STRUCTURE

• Introduction – What is waste water treatment (15 words)                     
• Body – Explain
  • Conventional methods of municipal waste water treatment (60 words)
  • Uses of treated waste water(60 words)
• Conclusion – Mention a short conclusion  (15 words)

ANSWER

Municipal wastewater treatment is basically applicable to those wastewater which has been collected from various residential localities through the sewage system of a city and town, and is treated before being dispersed in open field.

Municipal wastewater treatment plants carryout a series of treatment processes which may be summarized as follows:

• PRIMARY TREATMENT :
  • As the name indicates, it is a primary treatment or physical treatment. This treatment is carried out to remove coarse solids and settleable solids.
  • consists of temporarily holding the sewage in a quiescent basin where heavy solids can settle to the bottom while oil , grease and lighter solids float to the surface. the settled and floating materials are removed and the remaining liquid may be discharged or subjected to secondary treatment
• SECONDARY TREATMENT :
  • It is known as biological treatment. It comes after primary treatment. The aim of secondary treatment is to oxidize organic constituents of the wastewater by means of microorganisms and reduction of BOD also takes place.
  • removes dissolved and suspended biological matter. secondary treatment is typically performed by indigenous, water-borne micro-organisms in a managed habitat. Sometimes secondary treatment requires a separation process to remove the micro-organisms from the treated water prior to discharge or tertiary treatment.
• ADVANCED TREATMENT :
  • This treatment is carried out for the removal of additional objectionable substances to further reduce BOD. The treatment Includes removal of nutrients such as phosphorus and nitrogen that are responsible for algal blooms.
  • is sometimes defined as anything more than primary and secondary treatment in order to allow rejection into a highly sensitive or fragile ecosystem ( estuaries, low- flow rivers, coral reefs). Treated water is sometimes disinfected chemically or physically ( for example by lagoons and microfilteration).
• FINAL TREATMENT :It is also known as Chemical treatment. This is basically to disinfect and dispose of liquid effluents. Solid processing involves the treatment of sludge or biosolids for stabilization of its organic matter and water content. It can then be used as organic manure for agriculture.

USES OF TREATED WASTE WATER

• Irrigation - public parks, schools, road and building construction, landscaped areas, golf courses, etc.
• Commercial - vehicle washing facilities, laundry facilities, mixing pesticides and herbicides
• Construction - dust control, concrete production
• Toilet and urinal flushing
• Fire protection
• Groundwater Recharge