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The work and leisure environments
Published in Stephen Battersby, Clay's Handbook of Environmental Health, 2023
Jonathan Hayes, Stuart Wiggans
Cooling towers are of particular concern, and it is important that all parts of the system are thoroughly cleaned and disinfected, normally twice per year (in spring and autumn). In order to achieve adequate disinfection, sodium hypochlorite solution may be used to give a concentration of at least five parts per million (ppm) of free available chlorine. Water should be sampled periodically near the circulation return point. Chlorine levels can be determined using swimming pool testing kits. Regular chlorination of 1–2 ppm is normally advocated, but this is not appropriate in all cases as it may react adversely with other water treatments. Some biocides are known to be effective against Legionella bacteria, although resistance has been known to develop. In such cases, shock dosing using chlorination of 25–50 ppm of free chlorine is effective. A level of at least 10 ppm should be maintained in the system for 12–24 hours. The use of biocides can be alternated with the use of chlorination to achieve a satisfactory level of disinfection.
Role of Microbial Biofilms in Wastewater Management
Published in Bakrudeen Ali Ahmed Abdul, Microbial Biofilms, 2020
Anila Fariq, Anum Zulfiqar, Sidra Abbas, Azra Yasmin
Chlorination: It is one of the traditional methods of wastewater disinfection intended to remove harmful pathogens from the water by using chlorine. Chlorine reacts with organic matter and produce chlorinated organic compounds. Efficiency of chlorination depends on different parameters including pH, chlorine dose, nature of organic compounds, and other water parameters. Chlorination has been applied successfully to degrade endocrine disruptors and anti-inflammatory drugs including nonylphenol, bisphenol A, and triclosan. Water pH is reported to be most critical parameter that affects performance of the process (Noutsopoulos et al., 2015). Although chlorination is being used due to high efficiency and cost-effectiveness, sometimes the oxidized products are more toxic than the parent compounds. A study reported the presence of highly toxic iodinated products after disinfection. Hypoiodous acid was produced by chlorination of iodine compounds which further react with organic matter forming iodinated byproducts which are more hazardous (Gong & Zhang, 2015).
Health Aspects of Using Reclaimed Water in Engineering Projects
Published in Donald R. Rowe, Isam Mohammed Abdel-Magid, Handbook of Wastewater Reclamation and Reuse, 2020
Donald R. Rowe, Isam Mohammed Abdel-Magid
Chlorination, as a disinfection method, provides a means for prevention of the spread of waterborne diseases. Appropriate chlorination is reported to be highly efficient in the elimination of bacteria from wastewater. Unless the wastewater has a very low turbidity, there is a high probability that the disinfected wastewater will not be completely free of bacterial or viral pathogens.18 Chlorination is effective as a bactericide provided there is no interaction with the turbidity, organic matter, and ammonia present in the wastewater. Therefore, the use of chlorination to treat reclaimed wastewater may have some shortcomings. A problem is the formation of chloramines, simple and complex chlorinated organics, and free chlorine residuals which may be toxic, mutagenic, or carcinogenic.33
Silver-based nanomaterials: A critical review on factors affecting water disinfection performance and silver release
Published in Critical Reviews in Environmental Science and Technology, 2021
Ecem Bahcelioglu, Husnu Emrah Unalan, Tuba Hande Erguder
Conventionally, chemical disinfection (e.g. chlorination, ozonation), filtration techniques (e.g. ultrafiltration membrane, reverse osmosis), solar disinfection, ultraviolet (UV) treatment, coagulation/flocculation and thermal technologies are available for the point of use (POU) water treatment (Backer, 2019; WHO, 2011). However, these conventional methods have several drawbacks in today’s standards. Although chlorination is one of the most preferred disinfection methods, it produces carcinogenic disinfection by-products (DBPs) (Chakraborty et al., 2017; Tan et al., 2018). Besides chlorination, high-energy use and high-cost of UV and ozone disinfection limit the widespread use of these methods. Reverse osmosis is another method used for water disinfection, which is very costly and prone to fouling (Biswas & Bandyopadhyaya, 2016).
Occurrence of contaminants in drinking water sources and the potential of biochar for water quality improvement: A review
Published in Critical Reviews in Environmental Science and Technology, 2020
Kumuduni Niroshika Palansooriya, Yi Yang, Yiu Fai Tsang, Binoy Sarkar, Deyi Hou, Xinde Cao, Erik Meers, Jörg Rinklebe, Ki-Hyun Kim, Yong Sik Ok
Chlorination is commonly used for disinfection of drinking water, and is considered as one of the most effective public health measures of the 20th century. It has saved millions of people from infectious diseases, such as cholera and typhoid (Zhao, Qin, Boyd, Anichina, & Li, 2010). Chlorination exhibited high performance in removing organic compounds, such as triclosan (∼80%) and acetaminophen (∼86%) from drinking water (Azzouz & Ballesteros, 2013; McKie, Andrews, & Andrews, 2016). In contrast, poor removal rates were observed for pharmaceuticals such as carbamazepine and bromazepam (5%), whereas negligible removal was found for atenolol, acebutolol and bisoprolol (<5%) (Huerta-Fontela et al., 2011). Although disinfection is essential to inactivate microbial pathogens, it may produce DBPs from the reactions of disinfectants with organic matter naturally present in water (Pressman et al., 2010). DBPs of chlorine dioxide (ClO2) are present in drinking water as chlorite, chlorate, and THMs (Al-Otoum, Al-Ghouti, Ahmed, Abu-Dieyeh, & Ali, 2016). Epidemiological studies have suggested an association between the consumption of chlorinated drinking water and the increased risks of birth defects, bladder cancer, and rectal cancer (Han, Zhang, Liu, Zhu, & Gong, 2017). Nonetheless, it should be noted that DBPs can somehow be tackled by biochar. For example, THMs was totally removed (100%) by eucalyptus wood biochar produced at 350˚C in a batch adsorption experiment (Kearns, Shimabuku, Mahoney, Knappe, & Summers, 2015).
Solar-excited graphene quantum dots for bacterial inactivation via generation of reactive oxygen species
Published in Journal of Environmental Science and Health, Part C, 2019
Fangdong Zhao, Wei Gu, Jian Zhou, Qiang Liu, Yu Chong
Microbial contamination in drinking water is of great concern to public health around the world.1,2 It has been reported that millions of people died from diseases caused by waterborne pathogens each year.3 However, traditional water disinfection methods involving chemical oxidation such as chlorination, ozonation, and ultraviolet radiation have been faced with various secondary pollutions and energy-consuming problems.4 Therefore, solar-driven water disinfection has been regarded as an alternative disinfection technique due to its direct utilization of solar energy to inactivate the pathogens with a low cost and high efficiency.