`star` `color{Brown}"In Aeration Tank"`:
● The `color{Violet}"primary effluent"` is passed into `color{Violet}"large aeration tanks"` where it is constantly `color{Violet}"agitated mechanically"` and `color{Violet}"air is pumped"` into it.
● This allows `color{Violet}"vigorous growth"` of useful `color{Violet}"aerobic microbes"` into `color{Brown}"flocs"` (masses of bacteria associated with fungal filaments to form mesh like structures).
● While growing, these microbes `color{Violet}"consume"` the major part of the `color{Violet}"organic matter"` in the effluent.
● This significantly `color{Violet}"reduces the BOD"` (`color{Brown}"biochemical oxygen demand"`) of the effluent.
● BOD refers to the amount of the `color{Violet}"oxygen"` that would be consumed if all the `color{Violet}"organic matter"` in one liter of water were `color{Violet}"oxidised by bacteria"`.
● The sewage water is treated till the `color{Violet}"BOD is reduced"`.
● The BOD test measures the `color{Violet}"rate of uptake"` of oxygen by micro-organisms in a `color{Violet}"sample of water"` and thus, indirectly, BOD is a measure of the `color{Violet}"organic matter"` present in the water.
● The `color{Violet}"greater the BOD"` of waste water, more is its `color{Violet}"polluting potential"`.
`star` `color{Brown}"In Settling Tank"`:
● Once the `color{Violet}"BOD"` of sewage or waste water is `color{Violet}"reduced significantly"`, the effluent is then passed into a `color{Violet}"settling tank"` where the `color{Violet}"bacterial flocs"` are allowed to sediment.
● This sediment is called `color{Violet}"activated sludge"`.
● A small part of the activated sludge is `color{Violet}"pumped back"` into the aeration tank to serve as the `color{Violet}"inoculum"`.
`star` `color{Brown}"In Anaerobic Sludge Digesters"`:
● The remaining major part of the sludge is pumped into `color{Violet}"large tanks"` called `color{Violet}"anaerobic sludge digesters"`.
● Here, other kinds of bacteria, which `color{Violet}"grow anaerobically"`, digest the bacteria and the fungi in the sludge.
● During this digestion, bacteria produce a `color{Violet}"mixture of gases"` such as `color{Violet}"methane, hydrogen sulphide"` and `color{Violet}"carbon dioxide"`.
● These gases form `color{Violet}"biogas"` and can be used as `color{Violet}"source of energy"` as it is inflammable.
● The `color{Violet}"effluent"` from the secondary treatment plant is generally released into natural water bodies like `color{Violet}"rivers and streams"`.
● This methodology has been `color{Violet}"practiced"` for `color{Violet}"more than a century"` now, in almost all parts of the world.
● Till date, `color{Violet}"no man made technology"` has been able to rival the microbial treatment of sewage.
● Due to `color{Violet}"increasing urbanisation"`, sewage is being produced in much `color{Violet}"larger quantities"` than ever before.
● However the number of `color{Violet}"sewage treatment plants"` has `color{Violet}"not increased"` enough to treat such large quantities.
● So the untreated sewage is often `color{Violet}"discharged directly"` into rivers leading to their pollution and increase in `color{Violet}"water-borne diseases"`.
● The `color{Violet}"Ministry of Environment"` `color{Violet}"and Forests"` has initiated `color{Brwon}"Ganga Action Plan"` and `color{Brown}"Yamuna Action Plan"` to save these major rivers of our country from pollution.
● Under these plans, it is proposed to build a `color{Violet}"large number"` of sewage treatment plants so that only treated sewage may be `color{Violet}"discharged in the rivers"`.
`star` `color{Brown}"In Aeration Tank"`:
● The `color{Violet}"primary effluent"` is passed into `color{Violet}"large aeration tanks"` where it is constantly `color{Violet}"agitated mechanically"` and `color{Violet}"air is pumped"` into it.
● This allows `color{Violet}"vigorous growth"` of useful `color{Violet}"aerobic microbes"` into `color{Brown}"flocs"` (masses of bacteria associated with fungal filaments to form mesh like structures).
● While growing, these microbes `color{Violet}"consume"` the major part of the `color{Violet}"organic matter"` in the effluent.
● This significantly `color{Violet}"reduces the BOD"` (`color{Brown}"biochemical oxygen demand"`) of the effluent.
● BOD refers to the amount of the `color{Violet}"oxygen"` that would be consumed if all the `color{Violet}"organic matter"` in one liter of water were `color{Violet}"oxidised by bacteria"`.
● The sewage water is treated till the `color{Violet}"BOD is reduced"`.
● The BOD test measures the `color{Violet}"rate of uptake"` of oxygen by micro-organisms in a `color{Violet}"sample of water"` and thus, indirectly, BOD is a measure of the `color{Violet}"organic matter"` present in the water.
● The `color{Violet}"greater the BOD"` of waste water, more is its `color{Violet}"polluting potential"`.
`star` `color{Brown}"In Settling Tank"`:
● Once the `color{Violet}"BOD"` of sewage or waste water is `color{Violet}"reduced significantly"`, the effluent is then passed into a `color{Violet}"settling tank"` where the `color{Violet}"bacterial flocs"` are allowed to sediment.
● This sediment is called `color{Violet}"activated sludge"`.
● A small part of the activated sludge is `color{Violet}"pumped back"` into the aeration tank to serve as the `color{Violet}"inoculum"`.
`star` `color{Brown}"In Anaerobic Sludge Digesters"`:
● The remaining major part of the sludge is pumped into `color{Violet}"large tanks"` called `color{Violet}"anaerobic sludge digesters"`.
● Here, other kinds of bacteria, which `color{Violet}"grow anaerobically"`, digest the bacteria and the fungi in the sludge.
● During this digestion, bacteria produce a `color{Violet}"mixture of gases"` such as `color{Violet}"methane, hydrogen sulphide"` and `color{Violet}"carbon dioxide"`.
● These gases form `color{Violet}"biogas"` and can be used as `color{Violet}"source of energy"` as it is inflammable.
● The `color{Violet}"effluent"` from the secondary treatment plant is generally released into natural water bodies like `color{Violet}"rivers and streams"`.
● This methodology has been `color{Violet}"practiced"` for `color{Violet}"more than a century"` now, in almost all parts of the world.
● Till date, `color{Violet}"no man made technology"` has been able to rival the microbial treatment of sewage.
● Due to `color{Violet}"increasing urbanisation"`, sewage is being produced in much `color{Violet}"larger quantities"` than ever before.
● However the number of `color{Violet}"sewage treatment plants"` has `color{Violet}"not increased"` enough to treat such large quantities.
● So the untreated sewage is often `color{Violet}"discharged directly"` into rivers leading to their pollution and increase in `color{Violet}"water-borne diseases"`.
● The `color{Violet}"Ministry of Environment"` `color{Violet}"and Forests"` has initiated `color{Brwon}"Ganga Action Plan"` and `color{Brown}"Yamuna Action Plan"` to save these major rivers of our country from pollution.
● Under these plans, it is proposed to build a `color{Violet}"large number"` of sewage treatment plants so that only treated sewage may be `color{Violet}"discharged in the rivers"`.
