In the biological treatment of municipal and industrial wastewater via the activated sludge process, several sequential operations are performed to purify water and manage waste. Arrange the following steps of the process in the correct chronological order from first to last.
- 1Screening and primary sedimentation to remove coarse solids and heavy inorganic grit
- 2Aeration in tanks containing aerobic bacteria to digest dissolved organic pollutants
- 3Secondary clarification in settling basins to separate the activated biological sludge flocs from the purified effluent
- 4Disinfection of the clarified water using chlorine or ultraviolet light prior to discharge
Answer
The correct sequence is: (1) Screening and primary sedimentation to remove coarse solids and heavy inorganic grit, (2) Aeration in tanks containing aerobic bacteria to digest dissolved organic pollutants, (3) Secondary clarification in settling basins to separate the activated biological sludge flocs from the purified effluent, and (4) Disinfection of the clarified water using chlorine or ultraviolet light prior to discharge.
The logical sequence follows the engineering progression from coarse physical removal of solids, through microbial digestion of dissolved organics during aeration, solid-liquid separation of biomass in secondary clarifiers, and final pathogenic disinfection.
Step-by-Step Solution
Key Concept
Sequential physical, biological, and chemical stages of industrial biotechnology in activated sludge wastewater treatment.