Dr. Alaadin A. Bukhari

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Tertiary Treatment of Domestic WastewaterBy

• Dr. Alaadin A. Bukhari
• Centre for Environment and Water
• Research Institute
• KFUPM

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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

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DefinitionFurther removal of suspended and
dissolved contaminants, not normally removed by
conventional treatment
INTRODUCTION
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• 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

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

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Options for reuse of treated wastewater
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TERTIARY TREATMENT TECHNOLOGIES

• Classification of Technologies
• Primary Treatment Systems
• Secondary Treatment Systems
• Tertiary Treatment Systems

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• 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

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Typical performance data
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• What are the contaminants removed during tertiary
  treatment?
• Suspended solids
• Nutrients
• Toxic compounds
• Dissolved organics and inorganics

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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

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

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

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• Sizing of a filter
• 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)

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Removal of Suspended Solids by Microscreaning
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• (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

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• 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

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Control and Removal of Nitrogen (Biologically)

• Removal of Nitrogen by Nitrification/Denitrificati
  on Processes
• It is a two step processes
• aerobic
• NH4- gt NO3- (nitrification)
• anoxic
• NO3- gt N2 (denitrification)
• Removal of Nitrogen by Nitrification Processes
• 1) Single-stage process
• 2) Separate-stage process

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

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

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• 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

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• Fig. 9a. Combined-stage nitrification/denitrificat
  ion system (four-stage Bardenpho)

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• Fig. 9b. Combined-stage nitrification/denitrificat
  ion system (oxidation ditch)

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

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• Control and Removal of Nitrogen (Physical
  Chemical Methods)
• air Stripping
• breakpoint chlorination
• selective ion exchange

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

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• 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-

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Ion exchange process
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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)

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

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

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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

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• (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

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

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• (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

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• Fig. 17. Typical upflow countercurrent carbon
  column

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• (2) Chemical Oxidation
• Chemical oxidation mainly done by
• chlorine
• chlorine dioxide, and
• ozone
• Basic chemical equation
• Oxidant Compound ? CO2 H2O other products

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

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

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

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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

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• Table 21 Present and projected flow of
  wastewater, generated (m3/d) in three
  cities of kingdom
• YEAR DAMMAM AL-KHOBAR QATIF
• 2000 242,057 118,539 100,766
• 2005 291,324 137,419 120,735
• 2010 326,985 159,306 144,785
• 2015 375,794 187,100 173,627
• Source Al-Elaiw, M. (1994).

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• 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

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• 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

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Thank You