Question

Write a report showing the processes of the St Mary's wastewater treatment plant.

The report should include:

- General information about the plant (place, purpose, treatment capacity)

- Simplified flow diagram of the plant (showing only the important treatment processes)

- Functions of the each process (a few lines for each)

- Operational and maintenance issues of 2 processes in the plant

- References

Answer 1

• Before "disposing Wastewater to river, streams or land" or for "reuse of wastewater" it should be treated and make safe according to standards provided by government or Environmental Protection Agency .
• The degree of treatment depends on characteristics of wastewater, characteristics of disposal or reuse
• Typically a wastewater treatment process have four parts

1. Preliminary treatment
2. Primary treatment
3. Secondary treatment
4. Tertiary treatment

• According to degree of treatment required the parts of wastewater treatment plant may vary. Some may have 1-4 parts some may have 1-3 parts only etc.
• Example for Preliminary treatment is Screening. Preliminary treatment eliminates large floating particles.
• Example for Primary treatment is settling basins.
• Example for Secondary treatment is sedimentation tank. Biological decomposition of organic matter is carried in this treatment, it may be aeorobic or anaerobic.
• Example for Tertiary treatment is chlorination. Chlorination eliminates pathogens.
• In Screening, materials seperated from wastewater is to be cleaned or disposed. This disposal of floating matter is the major maintenance issue for screening. Similarly for sedimentation tanks sludge will be deposited in sedimentation tanks. Removal of sludge s the major maintenance issue for sedimentation tanks.