Environmental Science Part 2:Water Resources and Treatment Topic 3:Water and wastewater treatment Prof.LI Fengting UNEP-TONGJI Institute of Environment for Sustainable Development College of Environmental Science and Engineering Tongji University
Environmental Science Part 2: Water Resources and Treatment Topic 3: Water and wastewater treatment Prof. LI Fengting UNEP-TONGJI Institute of Environment for Sustainable Development College of Environmental Science and Engineering Tongji University
Outline Drinking water treatment Conventional treatment process Advanced treatment process Wastewater treatment Wastewater situation in China √ Wastewater treatment process Case Study of wastewater treatment plant √Algae separation √Reuse of wastewater Question: Which technology is“sustamable☒” Why?
Outline Drinking water treatment Conventional treatment process Advanced treatment process Wastewater treatment Wastewater situation in China Wastewater treatment process Case Study of wastewater treatment plant Algae separation Reuse of wastewater Question: Which technology is “sustainable?” Why?
Drinking Water Treatment
Drinking Water Treatment
Conventional scheme of water cycle Production of drinking water To protect the quality of the environment Assume a Effluents-之 safe water W treatment plant Adequate sanitation Sludges Open system-closed system
Conventional scheme of water cycle Sludges Effluents reject WW treatment plant Adequate sanitation Production of drinking water To protect the quality of the environment Assume a safe water Open system-closed system
Conventional treatment process of drinking water Coagulant C12 Disinfection Source Water Coagulation Sedimentation Filtration Clean water Distribution Customer← Pump COAGULATION SEDIMENTATION FILTRATION DISINFECTION STORAGE Source:US EPA
5 Source Water Coagulation Filtration Customer Pump Coagulant Sedimentation Clean water Cl2 Conventional treatment process of drinking water Disinfection Distribution Source: US EPA
Coagulation
Coagulation
Physical-chemical process involved in Coagulation- ORGANIC COAGULANT Flocculation (polyamine,polyDADMAC) MINERAL COAGULANT R (AI,Fe") FLOCCULANT A E Decantation A 人 D A T W Flottation E Coagulation Flocculation R tank tank (flash mixing) (slow mixing) Filtration Coagulation-flocculation:The use of chemical reagents to destabilise and increase the size of the particles;mixing;increasing of flocs size. Source:SNF FLOERGER(2003)
Source: SNF FLOERGER (2003) Physical-chemical process involved in CoagulationFlocculation Coagulation-flocculation: The use of chemical reagents to destabilise and increase the size of the particles; mixing; increasing of flocs size
COAGULATION DIAGRAM Stable colloids Destabilized colloids Microfloc formation A Coagulation destabilises the particles'charges.Coagulants with charges opposite to those of the suspended solids are added to the water to neutralise the negative charges on dispersed non-settable solids such as clay and organic substances. Once the charge is neutralised,the small-suspended particles are capable of sticking together
Coagulation destabilises the particles’ charges. Coagulants with charges opposite to those of the suspended solids are added to the water to neutralise the negative charges on dispersed non-settable solids such as clay and organic substances. Once the charge is neutralised, the small-suspended particles are capable of sticking together
DIAGRAM OF FLOCCULATION Destabilized colloids flocculation Following coagulation, Bridging flocculation,a gentle mixing stage,increases the particle size from Floc formation submicroscopic microfloc to visible suspended particles
Following coagulation, flocculation, a gentle mixing stage, increases the particle size from submicroscopic microfloc to visible suspended particles. flocculation
Coagulation What is coagulation? coagulant) coagulant forms precipitate and added. procipitato, trapped impuritios trapping impurities settle to bottom Coagulation Flocculation Flash Mix Flocculation Basin Raw water ntation High Medium Low speed speed speed →
Coagulation
