Proper disinfection ensures removal of pathogens from wastewater before it is discharged to the environment. Determination of residual chlorine in wastewater ef. Chlorine for wastewater disinfection trojanuv resources. The treatment of gemfibrozil solutions with sodium hypochlorite yielded a 4. Handbook of chlorination and alternative disinfectants geo. Disinfection with chlorine public water systems drinking. This technical brief describes a method of calculating the dose of chlorine required to disinfect small community water supplies. The safe water system sws was developed in the 1990s in response to epidemic cholera in south america by the centers for disease control and prevention cdc and the pan american health organization paho. Chlorine destroys diseasecausing organisms in water and is the most commonlyused disinfectant in. Consumption of chemicals increases by 70% to % based on gas chlorine consumption chlorine in waste water investment costs for civils. All valves including fire hydrant lead valves within chlorinated section to be left open during chlorination. Chlorination is commonly used because it can kill diseasecausing bacteria and control nuisance organisms such as ironreducing bacteria, slime, and sulfatereducing bacteria. The treatment method for the sws is pointofuse chlorination by consumers with a locally. Chlorine compounds usually destroy pathogens after 30 minutes of contact time, and free residual chlorine 0.
Chlorination is a widely used disinfection method in conventional wastewater treatment processes, in which byproducts formation is identified as a major drawback. Disinfection of treated wastewater university of washington. With most chlorination methods the operator should make up a solution of known concentration. Chlorination is the most widely ooo ooo o ooo used method of disinfecting drinkingwater. Sep 17, 2018 the large volumes of hypochlorite required means large storage tanks are needed, thereby increasing the total capital cost. New edition covers the latest practices, regulations, and alternative disinfectants. Design issues for chlorination chlorine dose and demand mixing good mixing at chlorine addition point is more efficient and effective plug flow reactor more efficient kinetics and lower coliform conc. Fact sheet on disinfection, one of the primary mechanisms for the inactivation or destruction of pathogenic organisms. The goal of an online control system is to accomplish 1 sufficient chlorine concentration at the end of chlorine contact chamber to. Application of ozone in water treatment was performed in 1893 in holland.
In the first years following the wpca, disinfected wastewater with significant levels of residual chlorine was routinely discharged into the receiving waters. History of chlorination techniques for chlorination of water supplies. Chlorination has been used widely to disinfect wastewater prior to discharge since passage of the 1972 federal water pollution control act wpca, finger et al. As a growing alternative and a direct replacement technology to chemical chlorine disinfection, it does not produce. Weao technical conference niagara falls, ontario april 1012, 2016 published by. Chlorine is one of the most practical and widely used disinfectants for wastewater. Since the publication of the fourth edition of whites handbook of chlorination and alternative disinfectants more than ten years ago, the water industry has made substantial advances in their understanding and application of chlorine, hypochlorite, and alternative disinfectants for water. Dechlorination of gaschlorine treated effluent heavily affects costs. Similar but distinct disinfectants include chloramine and chlorine dioxide.
In conjunction with an overall safety management program, chlorination is generally effective, comparatively inexpensive, and may be implemented in operations of any size. Shock chlorination is recommended whenever a well is new, repaired, or found to be contaminated. Formation potential of emerging disinfection byproducts. As some of the more common compounds that occur in chlorinated wastewater, like hypochlorous acid or chloramines, have varying degrees of disinfection efficiency, it is a complex. Chlorination is the use of chlorine gas, sodium hypochlorite or calcium hypochlorite to disinfect water. Free, uncombined chlorine, cl 2, is rarely found in wastewater since the conditions of formation are relatively extreme lind, 1995. The modified horrocks method of chlorination can be carried out without prior knowledge of the chlorine content of the chlorine product. Dechlorination involves removing any chlorinebased byproducts to ensure the water is truly safe. Chemicals used for chlorination and dechlorination in bc tend to be a function of the economies of scale and the operator training and certification level related to treatment plant size. The organisms of concern in domestic wastewater include enteric bacteria, viruses, and protozoan cysts. Several chlorine compounds, such as sodium hypochlorite and calcium hypochlorite, can be. Chlorine is available as compressed elemental gas, sodium hypochlorite solution naocl or solid calcium hypochlorite ca ocl 2 1. Presentation on the chemistry of ozone in wastewater.
In italy, urban wastewater disinfection is regulated in the third part. A large amount of research and many studies have been conducted to ensure success in new treatment plants using chlorine as a disinfectant. Gas chlorination is the most economic disinfectant available as gaseous or liquid chlorine supplied in cylinders or ton containers. Different processes can be used to achieve safe levels of chlorine in drinking water. Today, uv disinfection is widely accepted for municipal wastewater disinfection around the world. Since the publication of the fourth edition of whites handbook of chlorination and alternative disinfectants more than ten years ago, the water industry has made substantial advances in their understanding and application of chlorine, hypochlorite, and alternative disinfectants for water and wastewater treatment. Chlorination cdc pdf pdf 2 pages the safe water system sws was developed in the 1990s in response to epidemic cholera in south america by the centers for disease control and prevention cdc and the pan american health organization paho. Wastewater disinfection efficiency using one step and twostep. Proven and e ective wastewater disinfection why uv.
Included are chapters on the development and practice of wastewater chlorination, disinfection process chemistry and. The application of chlorination for various purposes is described but no attempt has been made to compare chlorination with other methods. Unlike superchlorination, shock chlorination is a one time only occurrence, and chlorine is depleted as water flows through the system. Wastewater technology fact sheet disinfection for small systems description the impact of untreated and partially treated domestic wastewater on rivers and community water sources continues to raise health and safety concerns. Nov 27, 2016 a large amount of research and many studies have been conducted to ensure success in new treatment plants using chlorine as a disinfectant. Home page of chlorination station and econochlor, the best liquid chlorination devices for aerobic septic systems. A leading advantage of chlorination is that it has proven effective against bacteria and viruses. Wastewater chlorination and dechlorination chlorine. Chlorination of process water is one of the primary elements of a properly managed postharvest sanitation program. Deciding on the right amount of chlorine to use can be difficult.
Chlorination systems should be protected from fire hazards, and water. The cholesterollowering pharmaceutical gemfibrozil is a relevant environmental contaminant because of its frequency of detection in u. When the chlorine residual is to be controlled to a level greater than or equal to 0. Continuing the tradition of combining theory and practice, the 5th edition of the handbook of chlorination is a major revision of this classic book. Notify engineer 3 working days before performing chlorination and dechlorination. Dec 21, 2009 new edition covers the latest practices, regulations, and alternative disinfectants.
Chlorine, ozone, peracetic acid, and uv light article pdf available in water environment research 7912. A digital flow meter controls these chlorination systems by generating digital pulses proportionate to the flowrate the source or booster pumps produce. Adding chlorine as a hypochlorite is much simpler, requires less training and is safer. This bulletin is directed toward chlorine, the most widely used chemical for disinfection, and sulfur dioxide for dechlorination.
The use of chlorine in municipal wastewater treatment is commonly practiced throughout north america. Bedner and maccrehan 44 investigated the reactions of the aminecontaining drugs fluoxetine and metoprolol during the chlorination and dechlorination processes used in the. Chlorine is available as compressed elemental gas, sodium hypochlorite solution naocl or solid calcium hypochlorite caocl 2 1. This manual has been revised to reflect best practice in drinking water disinfection and the supervisory role of the epa. Contains information on how to use chlorine as a disinfectant for municipal wastewater. Drinking water chlorination world chlorine council. The physicochemical characteristics are shown in table s1.
Uv is rapidly growing, given its a safe and costeffective alternative over chemical. Water chlorination chloramination practices and principles. Technical publication wastewater chlorination dechlorination. Epa set the first regulatory limits for thms in 1979. Since that time, its use has spread in europe and the us.
Detention time 1530 min average requirements but 1 hour detention time often recommended. Liquids such as bleach, powders such as bleaching powder, and purposemade tablets can be used. Chlorination is the most widely used method for disinfecting the effluents. Analytical and biological characterization of halogenated. Chlorine for wastewater disinfection treatment plant. With proper system calibration, monitoring, and operation and maintenance, liquid chlorination can be a very effective means of disinfection for onsite wastewater treatment systems. There is a discharge limitation on chlorine residuals in the. Municipal effluent chlorination and dechlorination. As chlorination processes gained further acceptance, new discoveries were limited to refinements in the existing methods and chemistry connell 1996. For treatment systems requiring chlorine residuals below 0. Chlorination is the process of adding chlorine to drinking water to disinfect it and kill germs. Chlorination is by far the most common method of wastewater disinfection and is used worldwide for the disinfection of pathogens before discharge into receiving streams, rivers or oceans. The degree of treatment of the wastewater prior to disinfection is a significant factor in the chlorine demand.
The epa first published a water treatment manual on disinfection in 1998. Iodine can also be used as a chemical disinfectant. Although the collective research does not definitively show that dbps in drinking water cause adverse health effects in humans, high levels of these chemicals are undesirable. Proper disinfection of treated wastewater before disposal is required for all plants. The chlorine residual that remains in the wastewater effluent can prolong disinfection even after initial treatment and can be measured to. Water research center chlorination of drinking water. For the past few decades, uv has been successfully used around the world for municipal wastewater disinfection. Chlorination equipment should operate between 25% and 75% of total operating range, to allow for adjusting flexibility at design average flow. Chlorine destroys target organisms by oxidizing the cellular material of bacteria. The chlorination wastewater treatment procedure creates byproducts in treated water. The control of sufficient chlorine dosages to ensure good. All valves including fire hydrant lead valves within chlorinated section to be left. Jun 01, 2018 the cost of chlorination equipment is typically a small part of the overall capital cost. Notify contract manager 3 working days before performing chlorination and.
Water pollution control federation, washington, dc. This adds additional concrete, civil works, excavation, and construction to the overall capital cost. Chlorine gas for disinfection and sulphur dioxide for dechlorination have been the chemicals of choice for the medium to larger capacity wastewater treatment. If uv equipment is to be retrofitted into an existing chlorine contact tank, the majority of the cost will come from the equipment, and additional space can be reclaimed because of uvs small footprint. Dechlorination in wastewater treatment processes sciencedirect. Wastewater sample represents treated effluent prior to chlorination. Chlorination, implemented to destroy microbial pathogens in wastewater, also destroys some pharmaceuticals, but incompletely. Because chlorination requires a lengthy retention time, a large chlorine contact tank or channel is required unless one already exists. Chlorine destroys diseasecausing organisms in water and is the most commonlyused disinfectant in all regions of the world. Chlorination disinfection is the process of destroying pathogenic microorganisms by physical means. Whites handbook of chlorination and alternative disinfectants. Tetrachloroethylene enters surface waters and thus drinking water from a variety of industrial sources other than wastewater treatment plants shakelford and keith, 1970. Sodium hypochlorite is a diluted liquid form of chlorine that is also commonly used. In this study, three disinfection processes ultraviolet, chlorination, and ozone were used to reduce levels of args in secondary effluents from a municipal wastewater treatment plant.
This treatment introduces high levels of chlorine to the water. This entire process allows wastewater to remain safe, without putting the community at risk. Chlorination is the most practical disinfection method in water and wastewater treatment plants. Online control of wastewater effluent chlorination and dechlorination involves three important aspects. Liquid chlorination operation and maintenance checklist. Once formed, the free chlorine reacts with natural organic matter in water and wastewater to form chlorinated organic compounds. Wastewater sample was also obtained from aeration tank. Drinking water chlorination chlorine chemistry division. This new edition is a thorough up to date reference on the use of chlorine, chlorine dioxide, ozone, peroxone bromine, bromine chloride, iodine, and ultraviolet radiation in water and wastewater. For larger plants, with more trained staff and resources, chlorine gas cl2 for chlorination and sulphur dioxide gas so2 for dechlorination have been popular, due to. Determination of chlorine demand in water and wastewater. The free chlorine also combines with ammonia to form mono, di. If large amounts of chlorine are required, the overall cost of gas chlorination may be lower. The survey of bc plants found that the chemicals used in chlorination and dechlorination of wastewater treatment plant effluent are a function of plant size and safety concerns.
Provide blow off with sample point at end of each branch and end of main line. Antibiotic resistance and wastewater effluent chlorination. Using a remote vacuum operated gas feeder, a chlorine solution is prepared on site from chlorine gas and water. Tsc is performed by dosing chlorine two times according to the dosage ratio. Antibiotics enter wastewater when a they are excreted by people taking antibiotics and b they are flushed, unused, down the toilet. For the reasons outlined on page 55, however, it is not usually possible to do this accurately. Chlorination is the most commonly used disinfection process for wastewater treatment. As compressedliquefied cl 2 gas in cylinders or drums. Chlorination of wastewater capital controls es2 inc. In holland, rook identified that the reaction of chlorine with organic materials dissolved in water pro. It wasnt until the 1970s that trace organic chlorination byproducts were discovered.