Disinfection Technologies for Small Water Systems

This course includes content developed by the Pennsylvania Department of Environmental Protection (Pa. DEP) in cooperation with the following contractors, subcontractors, or grantees: The Pennsylvania State Association of Township Supervisors (PSATS) Gannett Fleming, Inc. Dering Consulting Group Penn State Harrisburg Environmental Training Center

Most Basic Requirement for Sanitation and Protection of Public Health Prevent the Spread of Waterborne Disease – Typhoid, Salmonella, Cholera, Hookworm, etc. Kills or Inactivates Most Disease Sources - Bacteria, Protozoa, Parasites, and Viruses Used Widely Since Around the Turn of the Century with Huge Public Health Benefits Reduced Infant Mortality & Increased Longevity

Disinfection: is killing or inactivate of pathogenic organisms. It is necessary if the water to be used for drinking water is not hygienically reliable. In water treatment, aimed at the production of drinking water, disinfection is the most important treatment step.

The goal of water disinfection is the inactivation of microorganisms, such as viruses, bacteria and protozoa, which can cause serious illnesses and death. Although disinfection can be accomplished to a significant extent by a number of physiochemical water treatment processes, such as coagulation, sedimentation, filtration, lime-soda softening and adsorption, a specific chemical disinfection step is usually incorporated into surface water treatment process trains to prevent the transmission of waterborne diseases.

Drinking water supplies in Ireland are predominantly sourced from surface waters or groundwaters influenced by surface water. In recent reports on “The Provision and Quality of Drinking Water in Ireland” the Environmental Protection Agency (EPA) found that 81.6% originates from surface water (i.e. rivers and lakes) with the remainder originating from groundwater (10.3%) and springs (8%). Source waters, susceptible to surface contamination, particularly surface waters and groundwater and spring sources contain micro-organisms such as bacteria, viruses and protozoan parasites (e.g. Cryptosporidium) which can present a risk to human health if not effectively treated and disinfected. Since 2008 the EPA has set out as its policy that the most effective means of consistently ensuring the safety of a drinking water supply is through the use of a comprehensive risk assessment and risk management approach that encompasses all steps in water supply from catchment to consumer. The EPA has advised Water Service Authorities to implement the World Health Organisation (WHO) Water Safety Plan approach to risk assessment and risk management.