Environmental Engineering 343

ENVIRONMENTAL ENGINEERING

343Lecture 7:

Water Treatment

Philadelphia UniversityFaculty of Engineering

Department of Civil EngineeringFirst Semester, 2013/2014

OBJECTIVES OF WATER TREATMENT“ To remove harmful microorganisms

or chemicals, thereby preventing the spread of disease in order to supply clean and safe water for public demand”

WATER SOURCEWater source could be

River Lakes Groundwater; most likely better quality than

surface water Rainwater ++/ Dam

Raw water quality varies with the source, and if the source is surface water, the quality vary seasonally, particularly with flooding, upland and lowland, etc

WATER TREATMENT PROCESSES

SELECTION OF TREATMENT PROCESSESSelection of the set of Treatment Processes will be based

on : Sources of water intake Characteristic of waterDetailed raw water quality analysis for a minimum of

one year, or longer, at periods of high, low and medium flows. The parameters to be looked at all those listed in the legislative standards

Cost Suitability of the processes for removing particulate

impurities. Example: Turbidity; suitable process might be coagulation ,

sedimentation or filtration For pathogen, pre or post chlorination, UV, ozone,

or chloramines

WATER TREATMENT PROCESSES Pretreatment of water

Screening Storage, Equalization & Neutralization Aeration Chemical pretreatment

Sedimentation, coagulation and flocculation Filtration

Slow Sand filtration Rapid Gravity filters

Disinfestations Chloramines Ozone UV radiation Chlorination

Fluoridation Advance Water Treatment

Iron & Manganese Removal Water Softening by Chemical Precipitation Ion Exchange Adsorption Chemical oxidation Membrane Processes

SURFACE WATER TREATMENTTypical treatment plant for surface water1. Screening and grit removal2. Primary sedimentation (settling/clarification)3. Coagulation (Rapid mixing)4. Flocculation5. Secondary sedimentation6. Filtration7. Sludge processing8. Disinfection

GROUNDWATER TREATMENT 

Typical treatment plant for groundwater1. Aeration2. Flocculation/precipitation3. Sedimentation4. Recarbonation5. Filtration6. Disinfection7. Solids processing