Tertiary Treatment:Tertiary Treatment:Nutrient Removal, Solids Removal, and Nutrient Removal, Solids Removal, and

DisinfectionDisinfection

Treated Wastewater Effluent Treated Wastewater Effluent Contains…Contains…

BODBOD (biochemical oxygen demand)(biochemical oxygen demand)• Carbon matter, depletes O2, causes biomat growthCarbon matter, depletes O2, causes biomat growth

TSSTSS (total suspended solids)(total suspended solids)• Depletes O2Depletes O2

NH3NH3 (ammonia)(ammonia)• Toxic to fish, depletes O2, a nutrient that promotes biol. growthToxic to fish, depletes O2, a nutrient that promotes biol. growth

NO3NO3 (nitrate)(nitrate)• Toxic to babies, drinking water regulated, a nutrientToxic to babies, drinking water regulated, a nutrient

TPTP (total phosphorus)(total phosphorus)• A nutrientA nutrient

Pathogens Pathogens (bacteria/viruses)(bacteria/viruses)• Disease causingDisease causing

First, We Must UnderstandFirst, We Must Understand

Wastewater AssimilationWastewater Assimilation A site’s ability to handle the amount of liquid or A site’s ability to handle the amount of liquid or

the amount of pollutants without causing a public the amount of pollutants without causing a public health or environmental health concernhealth or environmental health concern

In-groundIn-ground or or In-stream In-stream dischargedischarge

Sometimes, high-quality effluent is necessarySometimes, high-quality effluent is necessary• Low BODLow BOD• Low fecal coliformLow fecal coliform• Low nutrients (Nitrogen and Phosphorus)Low nutrients (Nitrogen and Phosphorus)

Protection of sensitive waterbodies, nearby…Protection of sensitive waterbodies, nearby…• Or drinking water supplies (groundwater & wells)Or drinking water supplies (groundwater & wells)

““Discharge” PermitsDischarge” Permits In-ground dispersalIn-ground dispersal

• ADEM for flows of 10,000 gpd +ADEM for flows of 10,000 gpd + UIC Permit (underground injection control)UIC Permit (underground injection control)

• Specifies a certain effluent quantity and qualitySpecifies a certain effluent quantity and quality • BOD, TSS and groundwater monitoring for NOBOD, TSS and groundwater monitoring for NO33

• ADPH for smaller systemsADPH for smaller systems

Surface dispersalSurface dispersal• Stream DischargeStream Discharge

NPDES PermitNPDES Permit (specifies BOD, TSS, NH(specifies BOD, TSS, NH33, NO, NO33, TP, etc.), TP, etc.) Disinfection RequiredDisinfection Required

• Spray IrrigationSpray Irrigation NPDES PermitNPDES Permit 7-10 day holding pond required7-10 day holding pond required Disinfection RequiredDisinfection Required

Why is tertiary treatment needed?Why is tertiary treatment needed?

To better protect public health and To better protect public health and environmentenvironment

To provide additional treatment when soils To provide additional treatment when soils or receiving waters cannotor receiving waters cannot

Biological Nitrogen RemovalBiological Nitrogen Removal

Uptake into biological cell massUptake into biological cell mass

Nitrification Nitrification (conversion to Nitrate)(conversion to Nitrate)

Denitrification Denitrification (conversion to N(conversion to N22 gas) gas)

Biological NitrificationBiological Nitrification

Conversion of Ammonia to Nitrite Conversion of Ammonia to Nitrite (Nitrosomonas)(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 NHFor each mg of NH44++ converted… converted…

3.96 mg of O3.96 mg of O22 are utilized are utilized (Need Oxygen)(Need Oxygen)0.31 mg of new cells are formed0.31 mg of new cells are formed

7.01 mg of alkalinity are removed7.01 mg of alkalinity are removed

Nitrification (cont.)Nitrification (cont.)

Nitrifying bacteria are Nitrifying bacteria are sensitivesensitive and and susceptible to a variety of conditions.susceptible to a variety of conditions.

The following factors affect nitrification:The following factors affect nitrification:• Conc of NHConc of NH44

++ and NO and NO22--

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

• Dissolved oxygen conc Dissolved oxygen conc (need oxygen)(need oxygen)• TemperatureTemperature• pH (7.5 to 8.6)pH (7.5 to 8.6)

Nitrification ProcessesNitrification Processes

Suspended Growth Separate Stage Nitrification

Single State Nitrification

Nitrification ProcessesNitrification Processes

Attached Growth

Attached Growth Nitrification following Act. Sludge

Biological DenitrificationBiological Denitrification

A modification of aerobic pathways A modification of aerobic pathways (no oxygen)(no oxygen)• Same bacteria that consume carbon material aerobicallySame bacteria that consume carbon material aerobically

Denitrifying bacteria obtain energy from the Denitrifying bacteria obtain energy from the conversion of conversion of NONO33

-- to N to N22 gas gas, but, but

require a carbon sourcerequire a carbon source

NONO33-- + CH + CH33OH + HOH + H22COCO33 C C55HH77OO22N + N + NN22 + H + H22O + HCOO + HCO33

--

Organic matter Cell mass

DenitrificationDenitrification

Need low (no) oxygen (< 1 mg/L)Need low (no) oxygen (< 1 mg/L) Need carbon source (BOD in Wastewater)Need carbon source (BOD in Wastewater) Neutral pH Neutral pH (pH 7)(pH 7) Conc of nitrateConc of nitrate

Denitrification (cont.)Denitrification (cont.)

Separate denitrification reactorSeparate denitrification reactor

oror Combined Carbon Oxidation-Combined Carbon Oxidation-

nitrification-denitrification reactornitrification-denitrification reactor• A series of alternating aerobic and anoxic A series of alternating aerobic and anoxic

stagesstages• Reduces the amount of air neededReduces the amount of air needed• No need for supplemental carbon sourceNo need for supplemental carbon source

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

Phosphorus RemovalPhosphorus Removal

Chemical PrecipitationChemical Precipitation• Calcium (lime) addition at high pH (>10)Calcium (lime) addition at high pH (>10)

Reacts with alkalinityReacts with alkalinity

• Alum Alum ((Aluminum Sulfate)Aluminum Sulfate) precipitation precipitation• Iron precipitationIron precipitation

DisinfectionDisinfection

Selective destruction of disease-Selective destruction of disease-causing organismscausing organisms

1.1. ChlorineChlorine

2.2. UV LightUV Light

3.3. Ozone (gas)Ozone (gas)

Chlorine DisinfectionChlorine Disinfection

1.1. Liquid chlorine Liquid chlorine

2.2. Sodium hypochlorite (tablets) Sodium hypochlorite (tablets)

Note: not allowed to discharge chlorineNote: not allowed to discharge chlorine(it must be removed after disinfection)(it must be removed after disinfection)

* * chlorine removed with either…chlorine removed with either…

a. sulfur dioxidea. sulfur dioxide

b. sodium bisulfiteb. sodium bisulfite

Tablet ChlorinatorTablet Chlorinator(Calcium Hypochlorite)(Calcium Hypochlorite)

Chlorine DisinfectionChlorine Disinfection

To be effective…To be effective…• Chlorine concentrationChlorine concentration• Contact timeContact time• Proper mixingProper mixing• TemperatureTemperature• Number and type of organismsNumber and type of organisms

Chlorine DoseChlorine Dose

UV DisinfectionUV Disinfection

UV LightUV Light• Specific wavelengths have biocidal Specific wavelengths have biocidal

properties (~254 nm)properties (~254 nm)• Quartz, mercury-vapor lampsQuartz, mercury-vapor lamps• Cleaning required Cleaning required • No residualNo residual

UV DisinfectionUV Disinfectiona specific wavelength of lighta specific wavelength of light

UV DisinfectionUV Disinfection

Ozone DisinfectionOzone Disinfection

OO33 a gas, must be generated on-site a gas, must be generated on-site

Bubbled into a basin Bubbled into a basin (or pipeline)(or pipeline) with treated with treated effluenteffluent

Great disinfectant!Great disinfectant!

No residual…ozone degrades to oxygen, ONo residual…ozone degrades to oxygen, O22

Costs More, Need equipment and electricityCosts More, Need equipment and electricity

Ozone DisinfectionOzone Disinfection

Flow DiagramOzone Generation