Q: Is it true that the make-up water stream for WCTI technology has to have almost all of the calcium (Ca) and magnesium (Mg) removed?
A: Correct. The process requires sufficient removal of scale forming ions in the makeup water to maintain total hardness levels at less than 30 mg/L as CaCO3 in the tower water to maximize water conservation and performance. The WCTI HES Pre-Conditioning System is designed to achieve this state and maintain WCTI conditions.
Q: If we have high hardness, high silica and high alkalinity water, will we need a mixed bed demineralizer along with the WCTI HES Pre-Conditioner?
A: No. The WCTI process does not need or require a mixed bed demineralizer (IX) to remove hardness from the makeup water. Our proprietary technology welcomes high levels of alkalinity, total dissolved solids (TDS) and silica. In fact these higher levels are preferred. The WCTI HES Pre-Conditioning System maintains its efficiency through regeneration and removes only hardness from the water.
Q: Can we use a standard ion exchange system that is commercially available?
A: No. WCTI conditions are developed and maintained through the use of our proprietary WCTI HES Pre-Conditioning System. Excellent ion exchange efficiency and polished hardness removal quality are best provided using the WCTI design. For the WCTI process to succeed as designed, the use of WCTI system is required under our license agreement.
Q: Since cooling tower blowdown with the WCTI process will be eliminated, is it necessary to address the buildup of TDS?
A: No. WCTI Technology is a complete paradigm shift. Due to the removal of the scale forming ions there is no longer a need to remove TDS from the tower water, as it presents no scale or deposition risk with this technology. The remaining TDS are all highly soluble ions. Cycles of concentration (COC) of up to 200X COC are now easily achievable.
Please note that high TDS water from the WCTI process has never been an issue in all of the installations operating with Zero Blowdown Technology. In this total paradigm shift high TDS levels are an integral component in the control of biologicals (Note the Anderson Engineering report on the effects of pH and TDS on Bacteria, Viruses and Spores in Water in our Documentation Section)
Q: Since solids precipitate continuously in the tower water as described by the WCTI technology. How is TSS removed?
A: Tower TSS (Total Suspended Solids) accumulates primarily as a result of particles scrubbed from the air, not precipitation from the water. The accumulation rate is no greater with WCTI Technology than with conventional chemical treatment, minus, of course, the magnesium, calcium and chemical precipitates in the tower water eliminated by our system. The normal maintenance related to cleaning the tower basin of settled particulate once or twice a year should be continued. Side stream filtration, with basin flushing grids, are becoming more prevalent and their inclusion will not be a detriment to WCTI conditions or performance.
Q: Since Monovalent ions (Cl and Na and others) continuously build up in the tower water, how are they removed?
A: The WCTI HES Pre-Conditioning System replaces calcium and magnesium ions with sodium ions in the tower makeup water. These sodium ions are discharged with the spent regenerate along with the hardness ions removed. As noted previously, there is no need to remove such soluble ions since they have no scale impact. There is no corrosive impact because metals are protected with the highly effective silica film created by WCTI conditions. Again, within this complete paradigm shift, any additional TDS only aids in the development and maintenance of the biostatic process.
Q: Because the WCTI System allows TDS to be built up to and above 44,000 mg/L, how will the monitoring instruments continue to function at this level of TDS? Wouldn’t the maintenance on different probes (TDS/Conductivity, pH and other) be high?
A: No. We have customer systems operating from 10,000 TDS to 200,000 TDS without deposition, corrosion or biological issues. The final TDS level depends on customer choice and how effectively their systems are designed to control system leaks and drift. Use of pH control or monitoring becomes obsolete, as more highly concentrated tower water, with no acid or chemical feed, reaches natural pH equilibrium at given discharge or drift losses. There is no scaling potential with WCTI conditioned water, and traditional scale control indexes become obsolete. Most of our customers choose to eliminate TDS / Conductivity controllers. A trained professional will regularly visit each site, perform an array of tests to assure that proper conditions and equipment performance is maintained. Each customer will receive a written report with the resulting data for their files.
Q: At very high operating TDS, it appears as if drift mist could be depositing a lot of salts outside the tower and could create an issue with soil and groundwater contamination. It appears that WCTI relies on losing the concentrated TDS through the cooling tower drift. Will high TDS in the drift cause nearby equipment, buildings and other installations to experience severe exposure to TDS and potential damage?
A: No. First, the WCTI process does not rely on drift as a means of losing tower TDS. The goal of the program is to build TDS in the system and not reduce it through drift losses. All modern cooling tower designs minimize drift to very low levels. As noted previously, TDS level can be easily controlled at the optimum level for the site with respect to tradeoffs in water conservation, aesthetic impact from higher TDS (salt) concentration, and permitting. Most cooling towers will not fall under drift regulation requirements as modern drift eliminator designs minimize drift impact to levels well below the quantity impact limits that are regulated. Since the use of pre-conditioned makeup provides highly soluble sodium salts versus insoluble calcium salts, drift solids buildup is easily maintained by water wash down should minor build up occur.
The conclusion that “high TDS in the drift will cause all the nearby equipment, buildings and other installations to experience severe exposure to TDS and potential damage” is not accurate and can be readily verified by contacting end users or through site visits. Preventative maintenance with water wash down and use of TDS resistant coatings for immediate adjacent piping is beneficial and common practice even with traditional low TDS treatments. (Note the Anderson Engineering report on cooling tower drift and permitting in our Documentation Section)
Q: The technical aspects of the WCTI technology are sound and verifiable as far as water savings. However, doesn’t the regeneration process of the HES require some water usage and since that process requires use of NaCl isn’t there increased chlorides of sodium in the tower?
A: Yes but with major exceptions to previous paradigms. We’ll first address the HES water usage issue. As an example, a current customer with a 500 ton tower, running at 3.5 COC (cycles of concentration), had a projected tower blowdown requirement of 1,915,329 gallons per year. The customer wished to quantify the water used in the regeneration process and installed a meter to monitor the water usage for that process. The 10 month accumulated regeneration water consumption was 11,865 gallons. This equated to an annual regeneration water demand of 14,238 gallons vs. the 1,915,329 gallons that would have been required for tower blowdown with a traditional water treatment program. The elimination of the tower blowdown requirement saved almost two million gallons of water and over ten thousand dollars.
Secondly we’ll address the chlorides of sodium issue. There are no issues with the increased sodium in the tower as they are in a highly soluble form from the WCTI process. Though this process does increase sodium in the tower, its soluble form is highly beneficial to the WCTI process. These infinitely soluble odium ions produce a beneficial “common ion effect” in the tower water chemistry as well. There are increased chlorides in the regenerate waste, rather than the tower makeup, but they pose no problems to being discharged to a sewer. Most plants that operate boilers use water softeners, and softener regeneration waste though high in TDS, is typically discharged to the sewer. The Department of Ecology has verified that this is not an issue.
Q: Wouldn’t the claim of the WCTI’s HES regenerate can be discharged to the sewer have to be checked with the local sewer authorities?
A: We encourage you to check with the local sewer authorities or your regional Department of Ecology to ask that very question. In fact, the total quantity of TDS that will be discharged from the tower using the WCTI process should, except in rare situations, be zero. Old technology requires that TDS be diluted with make-up as the concentrated amounts of calcium and magnesium will exceed the controllable parameters and plate out as scale. This increased blowdown requirement is to make room for diluting make-up actually discharging vast quantities of TDS to the sewer. There is however regeneration discharge from the HES system. We have evaluated the increased TDS impact from the salt used and discharged during regeneration and found the TDS contribution to municipal discharge is no more or less than traditional chemical treatment water wastage at lower COC operation. Use of de-ionization will not provide more efficient ion exchange nor reduce TDS contribution, but more likely will increase total TDS contribution to the sewer.
Q: The heat balance for the cooling tower can be affected by the significant blow down reduction or elimination. One key point is that the boiling point elevation due to high TDS means that the lower temperature on the Cooling Tower will be higher?
A: No. If the cooling tower is not adequately designed to meet cooling water heat load requirements without using excess makeup to cool the tower return water, then that can certainly a problem. But that design flaw would not be a good excuse to avoid water conservation. Cooling tower manufacturers provide data on the impact of higher TDS on heat rejection efficiency from cooling towers, as related to operation with seawater cooling sources. This data shows a probable impact and recommended increase in tower heat rejection capacity ranging from 1% to 2%. Most cooling towers are designed to provide more capacity than peak loads conditions, and would not notice this potential impact if the tower is operated at higher range of TDS. Full scale installation experience verifies this point, as no end users that converted their systems to the WCTI process have experienced a reduction in cooling capacity. In fact, cooling capacity has been increased at many locations due to the elimination of scale and bio-fouling effects on heat transfer efficiency, which has a much higher impact on cooling capacity. It is also interesting to note that many tower systems have to operate at higher water flow and at capacities to compensate for poor heat transfer rates that result from scale, deposition and bio-fouling that occurs with traditional chemical treatment approaches. WCTI systems operate without scale or bio-fouling.
Q: Is it fair to claim WCTI Zero Blowdown Technology’s (often referred to as ZLD or Zero Liquid Discharge) regeneration waste is a substantial liquid waste that is high in TDS and Chlorides?
A: No. The term zero liquid discharge ZLD is the terminology used in the water treatment industry when the cooling tower discharge is eliminated. This cannot be done without some form of pretreatment or side stream treatment that removes some of the insoluble ions. The WCTI process is an advanced more efficient and more cost effective process to accomplish ZLD from the tower. In fact, the WCTI (HES) process substantially reduces the total volume of regenerate waste as compared to conventional softeners, demineralizers and RO processes.
Q: Are the LSI (Langelier Solubility Index) and other indexes of the circulating water applicable for evaluating WCTI treated towers?
A: No. This is a complete shift in paradigms. The LSI and other indexes are irrelevant with the WCTI process, since calcium and scale forming ions are removed, and no longer provide the basis for the calculations and their predictions. Hardness is maintained below 30 mg/L in the tower water with the polished quality of WCTI softening equipment, even at higher COC ranges. Any owner of a WCTI installation will verify that scale is not an issue. Corrosion and bio-fouling are non-issues as well.
Q: Do we need to conduct piloting of the WCTI before we try this process?
A: No. The WCTI process has been already been piloted and has been operating on all types and sizes of cooling water applications commercially for over six years, in addition to being professionally peer reviewed in major conference reports and papers. The WCTI process has enjoyed a 100% success in mitigating scale, corrosion and biological concerns in all applications without exception. We highly recommend that any interested customer investigate this technology through site visits and talking to end users to learn about this technology through their direct experience with it.
Q: This technology seems new to me. Would it be risky to implement it w/o having more information on its performance in the industry?
A: No. There are approaching 100 installations across the globe using this technology and more are being installed every month. Many of the locations who piloted the technology have provided for publication, empirical data, case studies, installed additional systems and some have moved into a global procurement posture for all their facilities. The technology is rapidly becoming main stream. WCTI and the licensees applying it are also very experienced with traditional chemical and non-chemical treatment approaches, performance evaluations and water conservation alternatives. Given that water and wastewater issues are becoming more and more important, this technology offers the best means to address water conservation, wastewater discharge and in using final effluent as a makeup source. You will find that communicating with WCTI or its licensees to learn more about the information will put this to rest. If you feel it is risky to implement WCTI without having more information on its performance, we encourage you to do just that – get more information. We will be happy to provide relevant application references, contact information and answer any questions you have, technical or otherwise.
Q: How would we determine what size system we would need to implement this process?
A: This would depend on your peak evaporation rate flow for your systems as we size the HES equipment based on peak load through put. WCTI can provide systems for as little as 7 gpm, and the technology is scalable to any size tower requirement.
Q: How much does it costs to run the program?
A: The WCTI program is consistent with performance contracting concepts where by the WCTI licensee is paid out of the savings generated for the end user. Our process, once installed, provides service on our part to verify the pre-conditioning process, maintenance on the units as needed, and verify controls so that the tower water is maintained within WCTI condition parameters. WCTI licensees charge a fixed monthly fee to use the technology that includes testing, reporting and maintenance services associated with the program that are comparable to traditional water treatment programs. The HES equipment typically has a payback between 3-9 months and the WCTI system usually shows a 30-50% reduction in water treatment costs over other programs.
Q: What if our water has very little alkalinity or silica available?
A: Both silica and alkalinity may be supplemented to the makeup to the tower during the brief commissioning period to establish method control residuals. Once a pH of 9+ has been achieved and the silica levels are achieved, no more products should be needed as constant evaporation and “no bleed” will keep the process in range.
Q: How is the program implemented?
A: If the system is on a traditional chemical program, there is no need for anything other than the installation and commissioning of the HES Pre-Conditioning System. Trained personnel keep close tabs on the tower total hardness to assure proper HES operation. Depending on prior treatment program deposition, with introduction of the new pre-conditioned water make-up, some hardness “leaching” can take place for a period of time. This is essentially the re-solubilizing of the hardness ions from the pre-existing scale deposits as they are removed. In time, the tower water should stabilize relative to hardness which will be maintained at or less than 30ppm. The pH in most cases will increase in time; however, some alkalinity may be added initially by the licensee to attain the pH needed.
Most inhibitors left over from the traditional program can continue to be pumped into the system to help deplete inventory but is not necessary.
New system start-ups are essentially easier depending on the incoming make-up. Low pH and soft water sources may require the addition of sodium silicate and NaCO3 at start-up to reach WCTI conditions. Once WCTI conditions are achieved the system essentially operates without the external introduction of chemicals.
Q: Is there any other equipment needed along with the HES Pre-Conditioning System?
A: No. However, some source waters or those utilizing grey water may find high TSS or iron concentrations that require a simple low micron filter upstream from the HES to filter out any undesirable suspended solids that could interfere with the pre-conditioner’s operation. Trained WCTI professionals will help determine if any type of filtration is recommended during the design phase.
Q: How are bacteria, spores and pathogens controlled by WCTI technology?
A: WCTI Technology creates a true biostatic environment where bacteria, spores, viruses and other pathogens activities are blocked (Note the Anderson Engineering report on the effects of pH and TDS on Bacteria, Viruses and Spores in Water in our Documentation Section)
At start-up, until the pH reaches around 9.2 and above, very limited supplemental non-oxidizing biocides specified by the licensee (such as Isothiazoline) or oxidizing biocides may be used by the licensee to control bio-growth. Natural biostatic chemistry starts to build with increasing pH and TDS as referenced in the Anderson Engineering study referenced above. The licensee may also increase pH by limited initial caustic addition to promote biostatic action inherent in WCTI conditions. Thereafter externally introduced chemicals are rarely if ever needed or used.
Q: What should be done if we have high levels of ammonia in our supply water or if we have ammonia leaks from or cooling process?
A: The WCTI process naturally removes ammonia (striped when circulated over the tower) contained in either the makeup or introduced into the tower water to very low residual (< 1 mg/L with tower water pH > 9.7). This will also eliminate potential odor issues as the ammonia is stripped incrementally as it is introduced by makeup to the larger circulating volume of the tower water. No further treatment is required unless copper metals are contained in the system, in which case the licensee will add a small quantity of copper inhibitor each month during service visits to further increase protection of copper metals. Very little inhibitor is consumed if there is mechanical system integrity since there should be no blowdown. Excessive sustained losses of ammonia from a leaking condenser may cause a volatile organics discharge issue and any such leak should be addressed by the owner or their mechanical contractor.
Q: What if the HES Pre-Conditioner fails and hard water is introduced into the tower?
A: Though our HES system is manufactured to the highest standards, is robust and highly reliable, any mechanical device can experience down time. In case of this rare type of event WCTI personnel would have instructed the owner’s staff on the short term procedure to follow until a WCTI representative can be on site and while the HES is being repaired. The system should be bled down. However, since the system will be at a highly buffered condition, this should not be a problem for several days allowing time for the HES to be repaired.
Q: Are the WCTI patents available for our review?
A: Yes. All current and pending patents are available for review in the documentation section of our website.
Q: Since our tower would be cycling up to such high TDS levels (in some cases >100 COC), aren’t more precipitants created than with other water treatment programs?
A: No. Precipitants do not form in the WCTI process to any greater extent than traditional chemical treatment, and side stream filtration is only needed to remove suspended solids scrubbed from the air by the tower, and only to the same extent it would be needed in other systems. This was presented in the patents and pilot process results. This should not be a concern.
Q: Are there negative sides to the WCTI Technology?
A: No. In fact, even deposits that might form on the drift eliminators are now chemically different due to the WCTI process. These deposits are now non-adherent and highly soluble since they no longer contain the hard scale forming ions of calcium and magnesium. Deposits can now be easily washed down with HES conditioned water at garden hose pressures saving man-hours and damage to the fill caused by high pressure cleaning.
Customers who have experienced severe biological issues in the past with chemical and NCD treatments may wish to operate at higher pH. This is made possible by WCTI’s ability to develop “sustained natural chemistry” and pH will begin to naturally buffer out at about a pH of 10. In this case, the owner may look at choosing seals and belts more tolerant to high pH as a part of their scheduled maintenance programs.
As with any cooling tower and water treatment program, drift under certain conditions, in areas sensitive to vehicles or building aesthetics can be addressed on a case by case basis to reduce the problem. Your WCTI professional will be happy to work closely with the owner’s staff and mechanical contractor to provide potential solutions.