It’s a beautiful day, and you’re on a river trip with your friends, and you’re wondering if it’s safe to drink this water because it hasn’t been treated.
From this point of view, questions like what is water disinfection and different methods of disinfection will be answered.
What is water disinfection?
Water disinfection means the removal, deactivation, or killing of pathogenic microorganisms.
Bacteria, viruses and protozoa are the most common disease-causing microbes found in water.
Because their influence on the body can be nearly immediate, these infections constitute a major threat to human health.
Physical or chemical disinfectants can be used to achieve disinfection.
Organic pollutants in water, which act as nourishment or habitat for microbes, are also removed by these agents.
Disinfectants should do more than just destroy bacteria.
Disinfectants must also have a residual impact, which implies that they must remain active in the water after disinfection.
A different method of water disinfection
Chemical and physical disinfection is the most common disinfection procedure.
Chemical agents are used in chemical procedures, while physical agents are used in physical methods.
Chlorine has long been the most widely used chemical agent.
Other chemical agents include
-Chlorine dioxide (ClO2)
– Hypochlorite (OCl-)
– Ozone (O3)
– Halogens: bromine (Br2), iodine (I)
– Bromine chloride (BrCl)
– Metals: copper (Cu2+), silver (Ag+)
– Kalium permanganate (KMnO4)
While physical water disinfection includes:
-Ultraviolet light (UV)
– Electronic radiation
– Gamma rays
– Sounds
– Heat
Chlorine Gas
Chlorine is a yellowish-green gas. The gas is turned into a liquid by applying high pressure.
Chlorine gas is mostly used to disinfect water.
Chlorine introduced into water is particularly effective at killing practically all harmful bacteria.
It can be used as a primary disinfectant as well as a secondary disinfectant.
Flexible, easily controlled dosing rate, low cost, and efficiency against a wide variety of pathogenic are the main advantages of chlorine gas in water disinfection.
Although chlorine gas is widely used in water disinfection, it has limitations.
The presence of byproducts and incompletely oxidized chemicals in chlorinated water, which increases its toxicity, may be a major source of worry.
Chloro-organics and trihalomethane are the most well-known chlorination byproducts (THMs).
Trihalomethane is generated when chlorine combines with Humic and fulvic acids.
Some of these chloro-organics are mutagens, poisons, or carcinogens in numerous studies.
Ozone
Ozone is unstable three molecular oxygen which is combined to produce a new molecular.
Ozone quickly decomposes to generate highly reactive free radicals which have a greater oxidation potential than chlorine.
The ozone system consists of an oxygen supply and a high-power electric supply which break down oxygen molecules, generate ozone molecules and act as oxidation radicals.
strong oxidizing power, short reaction time, no chemicals required, oxidization of iron and manganese and removal of all organic matter are the main advantages of ozone in water disinfection.
While instability under atmospheric pressure and toxicity in high concentration are the limits of ozone in water disinfection.
Ultraviolet light (UV)
Wastewater, drinking water, and aquaculture can be treated by UV treatment.
UV radiation disinfects germs by modifying their biological components, specifically disrupting chemical bonds in DNA, RNA and proteins.
The main advantages of using ultraviolet light in water disinfection include regrowth potential limitation of micro-organisms, no interaction with the pipe material, and no formation of by-product Compounds such as THM.
While the limitation of using ultraviolet light in water disinfection include energy requirement, sensitivity to water turbidity and not being active in high bacteria content.
Distillation
In addition to the removal of dissolved solids and suspended materials, distillation is considered the oldest method of water disinfection.
Although distillation is effective in bacteria and other pathogenic organisms and dissolved solids removal such as chloride, fluoride, nitrate, sulfate and carbonates it’s not effective in most volatile and semi-volatile organic compounds (VOCs) removal.
Production of free minerals and many contaminants or production of pure water is one of the great advantages of distillation.
Another advantage of distillation is the suitability for wet batteries and other household equipment requiring mineral-free water. The distillation process takes a long time and produces more acidic water.
What are the factors that influence water disinfection?
Many factors influence the effectiveness of disinfectants. Awareness of these factors should lead to better use of disinfection
1. Contact time of the disinfectant
as an example, ozone needs less contact time than chlorine to kill the micro-organism.
2. Concentration of the disinfectant
The amount of disinfectant to be used depends on the impurity level in the water as well as the volume of the fluid.
3. Physical and Chemical Factors
Water temperature is one of the physical aspects to consider, as the greater the water temperature, the faster the disinfectant’s reaction speed.
PH is one of the chemical factors that affect water disinfection, as each disinfectant act at different pH ranges.
How to select suitable disinfection equipment?
to select your disinfection equipment, you should take into consideration:
1. cost of disinfection equipment
2. Raw water quality
As you should take into consideration water turbidity and micro-organisms’ presence in the water.
3. Application of water
Application of water is an important factor to determine the disinfection equipment such as chlorine is not suited for bottled water application while ozone or UV is better.
Reference
[1] Disinfection methods, Muhammad Saqib Ishaq, Zobia Afsheen, Amjad khan, and Amjad Khan, October 18th, 2017 [online] Available at: https://www.intechopen.com/chapters/63788
[2] What is water disinfection? [online] Available at: https://www.lenntech.com/processes/disinfection/what-is-water-disinfection.htm
[3] what factors influence the efficiency of water disinfection, 2021-03-26 [online] Available at: https://dagaequipment.com/en/b/blog/p/que-factores-influyen-en-la-eficiencia-de-la-desinfeccion-del-agua-36
[4] Household Water Treatment: Disinfection Methods and Devices, Apr 11, 2018, Uttam K. Saha [online] Available at: https://extension.uga.edu/publications/detail.html?number=B1487&title=Household%20Water%20Treatment:%20Disinfection%20Methods%20and%20Devices
