Water treatment services: The Different Process Involved in Treatment.

The water treatment is a large process and uses a variety of method for the treatment of water so that the contaminated water can be used for the basic needs. Below we are going to discus o different way of water treatment. These processes are conducted by water treatment plants. Many of the process may or may not be used by the plant depending on the size and capacity.

Pre-Treatment: It consists of simple four steps:-

• Pumping and containment: The water from different source are pumped to a holding tank using pipelines. To avoid any more contaminant to water the holding tank must be made of appropriate material.



• Screening: The very first step of water purification. Here the unwanted material present on the surface of the water like, leaves, papers, plastics, trash, sticks and any other thing that can be removed simply without any chemical or biological process.



• Storage: The river water is stored in bankside reservoirs for periods between a few days and many months to allow natural biological purification to take place. This is mainly important if treatment is by slow sand filters.



• Pre-conditioning – Water rich in hardness salts is treated with sodium carbonate to precipitate calcium carbonate out utilizing the common-ion effect.

pH value for the distilled water is 7 and for the normal sea water is 8.3. The sea water is slightly alkaline, i.e. presence of salt. The pH value help us to find out the contaminants of the water an accordingly we can start the specific treatment required for the water. For example if we find the pH value of water less than 7 that means its acidic and we have to add soda ash or lime or sodium hydroxide to increase the pH of the water. Similarly acid like HCL or H2SO4 is added in water to lower the pH

Flocculation is a process which clarifies the water. Clarifying means removing any turbidity or colour so that the water is clear and colourless. Clarification is done by causing a precipitate to form in the water which can be removed using simple physical methods. Initially the precipitate forms as very small particles but as the water is gently stirred, these particles stick together to form bigger particles.

Waters exiting the flocculation sink may go in the sedimentation basin, also called a clarifier or settling basin. It is a huge tank with slow run, allowing floc to settle to the bottom. The sedimentation basin is best located close to the flocculation basin so the transit between does not permit settlement or floc break up. Sedimentation basins may be rectangular, where water flows from end to end or circular where flow is from the centre outward.

After separating most floc, the water is filtered as the final step to remove remaining suspended particles and unsettled floc. The most common type of filter is a rapid sand filter. Water moves vertically through sand which often has a layer of activated carbon or anthracite coal above the sand. The top layer removes organic compounds, which contribute to taste and odor. The space between sand particles is larger than the smallest suspended particles, so simple filtration is not enough. Most particles pass through surface layers but are trapped in pore spaces or adhere to sand particles. Effective filtration extends into the depth of the filter. This property of the filter is key to its operation: if the top layer of sand were to block all the particles, the filter would quickly clog.