1 CTC 450 Review WW Systems Operations WW Systems Operations

2 Objectives Understand the basics with respect to advanced WW treatment Understand the basics with respect to advanced WW treatment

3 Two systems Primary, Secondary, Sludge Primary, Secondary, Sludge Advanced (tertiary and ww reclamation) Advanced (tertiary and ww reclamation) Remove phosphorous Remove phosphorous Convert ammonia to nitrate (nitrification) Convert ammonia to nitrate (nitrification) Convert nitrate to nitrogen (denitrification) Convert nitrate to nitrogen (denitrification) Inactivate pathogens Inactivate pathogens Remove heavy metals Remove heavy metals Remove organic chemicals Remove organic chemicals Remove inorganic salts Remove inorganic salts Eliminate all pathogens Eliminate all pathogens

4 Limitations-Biological Treatment Doesn’t remove phosphorous or ammonia Doesn’t remove phosphorous or ammonia Incomplete disinfection Incomplete disinfection Doesn’t remove all toxins Doesn’t remove all toxins Doesn’t remove nonbiodegradable soluble chemicals Doesn’t remove nonbiodegradable soluble chemicals

5 Pathogens Conventional biological treatment Conventional biological treatment Up to 99.9% removal Up to 99.9% removal With disinfection up to 99.99% With disinfection up to 99.99% Protozoal cysts and helminth eggs are resistant Protozoal cysts and helminth eggs are resistant

6 SS Removal-Advanced Granular-Media filters (similar to water treatment) Granular-Media filters (similar to water treatment) Cloth Media filters Cloth Media filters Membrane filters Membrane filters

7 Pathogen Removal-Advanced Remove solids first via filtration (pathogens can be protected in the solids) Remove solids first via filtration (pathogens can be protected in the solids) Chlorination (similar to water treatment) Chlorination (similar to water treatment)

8 Toxic Substance Removal Toxic-Hazardous to aquatic life or human health Toxic-Hazardous to aquatic life or human health Priority toxic water pollutants-over 100 Priority toxic water pollutants-over 100 Evaluating toxicity Evaluating toxicity Test influent/effluent for specific substances Test influent/effluent for specific substances Biomonitor-fathead minnows, water flea Biomonitor-fathead minnows, water flea

9 Phosphorous Removal Soluble or organic (organically bound) Soluble or organic (organically bound) Conventional treatment removes 20-40% of phosphorus Conventional treatment removes 20-40% of phosphorus Example 1.3 Example 1.3 Advanced treatments Advanced treatments Chemical-biological Chemical-biological Reverse osmosis Reverse osmosis

10 Chemical-Biological Chemical precipitation using aluminum or iron coagulants Chemical precipitation using aluminum or iron coagulants Added to primary clarifier, before biological process, or to final clarifier Added to primary clarifier, before biological process, or to final clarifier Biological removal (conventional) Biological removal (conventional)

11 Nitrogen Organic Organic Decomposes to ammonia Decomposes to ammonia Ammonia Ammonia Nitrosomonas oxidize ammonia to nitrite Nitrosomonas oxidize ammonia to nitrite Nitrite Nitrite Nitrobacter oxidize nitrite to nitrate Nitrobacter oxidize nitrite to nitrate Nitrate Nitrate Under anaerobic conditions via facultative heterotrophs, nitrates are converted to nitrogen gas (which escapes into the atmosphere) Under anaerobic conditions via facultative heterotrophs, nitrates are converted to nitrogen gas (which escapes into the atmosphere) Nitrogen gas Nitrogen gas

12 Nitrogen in WW 40% ammonia; 60% is bound in organic matter 40% ammonia; 60% is bound in organic matter Not enough oxygen to convert to nitrites or nitrates Not enough oxygen to convert to nitrites or nitrates

13 Nitrogen Removal-Conventional Primary sedimentation (15% removal) Primary sedimentation (15% removal) Biological treatment (another 10%) Biological treatment (another 10%) Remainder is mainly in the form of ammonia unless oxidation occurs (activated sludge at low BOD loading) Remainder is mainly in the form of ammonia unless oxidation occurs (activated sludge at low BOD loading)

14 Nitrogen Removal-Advanced After biological treatment: After biological treatment: Aeration Aeration Final settling Final settling Alkalinity is reduced when nitrification takes place; lime or soda ash is added to maintain alkalinity Alkalinity is reduced when nitrification takes place; lime or soda ash is added to maintain alkalinity

15 Nitrate removal Nitrate can pollute groundwater Nitrate can pollute groundwater Denitrification converts nitrates to nitrogen gas Denitrification converts nitrates to nitrogen gas Process is anaerobic or anoxic Process is anaerobic or anoxic Process requires an organic carbon source (methanol or raw ww) Process requires an organic carbon source (methanol or raw ww) Via recycle, denitrification can be placed ahead of nitrification Via recycle, denitrification can be placed ahead of nitrification

16 EBPR-Enhanced Biological Phosphorous Removal Anoxic zone (0.5 to 3 hours detention time) followed by aerobic zone (6-24 hrs) Anoxic zone (0.5 to 3 hours detention time) followed by aerobic zone (6-24 hrs)