Wastewater Characterization NC Subsurface Operator School

Wastewater Characterization Why is this important? Why is this important? What is wastewater? What is wastewater? Where does it come from? Where does it come from? How much is there? How much is there? What’s in it? What’s in it? How can we measure it? How can we measure it?

Why is this important? Influent wastewater (raw sewage) Influent wastewater (raw sewage) Inform treatment system design Inform treatment system design STE and pretreatment effluent STE and pretreatment effluent Inform treatment system design Inform treatment system design Inform drainfield sizing Inform drainfield sizing Determine compliance Determine compliance

Why is this important? Pretreatment unit mixed liquor Pretreatment unit mixed liquor Process monitoring and control Process monitoring and control Ground/surface water discharge (after soil dispersal/treatment) Ground/surface water discharge (after soil dispersal/treatment) Determine risk and inform design Determine risk and inform design Determine compliance Determine compliance

What is Wastewater? Used water and water-carried solids Used water and water-carried solids Industrial Wastewater Domestic Wastewater

Commercial Commercial Schools Schools Restaurants Restaurants Other businesses Other businesses

Domestic Wastewater Food preparation Food preparation Restroom (sinks, toilets) Restroom (sinks, toilets) Laundry Laundry uniform in color and composition uniform in color and composition gray in color and musty smelling gray in color and musty smelling unusual colors or odors indicate abnormal discharges unusual colors or odors indicate abnormal discharges

Industrial Wastewater Manufacturing processes Manufacturing processes Car wash facilities Car wash facilities Variable in composition Variable in composition May contain high levels of chemicals or toxic substances May contain high levels of chemicals or toxic substances Pretreatment & industrial inputs can affect color/odor Pretreatment & industrial inputs can affect color/odor

Any source can be high strength Can predict strength of some sources… Can predict strength of some sources…

How much is there? Prescriptive codes Prescriptive codes Unit flow rates for different facilities Unit flow rates for different facilities Predict usage based upon past experience Predict usage based upon past experience Design flow Design flow Actual measurement captures peak usage Actual measurement captures peak usage Hourly Hourly Daily Daily Monthly Monthly

Actual average flow Varies considerably Varies considerably Hourly variation Hourly variation Fewer facilities, higher peaking factor Fewer facilities, higher peaking factor Daily variation Daily variation Schools, churches, businesses Schools, churches, businesses Weekly Weekly Variable use facilities: vacation rentals, etc. Variable use facilities: vacation rentals, etc. Seasonal Seasonal Long periods of inactivity Long periods of inactivity

Hourly variation in use Homes: Morning water usage, evening water usage, laundry day water usage Homes: Morning water usage, evening water usage, laundry day water usage

Hourly variation in use Restaurants: dishwashing and food prep Restaurants: dishwashing and food prep Schools: lunch time Schools: lunch time Grocery Stores: nighttime cleaning activities, monthly floor stripping and cleaning activities Grocery Stores: nighttime cleaning activities, monthly floor stripping and cleaning activities

Number of sources Household Household Wastewater produced by one household Wastewater produced by one household Components vary day to day Components vary day to day Community Community Wastewater produced by multiple households Wastewater produced by multiple households Higher values Higher values More constant More constant

Use by fixture

What’s in Wastewater? Pollutants or constituents of concern Pollutants or constituents of concern Organics/inorganics Organics/inorganics Solids Solids Pathogens Pathogens Nutrients Nutrients Metals Metals Persistent organic chemicals Persistent organic chemicals Fats, oils, grease Fats, oils, grease

Organic constituents Waste from plant or animal sources Waste from plant or animal sources Can be consumed by microbes Can be consumed by microbes Anaerobic and aerobic processes Anaerobic and aerobic processes Expressed as biochemical oxygen demand (BOD) or chemical oxygen demand (COD) Expressed as biochemical oxygen demand (BOD) or chemical oxygen demand (COD) A commonly-used indicator of wastewater strength. A commonly-used indicator of wastewater strength. Biological growth Biological growth

Metals: Inorganic chemical compounds Often found in industrial discharges Often found in industrial discharges Stable and resistant to decomposition Stable and resistant to decomposition Some essential for animal & plant nutrition Some essential for animal & plant nutrition At higher levels some metals can be highly toxic At higher levels some metals can be highly toxic Especially in soil with low pH Especially in soil with low pH More mobile More mobile

Solids Organic and inorganic materials Organic and inorganic materials Fractions: Fractions: Total Solids Total Solids Total dissolved solids (TDS) Total dissolved solids (TDS) Total suspended solids (TSS)* Total suspended solids (TSS)* Total settleable solids Total settleable solids Solids removal is a major goal of wastewater treatment Solids removal is a major goal of wastewater treatment Can clog treatment/dispersal components Can clog treatment/dispersal components *TSS is another commonly-used expression of wastewater strength.

 Disease-causing organisms Helminths (worms), protozoa, bacteria, viruses Helminths (worms), protozoa, bacteria, viruses  Comfortable in human digestive system  Conditioned to living in low oxygen  Difficulty surviving in air-filled environments  Many pathogens are removed when solids are removed Pathogens

22 Nutrients Elements essential for plant growth Elements essential for plant growth Nitrogen (N) Phosphorus (P) Potassium (K) Calcium (Ca) Magnesium (Mg) Sulfur (Su) Primary Secondary BoronChlorineCopperIronManganeseMolybdenumNickelZinc

Nutrients N and P are a major concern in wastewater N and P are a major concern in wastewater Can affect water quality Can affect water quality Nitrogen – more detrimental to marine environments Nitrogen – more detrimental to marine environments Can also cause methemoglobinemia and other problems Can also cause methemoglobinemia and other problems Phosphorous – more of an effect on freshwater Phosphorous – more of an effect on freshwater

Forms of Nitrogen Organic N NH 4 + NO 3 - /NO 2 - Total Kjeldahl Nitrogen TKN: Amount already mineralized to NH 4 PLUS nitrogen that is still bound in organics TKN: Amount already mineralized to NH 4 + PLUS nitrogen that is still bound in organics Total Nitrogen

Organic nitrogen Found in cells of all living things (proteins, peptides, amino acids) Found in cells of all living things (proteins, peptides, amino acids) Principle compound in feces and urine Principle compound in feces and urine Not available to plants until bacterial conversion to inorganic form through MINERALIZATION Not available to plants until bacterial conversion to inorganic form through MINERALIZATION Urea N N

26 Inorganic (mineral) nitrogen Ammonium (NH 4 + ) Ammonium (NH 4 + ) Nitrate (NO 3 - ) Nitrate (NO 3 - ) Mineralization NH 4 + NO 3 - Organic N Inorganic N Lysine

Inorganic Nitrogen Ammonium N (NH 4 + ) Ammonium N (NH 4 + ) Nitrate N Nitrate N (NO 3 - ) Available for plant uptake Available for plant uptake Negative charge: not held by soil Negative charge: not held by soil High potential for leaching to groundwater High potential for leaching to groundwater Can be converted to N 2 if: Can be converted to N 2 if: Low O 2 with C or S present Low O 2 with C or S present “Denitrification” “Denitrification” NO 3 - NH 4 + Available for plant uptake Available for plant uptake Positive charge: binds to soil particles Positive charge: binds to soil particles Volatilizes to atmosphere as NH 3 Volatilizes to atmosphere as NH 3 Converted to NO 3 - in aerobic conditions Converted to NO 3 - in aerobic conditions “Nitrification” “Nitrification” NH 3

Phosphorous Found in body wastes, food residues, fertilizers, detergents, industrial discharges Found in body wastes, food residues, fertilizers, detergents, industrial discharges Some forms available to plants Some forms available to plants P in soil often forms insoluble compounds P in soil often forms insoluble compounds “Precipitation” “Precipitation” Rarely mobile in soil, but can move with soil particles during erosion Rarely mobile in soil, but can move with soil particles during erosion Can promote algal growth in P-limited waters Can promote algal growth in P-limited waters Mainly inland Mainly inland

Fats, Oils, and Grease (FOG) Animal or vegetable-based FOG Animal or vegetable-based FOG Residential/Commercial kitchens Residential/Commercial kitchens Degradable by microorganisms Degradable by microorganisms Petroleum-based FOG Petroleum-based FOG Industry/automotive repair Industry/automotive repair Personal care products Personal care products NOT readily broken down by microorganisms NOT readily broken down by microorganisms

Persistent organic chemicals - Stable organic compounds Slow to decompose Slow to decompose Can persist in soil and groundwater for years Can persist in soil and groundwater for years Many are synthetic compounds Many are synthetic compounds Industrial discharges Industrial discharges Solvents & household cleansers Solvents & household cleansers Paint Paint Medical products Medical products Personal care products Personal care products

Inorganic constituents Minerals, metals, dissolved salts Minerals, metals, dissolved salts Sand, silt, cadmium, copper, lead, zinc, sodium Sand, silt, cadmium, copper, lead, zinc, sodium Stormwater, inflow and infiltration Stormwater, inflow and infiltration Cracked pipes, leaky manhole covers Cracked pipes, leaky manhole covers Residential, commercial, industrial sources Residential, commercial, industrial sources Stable compounds Stable compounds Not easily broken down by microorganisms Not easily broken down by microorganisms

Measuring wastewater strength How much treatment is required? How much treatment is required? What is the effluent quality at different stages of treatment? What is the effluent quality at different stages of treatment? Has wastewater been successfully treated? Has wastewater been successfully treated? Are we compliant with regulations? Are we compliant with regulations?

Methods of measurement Solids analyses (TSS) Solids analyses (TSS) Biochemical oxygen demand (BOD) Biochemical oxygen demand (BOD) Chemical oxygen demand (COD) Chemical oxygen demand (COD) Dissolved oxygen (DO) Dissolved oxygen (DO) Pathogens Pathogens pH pH Nutrients Nutrients

Solids analyses Total suspended solids (TSS) Total suspended solids (TSS) Sample filtered through pre-weighed filter Sample filtered through pre-weighed filter Filter and residue dried at degrees C Filter and residue dried at degrees C Increase in weight of filter represents TSS Increase in weight of filter represents TSS

Biochemical oxygen demand (BOD) Amount of oxygen consumed by microbes during decomposition of organic matter Amount of oxygen consumed by microbes during decomposition of organic matter Test performed over 5 day period: BOD 5 Test performed over 5 day period: BOD 5 High BOD means high levels of organics High BOD means high levels of organics Domestic wastewater ranges from 100 to 300 mg/L BOD Domestic wastewater ranges from 100 to 300 mg/L BOD

Chemical oxygen demand (COD) Amount of organic matter oxidized by a strong chemical oxidant Amount of organic matter oxidized by a strong chemical oxidant Measures additional compounds that microorganisms don’t decompose Measures additional compounds that microorganisms don’t decompose COD will be higher than BOD COD will be higher than BOD

Dissolved oxygen (DO) Concentration of O 2 dissolved in water Concentration of O 2 dissolved in water Most wastewater treatment processes Most wastewater treatment processes Require aerobic conditions Require aerobic conditions Cannot occur in anaerobic conditions Cannot occur in anaerobic conditions Measure with meter and probe or colorimetric kit Measure with meter and probe or colorimetric kit An indication of treatment efficacy An indication of treatment efficacy

38 Dissolved Oxygen (DO) Adequate levels Adequate levels Allow biological treatment Allow biological treatment Minimize objectionable odors Minimize objectionable odors Low levels can indicate Low levels can indicate Inadequate aeration Inadequate aeration Excessive amounts of organic material (BOD) Excessive amounts of organic material (BOD)

Pathogens Testing for all pathogens is impractical Testing for all pathogens is impractical Fecal coliform used as indicator organism Fecal coliform used as indicator organism Present in digestive system of warm blooded animals Present in digestive system of warm blooded animals High levels in wastewater indicate high levels of pathogens High levels in wastewater indicate high levels of pathogens

pH pH of domestic wastewater ranges from 6.5 to 7.5 pH of domestic wastewater ranges from 6.5 to 7.5 rapid changes can kill bacteria rapid changes can kill bacteria Measures acid or base quality of water Measures acid or base quality of water

Questions?