Cl exist as NHCl2 NH2Cl at the end of treatment Smell chlorine in pools NHCl2

Cl exist as nhcl2 nh2cl at the end of treatment smell

This preview shows page 11 - 13 out of 26 pages.

Cl exist as NHCl2 +NH2Cl at the end of treatment Smell chlorine in pools (NHCl2 and NH2Cl) Not strong oxidant (about 50 times less efficient than free chlorine but has longer residual effect); prevent bacterial regrowth in the distribution system Ozone Extremely reactive oxidant (more powerful than chlorine) Disinfectant and oxidant Primary disinfectant (cannot maintain a residual) Due to high cost, ozone application is often used for a combination of operations, including disinfection, taste, odour and colour control o physical Disinfection ultraviolet (UV) unit consists of UV light source enclosed in a sleeve made of quartz water passes through a flow chamber; UV rays are emitted and absorbed into the stream rays destroy bacteria and inactivate many viruses Limitations may include water hardness, iron and manganese concentrations Filtration Heat Boiling eater inactivates essentially all microorganisms Method is energy intensive Only practical application is when individual users are required to boil their water Physical methods are not acceptable for secondary disinfection as they do not provide a persistent residual o Primary disinfection – in water treatment plant o Secondary disinfection – in distribution system Disinfection By-Products (DBPs) o Chemicals formed when certain disinfectants are added to water o Formed from reactions between strong oxidants (disinfectants) and natural organic matter in the water (e.g. THMs – trihalomathanes) o Chemical breakdown of disinfectant (e.g. Chlorite and chlorate) o Reactions with inorganics such as bromide (ozonation) find more resources at oneclass.com find more resources at oneclass.com
o New standards and testing requirements for others phased in 2017-2020 Arsenic: “The largest Mass Poisoning in History” o Bangladesh (more than 100 million people affected) o WHO – max. permissible level for arsenic is 50 ug/l and recommends 10ug/ o Groundwater wells o Filtering arsenic: buckets of river sand, pieces of cast iron and charcoal Point-of-use method to purify drinking water o Inadequate sanitation increases user exposure to fecal pathogens and indirect exposure through water, food, soil or flies o POU treatments  variety of technique that individual housholds can use: Ceramic filter, adding bleach, hypochlorate tablets, sunlight treatment, adding packets with flocculant and disinfectant Straining storage/settlement  filtration  Disinfection Municipal Sewage Treatment of Wastewater Treatment o Primary treatment  remove suspended and floating particles o Secondary treatment  Decompose suspended organics o Tertiary treatment Dissolved substances, mostly for nutrient N and P removal o Humber wastewater treatment plant Capacity  473,000 m3/day  Population of 685,000 o Row sewage skimmer in primary sedimentation  final sedimentation Wastewater treatment for homes and small communities o Home treatment o

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture