During the secondary treatment of sewage, the primary effluent is constantly agitated and air is pumped into it. Select the option which gives the correct reason for this.
During the secondary treatment of sewage, the primary effluent is constantly agitated and air is pumped into it. Select the option which gives the correct reason for this.
The correct option is C For the vigorous growth of aerobic microbes
Sewage is the municipal waste water generated every day from the towns and cities. Due to the huge levels of organic wastes and microbes present in sewage, it cannot be directly drained into water bodies. It is first treated in sewage treatment plants to remove the wastes and impurities.
The primary treatment of sewage involves removal of floating debris, stones, grit, etc by using physical techniques such as filtration followed by sedimentation. Filtration is used to remove the floating particles with the help of several filters of varying pore sizes. Sedimentation removes the insoluble heavier particles which settle down as primary sludge when sewage is allowed to sit undisturbed in large sedimentation tanks.
The supernatant (fluid above the sediment) is known as primary effluent and is passed into large aeration tanks for secondary treatment. Secondary treatment of sewage is a biological process which involves enzymatic degradation of the organic matter in sewage by the action of aerobic heterotrophic microbes. The primary effluent is poured into huge aeration tanks where it is inoculated with microbial flocs. The microbial flocs consist of a mass of heterotrophic and aerobic microbes (bacteria and filamentous fungi). Air is continuously pumped and the effluent is continuously agitated to ensure continuous supply of oxygen to the microbial flocs. This leads to the rapid (vigorous) growth of the flocs that feed on the organic wastes present in the sewage and degrade it in the presence of oxygen.
After the secondary treatment, the effluent is passed through a sedimentation tank where the microbial flocs settle down to form activated sludge. Some of this activated sludge is added to the aeration tank as an inoculum. The rest is fed into an anaerobic sludge digester where anaerobic microbes digest the bacteria and fungi present in it in the absence of oxygen.
Sewage is the municipal waste water generated every day from the towns and cities. Due to the huge levels of organic wastes and microbes present in sewage, it cannot be directly drained into water bodies. It is first treated in sewage treatment plants to remove the wastes and impurities.
The primary treatment of sewage involves removal of floating debris, stones, grit, etc by using physical techniques such as filtration followed by sedimentation. Filtration is used to remove the floating particles with the help of several filters of varying pore sizes. Sedimentation removes the insoluble heavier particles which settle down as primary sludge when sewage is allowed to sit undisturbed in large sedimentation tanks.
The supernatant (fluid above the sediment) is known as primary effluent and is passed into large aeration tanks for secondary treatment. Secondary treatment of sewage is a biological process which involves enzymatic degradation of the organic matter in sewage by the action of aerobic heterotrophic microbes. The primary effluent is poured into huge aeration tanks where it is inoculated with microbial flocs. The microbial flocs consist of a mass of heterotrophic and aerobic microbes (bacteria and filamentous fungi). Air is continuously pumped and the effluent is continuously agitated to ensure continuous supply of oxygen to the microbial flocs. This leads to the rapid (vigorous) growth of the flocs that feed on the organic wastes present in the sewage and degrade it in the presence of oxygen.
After the secondary treatment, the effluent is passed through a sedimentation tank where the microbial flocs settle down to form activated sludge. Some of this activated sludge is added to the aeration tank as an inoculum. The rest is fed into an anaerobic sludge digester where anaerobic microbes digest the bacteria and fungi present in it in the absence of oxygen.
