Wastewater treatment (sức KHỎE môi TRƯỜNG SLIDE)

Wastewater Treatment: An Overview Simply Stated… • “Wastewater treatment is enabling and allowing a natural process to occur in a controlled environment instead of in a body of water.” What are we trying to remove? • It depends on the sophistication of the process! • Normally, all of the following: – – – – – Trash & grit Organics Solids Nutrients Ammonia - Disease causing organisms - Metals - Toxic compounds How we remove it? • Physical Processes – Screening – Sedimentation – Skimming • Biological Processes – Microorganisms • Disinfection – Chlorine, UV light, etc Physical Processes • Screening- used to remove sticks, rags, etc • Grit removal – used to remove egg shells, sand, etc • Sedimentation – giving solids and organics time to sink • Skimming – giving oils, greases, and plastics time to float Coarse Bar Screen Primary Clarifier Automated Fine Bar Screen Aerated Grit Chamber Biological Processes * Using microorganisms to turn organic matter into CO2 and more microorganisms through RESPIRATION and SYNTHESIS + Food + Oxygen (O2) Food, Air, & 'Bugs' CO2 + more Trickling Filter Brush Aerator Surface Aeration Diffused Aeration Disinfection • Removal of disease causing microorganisms – Chlorination – UV light – Ozone Treatment Types M e c h a n ic a l S u s p e n d e d G ro w th A c t iv a t e d S lu d g e O x id a tio n D itc h e s S B R 's E x te n d e d A e r a tio n N o n -m e c h a n ic a l A tta c h e d G ro w th T r i c k l in g F i l t e r s R o ta tin g B io lo g ic a l C o n ta c to r s S e p tic ta n k s Im h o ff T a n k s Lagoons Lagoons Un-aerated Lagoon Aerated Lagoon Trickling Filters Rock Media Plastic Media Activated Sludge Conventional Aeration Basin Oxidation Ditch with Brush Aeration 1 E q u a liz a t io n B a s in P r im a r y C la r ifie r S e c o n d a ry C la r if ie r A e r a tio n B a s in N itr ific a tio n B a s in P la n t In le t (In flu e n t) R e tu r n A c tiv a te d S lu d g e (R A S ) G r a v ity S lu d g e T h ic k e n e r F in a l F iltr a tio n W a s te A c tiv a te d S lu d g e (W A S ) S lu d g e D e w a te r in g C e n tra te D is in fe c tio n A e r o b ic / A n a e r o b ic S lu d g e D ig e s te r S lu d g e D is p o s a l P la n t E fflu e n t 1 E q u a liz a t io n B a s in P r im a r y C la r ifie r Seco C la r A e r a tio n B a s in P la n t In le t (In flu e n t) R e tu r n A c tiv a te d S lu d g e (R A S ) G r a v ity S lu d g e T h ic k e n e r • W a s te A c tiv a te d S lu d g e (W A S ) S lu d g e D e w a te r in g C e n tra te A e r o b ic / A n a e r o b ic S lu d g e D ig e s te r S lu d g e D is p o s a l E q u a liz a tio n B a s in P r im a r y C la r ifie r P la n t In le t (In flu e n t) S e c o n d a ry C la r ifie r A e r a tio n B a s in N itr ific a tio n B a s in R e tu r n A c tiv a te d S lu d g e (R A S ) G r a v ity S lu d g e T h ic k e n e r • Secondary Treatment – – – – – – – Biological treatment Aeration basins, clarifiers, Return sludge, waste sludge S lu d g e D e w a te r in g Dissolved oxygen is added Removes 90% to 95 % of organics Removes 90% to 95% of solids Organics stabilized by bacteria A e r o b i c / A n a e r o b i c Ammonia nitrogen converted to nitrates S lu d g e D ig e s te r • D.O approx mg/L F in a l F iltr a tio n W a s te A c tiv a te d S lu d g e (W A S ) C e n tra te D is in fe c tio n S lu d g e D is p o s a l – Return sludge/waste sludge used to maintain balance between ‘food’ and ‘bugs’ P la n t E fflu e n t 1 E q u a liz a tio n B a s in P r im a r y C la r if ie r S e c o n d a ry C la r if ie r A e r a tio n B a s in N itr ific a tio n B a s in P la n t In le t (In flu e n t) R e tu r n A c tiv a te d S lu d g e (R A S ) G r a v ity S lu d g e T h ic k e n e r F in a l F iltr a tio n a s te A c tiv a te d S lu d g e (W A S ) • Tertiary Treatment or WNutrient Removal S lu d g e – Ammonia converted to D nitrates e w a te r in g C e n tra te – Nitrates converted to Nitrogen gas • DenitrificationA e r o b i c1 / A n a e r o b i c S lu d g e D ig e s te r S lu d g e D is p o s a l – Phosphates removed – Can be done in Aeration Basin in step D is in fe c tio n P la n t E fflu e n t P la n t In le t (In flu e n t) R e tu r n A c tiv a te d S lu d g e (R A S ) G r a v ity S lu d g e T h ic k e n e r F in a l F iltr a tio n W a s te A c tiv a te d S lu d g e (W A S ) S lu d g e D e w a te r in g C e n tra te D is in fe c tio n A e r o b ic / A n a e r o b ic S lu d g e D ig e s te r S lu d g e D is p o s a l P la n t E fflu e n t • Disinfection – Removal of harmful microorganisms • Sludge Handling – Processing and disposal of solids and excess ‘bugs’ Controlling the Process Process Control Basics • Establish ‘targets’ or ‘norms’ – D.O levels – Proper balance of ‘food’ & ‘bugs’ • F/M ratio – pH values – Sludge Age – Sludge settling characteristics Lots of options! PRO CESS CONTRO L C A T E G O R IE S B IO M A S S M L S S /M L V S S S L U D G E Q U A L IT Y O R G A N IC L O A D IN G S LU D G E LE V E LS W A T E R Q U A L IT Y B O D [7 D M A ] D O SLUDGE AGE SETTLO M ETER CO D pH C E N T R IF U G E M IN S E T T O C o f IN F TEM P R S R /W S R M IC R O S C O P E FLOW C H L O R IN E R E S TO C of RS SVI SOUR S E C C H I D IS C F /M R A T IO ORP * Pick a few that work for you! O R G A N IC S Which tests to use? PRO CESS CONTRO L C A T E G O R IE S • Depends on: B IO M A S S M L S S /M L V S S S L U D G E Q U A L IT Y O R G A N IC L O A D IN G S LU D G E LE V E LS W A T E R Q U A L IT Y B O D [7 D M A ] D O SLUDG E AGE SETTLO M ETER CO D pH C E N T R IF U G E M IN S E T T O C o f IN F TEM P R S R /W S R M IC R O S C O P E FLOW C H L O R IN E R E S TOC of RS SVI SO UR S E C C H I D IS C F /M R A T IO O RP – Size of facility – $$$$! – Available Lab equipment – Operator Training – Speed of results – Ease of use O R G A N IC S ...Simply Stated… • ? ?Wastewater treatment is enabling and allowing a natural process to occur in a controlled environment... a te d S lu d g e (R A S ) G r a v ity S lu d g e T h ic k e n e r • Secondary Treatment – – – – – – – Biological treatment Aeration basins, clarifiers, Return sludge, waste sludge S lu d g e... Aeration Disinfection • Removal of disease causing microorganisms – Chlorination – UV light – Ozone Treatment Types M e c h a n ic a l S u s p e n d e d G ro w th A c t iv a t e d S lu d g e O x id