Wastewater Disinfection Faceoff: Chlorine vs. Bleaching Powder
Disinfection: In order to make water feasible for drinking purposes, the process of disinfection plays an important role. Disinfection is the process of mixing some chemical substance in appropriate quantity in order to kill the pathogenic organisms present in water. These pathogenic microorganisms cause various diseases like cholera, typhoid, hepatitis, gastro-intestinal diseases and scabies, etc. Various chemicals and laser technologies have been used till date in order to improve the disinfection process. The list is as follows:
- 1. Chlorine.
- 2. Chlorine Dioxide.
- 3. Ozone.
- 4. Monochloroamine
- 5. Epichlorohydrin.
Chlorine has been prominently used as a disinfectant due to its residual properties (maintenance of certain level whilst the water travels from treatment plant to consumers). The other reasons are its feasibility and financial stability.
Head to Head (Chlorine vs. Bleaching Powder)
Chlorine (gaseous form) has been discovered around 13th Century and was firstly prepared by Swedish chemist named as Carl Wilhelm. It is one of the most reactive elements which can be found around many different areas of world. Chlorine has been widely used to deactivate pathogenic organisms present in water.
Applications of Chlorine Gas: It can be easily applied, measured and thereby assures quality control in the disinfection process.
1. One of the most prominent reasons for its application is its economic value and persistency. Application of Chlorine forms hypochlorite ion which can infiltrate the cell membrane of pathogenic bacteria and halts its metabolism which in turn results in death of the microorganism. It took a long time for researchers to understand that microorganisms are diseases causing agents present in water despite the fact that Chlorine was discovered way before that. It was only after the discovery of Louis Pasteur (organisms causing diseases) that Chlorine has been widely used as a disinfectant in water treatment, swimming pools and hospital sanitization.
2. Chlorine has immensely helped in lengthening the life expectancy of humans and has eradicated diseases which were considered fatal before the application of Chlorine. The residual effect of Chlorine has been considered as its one of the biggest advantage as in water may get polluted while it is supplied to the consumers.
3. Chlorine has the capability to maintain certain amount of residual concentration in water which is neither harmful for human intake nor for the distribution system components which are mainly made of steel, copper and concrete.
Bleaching Powder: Various surfaces can be disinfected with the help of bleaching powder. Bleach is simply combination of gaseous form of chlorine with an alkali solution for example Sodium Hydroxide whilst bleaching powder is combination of calcium hydroxide with gaseous form of Chlorine.
The advantage of bleaching powder is that it is in solid form and thereby enables the control over concentration. This makes it easier to apply and control the dosage which is most prominent factor while disinfecting. Bleaching powder also produces hypochlorite ions and eradicates the pathogens the same way as discussed in Chlorine disinfection.
The disadvantage of adding bleaching powder to water is that it adds to the hardness of water as calcium is present. Additionally, it goes under decomposition continuously hence making it difficult to analyze the chlorine concentration.