FM Techie

FILTER FEED PUMPS Filter Feed Pumps are used to draw water from the clarified water sump and pass it through the Pressure Sand Filter (PSF) and Activated Carbon Filter (ACF), which are installed in series to improve water quality. PRESSURE SAND FILTER (PSF) Working Principle: The upper layers of sand perform the actual filtration function, while gravel layers provide physical support. Specialized sand with a specific particle size is used to trap solid impurities present in water. The particles get entrapped in the spaces between sand grains, eventually blocking water flow. When the pressure drops beyond a set limit, the sand is cleaned by backwashing with water. Backwashing reverses the flow, fluidizing the sand bed and removing lighter solid particles as waste. Operation And Maintenance Considerations Filtration is followed by a short backwash sequence. The filter requires backwashing when the pressure drop across the filter reaches 0.5 kg/cm². Best practice: Backwash once per shift,...

CLARIFIER/ SETTLING TANK 1 The sewage inlet pipe brings sewage from the aeration tank. 2 The center-feed well takes this incoming sewage and gently releases it in the settling tank, without causing any disturbance or turbulence. 3 The sludge is only slightly heavier than water; so it takes time to sink. It slides down the steeply sloped walls of the tank toward the center of the bottom. 4 The bacterial flocs7 collect here in high concentration. 5 The sludge delivery pipe delivers the slurry to the pumps (6). 6 There are two identical pumps. Since the flow rate of these pumps is fixed, they need to be turned off periodically to bring down the net flow rate to achieve the desired MLSS ratio. This is a critical operation, because if flocs remain in the settling tank for more than 30 minutes, the microorganisms die due to lack of oxygen. 7 The T-shaped header assemble joins the outlet pipes of both pumps, and delivers the sludge to the aeration tank. 8 The clear water rises to the top of t...

 AERATION TANK The Aeration tank is at the heart of the treatment system. The bulk of the treatment is provided here, employing microbes/bacteria for the process.  The main function of the Aeration tank is to maintain a high population level of microbes. This mixture is called MLSS (Mixed Liquor Suspended Solids). The mixed liquor is passed on to the clarifier tank, where the microbes are made to settle at the bottom.  The settled microbes are recycled back to the aeration tank. Thus they are retained for a long period within the system. 1 The inlet pipe brings sewage from the raw sewage lift pump  2 The baffle wall does not let the incoming sewage and sludge go across the tank toward the outlet pipe (6). The wall forces the mix toward the bottom of the tank;  3 The tank is always filled till this level 4 The Outlet Launder collects the sewage and delivers it to the outlet pipe (6). 5 The net prevents entry of debris in the outlet pipe (6).  6 The outlet pi...

Equalization Tank The sewage from the bar screen chamber and oil, grease and grit trap comes to the equalization tank. The equalization tank is the first collection tank in an STP. Its main function is to act as buffer:  To collect the incoming raw sewage that comes at widely fluctuating rates, and pass it on to the rest of the STP at a steady (average) flow rate. During the peak hours, sewage comes at a high rate. The equalization tank stores this sewage, and lets it out during the non-peak time when there is no/little incoming sewage. 1 The inlet pipe  2 The sewage is collected in the tank.  3 The raw sewage lift pumps 4 The delivery pipe takes the sewage to the aeration tank. 5 The coarse bubble diffusers are short length of tubes that have holes at regular spacing. They release large bubbles in the tank to lightly aerate the sewage, and also to agitate the mix continuously. 6 Compressed air comes though this air supply pipeline.  Operation And Maintenance Conside...

BAR SCREEN CHAMBER The function of the bar screen is to prevent entry of solid particles above a certain size; such as plastic cups, paper dishes, polythene bags into the STP.  The screening is achieved by placing a screen made out of vertical bars, placed across the sewage flow. The gaps between the bars may vary between 10 and 25 mm. Larger STPs may have two screens: A coarse bar screen with larger gaps between bars, followed by a fine bar screen with smaller gaps between bars.  In smaller STPs, a single fine bar screen may be adequate.  1 Inlet pipe for the STP. 2 Debris  3 Muck accumulates  4 Grill. Must be cleaned regularly to avoid a build-up of debris (2) and muck (3). 5 Screened sewage.  6 Outlet pipe (goes to the Equalization Tank) 7 Platform with weep holes. The STP operator stands here to rake the debris (2). Operation And Maintenance Considerations Check and clean the bar screen at frequent intervals Do not allow solids to overflow/ escape from ...

Sewage treatment is a crucial process that removes contaminants from wastewater, household sewage, and effluents. It involves physical, chemical, and biological methods to ensure that the treated water is safe for disposal or reuse. Proper sewage treatment helps protect the environment and reduces the demand for portable water in buildings. Stages of Sewage Treatment Sewage treatment typically involves three main stages: primary, secondary, and tertiary treatment. 1. Primary Treatment (Solid Separation) Large solid particles and sediments are separated from the wastewater. The solids settle at the bottom, while lighter materials like oils and grease float and are removed. 2. Secondary Treatment (Biological Process) The remaining wastewater contains dissolved organic matter. This is broken down using water-borne microorganisms that convert waste into a solid mass. The biological solids are then neutralized and either disposed of or reused. 3. Tertiary Treatment (Final Purification &...