Tertiary treatment nutrient removal solids removal and disinfection
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Tertiary Treatment: Nutrient Removal, Solids Removal, and Disinfection. Treated Wastewater Effluent Contains…. BOD (biochemical oxygen demand) Carbon matter, depletes O2, causes biomat growth TSS (total suspended solids) Depletes O2 NH3 (ammonia)

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Tertiary treatment nutrient removal solids removal and disinfection

Tertiary Treatment:Nutrient Removal, Solids Removal, and Disinfection

Treated wastewater effluent contains
Treated Wastewater Effluent Contains…

  • BOD(biochemical oxygen demand)

    • Carbon matter, depletes O2, causes biomat growth

  • TSS(total suspended solids)

    • Depletes O2

  • NH3(ammonia)

    • Toxic to fish, depletes O2, a nutrient that promotes biol. growth

  • NO3(nitrate)

    • Toxic to babies, drinking water regulated, a nutrient

  • TP(total phosphorus)

    • A nutrient

  • Pathogens (bacteria/viruses)

    • Disease causing

First we must understand wastewater assimilation
First, We Must UnderstandWastewater Assimilation

  • A site’s ability to handle the amount of liquid or the amount of pollutants without causing a public health or environmental health concern

  • In-ground or In-stream discharge

  • Sometimes, high-quality effluent is necessary

    • Low BOD

    • Low fecal coliform

    • Low nutrients (Nitrogen and Phosphorus)

  • Protection of sensitive waterbodies, nearby…

    • Or drinking water supplies (groundwater & wells)

Discharge permits
“Discharge” Permits

  • In-ground dispersal

    • ADEM for flows of 10,000 gpd +

      • UIC Permit (underground injection control)

        • Specifies a certain effluent quantity and quality

        • BOD, TSS and groundwater monitoring for NO3

    • ADPH for smaller systems

  • Surface dispersal

    • Stream Discharge

      • NPDES Permit(specifies BOD, TSS, NH3, NO3, TP, etc.)

      • Disinfection Required

    • Spray Irrigation

      • NPDES Permit

      • 7-10 day holding pond required

      • Disinfection Required

Why is tertiary treatment needed
Why is tertiary treatment needed?

  • To better protect public health and environment

  • To provide additional treatment when soils or receiving waters cannot

Biological nitrogen removal
Biological Nitrogen Removal

  • Uptake into biological cell mass

  • Nitrification (conversion to Nitrate)

  • Denitrification (conversion to N2 gas)

Biological nitrification
Biological Nitrification

Conversion of Ammonia to Nitrite (Nitrosomonas)

NH4+ + 2 O2  NO2- + 2 H+ + H2O

Conversion of Nitrite to Nitrate(Nitrobacter)

NO2- + 0.5 O2    NO3-

Nitrification cont
Nitrification (cont.)

  • For each mg of NH4+ converted…

    3.96 mg of O2 are utilized(Need Oxygen)

    0.31 mg of new cells are formed

    7.01 mg of alkalinity are removed

Nitrification cont1
Nitrification (cont.)

  • Nitrifying bacteria are sensitive and susceptible to a variety of conditions.

  • The following factors affect nitrification:

    • Conc of NH4+ and NO2-

    • BOD/TKN ratio (BOD should be gone/removed)

    • Dissolved oxygen conc (need oxygen)

    • Temperature

    • pH (7.5 to 8.6)

Nitrification processes
Nitrification Processes

Suspended Growth Separate Stage Nitrification

Single State Nitrification

Nitrification processes1
Nitrification Processes

Attached Growth

Attached Growth Nitrification following Act. Sludge

Biological denitrification

A modification of aerobic pathways (no oxygen)

Same bacteria that consume carbon material aerobically

Denitrifying bacteria obtain energy from the conversion of NO3- to N2 gas, but

require a carbon source

NO3- + CH3OH + H2CO3  C5H7O2N + N2 + H2O + HCO3-

Biological Denitrification

Cell mass

Organic matter


  • Need low (no) oxygen (< 1 mg/L)

  • Need carbon source (BOD in Wastewater)

  • Neutral pH (pH 7)

  • Conc of nitrate

Denitrification cont
Denitrification (cont.)

  • Separate denitrification reactor


  • Combined Carbon Oxidation-nitrification-denitrification reactor

    • A series of alternating aerobic and anoxic stages

    • Reduces the amount of air needed

    • No need for supplemental carbon source

Combined nitrification denitrification note alternating regions of aerobic and anoxic
Combined Nitrification/Denitrification(note alternating regions of aerobic and anoxic)

Phosphorus removal
Phosphorus Removal

  • Chemical Precipitation

    • Calcium (lime) addition at high pH (>10)

      • Reacts with alkalinity

    • Alum (Aluminum Sulfate) precipitation

    • Iron precipitation


  • Selective destruction of disease-causing organisms

    • Chlorine

    • UV Light

    • Ozone (gas)

Chlorine disinfection
Chlorine Disinfection

  • Liquid chlorine

  • Sodium hypochlorite (tablets)

    Note: not allowed to discharge chlorine

    (it must be removed after disinfection)

    * chlorine removed with either…

    a. sulfur dioxide

    b. sodium bisulfite

Tablet chlorinator calcium hypochlorite
Tablet Chlorinator(Calcium Hypochlorite)

Chlorine disinfection1
Chlorine Disinfection

  • To be effective…

    • Chlorine concentration

    • Contact time

    • Proper mixing

    • Temperature

    • Number and type of organisms

Uv disinfection
UV Disinfection

  • UV Light

    • Specific wavelengths have biocidal properties (~254 nm)

    • Quartz, mercury-vapor lamps

    • Cleaning required

    • No residual

Uv disinfection a specific wavelength of light
UV Disinfectiona specific wavelength of light

Ozone disinfection
Ozone Disinfection

  • O3 a gas, must be generated on-site

  • Bubbled into a basin (or pipeline) with treated effluent

  • Great disinfectant!

  • No residual…ozone degrades to oxygen, O2

  • Costs More, Need equipment and electricity

Ozone disinfection1
Ozone Disinfection

Flow Diagram

Ozone Generation