Question

1.

Make a scheme to describe the municipal wastewater treatment systems? Add the removal BOD and solids rates for each treatment.

Answer 1

Make a scheme to descibe municipal wastewater treatment sų sicm Add the rembval BoD and solid rate far eadh treatment Treated as Treated wastewater --Application t. (Sludge) Conventional Munirinal ㅡㅡㅡ wartewater treatment wartewater ather reuse Sluda opportunitie SLu Effluent discharged to sutare water DISDOS Cansider a typical wartewatz producion unit 20aoca peaple having aver age paoductian a raw wastewater) treated effluent must comply- hat a month 21n-united-stater-the-quality-of- ly average d th the Federal Regulation suspended salidr

Preliminary Treatment:-

During this step heavy rags are removed that can interfere with the machine. Inorganic and sand like solid components are removed to prepare the preliminarily treated water for primary and secondary treatment.

Primary Treatment:-

This process works on the principle of sedimentation. Once rags and degritting is done, the remaining wastewater is then processed through primary treatment where other components undergo sedimentation. Around 1/3rd of the total BOD is being settled. One half of suspended solids also undergo sedimentation and can be removed. Mainly used to remove metabolic contents, toxic substances and pathogens.

Primary sludge is discharged after this treatment.

Secondary Treatment:-

This treatment includes use of microbes. These undergo the process of flocculation during which they form sedimentary particles that settles forming a bed and usually oxidize the organic components in the wastewater thereby producing CO2 and other end products out of which some can be utilised by the microbes as a source of nourishment.

Excess microbial biomass is separated as secondary sludge which can be utilised again for next treatment cycle as the efficiency is not reduced.

Tertiary Treatment:-

The secondary sludge may be associated with pathogens and other polluting components. This needs Tertiary treatment to enhance the efficiency of the wastewater. It includes use of antimicrobial agents or other chemicals specific for destruction of microbes.

BOD and solid waste can be removed by means of filtration and adsorption by using a component such as activated carbon. This sludge is basically mixed with the primary and secondary sludge which has different modes of utilisation.

Protection of health and environment policy helps to locate the type of treatment that should be provided to the wastewater prior to irrigation or its application to the crops.

This sets the criteria for the removal of organic solid waste and BOD on the basis of various efficient strategies as mentioned above.

According to these policies set up by country or state specific authorities, chlorination can be carried out after respective treatment in which remaining pathogens can be destroyed.

​​​​​