STANDALONE ADVANCE DISINFECTION SYSTEM FOR SWIMMING POOL WATER TREATMENT

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1 STANDALONE ADVANCE DISINFECTION SYSTEM FOR SWIMMING POOL WATER TREATMENT AMRIT F. SANGHAI Technology description: Advance Disinfection System (ADS) is based on the principle of hydrodynamic cavitation. Cavitation is a physical phenomenon associated with three aspects: formation, growth and collapse of a vapour or gas-vapour bubbles within the body of a liquid due to variations in local static pressure. Decreasing the pressure over a liquid and bringing it to its vapour pressure at the operating temperature generates vapour bubbles in the liquid. When the pressure is brought back to normal pressure, these vapourous bubbles collapse with a bang to generate intense conditions like 5,000 atmospheres, temperature of 12,000 K, intense turbulence and free radicals (Figure 1). These intense conditions and resulting shock wave can bring about several physical, chemical and biological transformations, even when the bulk conditions are ambient. Figure 1: Principle: Hydrodynamic Cavitation Using ADS technology, we make the bubble travel in a particular direction, over a particular distance, grow it to a particular size and then collapse it in such a way that at every point of a flowing fluid inside our system, a bubble is collapsing to create controlled pressure, temperature, turbulence and formation of free hydroxyl radicals due to the cavitation phenomena. The developed high turbulence and mechanical shock is utilized for cellular breakdown and makes micro-organisms unviable and increases the disinfection process by minimizing any external biocide dose. ADS can be retrofitted to make disinfection processes more effective and efficient by reducing treatment time and costs as well as the usage of chemicals (saves up to 90% biocide consumption) in an environment friendly way. 22 / July 2016 / Indian Plumbing Today

2 Retrofitting ADS into existing swimming pool Figure below shows schematic of a typical swimming pool circuit and an installation of standalone ADS for preventing bio-fouling. ADS is a standalone unit which will take its feed from swimming pool sump, pass it through the ADS and the treated swimming pool water will be discharged to the swimming pool sump as a closed circuit. ADS is available in a package having centrifugal pump which will take care of required flow rate and pressure needed for ADS to work with its full efficiency. Figure 2: Schematic diagram of Standalone Advance Disinfection System Potential Benefits: ADS prevents the bio-fouling and reduces the blow down to a very low value which in turn will reduce the makeup water rate. Once the frequency of makeup water is reduced, the addition of other chemicals will also reduce and other impurities due to addition of chemicals will also reduce significantly. Indian Plumbing Today / July 2016 / 23

3 Key benefits of the ADS are: : Minimum footprint Can be easily fitted in congested places, makes retrofitting possible Reduces chemicals usage Less polluting Highly efficient Uses lesser energy for same work Clean Prevents side products Speeds up processing time Increases plant capacity with same Can handle large flows Industrial scale operations Technology allows for retrofitting Makes existing plants more Can combine with other Makes existing plants more Low Cost 100 % depreciation in first year, extremely attractive paybacks In general for normal feed water quality the potential benefits are: 1. Helps in the prevention of bio-fouling, corrosion problems and scale formation. 2. Environmentally Safe less chemicals added and thus, less unwanted residuals created by the process. 3. No need of biocides chemicals. 4. Reduces up to 40 % consumption of dispersants and corrosion inhibitors. 5. Reduced blow down of water due to operation at higher cycles of concentration. 6. Reduces about 40-80% consumption of blow down water. Answers to Frequently Asked Questions (FAQ s) by potential buyers Equipment What is the space requirement for ADS? Standalone ADS requires very less footprint. Typically, it is the space required for installation of pump set. The ADS to be installed at the pump discharge side. What will be the weight of ADS? Based on the pipe size, the typical weight of ADS will be 100 kg. to 400 kg. However the actual weight and size of ADS may vary depending upon pipe size, pump size, sump volume, capacity of swimming pool and blow down frequency. If needed, how can we separate the ADS from the main line? A bypass valve is provided in ADS and it can be completely bypassed from the existing swimming pool circuit whenever required or the complete system can be bypassed as it is a standalone unit. Saving Does the standalone ADS require any external energy supply? An external energy source is required to an electric motor which will run the standalone ADS. 24 / July 2016 / Indian Plumbing Today

4 What additional hardware or manpower is required for installation? No additional hardware is required. For installation, client needs to arrange only fitter, welder and an electrician. Tuning of the ADS is very easy. Is this technology cost effective? Yes it is, because it saves water and chemicals. The process generally is approximately 20-40% less costly than conventional chemical treatment. What about the payback period? The average pay back period is in range of 1-2 years which is dependent on the quality of water used. Operation and Installation Does standalone ADS require continuous monitoring? Standalone ADS does not require continuous monitoring. It operates on Fit and Forget principle. ADS requires zero operational supervision and maintenance, freeing the personnel for other productive work. Is Installation of standalone ADS difficult? Installation of standalone ADS is very easy and needs only fitting it in bolted flanges at the required location. The weight of the ADS ranges from 100 kg. to 400 kg. depending on the swimming pool sump size. What will be the operational cost of standalone ADS? The exact operational cost of ADS can be estimated only after receiving swimming pool details as per a standard questionnaire. What is the procedure to monitor / evaluate performance of ADS? The performance can be monitored by analyzing (ph, CFU, TDS, total hardness and total alkalinity) of the swimming pool water. The tests and testing procedure of water is the same as is presently done for all pools. Environmental & Safety Issues Is ADS environmentally safe? Yes it is, because it reduces the total consumption of chemicals used for given capacity of swimming pool. What are the safety issues to be adopted during its course of operation and handling? Standalone ADS demands no critical safety measures; however some of the general safety measures are as follows: 1. The weight of standalone ADS will be 100 kg. to 400 kg. So, use of appropriate chain pulley blocks or other lifting equipment is recommended during its installation. 2. Give proper support to the equipment and the adjoining piping. ADS can be installed in any orientation, either vertical or horizontal. 3. While in operation, standalone ADS does NOT generate any pressure or temperature higher than the inlet water pressure and temperature. Normal safety precaution needs to be taken as per established policy. 4. Install and operate the equipment as per the instructions given in installation and operating manual supplied with the equipment. Remedial solutions for existing problems What are the remedial solutions for (a) Bacterial Growth, (b) Microbiologically Influenced Corrosion and (c) Scale Formation? a) Bacterial Growth: Biofilm is a consortium of microbial life, and swimming pool acts as a complex ecosystem where bacteria and other organisms can thrive and safely multiply using different types of nutrients. Salts (including added chemicals), ingressed hydrocarbons and macromolecules present in the water are used up by the biofilm adsorbed onto pipe walls or other system surfaces. When these nutrients are used up by these microorganisms, they will reproduce with an exponential rate, leading to the development and stabilization of 26 / July 2016 / Indian Plumbing Today

5 the biofilm leading to the bio-fouling. ADS kills or disinfects the microbes by means of local mechanical shock and heat generated using the phenomena of cavitation in the system. Also, it decreases the need of the external addition of many chemicals / salts serving as biocides and corrosion inhibitors, ingressed hydrocarbons and other macromolecules reduced or no nutrients are likely to be available for microbes to grow further. Hence, our system saves close to 90% biocide and 25% disinfect dosing in your swimming pool system and reduces the growth potential of the microbial growth and the biofilm formation. b) Microbiologically Influenced Corrosion: Bio-films can harbour a variety of bacteria including anaerobic Sulfate-Reducing Bacteria (SRB). SRB obtain oxygen by reducing sulfate and produce hydrogen sulfide as a byproduct. Hydrogen sulfide disassociates in water to form a weak acid, which corrodes the underlying metal to which SRB are attached. This process of microbiologically influenced corrosion (MIC) is known to create pits with localized corrosion. With the use of ADS, you can save up to 50% of corrosion inhibitors since the system restricts the growth and surveillance of microbes which mainly contribute to corrosion along with reduced bio-fouling. c) Scale Formation: As bio-films grow on heat exchange surfaces, the carboxylate groups present in the extracellular polysaccharide matrix can attract scale-forming cations such as calcium. The biofilm acts as a binding agent for these minerals, resulting in an even more mechanically robust biofilm with calcium occlusion close to the heat exchange surface. This altered surface structure can act as seed crystals in the bulk water, promoting the formation of mineral scales. By using ADS, the microbial growth and its reproducibility get reduced which helps to prevent the scale formation due to insufficient binding to the surface of pipes via bio-films. Hence, this system reduces the ant-scaling chemicals usage up to 25%. Whether outlet conditions of system will improve in comparison with inlet conditions at any point of time. If so, what are the parameters and what will be the percentage improvement in the range of values? The time and the treatment duration will depend on the water quality desirable, at least the same or better quality in terms of microbial. COD reduction is expected and since the added chemical will be less and the ADS will keep reducing the COD as well, substantially reducing the microbial growth due to the reduced or non availability of food, substrate. The same parameters as measured currently are to be used. In addition, the BOD and COD will be measured. The operation of the reduced bio-fouling can be assessed by measuring the temperature differential across the heat exchangers and its change over a period of one to three months. If no change or small change is indicated, then it clearly indicates the reduced bio-fouling. It is also possible to measure the discharge pressure of the circulating pump or the current drawn by the motor of this pump to assess the biofouling. Whether System Performance has to be checked only based on the reduction of chemical. If so, please mention the economics of chemicals reduction versus system and associated CAPEX? The same parameters as measured currently are to be used. In addition the BOD and COD will be measured. The operation of the reduced bio-fouling can be measured by measuring the temperature differential across the heat exchangers and its change over a period of one to three months. If no change or small change is indicated, then it clearly indicates the reduced bio-fouling. Whether the bio-fouling, fouling, corrosion can be reduced independently by system over a period of time. If so, what will be the time period requirement what the parameters to be checked are and what will 28 / July 2016 / Indian Plumbing Today

6 be the percentage improvement in the ranges of their values? As answered in the foregoing, typically one to three months of operation will be needed and a maximum of six months depending on the current frequency of heat exchange equipment cleaning. This is not quantitatively possible at this stage as we do not know what chemicals (the nature and the type) are added currently and what is the extent of hydrocarbon ingress and it being used by the microbes as a food and nutrient source. It has to be systematically estimated as described above over a period. Chemical Cost Savings How much percentage reduction in chemical dosage will occur with use of ADS? The percentage reductions in chemical usage which we have mentioned in cost benefit analysis are specific to situations observed in many of our sites. However, what would be the exact reduction of chemicals would depend on site conditions, quality of water and chemicals used. Amritlal F. Sanghai Amritlal F. Sanghai is Founder Director of Everlast Composites Pvt. Ltd. and Director, House of Doors, Mumbai. Indian Plumbing Today / July 2016 / 29