Wastewater Operator Certification Information

1. Wastewater OperatorCertification Information

2. Terms • CWA – Clean Water Act passed in 1972 • NPDES – National Pollutant Discharge Elimination System – permit good for 5 years (must reapply 180 day prior to expiration date) • PE – Population Equivalency – how plants are designed – design for 20 years future growth PE, capita = (Flow, MGD)(BOD, mg/L)(8.34lb/gal) 0.17 lbs/BOD/capita/day * An operator should be present during construction to become familiar with the plant, including the equipment, machinery and the operation of it. Provides you with the opportunity to relate your plant to the drawings.

3. Overview • Collection Systems • Rain Water I & I • Wastewater Flow • Preliminary Treatment • Secondary Treatment • Solids Handling • Tertiary Treatment • Laboratory • Safety

4. Rain Water Inflow and Infiltration (I&I) • Enters collection system through cracks and holes in pipes, open cleanouts, cross connections, manholes, #1 cause – leaking pipe joints • Can cause hydraulic overload at WPCF, decreased capacity due to sand and grit accumulation, lift station pump failures and overflows, increased operating costs • Accounts for 30% of wastewater flow

5. Liftstations • Must maintain a velocity of 2ft per second to stop solids from settling and H2S from forming, when unable to reach that velocity build a lift station – lift flow to a higher elevation where it can again flow by gravity • Has forced ventilation to prevent toxic gas fume build-up • Most common is air-lift pump

6. Wastewater Contents • Domestic waste is 99.9% water • Contains pathogenic (disease causing) bacteria, viruses, cysts that can cause Typhoid, Cholera, Dysentery, Polio and Hepatitis • Floatable – floats to surface (scum & grease) • Settleable – settles to bottom • Suspended – won’t float or settle (same weight as water) • Dissolved – such as food dye • Colloidal – finely dissolved that remains in suspension causing turbidity (cloudiness) due to its size and electrical charge

7. Raw Wastewater Solids Composition Wastewater is 99.9% water Dissolved solids makes up the highest percent of solids Dissolved and Suspended Solids make up Total Solids

8. Preliminary Treatment • To remove material that can damage or plug up equipment – grit, rags, plastics, sticks, etc. • Flow Equalization / Surge Basins • Bars Screens / Bar Racks • Moving or Rotating Screens • Shredding / Grinding • Grit Chambers / Channels • Odor Control • Pumps (not considered treatment, but located in head works of plant)

9. Pumps Impeller vane damage Cavitation • The formation of partial vacuums in a liquid by a swiftly moving solid body (as a propeller) or by high-intensity sound waves • The pitting and wearing away of solid surfaces (as of metal or concrete) as a result of the collapse of these vacuums in surrounding liquid

10. Sedimentation and Floatation • Sedimentation and Floatation happens in both Primary and Secondary (or final) clarifiers • Purpose – to remove settleable and floatable solids from raw ww • Organic solids have high oxygen demand (BOD) • Primary Clarifiers follows grit removal • Velocity 1.0 to 2.0 feet per minute • Secondary Clarifier follows any biological treatment

11. Rotating Biological Contactor (RBC) • Mechanical or air operated drive units rotate the media through wastewater • Biomass is attached to the moving media (attached growth) • 40% of the media is immersed in ww Covered RBCs

12. Sequencing Batch Reactors (SBR) • Treatment is carried out in a single tank through sequencing stages • Handles periodic flows or batch dumps with ease • Especially well suited for industries • Automatic control through Programmable Logic Control (PLC) • Stable due to high sludge age and long retention time • Less costly to build – no need for sludge handling – can be sent directly to drying beds or composting process

13. BOD/N/P • The ratio of biochemical oxygen demand to nitrogen to phosphorus should be 100/5/1. If the organic loading rate increases the appropriate N & P need to be added at a point where the incoming wastewater is highly mixed to provide nutrients needed by the microbes. The pounds of N & P required per day will be about 10% of the organic solids (dry weight) produced every day. The P required will be one-fifth of the N requirement. The amount of P & N added daily are equal to the difference between the quantity required and the quantity in the waste. Aqueous ammonia or anhydrous ammonia may be added to provide the nitrogen. Phosphate fertilizers or phosphoric acid from a waste acid facility may be used to provide P.

14. Conventional Activated Sludge • Detention time – 4 to 8 hours (6 hrs) • Sludge Age – 3.5 to 7 days • MLSS – 1,000 to 3,000 mg/L • DO – 2 to 4 mg/L or ppm • High (>5.0) shear floc, waste energy • Low (<0.5) lead to bulking, poor effluent • Mixing • Distributes oxygen evenly • Brings food in contact with microorganisms • Prevents septic conditions on bottom of tank

15. Nitrification Cycle Heterotrophic Bacteria – Carbonaceous Stage • Get energy from the oxidation of organic materials • Common bacteria in wastewater • This bacteria is responsible for denitrification • Form floc – fast growing Autotrophic Bacteria – Nitrogenous Stage • Get energy from inorganic materials or from the sunlight (some are algae) • Are the nitrifiers • Sulfide oxidizing organisms • Do not form floc – slow growing

16. Ponds Secondary or Two Stage Pond Tertiary or Three Stage Pond Primary Pond or Lagoon This is how it works

17. Feed the Primary Digester with Primary or Secondary (WAS) Sludge Heat and Mix the Primary Digester – called primary because it is the first digester – creates gas Sludge is transferred (pumped) from the Primary Digester to the Secondary Digester No Heating or Mixing – allow solids to settle and liquids (supernatant) to float to the top – some gas production

18. Chemical Stabilization • Lime • Addition of lime adds to the overall quantity of solids that must be disposed • High costs • Chlorine • pH will drop <3.5 (acidic) • Lime may be added before dewatering

19. Sludge Incineration • Use dewatered sludge • Converts dewatered sludge by combustion to carbon dioxide and water vapor • Reduce volume up to 90% • Most common is MHF (multiple hearth furnace) • Temperature 1,300 – 1,700°F

20. Only use the chlorine wrench when opening or closing cylinders – open 100%, close then reopen ¼ turn only Trunions – used to turn ton cylinders so the valves are straight horizontally when opening Fusible plug – center is lead – will melt at 158 to 165ºF to release gas instead of liquid or explosion Train cargo cars (Class C) Ton (2,000 lb) cyliners (Class B)

21. Biological Treatment • Luxury Uptake of Phosphorous – modification of activated sludge • Definitions • Aerobic (oxic): free DO is present • Anoxic: oxygen is deficient or present as combined oxygen in Nitrate (NO3) and Sulfate (SO4) • Anaerobic: No oxygen

22. Lab Miscellaneous • Meniscus (commonly found in pipettes) – read at the bottom of the curve or the top of the curve • You can preserve a metals sample for 6 months • BOD solution water make-up – phosphate buffer, magnesium sulfate, calcium chloride, ferric chloride • A bottle containing only dilution water is called a blank

23. Pretreatment • Total toxic organics (TTO) refers to the sum of the masses or concentrations of certain toxic organic pollutants found in the regulated discharge at a concentration greater than 0.01 mg/L • Inspection – minimum of once per year or as needed • Sampling – Significant Industrial User (SIU) at least annually and self monitored semi-annually