Water is pure until some pollutants such as sand, minerals, chemical waste, and artificial pollutants share some space. All this dirt makes the water undrinkable and can cause serious diseases if indulged without treatment. There are so many water treatment solutions are available in the market. But which method to follow depends entirely upon the type of pollutant contaminating the water. Let’s discuss the most common methods of mobile water treatment.
Coagulation & Flocculation
Coagulation itself means clotting. It clots together the dust particles present in water to remove them. Also, it is the most common water treatment used to remove solids from water. A liquid coagulant, such as ferric sulfate, aluminum sulfate, or alum, is added to the raw or untreated water to attract suspended particles. The water is then gently stirred to allow the particles to stick together. Stirring also manipulates the electrostatic charge of particles suspended in water and groups larger particles together. The grouping of these larger particles is called flocculation. The solids are further removed by settlement, sedimentation, or filtration.
The settling process of floc underwater is called sedimentation. When water stays stagnant, all heavy or light particles eventually settle down due to the force of gravity. You can improve water quality by simply storing it in a storage tank. Here’s how. When you store water for a long time, non-colloidal, suspended particles slowly settle down to the bottom of a storage tank. Also, solar radiation will help kill harmful microorganisms such as larvae or algae. If the suspended particles are pretty small in size, then you need to keep water in the reservoir for a much longer time.
Water and flocs need to undergo the storage treatment process. They are kept in storage basins. The slow movement of particles makes the heavy floc particles settle to the bottom. When the floc gets accumulated on the bottom, it is termed sludge that is further carried on to drying lagoons. Direct Filtration does not include the sedimentation step, and the floc is just removed by filtration.
Filtration is when solid particles are removed from water using slow or fast filters. These filters allow only water to pass through, and the solid is left behind the filters. The filtration process is basically categorized into two types— slow sand filtration and rapid sand filtration.
Filtration means using the physical barrier to remove contaminants and make water undergo chemical or Biological Wastewater Treatments.
The different water filters are strainers, precoat filters, pressure filters, membrane filters, etc. Let’s read about Slow sand filters.
Slow Sand Filtration
Slow sand filtration uses combined biological, chemical, and physical processes for a slow water passage through a bed of sand. It helps in filtering fine particles. On top of the filter bed, accumulated microorganisms feed on bacteria, viruses, and organic matter in the water. The filter basins have drains on the bottom covered with dirt and grime. Raw water slowly enters the filter through an inlet. Clean or treated water is further pulled to the clean-water mains.
Rapid sand filtration
The rapid sand filtration method is used to remove suspended solids. This method is effective after the water has been cleared with the coagulation and flocculation process. The water flow rate is higher than the slow sand filtration method, and the sand used is more coarse than the former method. There is no build-up of the biological film; hence the water will still need to be disinfected. Removing trapped gravel and sand becomes easy and effective when water flow is upward rather than in filters carrying the water flows downwards.
Sun emits UV rays that help in destroying most pathogens and harmful microbes. It does so by heating the water, which further helps in the effective demolishing. If you expose the water for five straight hours in the sun, you can effectively kill most pathogens. If you want to implement solar disinfection at home, you just need to expose semi-blackened plastic water bottles to the sun. The water must be clear for this treatment to be effective.
We all know that microorganisms are vulnerable to light and heat; thus, they get dismantled when exposed to the sun. One easy and simple way to treat water is to use the SODIS treatment which is tried and tested in the laboratory. A transparent container is filled with water and exposed to full sunlight for several hours. As the water temperature reaches 50 °C, the inactivation process effectively results in complete bacterial disinfection.
The chemical disinfection method involves mixing disinfectant into the water, which reacts with the organic matter and microbial organisms. This method is also called chlorination. Chlorination is the most widely used method of disinfecting drinking water. The most common chemical disinfection compounds are chlorine, chlorine dioxide, chloramines, ozone, iodine, etc.
There are also other methods available such as sludge drying, fluoridation, and pH correction, that further helps in making water potable.