimum operating conditions, which involves controlling bacteria and algae, preventing scale, and corrosion. Scale and bacteria degrade the thermal and flow efficiencies of a water system, and together can cause corrosion of metal that results in high maintenance and replacement costs.
Traditionally, a range of chemicals are added that include scale inhibitors, biocides, corrosion inhibitors and other site specific additives to extend the use of water while preventing accumulation of scale and biologicals in the equipment. Many cooling systems have a sidestream filtration system that processes approximately 10% of water to remove suspended solids from the water stream while allowing the primary circulation to continue. It is our belief that ALL cooling systems should use sidestream filtration in order to preserve the useful life of the system, and extending the effective usefulness of water before discharging and replacing it with makeup water.
Under these operating conditions, water is discarded by blow down or bleed off when a sensor records a specific level of conductivity. Accumulated water loss is undesirable for cost and stewardship reasons, and every thousand gallons of purged water contains expensive chemicals that must be replenished.
Water Technologies with Short ROI
In practice, a cooling tower that maintains low levels of suspended solids will have lower conductivity in water, while also eliminating surface area for biologicals to grow. By removing particles to sizes of 1 micron, the effective use of water will be increased significantly. Further, the chemicals in the water will be conserved due to less frequent bleed off and they will have less total suspended solids (TSS) and organic matter that consumes them. We believe that a balanced chemistry program is important for consistent cooling tower operation, and offer technologies that reduce chemical use by up to 75%.
ElectroCell Systems provides a high efficiency electrostatic precipitator for sidestream filtration that uses no filter media, and requires minimal maintenance. The electrostatic electrodes neutralize particles and keeps them in suspension until they are automatically discharged in small batches, which saves significant water. The patented ElectroCell system is controlled by PLCs that allow remote operation while providing continuous water quality monitoring by sensors that inform SmartBuilding systems with operating data in real-time.
HydroFLOW is installed on the exterior of a flowline and emits a 150 kHz frequency that extends throughout the system. The patented transducer creates a pulse that includes a pause between signals that allows the positive and negative ions to bond after being excited by each pulse. The result is the dissolved calcium particles form clusters in water, preventing attachment to pipe and system surfaces. Scale is prevented and existing scale is reduced over time. The ElectroCell removes the scale particles that cluster in water, down to the size of 1 micron.
Bacteria and algae are controlled by the HydroFLOW’s frequency which unlike magnetic applications, uses AC current that extends throughout the system. Algae, biofilm and free-floating bacteria are deactivated and flocculated by the HydroFLOW and removed by ElectroCell sidestream, along with scale clusters and TSS down to 1 micron in size.
Capturing the Savings
Frequent blowdowns are reduced to brief bleed-off episodes using 50% less water, and due to significantly improved water quality from ElectroCell and HydroFLOW, less chemistry is wasted. Water may to be reused for irrigation or other beneficial uses rather than discharged into a sanitary sewer. ElectroCell manages the bleed-off process and collects key performance data.
HydroFLOW electronic water conditioning and ElectroCell sidestream filtration need little or no maintenance, and require no chemical additives. The cost savings provide a return on investment (ROI) of less than 12-24 months, based on cost savings derived from:
50% Water Reduction
75% Chemical Reduction
12-15% Energy Reduction
Sustainable Water Management requires frequent data collection to measure water, electricity and chemical use. In terms of calculating cost savings, maintenance events may be included, as well as a broader monitoring of asset lifecycle management metrics. The suite of water efficiency tools and resources developed by AT&T and the EDC offer tremendous value for a single facility as well as providing the ability to drive costs down systematically across a portfolio of facilities.
HydroTech has adopted these tools for evaluating their cooling system efficiencies, and apply the metrics to validate the performance of electronic water conditioning where we have installed our technologies.
HydroTech was formed to provide sustainable water management technologies to commercial and industrial users that save water, energy and chemical use; along with sensors that measure water chemistry and key performance metrics. Contact us with questions or ideas. We would enjoy the opportunity to share perspectives.
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