Bacteria removal

ULTRAVIOLET (UV) DISINFECTION

The water treatment for potable water is considered to be incomplete even after removal of contaminants like Arsenic, Iron, Suspended Solids, if the water is not made free from pathogenic micro organism or disinfected.

The disinfection by Ultraviolet (UV) ray is most popular among the physical disinfection processes. UV has an effect on microorganism and not on water.

UV does not kill micro-organisms, but UV inactivates them. UV light at a specific wavelength of 260 nm penetrates the cell wall and cytoplasmic membrane of the microorganisms and is readily absorbed by the genetic material of microorganism. UV, at this wavelength is readily absorbed at the point on the micro-organism’s DNA strand which codes for reproduction and makes some molecular rearrangement which prevents it from reproduction. Micro-organisms cannot reproduce, they cannot make colonies and therefore cannot infect when consumed. In other words, the microorganisms have been sterilized or denatured. They will eventually die off. The treatment works because UV light penetrates an organism’s cell walls and disrupts the cell’s genetic material, making reproduction impossible.

ACTIVATED CARBON SYSTEM

Activated Carbon not only improves taste and minimizes health hazards; it protects other water treatment unit from possible damage due to oxidation or organic fouling. Activated carbon is a favoured water treatment technique because of its multifunctional nature and the fact that it adds nothing detrimental to the treated water.

The two principal mechanisms by which activated carbon removes contaminants from water are adsorption and catalytic reduction.  Organics are removed by adsorption and residual disinfectants are removed by catalytic reduction.

Activated carbon beds are filters and need to be backwashed periodically. The backwash process does not 'regenerate' the carbon or de-adsorb contaminants. The backwash process reclassifies the bed and removes any fines or suspended matter.

BACK WASH

The plant has been designed so that the bed of the filter media can be cleaned periodically by backwashing (i.e. allowing the water to flow in the reverse direction). Filters should be backwashed until the backwash water is clean. During backwashing, the flow of water through the filter is reversed, i.e, water is forced from bottom to top cleaning out trapped particles. All the Filters are backwashed according to necessity. Back wash water from all filters are sent to the soak pit.

SOAK PIT

Soak pit, also known as a soak away or leach pit, is a covered, porous-walled chamber that allows water to slowly soak into the ground. It is a relatively safe way of discharging backwash to the environment and therewith recharging groundwater bodies.