presantation on reverse osmosis
DESCRIPTION
presantation Slide on Reverse Osmosis Techniqe ues in drinking water purification processTRANSCRIPT
WATERThe earth is so blessed with water resources that it is called the `WATER PLANET’. But a mere 2.5% of the earth`s water is freshWater usable by human beings; the remaining 97.5% is Sea water.Now a days due to increase in population & industries, demand of Water has been increased rapidly.Pollution is also increases. Due to lack of water resource, HumanBeings find new technology, called ` Reverse Osmosis’
Reverse Osmosis
Technical Presentation
Reverse Osmosis Terminology
Principles of Reverse Osmosis
Types of R O Membranes Membrane Configurations
Typical Applicationsof
Reverse Osmosis
Industrial process water
Production of potable water
Food processing Waste treatment
Principles ofReverse Osmosis
Osmosis
The spontaneous flow of water from a dilute solution to a concentrated solution, when the two solutions are separated by a semipermeable membrane.
Dilute Solution
semi-permeable membrane
Concentrated Solution
Osmotic Pressure
The pressure that must be applied to a concentrated solution to prevent osmosis.
P =
P
Dilute Solution
Concentrated Solution
Reverse Osmosis
P >
Reversing osmotic flow by applying a pressure in excess of the osmotic pressure
P
Dilute Solution
Concentrated Solution
Three Cases of Osmosis
osmosis equilibrium reverse osmosis
P
P
P = P >
Factors Influencing Permeation Rates of Dissolved Materials
Greatest Influence: Electrical Charge
Moderate Influence: Molecular Weight
Slight Influence: Molecular Structure
FEED WATER LIMITING CONDITIONS
Oxidizing Agents like chlorine - Nil COD & BOD with in limit. OIL & GREACE NIL SDI LESS THAN 5. pH range 3 to 11 Turbudity – less than 1 NTU
Permeation Rates of Other Dissolved Species
•Dissolved Gases pass freely through the membrane.
•Many Dissolved Organics are weak acids. Their rate of permeation will depend not only on their molecular weight and structure but on their degree of ionization.
HX H+ + X-
Permeation Rates of
Weak AcidsWeak acids are those acids that do not become completely ionized in water. Included in this group of acids are chromic, boric and many organic acids.
H2CrO4 H+ + HCrO4-
HCrO4- H+ + CrO4
- -
H3BO3 H+ + H2BO3-
Reverse Osmosis
TerminologyPRODUCT FEED
REJECT
RECOVERY = PRODUCT FLOW / FEED FLOWSALT PASSAGE = PRODUCT TDS / FEED TDSSALT REJECTION = 100 – SALT PASSAGE IN %
Reverse Osmosis
TerminologyPRODUCT
FEED PRESSURE
REJECT PRESSURE
P = FEED PRESSURE – REJCT PRESSURE
REVERSE OSMOSIS
System has divided into three parts.
1. PRE-TREATMENT2. R.O. SYSTEM3. POST TREATMENT
Reverse osmosis system
Pretreatment
RO hydra block
Cleaning system
Clarification
Coagulation
Filteration
De-chlorination
Dosing system
Cartridge filter
Membrances
Pressure tubes
HP pumps
Control pannel
Cleaning tank
Pump (SS)
Cartridge filter
DM plant
pH adjustment
DegassificationPost treanment
Coagulation, sedimentation, Chlorination
Sand filter
Activated carbon filter
Dechlorination.
Anti scale
High pressure pump
DESALATION SECTION Membrane modules
Product water
Waste brine
Cartridge filter
Schematic diagram of RO unit for waste water
Block Diagram of RO
(PERMEATE )
PRODUCT WATER
REJECT WATER
(CONCENTRATE)
MEMBRANE
HIGHPRESSURE
PUMP
SALTWATER
The basic expanded design of a single system includes the following:Raw water feed pump to supply water to the pre treatmentPre treatment system for Turbidity,TSS,Colloidal particles & Organic matter.Cartridge filter to remove micron size particle to control the SDI( Silt density index) of feed waterAnti scalant dosing system.High pressure pump&feed control valve to pressurize the feed water.Membranes housed in Pressure tubes.
RO System components
A reject control valve to control the recovery of the RO system.
A skid to mount to all mechanical equipment .
Flow indicators to measure permeate and reject flow rates.
Pressure gauges for monitoring the differential pressures across the RO feed, reject and intermediate stages.
Conductivity & pH meter for measuring the quality of the permeate water.
And other necessary instruments for monitoring easy operation and critical parameters.
A cleaning system consisting of Tank,CF,Pump and necessary instruments.
Recovery Rate
Ratio of permeate flow to feed flow
Expressed as % Recovery = (permeate
flow/feed flow) * 100
Role of Pretreatment in RO To reduce particulates & improve SDI.
– Clarification / Filtration.– Polymer/coagulant addition.– Micro-filtration.
Minimize Scaling &fouling.– Softening.– Acid & anti scalant addition.– Anti scalant addition.
Chlorine Removal.– Carbon Filtration.– Bisulfite Addition.
Role of Pretreatment in RO Minimize Silica Scaling.
– Antiscalant addition.– Softening & pH control.– Turbocirculator.
Controlling Organic.– Dissolved Organic.– Colloidal Orgabic.
Role of Pretreatment in RO Silt Density Index : It is the second
parameter used to determine colloidal quantity of the RO Feed water. A test is run to determine the rate of the pluggage of a 0.45 micron filter at 30 psig for 15 minutes. This test consists of determining amount of time it takes to collect a 500 ml sample at the start of the 15 minutes test and comparing this time to the amount of time it takes to collect a 500 ml sample at the end of the 15 minutes.
Cross section ofSpiral Wound Membrane
Mesh Spacer
Permeate Carrier
Membrane
“O” Ring
Permeate Tube
Membrane Backing
Outer Cover
Membrane Assembly
Reverse Osmosis
Membranes - Types
Cellulose Acetate Thin Film Composite Polysulfones
Thin Film Composite Membrane Characteristics
Lower Operating Pressure
High Salt Rejection Available for Sea
Water Stable to pH 11 Sensitive to Oxidants
Operating Parameters
Feed Pressure Concentration pH Temperature
Permeate Concentration Flow Pressure
Concentrate Flow Pressure Concentration
INSTRUMENTATION
Instruments used in RO System
•PH * ORP•Conductivity Meter * Level Switches•Rotameter * Pressure Switches•Pressure Gauges * Electrical Control
Fouling
There are Six main causes of membrane Fouling.•Scaling by hardness salts.•Scaling by Silica.•Fouling by Metal Oxides.•Plugging by suspended solids.•Biological Fouling.
Scaling
The deposition of sparingly soluble salts onto the
membrane surface and/or the feed channel material.
– Scaling occurs primarily in the downstream elements because of the higher concentrations existing in this portion of the RO system.
– Common scalants include calcium sulfate, silica and calcium carbonate.