Distillation Process

Distillation

This is one of the oldest methods of removing impurities from water. It is a physical method of obtaining pure water, not a chemical process. During this process water is boiled and is converted into steam or water vapors. The steam rises to a condenser. Cooling mechanism in the condenser lower the water temperature and steam is condensed to water again. This water is then collected and stored as pure distilled water. Most of the contaminants stay behind in the distillation column. Simplest of the distillation process is shown below as Figure 1.

Figure 1: Distillation process (Water Quality Research Council, 1995)

Process is repeated in batches to obtain large volumes of purified process. This method is effective for removing

Water taste remains unchanged and can easily be installed. It is also environment friendly and low maintenance cost is required.

Reverse Osmosis

Reverse osmosis is a conventional membrane method which is in use for removal of contaminants. In this process osmotic pressure drives the water through a partially permeable membrane at a high pressure. High pressure is required to counteract the osmotic pressure. These membranes restrict the passage of salt, magnesium, calcium, lead as well as certain chemicals, allowing the pure water to pass through. Simplest setup of reverse osmosis plant is presented below as figure 3. Figure 3: Reverse Osmosis process (Desalination, n.d.)

Above figure reveals that water needs to be pre-treated and post-treated for process of reverse osmosis in being effective. Pre-treatment is required to enhance the productivity of reverse osmosis membranes. Post-treatment is necessary since water obtained through this process is de-mineralized during purification. Naturally occurring minerals in the water are retained by these membranes thus making it unhealthy for

Distillation is a method that employs large amount of energy resources, is very slow, water recovery is in batches and costs a large sum of money. It is a chemical free process though water obtained through this process is not fit for human consumption as it lacks minerals that are necessary for human body.

UV radiation process cleanses water that is free from chemicals but it is not fit for drinking. No doubt ultraviolet radiation process is economical as compared to distillation but this process does not clear the water from suspended solids and particles.

Reverse osmosis is a membrane process that works on the same principle as nanomembranes. However, this process also has limitations as compared to the method of water purification in terms of cost and energy efficiency. Drinking water obtained through reverse osmosis lacks in important minerals as well and is not considered healthy for human consumption. In order to make this water drinkable it has to be