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By:ABDULRAHMAN AL-BETAR

ECU 2001

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Outline

Introduction

Dhahran S.T.P in Saudi Aramco

Sewage Treatment Processes:

A. Preliminary

B. Primary

C. Secondary

D. Tertiary

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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.

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Compositions: Human waste

paper

Food

Grease

Mineral matter

and almost any things that can be carried by water

Introduction Cont’d

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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:

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Sewage Treatment Processes

Preliminary

Primary

Secondary

Tertiary

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Solids like wood paper, rags and plastic are removed by screens

Preliminary Treatment

Sewage Treatment Processes Cont’d

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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

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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 CO2 + H2OBacteria O2

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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

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Sewage Treatment Processes Cont’dAeration Tank

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Bacteria Found in the Sewage Bacteria Found in the Sewage

AerobicRequire dissolved oxygen for their existence

Ex: Earobacter

FacultativeCan grow with or without oxygen

Ex: Salmonella

AnaerobicExist in the absence of dissolved oxygen

Ex: Sulfate Reducer

Sewage Treatment Processes Cont’d

Secondary Treatment

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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

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Summary of Sewage Treatment Processes

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