Pre-Treatment
Pre treatment of wastewater consists mainly of the following processes:
Pumping & Containment
Be it from wells or huge water bodies, water has to be pumped from its source into pipes and holding reservoirs. To make sure that no extra contaminants are added in the process, stringent measures have to be taken right from fabricating the physical infrastructure to maintaining it, so as to eliminate all chances of accidental contamination.
Screening
Screening is the first step undertaken to purify raw water. It is in this step that all large debris such as sticks, leaves, trash and other large particles are removed from the oncoming water. This ensures that there remains no such particles that might tend to interfere with the subsequent purification steps. Ideally, deep groundwater is generally free from such large pollutants and hence does not need screening before other purification steps.
Storage
After the water is pumped out it is generally stored in large reservoirs for a period that range from a few days to months together. This is a crucial stage as it facilitates the natural biological purification to take place, especially if slow treatment methods sand filters are used. Storage reservoirs also provide a buffer against short periods of drought or to allow water supply to be maintained during transitory pollution incidents in the source river.
Pre-conditioning
In this stage, the hard salts are desalinated using soda-ash (sodium carbonate) to precipitate calcium carbonate.
Pre-chlorination
In the pre-chlorination stage, the raw water is chlorinated to minimize and eliminate the growth of fouling organisms on the pipe-work and tanks. But, in contemporary times, this process is obsolete due to the potential adverse quality effects of chlorine.
pH Adjustment
Another important challenge in the pre treatment process is adjusting the pH of the water. pH level of acidic water (lower than 7) can be adjusted by adding lime, soda ash, or sodium hydroxide.
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is continually depleting with its increasing demand. Key reasons that account for the growing demand of water.