Water Treatment Process Flow Diagram and Description

The simple process flow diagram of 

Water Treatment is the following:

Figure 1: Simple process of Water Treatment Plant.

The explanation of above picture:

DAF (Dissolved Air Flotation)

The Seawater which contain suspended solid and high conductivity is treated firstly on DAF (Dissolved Air Flotation). 

The Function

Reduce total suspended solid ( TSS ) & Oil by using coagulation agent ( FeCl3 ) and flocculation agent ( Polymer ). TSS is decreased from 86.88 mg/l to 10 mg/l

The Principle  of work

The main process is the Coagulation, Flocculation and Flotation.

Basic process terminology at raw water treatment

Coagulation àSedimentation process with chemical injection ( FeCl3 ) as coagulant  is aided by 
                         mixing with agitator or static mixer that higher speed  for compose the flock. 

Flocculation àProcess establishment flock from coagulation by adding Polymer as flocculation 
                           agent helped by mixer that slowly speed. And with system gravitation, flock down to 
                           blow down. But by using air flotation, flock can be collected or appeared on above.

Flotation        à A method for the separation of mixtures by the removal of    suspended matter 
                             such as oil or solids using air

Reverse Osmosis à A water purification technology that uses a semipermeable membrane to 
                               remove ions, molecules and larger particles from raw water by using high pressure.

DMGF (Dual Media Gravity Filter) & FSPF (Fine Sand Pressurize Filter)

The Function

To reduce Total Suspended Solid (TSS) by filtrate raw seawater thus divided the clear water and the dirty one.

The Principle  of work

The filtration process by use media consists of coarse/fine sand and anthracite.

Figure 2. DMGF Figure

SWRO (Sea Water Reverse Osmosis)

The Function

To decrease Total Dissolve Solid (TDS) or generally as desalinization of sea water. It decrease TDS from 33,279 mg/l to 205 mg/l

The Principle  of work

Reverse Osmosis is the opposite of osmosis process. So the process need additional energy to resist Osmosis process by high pressure pump. In this process, sea water can pass the semipermeable membrane thus result product (permeate) and concentrate (brine or reject).

Figure 3 SWRO Diagram

Calcite Contactor

The Function : Remineralize the desalinated water (typically low in hardness and alkalinity) such that it will not be corrosive to the service water distribution pipelines. The result of the process also become living water.

CO2 + H2O          ↔    H2CO3

CaCO3 + H2CO3   ↔   Ca(HCO3)2

The Principle of Work : carbonic acidified water (through the dosing of CO2) flows through a bed of crushed and sieved calcite, dissolving the carbonate minerals from the calcite packed bed. The carbonic acid is injected counter flow with the product water. This injection causes a vortex which ensures complete mixing of the carbonic acid with the process water. As calcite dissolves, the calcite bed height reduces thus reducing the calcite dissolution rate as well. Thus, the calcium carbonate within the bed has to be topped up periodically to ensure that the dissolution rate is maintained.

DEMINERALIZATION

The  Goal is produce Demineralized Water for Boiler Feed Water and Regeneration Water for Demineralization Plant and Condensate Polishing Unit. Close cooling water also supplied by Demineralization Plant.

Figure 4. Demineralization Plant

CATION EXCHANGER

qThe Function : Remove positive ions of sodium, calcium and magnesium etc from the pretreated 

    water

qThe Principle  of work : Ion Exchange generally as ion transfer that reversible between solid and 

    liquid without changing of solid structure. The reaction is following:

    HR: Cation Resin

NaCl              +     HR           →    NaR        +         HCl

MgSO4          +     2HR         →    MgR₂      +        H₂SO₄

Ca(HCO₃)      +     2HR         →    CaR₂       +       CO₂   +   2H₂O

ANION EXCHANGER

Remove negative ions such as chloride, sulphate, nitrate, silica, bicarbonates etc.

          HCl + ROH → RCl + H2O

MIXED BED EXCHANGER

The Function : Polish the deionized water to meet the required water quality

The Mixed Bed Exchanger consists of cation and anion resins mixed in the ion exchanger vessel. 

Both cation and anion from feed water are changing by cation and anion resin.