TRAINING PROGRAM ON OPERATION AND MAINTENANCE OF
WATER TREATMENT PLANTS FOR ENGINEERING ASSISTANTS
AGENDA
10.00 – 10.15
INTRODUCTION TO MAIN COMPONENTS IN
WATER TREATMENT
10.30 - 11.30
FUNCTIONS OF EACH COMPONENTS IN WATER
TREATMENT PROCESSES
11.30 – 12.30
OPERATION AND MAINTENANCE OF WATER
SUPPLY SYSTEM
12.30 – 13.15
LUNCH TIME
13.15 – 14.30
SCHEDULES OF OPERATION AND PREVENTIVE
MAINTENANCE
14.30 – 16.00
FIELD VISIT
INTRODUCTION TO MAIN COMPONENTS IN
WATER TREATMENT
1.
Water intake
- Coarse screen
- Fine screen
- Intake well
- Intake pump house
2.
Settling tanks
- Chemical dosing
- Coagulation & Flocculation structures
3.
Filters
- Rapid sand Gravity Filters
- Filter back washing system
4. Storage & Distribution
- Post chemical feeding systems
- Clear water tank
- High lift pumping
FUNCTIONS OF EACH COMPONENTS IN WATER
TREATMENT PROCESSES
WATER TREATMENT PROCESS
Raw Water Extraction
Pre Cl2 + Alum + Lime
Coagulation & Flocculation
Sedimentation
Filtration
Lime + Cl2
Disinfection
Storage & Distribution
RAW WATER EXTRACTION
Screening
Water from the river flows to the Intake well
through this make-shift screen
The water from the river passes through this mechanically
operated screen before entering the main intake well. All
floating matter is trapped here.
INTAKE WELL
Screening :
Debris, such as rocks, sticks, limbs, logs and
other large objects that can clog or damage
plant equipments is trapped on screens and
removed.
Pre-sedimentation:
Silt, sand and grit which can damage or over
load later processes are removed by gravity in a
basin.
Intake Pump House - Pumps Water to the
Water Treatment Plant
AERATION
Aeration of water
- removes troublesome gasses - NH3 , H2S
- oxidizes impurities such as iron and manganese
to facilitates their removal later in the
treatment process.
- reduces certain types of tastes and odors
- introduces oxygen into the water
COAGULATION AND FLOCCULATION
 Coagulation and flocculation consist of adding a
floc forming chemical reagent to a water to
combine with non settleable colloidal solids and slow
settling suspended solids to produce a rapid-settling
floc.
 The floc is subsequently removed in most cases by
sedimentation.
 Flocculation is the slow stirring or gentle agitation
to aggregate the destabilized particles and form a
rapid settling floc
Coagulation
 Large particles can easily be removed by settling.
Their mass allows them to settle to the bottom of a
tank and then be removed as sludge.
 However, colloidal particles in water have
insufficient mass to overcome the fluid forces on
their surfaces.
COAGULATION
 Most naturally occurring particles in water are
negatively charged. Since like charges repel, these
small particles, or colloids, will remain suspended
almost indefinitely.
 Coagulants reduce colloidal surface charge and
form precipitates that enhance the clustering
process and sedimentation
 The most widely used coagulants in water
treatment are Aluminum Sulfate and Poly
Aluminum Chloride (PAC)
• Rapid mixing, intense mixing or agitation is required to
disperse the chemicals uniformly.
• Slow mixing, flocculation, the fine microfloc begins to
agglomerate into larger floc particles.
 The principal factors affecting the coagulation
and flocculation of water are:
• Turbidity
• Suspended solids
• Temperature
• pH
• Cationic and anionic composition and
concentration
• Duration and degree of agitation during
coagulation and flocculation
• Dosage and nature of the coagulant
Jar Test

Usually laboratory studies using the jar test are
adequate for selecting a coagulant for a water
treatment plant
Jar Test
A jar test is usually used to determine the proper
coagulant and coagulant aid, if needed, and the chemical
dosages required for the coagulation of a particular water.
 Samples of the water are poured into a series of containers
 Various dosages of the coagulant and coagulant aid are
added
 The contents are rapidly stirred to simulate rapid mixing
 Then the contents are gently stirred to simulate flocculation
 After a given time, the stirring is ceased and the floc formed
is allowed to settle.
Jar Test
The most important aspects to note are:
 the time for floc formation,
 the floc size,
 its settling characteristics,
 the percent turbidity and color removed, and
 the final pH of the coagulated and settled water.
SEDIMENTATION TANK
SEDIMENTATION TANK
SEDIMENTATION TANK
( SETTLING TANK )
 Basins designed for efficient sedimentation
allow the water to flow very slowly.
 Because velocity is low and turbulence is
decreased, the suspended solids settle to
the bottom of the basin.
 Sedimentation helps to reduce turbidity
making longer filter runs possible and
remove large amount of chemical precipitates.
RAPID SAND GRAVITY FILTERS
 Filtration primarily depends on a combination of
complex physical and chemical mechanisms, the most
important being adsorption.
 As water passes through the filter bed, the suspended
particles contact and adsorbs (stick) onto the surface
of the individual filter grains or onto previously
deposited material.
Rapid Sand Gravity Filters
DISINFECTION
 The prime purpose of chlorinating public water
supply is to prevent the spread of waterborne
diseases.
Chlorinators
pH correction - Addition of Post Lime
Corrosive
pH = < 7.0
Treated Water
Stable
Ph = 7.0
Scale Forming
pH = > 7.0
Treated Water Pumping
OPERATION AND MAINTENANCE OF WATER
SUPPLY SYSTEMS
OPERATION of water supply system is timely
and daily operation of the components of a
water supply system such as head works,
treatment plant, machinery and equipment,
transmission mains, service reservoirs and
distribution system etc. efficiently and
economically to attain the objective of
supplying safe and clean water equitably to
the consumers.
OPERATION AND MAINTENANCE OF
WATER SUPPLY SYSTEMS
MAINTENANCE of water supply system is
defined as the art of keeping the structures,
plants, machinery and equipment and other
facilities in an optimum working order and
proper functioning without any interruption.
There are two types of maintenance viz.,
Preventive Maintenance and Corrective
Maintenance.
OPERATION AND MAINTENANCE OF
WATER SUPPLY SYSTEMS
 PREVENTIVE MAINTENANCE constitutes routine
works and precautions to be taken periodically to
prevent the system from mal-functioning by
mechanical adjustments, repairs, corrective action
and planned maintenance.
 CORRECTIVE MAINTENANCE involves carrying out
works related to break down, which has actually
occurred by replacements, correction of defects etc.
 Preventive maintenance is more economical than
corrective maintenance and it provides
uninterrupted service and avoids the need for
corrective maintenance.
NEED FOR OPERATION AND MAINTENANCE
 Poor O&M practices have, contributed to decreased
utility or even to an early failure of newly constructed
water supply facilities
 Thus the health and social benefits for which the facilities
were designed and implemented have not been realized
 Capital investment have been wholly or partially lost
 Scare resources are expended on the premature
replacement of equipment or for the rehabilitation of
facilities before they have been in operation for the full
span of their useful lives
 Hence, proper O&M is absolutely essential for deriving
the benefits continuously from the investments made.
BASIC REQUIREMENTS OF O&M
 Availability of Detailed Completion Plans and
Operators’ Manuals
 Understanding the Plant
 Schedules of Operation and Preventive maintenance
 Schedule of Inspection of Machinery
 Training
 Records of Equipment and Machinery
 Records of water quality
 Records of Key activities of O&M
 Overall Supervision and Inspection
SCHEDULES OF OPERATION AND PREVENTIVE
MAINTENANCE
• CLEANING RECORD OF SEDEMENTAION TANKS, AERATOR AND
CHANNELS
• FILTER BACK WASH RECORD
• SCREEN CLEANING RECORD
• CHECK LIST FOR CHLORINATION SYSTEM
• CHEMICAL CHECK LIST
• PUMP OPERATION RECORD
• PREVENTIVE MAINTENANCE RECORD