VISIT EXPERIENCE AT WATER TREATMENT PLANT.

To become a Civil Engineer its very important to have a balance Theoretical Knowledge as well as Practical Knowledge. Eventually with the same concept our visit was organized to WATER TREATMENT PLANT at Nigdi.

The visit was plan with the intention to enhance our theoretical knowledge with practical experience.

The Water Treatment Plant is operated by Pimpri-Chinchwad Municipal Corporation  (PCMC). Water is treated here and then supplied to the entire twin city.

The Water Treatment Plant works with basic aim to make water more acceptable for a specific end-use. The end use may be drinking, industrial water supply, irrigation, river flow maintenance, water recreation or many other uses, including being safely returned to the environment.

Water treatment plant Procedure

The Operation Cycle of Water Treatment Plant.

The Water Treatment Plant  work is distributed in 6 parts.

1) Intake source management to get fullfill amount of water every day.

2) Sampling Unit.

3) Processing Unit.

4) Storage unit.

5) Supervision & Control Unit.

6) Maintenance Unit.

Pavana Dam

The Intake Source


The intake source of Water Treatment Plant plays a very important role as the intake source should be sufficient to provide every day water requirement of Plant so as to avoid shortage of water.

The Intake Source of Water treatment Plant Nigadi is Pawna dam situated nearly 4km away from the plant. The plant treats 420 MLD ( ie Milions Litres Per Day).

PCMC is planning to build fourth water treatment plant in Chikhali.The new plant will enable the PCMC to treat water that will be drawn in future from Andra and Bhama Askhed dams to meet the growing needs of Pimpri Chinchwad.

The city's population is expected to rise to 25 lakh by 2025, which means the water supplied through Pavana dam will prove inadequate. As per the plan, the areas in Pavana and Mula river basins will get water drawn from Pavana dam while the areas in the Indrayani river basin will get water from Bhama Askhed and Andra dams, located around 20 kms away. From reports for Pimpri Chinchwad, the state government has sanctioned 167 MLD water from Bhama Askhed and 100 MLD water from Andra dam.

Laboratory Tests in WTP LAB

Laboratory Treatments

The water sample from source is been treated to examine the amount of contaminants and the selection of the suitable procedure of treatment.

The is managed by Mr. Sanket Mote and he guided us with the procedure conducted at the plant.

The test conducted are:
•)Turbidity
•)pH
•)Hardness
•)Heavy metals concentration

Equipments in Lab

Turbidity test is conducted to determine the amount of mud silt and other containments in water which cant be seen through naked eyes.

Turbidity is generally high in Rainy season as compared to other season therefore extra efforts are taken at the time of Rainy season.

Turbidity can be measured using either by an electronic turbidity meter or a turbidity tube. Turbidity is usually measured in Nephelometric turbidity units (NTU) or Jackson turbidity units (JTLJ),
depending on the method used for measurement. The two units are roughly equal. At Water treatment Plant the Turbidity is measured by Turbidity Meter
HACK2100QT.

Drinking water should have a turbidity of 5 NTU/JTU or less. Turbidity of more than 5 NTU/JTU would be noticed by users and may cause rejection of the supply. Where water is chlorinated, turbidity should be less than 5 NTU/JTU and preferably less than 1 NTU/JTU for chlorination to be effective

The dosage for alum to form coagulant is determined and added after aeration to for proper sedimentation. However if the amount of coagulant is more then it affects the filtration process.

Bacterial Test

The bacterial test is conducted to determine the Pathogenic bacteria's present in the sample.

There are some types of bacterial test like

1. MPN method.
2. Radicals.
3. Single path method.

The Equipment used to conduct Bacterial test at Water treatment Plant Nigdi was Single path kit for the 3rd method.

The aim of conducting the bacterial tests  determine the Pathogenic bacteria's present in the sample so as to determine the amount of Chlorine dosage for bacterial degradation of water is designed.

Residual Chlorine Test.


The Residual Chlorine test is to determine the quantity of residual chlorine in the sample to preserve the quality  of  water supplied


Orthotolidine Test

In this test, 10 ml of chlorinated sample of water is taken after the required contact period, in a glass tube. To this 0.1 ml of orthotolidine solution is added. The color formed is observed after 5 minutes. The formation of yellow color normally indicates the presence of chlorine (either combined or free) in the water. The more yellow the color, the greater, is the chlorine residual. The amount of residual chlorine can be ascertained by comparing the colour developed in the glass tube with the standard colors already kept in the laboratory. This test, is therefore, very simple and does not require much technique or time. Under normal conditions, a lemon yellow color is satisfactory for public water supply. The orthotolidine test will normally gives the total residual chlorine present in water. However, it may be adjusted so as to give separately the quantities of free residual as well as combined residual of chlorine.

The free residual chlorine forms the yellow color during the first 5 seconds of the addition of orthotolidine, while the combined residual chlorine goes on forming the colour for about 5 minutes. Hence, the colour after 5 seconds will give the quantity of free residual chlorine, and the colour after 5 minutes will give the free and combined chlorine. The difference in value between the two values is the combined chlorine.

The orthotolidine test, however, is not accurate, because the impurities such as iron, manganese, nitrate etc., are likely to cause a false yellow colour, and indicating wrong and increased chlorine residual.

Cascaded Areator

Aeriation unit

This  is  the  starting  unit  of  the  water  treatment procedure. Once  the  sample  is  tested  the  water  coming from  Ravet  is  pumped  through  this  cascaded  aerator.  The purpose  of  having  an  aerator  is  to  improve  the  amount  of dissolved  oxygen  in  the  water  and  to  release  the  other gases,  also  a  few  metals  get  oxidized  during  this  procedure.

This  procedure  is  important  to  make the  water  odorless  as there  is  transmission  of  gases  during  this  process. Water is allowed to freely  fall  on the  cascaded steps and  which  each  fall  the  water  particles  are  exposed  to  the fresh  air  from  the  surrounding.  This  process  promotes  the exchange  of  gases  like  CO2,  etc. 

 

Clariflocculator

This is the second unit placed after Aeration unit.

flocculation  is  the  central  portion  of  the  tank  which  consist  of  a  mixer  that  is rotating  at  a  low  speed  to  facilitate  the  collision  of  the  charged  particles  and  their  conversion into  sludge which are  settled  down.

The water contains negatively charged particles whose amount is been analyzed and the same quantity of positive charged particles are supplied in so as the positive charged particles and negative charged particles gets attracted to each other and as the size of this particles increases they settled down in Sedimentation zone.

Sedimentation zone is the outer zone which is curved in nature and there is depression at the center.

The  water  is  having  a  detention  time  of  0.5hr  in  the  flocculation  and  3hr  in  the sedimentation  zone.

Chlorination Unit

Chlorine is used to destroy disease-causing organisms in water, an essential step in delivering safe drinking water and protecting public health. Chlorine is by far the most commonly used disinfectant
in all regions of the world. Where widely adopted, chlorine has helped to virtually eliminate water- borne diseases such as cholera, typhoid and dysentery. Chlorine also eliminates slime bacteria, molds
and algae that commonly grow in water supply reservoirs, on the walls of water mains and in storage tanks. Only chlorine-based disinfectants leave a beneficial “residual” level that remains in treated
water, helping to protect it during distribution and storage. Chlorine is a versatile and low-cost disinfectant appropriate for any size water system, whether it serves a remote rural village or a large modern city. Where piped water supplies are not available, chlorine can also be used for treating water in individual households. Specially-packaged chlorine
bleach can disinfect household water.



However there are other disinfectants too like UV, Ozone, Boiling, Potassium Permaganet. But the main objective of adding disinfectant to water is to provide safe drinking water till it reach large span consumers. Therefore chlorine is the best option which satisfy all the requirements.



Storage  unit  and  pumping

In  this  unit  the  treated  water  is  allowed  to  stay  for  sometime  and  them  pumped  to the  distribution  network  by  using  mechanically  operated  pumps.  The  plant  is powered  by  electricity  from  the  MSEDCL

Filtration unit

This  is  a  big  unit  comprising  of  a  number  of  filter  pits.  The  filter  used  in  this  tank  was rapid  sand  filter  in  which  the  water  is  allowed  to  pass  through  the  sand  and  it  gets  filtered  as it  passes  down  under  the  action  of  gravity.  The  sand  is  having  small  pores  which  allows  water to  pass  through  it  preventing  the  suspended  matter.

During filtration the water enters the filter through upper valve, moves down towards the filter bed, flows through the filter bed, passes the underdrainage system (filter bottom)and flows out through lower valve. The unit used to measure filtration rate is actually the approach velocity, which is the inflow rate (m^3/h) divided by the filtration area (m^2).

When, after a period of operation, the filter rate controller is fully opened, further
clogging of the filter bed cannot be further compensated and the filtration rate will fall.
The filter is then taken out of service for backwashing.

For this, the upper and lower valves closed, and upper back wash valve  is opened to drain the remaining raw water out of the filter. A few minutes later lower backwash valve  is opened to admit the wash water.

The backwash rate should be high enough to expand the filter bed by about 20% so that the filter grains can be scoured, and the accumulated deposits carried away with the wash water. The wash water is collected in the wash water troughs from where it drains to waste. When the backwashing is completed, backwash valves  are closed and upper valve  is re-opened, admitting raw water to begin a new filter run.

Use  of  Supervisory  Control  and  Data  acquisition (SCADA)


This  plant  employs  one  of  the  most  advanced  techniques  for  its  daily  operations.  SCADA  is  a cloud  based  tool  that  is  developed  for  the  plant  and  helps  the  plant  management  to  monitor  and control  the  daily  activities  at  the  plant  in  the  supply  network.

Diagram Explaination

Level 0 contains the field devices such as flow and temperature sensors, and final control elements, such as control valves.

Level 1 contains the industrialised input/output (I/O) modules, and their associated distributed electronic processors.

Level 2 contains the supervisory computers, which collate information from processor nodes on the system, and provide the operator control screens.

Level 3 is the production control level, which does not directly control the process, but is concerned with monitoring production and targets.

Level 4 is the production scheduling level.

I would like to thank Civil Department of Trinity College of Engineering for conducting the visit to Water Treatment Plant Nigadi. Especially  Meenakshi Khapre mam  & Harshal sir for conducting the visit.

I would also like to thank
Mr.  Praveen  Ladkat Executive  Engineer,  PCMC for allowing us to visit the plant and to grab the pratical experience.