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Environmental Engineering (Wastewater treatment)
Core Course
Laboratory of Environmental Engineering & Planning
Department of Civil Engineering
Aristotle University of Thessaloniki
Environmental Engineering
Course description• Introduction to urban wastewater treatment.• Introduction to environmental biochemistry and biotechnology.• Physical, chemical and biological characteristics of urban sewage.
• Mechanical treatment (screens, grit chambers, sedimentation basins).• Biological treatment (activated sludge bioreactors, trickling filters,
rotating disc contactors).
• Natural systems for sewage treatment.• Chemical treatment.• Disinfection and disposal.• Sewage sludge treatment (thickening, stabilization and dewatering).
3
Teaching
• Lectures (5 hours/week)• Labs (3 hours/semester)• Exercise (Dimensioning a WWTP)• Visit to a WWTP
• Interactive environment (Blackboard)– https://blackboard.lib.auth.gr
• Literature:– Metcalf & Eddy, Inc., “Wastewater Engineering, Treatment and Reuse”
4th edition, Revised by George Tchobanoglous, Franklin L. Burton, H. Daviv Stensel.
– Efthymios Darakas ,“Environmental Engineering” A.U.Th.
Environmental Engineering
Environmental Engineering
Biological Treatment
Suspended Biomass Treatment (Activated Sludge)
Attached Growth Treatment(Trickling filters, RBC)
5
Influent
Primary clarifierBar Grit chamber Disinfection
Effluent
Secondary clarifierBioreactor
Ο2
Sludge return
Thickening Anaerobic digestion
(Post thickening) Dewatering
Dewatered sludge
BiogasSupernatant liquor
Sludge
Mechanical Treatment
Biological Treatment
Sludge treatment
Advanced treatment
P.S.
Environmental Engineering
WWTP (Typical diagram, Activated Sludge)WWTP (Typical diagram, Activated Sludge)
Environmental Engineering
7
Mechanical Treatment
BarsInfluent Effluent
Grit chamber
Sludge
Sedimentation tank
Screenings Sand
8
Biological Treatment – Activated Sludge
Effluent
Sludge
Sludge return
Air - Ο2
Influent
Suspended biomass
Bioreactor Secondary clarifier
9
Wastewater treatment - Aeration techniques
10
Nitrification - Denitrification
Nitrification - Denitrification
11
AerobicNitrification
Secondary Clarifier
AnoxicDenitrification
Air - Ο2
Effluent
InfluentΝΗ4
+
C
N2
Sludge return
Mixed Liquor
Sludge
1
12
Influent
Effluent
Anoxic zoneDenitrification
Aerobic zone Nitrification
Aerobic zone Nitrification
Aerobic zone Nitrification
2Nitrification - Denitrification
13
InfluentΝΗ4
+
C
Ο2
Effluent
N2 N2
Secondary clarifier
Recirculation
Sludge
N2N2
3Nitrification - Denitrification
14
AerobicNitrification
Secondary clarifier
Anoxic zone
Αέρας - Ο2
Effluent
InfluentΝΗ4
+
C
N2
Recirculation
Carbon (Organic matter)
Sludge
4Nitrification - Denitrification
15
Attached Growth Treatment
16
Effluent
Ιλύς
Influent
Recirculation (Optionally)
Clarifier
Biological filters
Pebbles or gravel
Moving Bed Biofilm Reactor (MBBR) - Synthetic materials
17
Trickling filters
18
Rotating Biological Contactors (RBC)
19Sedimentation tanks
Sedimentation tanks - Clarifiers
20
21Sedimentation tank
Tertiary treatment
• Membranes
• Adsorption (activated carbon)
• Ion exchange (resins)
23
Disinfection of wastewater (Chlorination)Influent
Effluent
Disinfection tanks
Cl2
24
UV Disinfection channels
25
Ozone
Effluent
Influent
Ο3 Ο3Ο3
Ozone generator
Liquid oxygen Evaporation
unit
Ozone reactor
Gases to be destroyed
26
Sludge treatment
Drying and disposal
Dewatering
Conditioning
Stabilization (aerobic – anaerobic)
Thickening
27
Thickeners
Ευθ. Νταρακάς 28
Bioreactor Secondary sedimentation
Primary sedimentation
Stabilization tank (Aerobic)Thickener
Supernatent liquid
Sludge
Excess sludge Recirculation
Dewatering
Effluent
Sludge stabilization (Aerobic)
Anaerobic digestion of sewage sludge
29
In
Biogas
Out to dewatering
Heating elements
33- 37 oC
Cover
30
Anaerobic digesters
31
Dewatering beds
Sludge 30 cm
Sand 10 cm (0,2-0,6 mm)
Sand 10 cm (7-15 mm)
Gravel 20 cm (15-30 mm)
Drainage
32
Dewatering(Solar energy)
33
Presses
Filter presses
34
Decanters
35
Sewage sludge management
