1. Tertiary Treatment of Domestic Wastewater By
Dr. Alaadin A. Bukhari
Centre for Environment and Water
Research Institute
KFUPM

2. PRESENTATION LAYOUT Introduction Tertiary Treatment Technologies
Removal of Residual Constituents
Suspended Solids Removal
Nutrients Removal
Removal of Toxic Compounds
Removal of Dissolved Inorganic Compounds
Tertiary Treatment of Wastewater in Saudi Arabia
Summary

3. INTRODUCTION
Definition Further removal of suspended and dissolved contaminants, not normally removed by conventional treatment

4. Need of Tertiary Treatment of Wastewater:
Continued increase in population
Limited water resources
Contamination of both surface and groundwater
Uneven distribution of water resources and
periodic draughts

5. Typical Constituents Present in Wastewater:
Suspended solids
Biodegradable organics compounds
Volatile organic compounds
Toxic contaminants
Nutrients
Other organics and inorganics

6. Options for reuse of treated wastewater

7. TERTIARY TREATMENT TECHNOLOGIES
Classification of Technologies
Primary Treatment Systems
Secondary Treatment Systems
Tertiary Treatment Systems

9. Factors affecting the selection of treatment processes:
The potential use of the treated effluent
The nature of the wastewater
The compatibility of the various operations and processes
The available means to dispose of the ultimate contaminants, and
The environmental and economic feasibility of the various systems

10. Typical performance data:

11. What are the contaminants removed during tertiary treatment?
Suspended solids
Nutrients
Toxic compounds
Dissolved organics and inorganics

12. REMOVAL OF RESIDUAL CONSTITUNTS
Suspended Solids Removal:
Granular-medium filters
the bed depth
the type of filtering medium used
whether the filtering medium is stratified or unstratified
the type of operation
Microstrainers

13. Fig. 12a. Types of shallow-bed filters (a) mono-medium
Fig. 12a. Types of shallow-bed filters (a) mono-medium downflow, (b) dual-medium downflow

14. Fig. 12b. Types of deep-bed filters (a) mono-medium
Fig. 12b. Types of deep-bed filters (a) mono-medium downflow, (b) mono-medium upflow

18. Sizing of a filter: Flow rate
Principal design criteria of a filter design is water flow rate and head loss
Usually we know
flow rate of influent
surface loading rate
Flow rate
Surface area of filtering unit =
Surface loading rate
Head loss can be calculated using reference (MetCalf & Eddy, 1991)

19. Removal of Suspended Solids by Microscreaning:

21. Basic nutrients present in the domestic wastewater are
(II) Nutrients Removal
Basic nutrients present in the domestic wastewater are
Nitrogen (ammonia, nitrite, nitrate)
Phosphorus (soluble and insoluble)
Sulfate
Other compounds of nitrogen & phosphorus
Problems associated with nutrients presence in wastewater are
accelerate the eutrophication
stimulate the growth of algae & rooted aquatic plants
aesthetic problems & nuisance

22. Nutrient Control could be accomplished by:
depleting D.O. concentration in receiving waters
Toxicity towards aquatic life
increasing chlorine demand
presenting a public health hazard
affecting the suitability of wastewater for reuse
Nutrient Control could be accomplished by:
physical methods
chemical methods, and
biological methods

23. Control and Removal of Nitrogen (Biologically):
Removal of Nitrogen by Nitrification/Denitrification Processes:
It is a two step processes
aerobic
NH4- —> NO3- (nitrification)
anoxic
NO3- —> N2 (denitrification)
Removal of Nitrogen by Nitrification Processes:
1) Single-stage process
2) Separate-stage process

24. Fig. 8a. Typical carbon oxidation and nitrification processes
Fig. 8a. Typical carbon oxidation and nitrification processes (single-stage)

25. Fig. 8b. Typical carbon oxidation and nitrification processes
Fig. 8b. Typical carbon oxidation and nitrification processes (separate-stage)

27. Nitrification/Denitrification systems can be classified as:
(a) Combined Nitrification/Denitrification Systems
1) Bardenpho process(four stage)
2) Oxidation Ditch process
(b) Separate-Stage Denitrification Systems

28. Fig. 9a. Combined-stage nitrification/denitrification
Fig. 9a. Combined-stage nitrification/denitrification system (four-stage Bardenpho)

29. Fig. 9b. Combined-stage nitrification/denitrification
Fig. 9b. Combined-stage nitrification/denitrification system (oxidation ditch)

30. Fig. 10. Separate-stage denitrification process using
Fig. 10. Separate-stage denitrification process using a separate carbon source

31. Control and Removal of Nitrogen (Physical & Chemical Methods):
air Stripping
breakpoint chlorination
selective ion exchange

32. Fig. 11. Cross-section of a countercurrent ammonia-stripping tower

33. Breakpoint chlorination:
Oxidation of ammonia-nitrogen can be done by adding excess chlorine
Basic chemical equations:
Cl2 + H2O  HOCl + H+ + Cl-
NH3 + HOCl  N2  + N2O  + NO2- + NO3- + Cl-

34. Ion exchange process

36. Phosphorus Removal Biologically:
Key to the biological phosphorus removal is the exposure of the microorganisms to alternating anaerobic & aerobic conditions
Phosphorus Removal Processes
(1) Mainstream process
(2) Sidestream process
(3) Sequencing Batch Reactor (SBR)

37. Fig. 12a. Biological phosphorus removal (mainstream process)

38. Fig. 12a. Biological phosphorus removal (sidestream process)

40. Removal of Phosphorus (Chemically)
Commonly used chemicals are
alum, sodium aluminate, ferric chloride, ferric sulfate, lime, and etc.
Factors affecting the choice of chemicals
Influent phosphorus level
Wastewater suspended solids
Alkalinity
Chemical cost
Reliability of chemical supply
Sludge handling facilities
Ultimate disposal method
Compatibility with other treatment processes

43. (III) Removal of Toxic Compounds:
Special attention is given to priority pollutants & refractory organic compounds in recent years, due to:
carcinogenic
mutagenic
teratogenic
they are resistant to microbial degradation

44. Treatment methods Biological Chemical Physical chemical oxidation
coagulation, sedimentation, and filtration
Physical
carbon adsorption
air stripping

45. Types of carbon contactors:
(1) Carbon Adsorption:
It is an advanced wastewater treatment method used for the removal of refrectory organic compounds as well as residual amount of inorganic compounds
Types of carbon contactors:
Upflow columns
Downflow columns
Fixed beds
Expanded beds

46. Fig. 17. Typical upflow countercurrent carbon column

47. (2) Chemical Oxidation: Chemical oxidation mainly done by
chlorine
chlorine dioxide, and
ozone
Basic chemical equation:
Oxidant + Compound  CO2 + H2O + other products

48. (IV) Removal of Dissolved Inorganic Compounds
chemical precipitation
ion exchange
ultra-filtration
reverse osmosis
electrodialysis

49. Fig. 19. Ultrafiltration and reverse osmosis for the removal of
Fig. 19. Ultrafiltration and reverse osmosis for the removal of dissolved organics

50. Fig. 20. Processes of reverse osmosis (a) direct osmosis, (b) osmotic
Fig. 20. Processes of reverse osmosis (a) direct osmosis, (b) osmotic equilibrium, (c) reverse osmosis

52. Tertiary Treatment of Wastewater in Saudi Arabia
Large quantity of wastewater is being generated in kingdom of Saudi Arabia
Quantities of wastewater generated
In 1994: Water Demand = 1.8 billion m3
WW Generated = 1.0 billion m3
WW Treated = 0.4 billion m3
WW Recycled = 0.1 billion m3
Water Demand in year 2000 = 2.8 billion m3

53. Table 21: Present and projected flow of wastewater, generated
Table 21: Present and projected flow of wastewater, generated (m3/d) in three cities of kingdom
YEAR DAMMAM AL-KHOBAR QATIF
, , ,766
, , ,735
, , ,785
, , ,627
Source Al-Elaiw, M. (1994).

54. Secondary treatment is practiced in Dammam, Khobar, Qatif and Khafji
Tertiary treatment is practiced in Royal Commission of Jubail and Yanbu (RCJY)
In Jubail 100% of tertiary treated wastewater is being reused

56. Summary:
Growing demand and scarcity of water resources necessitate the need for the tertiary treatment of wastewater for reuse purposes
Tertiary treatment of wastewater mainly depends on the availability and practicality of technologies
Selection of the processes depends on the requirement
Residual contaminants to be removed during tertiary treatment are suspended solids, nutrients, toxic compounds, and dissolved inorganics

57. Thank You