REQUIREMENT OF SEWAGE TREATMENT PLANT
Clean water is one of our most precious natural resources. Yet every time we flush a toilet, pour oil down the drain or clean with strong household chemicals, we contaminate that resource. Before wastewater can be safely released back into our waterways, it must first be adequately treated.
That typical municipal sewage treatment plant in an industrialized country may include primary treatment to remove solid material; secondary treatment to remove dissolved and suspended organic material as well as the nutrients nitrogen and phosphorus, and – sometimes but not always – disinfection to kill disease-causing micro-organisms; Tertiary treatment to remove Nitrates can be removed from wastewater.
OBJECTIVES OF SEWAGE TREATMENT
(i) To Provide Treated Effluent.
(ii) Free From Odour.
(iii) To Reduce Suspended Solids & BOD.
(iv) To Reduce Organic & Inorganic Substances.
(v) To make effluent useful for irrigation.
PURPOSE OF SEWAGE TREATMENT PLANT
(i) Reuse in Industries (Industrial Grade Water).
(ii) Gardening and Developing Green belts.
(iii)Used as cooling tower water.
(iv) To save the ground water and energy.
(v) Increasing Ground Water Table.
(vi) Used as irrigation water.
COLLECTION AND ESTIMATION OF WASTEWATER
Every human society uses water for different purpose of activities like as domestic, commercial and industrial as a result of that there is formation of wastewater. The wastewater from the residential and commercial area is known as domestic wastewater and the wastewater from industrial area is known as industrial wastewater.
In cities and towns large quantities of wastewater produce and that’s way disposal of wastewater is necessary because of the following reasons:
(1) Wastewater from residential area contains human excreta urine, micro-organisms.
(2) Domestic wastewater may have pathogenic organisms in it.
(3) Inhygienic conditions shall be developed if proper collection, conveyance treatment and disposal systems do not exist.
Normally in cities sewage wastewater generated in latrines and sullage wastewater generated in bathrooms and kitchen. The system of sewers traps and other sanitary fixtures conveying wastewater from house to the municipals sewer is known as house drainage system. The wastewater of a house is discharged in municipal sewer and Lateral sewers meet the large sewers called branch sewers.
All the branch sewers are connected with the main sewer and main sewer conveys the wastewater to the outfall sewer and outfall sewer carries wastewater to the treatment plant.
The system of sewers of different diameters connected with each other and appurtenances for the purpose of conveying wastewater to the wastewater treatment plant is called as sewerage system.
In the above fig. industrial zone is shown separately. Nowadays, industries to collect the industrial wastewater from all industries and convey to a common effluent treatment plant. The treated industrial wastewater is discharged in to the branch or main sewer and the industrial wastewater is mixed with the wastewater coming from the domestic zone. The mixture of the industrial and domestic wastewater is conveyed to the wastewater treatment plant.
A treatment plant for municipal wastewater is very much necessary as stated earlier. At this stage it should be remembered that.
They can be classified as follows:
(1) Combined system:
In this system the storm water (rain water) and domestic wastewater as well industrial wastewater are flowing in one sewerage system only. There are no separate sewers for flow of storm water. In such a system sewers are designed for the combined flow of storm water, domestic wastewater and industrial wastewater.
(2) Separate system:
In this system, a separate network of sewers is provided for storm water as well as domestic plus industrial wastewater. Thus in separate systems the sewers carrying the rain water (storm water) do not carry domestic and industrial wastewater and sewers carrying domestic and have either separate or combined sewerage system.
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