1 By: ABDULRAHMAN AL-BETAR ECU 2001

2 Outline Introduction Dhahran S.T.P in Saudi Aramco Sewage Treatment Processes: A. Preliminary B. Primary C. Secondary D. Tertiary

3 Introduction Definitions: Sewage: The content of sewer or drains Sewage Treatment : Removing of impurities so that the remaining waste water can be safely returned to the river or sea and become part of the natural water cycle again.

4 Compositions:  Human waste  paper  Food  Grease  Mineral matter  and almost any things that can be carried by water Introduction Cont’d

5 Saudi Aramco  Biggest sewage treatment plant operated by the company  Treat 10 million gallons per day of raw sewage  Sodium Hypo-chlorite is used in secondary and tertiary treatments for disinfections  Treated water is used for the irrigation purposes Dhahran S.T.P:

6 Sewage Treatment Processes  Preliminary  Primary  Secondary  Tertiary

7  Solids like wood paper, rags and plastic are removed by screens Preliminary Treatment Sewage Treatment Processes Cont’d

8  The remaining solids that passed from the preliminary treatment are removed  About 70% of solids settle out at this stage Primary Treatment Sewage Treatment Processes Cont’d

9 Secondary Treatment Sewage Treatment Processes Cont’d  Biological treatment to reduce organic matter in the waste stream  Aerobic bacteria is the main cause for this reduction  The chemical reaction: Organic matter CO 2 + H 2 O Bacteria O2O2

10  This process can be speeded up by blowing air into tanks of sewage  These treatment units are called Aeration Tanks. Sewage Treatment Processes Cont’d Secondary Treatment

11 Sewage Treatment Processes Cont’d Aeration Tank

12 Bacteria Found in the Sewage Aerobic Require dissolved oxygen for their existence Ex: Earobacter Facultative Can grow with or without oxygen Ex: Salmonella Anaerobic Exist in the absence of dissolved oxygen Ex: Sulfate Reducer Sewage Treatment Processes Cont’d Secondary Treatment

13  Several forms of tertiary treatment are available for example: 1. Passing the effluent over grass plots 2. Retaining the effluent in lagoons 3. Filtering through sand beds Tertiary Treatment Sewage Treatment Processes Cont’d

14 Summary of Sewage Treatment Processes

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