同济大学：《环境科学概论》课程教学资源（教案课件）Part 2 Water Resources and Treatment Topic 3 Water and wastewater treatment 水处理

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 Coagulation￾Flocculation 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