A factual look at the chlorine based methods of disinfecting water in North America

Transcription

1 A factual look at the chlorine based methods of disinfecting water in North America Kevin Kinback, Engineering Manager, Wallace & Tiernan USA Evoqua Water Technologies LLC July 2015 Summary Chlorination of potable water can be achieved by employing one of three chemicals, elemental Chlorine gas, liquid Sodium Hypochlorite, or dry Calcium Hypochlorite. These all have their own advantages and disadvantages. In total, 98% of North American community Water Systems use Chlorine for disinfection 1. Of those, 62% employ Elemental Chlorine, 33% use Sodium Hypochlorite, and 2% use Calcium Hypochlorite. The application of Calcium Hypochlorite is generally reserved to smaller Treatment systems when it is utilized. About 3% use On-Site Hypochlorite Generators 4. In this paper we attempt to cover the initial equipment costs, maintenance costs, chemical costs, impurities and/or chemical byproducts, and safety aspects of each. Evoqua Water Technologies LLC 2015 page 1

2 Background Information and Methodology The following Water Treatment Plant Data was taken from the US EPA 2006 Community Water System Survey, Volume II: Detailed Tables and Survey Methodology, and US EPA Factoids: Drinking Water and Ground Water Statistics for , 17. There are approximately 52,000 Community Water Treatment Systems in the United States, 47,000 of these systems serve populations from 100 to 50,000 people. There are 34,000 plants in the 100 to 50,000 population range that are 100% Ground Water systems and deliver an average daily flow around 3 MGD or less, with a maximum flow of around 5 MGD. The remaining 18,000 systems serve the largest communities and are mainly Surface Water systems, or are small plants that are Surface Water systems. These plants have unique treatment requirements which makes them difficult to include in this report. For that reason we will be concentrating on Ground Water systems in the population range of 100 to 50,000 serviced. These plants produce potable water in the 0.05 to 5 MGD range. The Chlorine feed systems in this group are simple and typically use a Flow Paced Control system or on - off Control for Chlorine feedrate control. All of the Chlorine feed systems depicted in this report are sized to provide an actual chlorine dosage rate of approximately 2.4 mg/l (5MGD X 8.34 X 2.4) = 100 pounds chlorine per day. Note: 2.4 mg/l dosage is an average, local water conditions and distribution system details will determine the actual dosage rate. Elemental Chlorine Introduction In all of the forms of Chlorine used in the Water Treatment industry, Elemental Chlorine is the only one that contains 100% Chlorine. It has been the primary disinfectant used in the treatment of potable water for over 100 years. The technology, processes, and procedures used to inject Elemental Chlorine into water are time tested and proven. Modern chlorination systems are almost completely operated with the chlorine under a vacuum, any piping or apparatus failure would result in air being drawn in to system not chlorine gas escaping. The Chlorine gas under pressure in the transportation/storage vessel is reduced to a pressure below atmospheric as soon as it leaves the vessel when the chlorinator is mounted directly to the chlorine vessel. This minimizes the possible piping and apparatus that if failed would release chlorine gas to the atmosphere. Evoqua Water Technologies LLC 2015 page 2

3 Typical Feed System A typical system to feed in the area of 100 pounds in a 24 hour period would at a minimum look something like this: Fig. 1: The above Diagram is for illustrative purposes only and is not a complete system. Financial Analysis This equipment with proper maintenance should easily last 20 years before needing to be replaced. Initial cost of the above simple system, not including installation and piping supplies, would in the $12,000 - $15,000 range. Maintenance costs would run around $400 per year using Preventive Maintenance Kits. Labor Hours to maintain system would be hours/yr. Chemical costs. The cost per pound of Elemental Chlorine varies based on location and supply and demand. An average number for 150 pound cylinders is $1.00/lb. $100.00/day = $36,400/year Evoqua Water Technologies 2015 page 3

4 Advantages Proven Technology Lowest total cost Pure Chemical, less fouling and system maintenance The best chemical shelf-life Disadvantages Additional Safety requirements and paperwork If you have 2,500 pounds of chlorine On-Site at any time you must comply with the EPA Risk Management Program Other State and Local regulations may have requirements as it pertains to the storage and usage of Chlorine Gas Impurities and/or Chemical byproducts AWWA Water Works grade Chlorine is 99.9% pure. There will be trace amounts of Ferric Chloride in the container. Safety In recent years there was been a focus on the environmental impact of Chlorine releases into the atmosphere and the transportation of Chlorine on our nation s roads and rails. Some of this interest is in response to Homeland Security concerns that Chlorine could be used in a Terrorist Attack. Regulations to control the release of any hazardous substance is the right thing to do. It causes the users of a particular hazardous material to take a fresh look at the materials they use in their processes and how they handle those substances in their daily operations. Two examples of these legislations are the US EPA Risk Management Program and New Jersey s Toxic Catastrophe Prevention Act. This attention helps employers and their employees that work in industries that handle hazardous substances to review how they can improve their processes and the procedures. Ultimately this results in improved processes and a safer working environment for their employees and the communities around them. It is important to understand the actual amount of Elemental Chlorine that is used in the Water Industry. Evoqua Water Technologies 2015 page 4

5 2% 4% 4% 14% 30% 46% Organic Chemistry PVC and Vinyl Inorganic Chemistry Water Treatment Pulp and Paper Other Direct Applications Fig. 2: US Chlorine Production by End Users Annually there is approximately 12 million tons of Chlorine produced in the United States. Only 4%, or 480,000 tons of that production is used in the Water Industry 3. This Chlorine is produced at 15 locations through the United States 4. It is shipped in bulk, typically by railcars to 44 Chlorine Repackaging Plants located throughout the Continental United States 4. In turn they supply the Chlorine in 150LB or 1 Ton Containers to Water Treatment Systems in their geographical area mainly by truck. Only a few of the largest Water Treatment Systems use Tanker Trucks or Railcars to receive their Chlorine directly from the producers. Chlorine Accidents and Releases United States Coast Guard operates the National Response Center. All releases of chemicals into the environment must be reported to the Center. All calls to the center are logged into a database that can viewed on their website 12. While the information is unfiltered it can be sorted by chemical. This database was used to estimate the number of incidences of reported Elemental Chlorine releases in Each release was reviewed by conducting further research to insure that the release was in fact the chemical that was released, and the location, and type of facility confirmed. The raw data for 2014 was further culled down, by removing follow up calls, test or drill reports, and unrelated reports. Evoqua Water Technologies 2015 page 5

6 The 2014 results of this are: 74 total releases for Elemental Chlorine were reported. o 3 releases were Transportation related. o 28 releases were associated with Industrial Processes using Elemental Chlorine. o 25 releases were associated with the manufacture of Elemental Chlorine. o 1 release at a scrap yard. o 17 releases were associated with Potable Water, Wastewater, and Recreation Water. The majority of the releases associated with water plants were releases during cylinder or ton container changes. This points to the need for more training, better tools, or a review of operational procedures. Good references that detail each reported incident can be found on the internet for other countries such as the United Kingdom and Australia 5, 6. After reviewing the information that is available and comparing with the experiences from both the United Kingdom and Australia which closely matched the available data for the US which works out to be that 60% of the reported chlorine releases are a result of mishandling Sodium or Calcium Hypochlorite and 40% of the releases or due to Elemental Chlorine incidents. Sodium Hypochlorite Introduction There is documentation that indicates that first use of Chlorine in Water Treatment was in England in the 1880 s. This treatment appears to have been done using one of the Hypochlorites or Chloride of Lime 7. Sodium Hypochlorite is typically produced with 12-15% available Chlorine. An important point to keep in mind when working with Sodium Hypochlorite is that it is constantly degrading, losing strength and developing by-products. There are ways to slow this degradation to a manageable rate but require additional considerations, such as cooling systems, dilution systems, and ph management systems. Evoqua Water Technologies 2015 page 6

7 Typical Feed System A typical system to feed in the area of 100 pounds equivalent Chlorine in a 24 hour period would at a minimum look something like this: Fig 3: The above Diagram is for illustrative purposes only and is not a complete system. Financial Analysis This equipment with proper maintenance should easily last years before needing to be replaced. Typically the Tanks are the weak link 8. Initial cost of the above simple system, not including installation and piping supplies, would in the $35,000 - $40,000 range. Maintenance costs would run around $200 per year using Preventive Maintenance Kit for the Metering Pump. Labor Hours to maintain system would be hours/yr., depending on the amount of scaling based upon water hardness and piping system. Chemical costs. The cost per gallon of Sodium Hypochlorite varies based on location and supply and demand. An average cost per gallon (not considering the loss of strength due to degradation) for this size system would be in the $0.90 range. $90/day = $32,850/year Evoqua Water Technologies 2015 page 7

8 Advantages Proven technology Use of Sodium Hypochlorite simplifies regulatory compliance No need to handle heavy containers. Small spills are easier to deal with. Disadvantages Degradation of Sodium Hypochlorite and the creation of byproducts. Because it is not regulated under the USEPA RMP rule does not mean that it is not a Hazardous Substance. The concern is that Operators will not be as cautious in their dealings with this chemical as they would be with Chlorine Gas. The high ph of Sodium Hypochlorite could interfere with maintaining finished water ph. Adds sodium to the finished water. Off gassing and scaling are consequences of feeding Sodium Hypochlorite. Impurities and/or Chemical byproducts Sodium Hypochlorite is typically manufactured in one for two ways, it is either made in a packaged system that adds Elemental Chlorine to Caustic Soda, or by dissolving salt in softened water, which results in a concentrated brine solution. The solution is electrolyzed and forms a sodium hypochlorite solution in water. The process of adding Elemental Chlorine to Caustic Soda is by far the most widely used process. There are approximately 60 producers of Sodium Hypochlorite in the Continental United States 4. These facilities are mostly located in or near the Chlorine Repackaging Plants since Elemental Chlorine is one of their raw materials. The fresh Sodium Hypochlorite is shipped to the local Water Treatment Plants by Tanker Trucks or packaged in small Carboys for the smaller plants. Decomposition Sodium Hypochlorite will decompose due to ionic strength, ph, temperature, time, and heavy metal content. It is very important to understand the causes and the resultant consequences of this decomposition. It will help you plan, design, and operate your system, and reduce operational issues down the line. Evoqua Water Technologies 2015 page 8

9 This decomposition will occur due to the following two reactions: 1. Transformation into Chlorate 2. Release of Oxygen Transformation into Chlorate This Chlorate reaction accounts for about 90% of the total decomposition 9. This reaction is tied to: 1. Time This prohibits you from storing more than a few weeks worth of product On-Site. The general consensus is 30 days maximum. Local conditions will dictate whether a 30 day supply feasible. Powell, the largest manufacturer of Sodium Hypochlorite manufacturing systems, recommends installing two storage tanks to prevent contaminating new product by adding it on top of old product Temperature the warmer the product is the faster conversion to Chlorate will be. Some sources of information such as Powell, recommends that air conditioning the Storage building be considered some cases. 3. Light Dark Tanks located away from sunlight and direct lighting will help preserve the solution. 4. ph The ph level in the storage tank should be monitored. ph levels below 11 accelerates the formation of Chlorate and ph levels above accelerates the formation of Perchlorates There is increasing concern in the government regulating bodies at both the Federal and State level as it pertains to Perchlorate and Chlorate in potable water. Currently the USEPA has issued an Interim Health Advisory of 15 ppb. California has already set the Perchlorate level at 6ppb, Massachusetts at 2ppb, and New Jersey at 5ppb. New Jersey has deferred action until USEPA issues a regulatory determination 1, 10. If these changes are put in place there will be an impact to how Sodium Hypochlorite is used and stored in potable water applications. The release of Oxygen This reaction is caused by trace amounts of heavy metals, such as nickel and copper, left in the product after production. Increasing strength and temperature, decreasing ph, and exposure to light in combination with these heavy metals will increase the rate of this oxygen formation and increase the reduction of hypo strength 8. This reaction is one of issues responsible for the feed problems that plagues Sodium Hypochlorite metering systems. Additionally rapid acceleration of the solution through piping and equipment restrictions also adds to this issue. Avoid trapping solution in piping sections as this reaction could generate very high pressures, also if ball valves are used be sure they are equipped with vented balls. Evoqua Water Technologies 2015 page 9

10 Safety Sodium Hypochlorite should be treated the same respect that has been instilled in Water Plant operations that employ Elemental Chlorine gas as their Disinfectant. Lack of proper training and knowledge can result in the improper handling of Sodium Hypochlorite resulting in the release of large amounts of Chlorine gas to the atmosphere. Ironically, the largest Chlorine release at a Water Treatment plant was from a plant using Sodium Hypochlorite. 12,000 pounds of Chlorine gas was almost instantly released from a tank when Ferric Chloride was mistakenly added to the Sodium Hypochlorite tank 11. Sodium Hypochlorite Accidents and Releases As was stated previously under the Elemental Chlorine Section, the same NRC database was used to determine the number of Chlorine Releases from Sodium Hypochlorite Solutions that occurred in The 2014 results of this are: 84 total Chlorine releases from Sodium Hypochlorite were reported. 9 releases were Transportation related. 29 releases were associated with Industrial Processes using Sodium Hypochlorite. 13 releases were associated with the manufacture of Sodium Hypochlorite. 1 release at a Farm. 1 release at Pool Supply Co. 31 releases were associated with Potable Water, Wastewater, and Recreation Water. The majority of the Sodium Hypochlorite releases were a result of Tank or Tank Piping failures. Operators need to keep an eye out for signs or Storage Tank Deterioration. Approximately 60% of the Chlorine releases at Water Plants are a result of Sodium Hypochlorite releases. This is in line with the historic information collected over the years, it is also in line with the findings of ongoing studies in United Kingdom and Australian studies 5, 6. Calcium Hypochlorite Introduction Calcium Hypochlorite has been used in Water Treatment for as long as we have been treating water. In an article written by Howard C. Hottel for The Municipal Journal, Titled Water Purification at Trenton. As a result of investigations made by the New Jersey State Board of Health, the city of Trenton, on November 9, 1911, started to purify its drinking water supply, raw Delaware River water, by the use of calcium hypochlorite 13. Evoqua Water Technologies 2015 page 10

11 In the past 10 years there has been a growing interest in the use of Calcium Hypochlorite in the Potable Water segment. This interest is based on the security and reporting requirements when using Elemental Chlorine, and the degradation and by-product issues when using Sodium Hypochlorite. Historically Calcium Hypochlorite has been used in the smaller Water Treatment systems requiring Chlorine feed rates at or below 50 pounds of available CL/day. Today Calcium Hypochlorite Feed Systems can handle Water Treatment Systems with requirements up to 400 pounds of available CL/day. Typical Feed System A typical system to feed in the area of 100 pounds equivalent Chlorine in a 24 hour period would at a minimum look something like this: Fig 4: The above Diagram is for illustrative purposes only and is not a complete system. Financial Analysis This equipment with proper maintenance should easily last 20 years before needing to be replaced. Initial cost of the above simple system, not including installation and piping supplies, would in the $8,000 - $10,000 range. Maintenance costs would run around $300 for Metering Pump Preventative Maintenance. Labor Hours to maintain system would be hours/yr., depending on the amount of scaling based upon water hardness. This would mainly consist keeping the scaling in the Feeder and delivery piping under control. Evoqua Water Technologies 2015 page 11

12 Chemical costs. The cost per pound of Calcium Hypochlorite varies based on location and supply and demand. An average price for Treatment Plants in this size range $2.00/lb. Since Calcium Hypochlorite contains 65% chlorine the cost for a Chlorine equivalent of 100lb/24hr would require pounds of Calcium Hypochlorite. $2.00 X = $307.60/day = $112,274/year. Advantages Proven Technology Use of Calcium Hypochlorite Simplifies Regulatory Compliance Degradation is much slower than Sodium Hypochlorite. 3 5% in a year provided it is properly stored. Disadvantages Typically solutions of Calcium Hypochlorite created in feed/dissolving systems only make 1-2% solutions. Because it is not regulated under the USEPA RMP rule does not mean that it is not a Hazardous Substance. The concern is that Operators will not be as cautious in their dealings with this chemical as they would be with Chlorine Gas. Off gassing and scaling are consequences of feeding Calcium Hypochlorite. Systems with water hardness approaching 300 ppm should consider water softening, which will add to the operating cost of the system. Calcium Hypochlorite solutions should be used soon after they made to avoid developing perchlorate 1. Very reactive with organic materials, it is a Fire Hazard. Store only in its original container in a cool dry protected location. High cost of Chemical Impurities and/or Chemical byproducts Currently there are 25 manufactures that make Calcium Hypochlorite products that carry the NSF/ANSI 60 listing for use in Potable Water. Of these there are differences between them that could troublesome in your feed system. It is wise to follow the recommendations of the Calcium Hypochlorite Feeder/Wetting system. Calcium Hypochlorite solutions can form by-products, mainly perchlorate and chlorate. Since Calcium Hypochlorite solutions are created in very small batches as the Chlorine is used these by-products normally are not an issue. Evoqua Water Technologies 2015 page 12

13 Safety Calcium Hypochlorite should be treated the same respect that has been instilled in Water Plant operations that employ Elemental Chlorine gas as their Disinfectant. Lack of proper training and knowledge can result in the improper handling of Calcium Hypochlorite resulting in the release of large amounts of Chlorine gas to the atmosphere, or generate enough heat to start a fire. Calcium Hypochlorite Accidents and Releases As was stated previously under the Elemental Chlorine Section, the same NRC database was used to determine the number of Calcium Hypochlorite releases that occurred in The 2014 results of this are: 3 total releases for Calcium Hypochlorite were reported. o 2 releases were Transportation related. o 1 release was associated with Potable Water, Wastewater, and Recreation Water. On-Site Generation of Sodium Hypochlorite Introduction On-Site Generation of Sodium Hypochlorite for use in Water Treatment dates back to the late 1920 s. It wasn t until major advances in the anode coatings and base materials in the early 1970 s that this process became a viable Chlorine supply for Water Treatment applications 15. On-Site Generators produce a 0.8% solution of Sodium Hypochlorite. For each 1 pound Chlorine equivalent required the On-Site Generator will require 3 pounds of salt, 15 gallons of softened water, and 2 KWH of electrical energy. On- Site Generators almost always are operated in the batch configuration using a storage tank to store the product as it is being metered to the Point of Application. Storage tank capacity should be sized to hold 2 or more days worth of finished product to cover for outages and short term equipment service events. Some Water Systems install a backup Commercial Sodium Hypochlorite feed system to cover longer term shutdowns. The major difference between the On-Site Generation of Sodium Hypochlorite and the other methods of Water Chlorination used, is that you are responsible for the production of your Chlorinating Agent as well as the Storage and Metering of that agent. This has advantages and disadvantages that should be considered. Evoqua Water Technologies 2015 page 13

14 Typical Feed System A typical system to feed in the area of 100 pounds equivalent Chlorine in a 24 hour period would at a minimum look something like this: Fig. 5: The above Diagram is for illustrative purposes only and is not a complete system. Financial Analysis This equipment with proper maintenance should easily last 20 years before needing to be replaced. Initial cost of the above simple system, not including installation and piping supplies, would in the $160,000 - $185,000 range. Maintenance costs would run around $400 for Metering Pump Preventative Maintenance. Labor Hours to maintain system would be hours/yr., depending on the amount of scaling of the cell plates. This would mainly consist of acid washing the Cells to remove the scaling. The amount of scaling is dependent on the quality of the water and salt. Every 5 to 7 years the Cell plates will need to be replaced. This process can cost as much as $35,000. Operational Costs. To generate a Chlorine equivalent of 100lb/24hr you would consume 300lb of Salt/24hr, 1,500 gals of softened water/24hr, and use 200KWH of Electrical energy. Based on average rates and moderately hard water the raw material costs would be, 336 pounds/day of salt for Softener and Brine plus 200 KWH/day = $40.00/day, $14,600/year raw material costs. Evoqua Water Technologies 2015 page 14

15 Advantages On-Site Generation of Sodium Hypochlorite technology is stable. Use of On-Site Generation of Sodium Hypochlorite Simplifies Regulatory Compliance. Degradation is much slower than Commercial Sodium Hypochlorite. Smaller batches, lower concentrations eliminate most of that concern. Disadvantages Hydrogen is produced during the production of Sodium Hypochlorite and must be safely diluted and vented to the outside. On-Site Generation of Sodium Hypochlorite creates a 0.8% solution, which means you are moving a lot of water for each equivalent pound of Chlorine. As with Commercial Sodium Hypochlorite, On-Site Generated of Sodium Hypochlorite is not regulated under the USEPA RMP rule does not mean that it is not a Hazardous Substance. The concern is that Operators will not be as cautious in their dealings with this chemical as they would be with Chlorine Gas. Bromide in the Brine will turn into Bromate in the finished solution. A water chiller or heater may be needed to hold the incoming softened water at a temperature of 600 F to 700F16. High cost of equipment and maintenance. The Plant Operators are also responsible for manufacturing the Chlorine as well as controlling the application of the Chlorine. Impurities and/or Chemical byproducts On-Site generated chlorine, because of the higher temperatures that are generated during process and the lower ph values have a much higher initial concentration of chlorate. But due to its low initial concentration, the additional decomposition is much slower than the decomposition of Commercial Sodium Hypochlorite. To avoid high Bromate levels in the finished product use a Salt that has little to no Bromide. On-Site Generated Hypochlorite Accidents and Releases All manufacturers of this equipment design in features and interlocks to prevent the ignition of the Hydrogen in the system components and solution. However, they do occur. Evoqua Water Technologies 2015 page 15

16 The Environmental Sustainability A study prepared for the American Chemistry Council and American Water Works Association, compared the environmental impact of various chemical disinfectants used in Water Treatment. Multiplier 3,5 3 2,5 2 1,5 1 0,5 Electric Consumption Relative to Elemental Chlorine 0 Elemental Sodium Calcium OSHG Chlorine Hypochlorite Hypochlorite Fig. 6: The chart above compares the Power Consumption used to produce a disinfectant in relative comparison to Elemental Chlorine. Summation Multiplier 2,5 2 1,5 1 0,5 Greenhouse Gas Emissons Relative to Elemental Chlorine 0 Elemental Sodium Calcium OSHG Chlorine Hypochlorite Hypochlorite Fig. 7: The chart above compares the Greenhouse Gas Emissions generated to produce a disinfectant in relative comparison to Elemental Chlorine. The intent of this report was to provide the reader with an unbiased overview of the three Chlorine based disinfectants used in the treatment of Potable Water. Choosing the Chlorinating agent that is right for you is an important decision. There is no one size fits all solution that is best in all situations. It is undeniable that Elemental Chlorine has the lowest total life cost, is the purest chemically, and offers the smallest carbon foot print. Elemental Chlorine does not degrade, does not add additional Bromate or Chlorate to the finished Evoqua Water Technologies 2015 page 16

17 water. Elemental Chlorine feed systems require fewer unplanned maintenance interruptions caused by gas binding and scaling. Elemental Chlorine feed systems can easily be paced by a Flow Signal since there is no degradation taking place in the Chlorine supply. With that said, there is the Governmental Regulations that only apply to Elemental Chlorine that add extra costs to system to cover paperwork, Operator Training, and interaction with State and Local Emergency Response Teams. This is especially true when operating larger systems than the systems modeled in this report. On-Site Generation comes in second in total life cost based on a single generator system with no back up. However, due to the fact that the Water Plant is their own Chlorine supplier, some form of a backup system or alternate source for Chlorine is needed. This is required to cover for longer term break downs and equipment outages due to planned maintenance. Some plants op for a complete or partial redundant backup generation system, others install pumps and associated items required so they can have commercial Sodium Hypochlorite delivered and stored in the existing On- Site Generator storage tank. Since the Water Plant is also the Chlorine Supplier a higher level of operator training is needed. While On-Site Generation s Carbon Foot Print is pretty much the same as Sodium Hypochlorite, its electrical power usage is much higher. Sodium Hypochlorite feed systems, when looking at Water Plants in this size range, have a slightly higher total life cost than the On-Site Generation systems. These systems do not require the level of operations training as compared to the On-Site Generation systems. In some cases a more complex pacing system may be needed that includes feedback from a Chlorine Residual Analyzer to adjust the feed rate based on the changing Chlorine strength. When the USEPA s final perchlorate ruling is finalized Water Plants may have to make adjustments in the way they store and feed this form of Chlorine. While the percentage of Water Plants using Calcium Hypochlorite feed systems is very low as compared to the other systems they are gaining acceptance as a viable means of supplying Chlorine for disinfection of Potable Water systems. This especially true when looking at Water Plants in this size range. Granted this method carries the highest total life cost of the methods of disinfection covered in this report. Calcium Hypochlorite also has the largest Carbon Foot Print. These systems have relatively small storage capacity therefore degradation of the product during off times will not have a large impact on the finished water. For the smaller remote Pumping stations and remote Re-chlorination stations Calcium Hypochlorite feed systems are a good match. Evoqua Water Technologies 2015 page 17

18 Bibliography 1. Snyder, S. A.; Stanford, B. D.; Pisarenko, A, N.; Gordon, G.; & Asami, M., Hypochlorite An assessment of factors that influence the formation of Perchlorate and or contaminants. American Water Works Association and Water Research Foundation, EPA, 2006 Community Water System Survey. Volume II: Detailed Tables and Methodology - United States Environmental Protection Agency, Chlorine Chemistry Chlorine Production FAQs. Chlorine Chemistry Council. 4. Societal and Macroeconomic Assessment of Alternative Technologies for Disinfecting Drinking Water. The American Chemistry Council and the American Water Works Association, Travaglia, Teresa - Chlorine Gas vs Sodium Hypochlorite. Presented at the 67 th Annual Water Industry Engineers and Operators Conference. Wodonga, Australia, Gregson, E. M. - Review of Chlorine incidents , Health and Safety Executive, Connell, Gerald F. The Chlorination/Chloramination Handbook. American Water Works Association, Sodium Hypochlorite General Information Handbook. Powell Fabrication & Manufacturing, Sodium Hypochlorite Stability. Solvay Chemicals International, Stanford, Benjamin D. Perchlorate, Bromate, and Chlorate in Hypochlorite Solutions: Guidelines for Utilities. Water Research Foundation/American Water Works Association, White, George C. Handbook of Chlorination and Alternative Disinfectants, United States Coast Guard. National Response Center, Nrc.uscg.mil/ 13. McGuire, Michael J. The Chlorine Revolution: water disinfection and the fight to save lives. American Water Works, Morley, Kevin, M.; Sloan, Jeffery, T. The Complexities of Disinfection in the Twenty-first Century. American Water Works and the American Chemistry Council, Casson, Leonard, W.; Bess, James, W, Jr On-Site Chlorine Generation. University of Pittsburgh. Water Environment Foundation, Fletcher, Ken; Severn Trent Water Purifications, Inc. On-Site Generation Today s Disinfection Alternative, EPA Factoids: Drinking Water and Ground Water Statics for United States Environmental Protection Agency, Wooten Road, Colorado Springs, CO 80915,USA +1 (856) information@evoqua.com Evoqua Water Technologies LLC WT UE.TP.0715