The document discusses chemical dosing processes in water treatment. Alum and other chemicals are added to water to form clumps called 'floc' that attract dirt particles so they sink during sedimentation. Common chemicals used include coagulants, pH adjusters, and disinfectants such as sodium hypochlorite. Sodium hypochlorite offers advantages over chlorine gas for water disinfection but requires metering pumps due to decomposition. Progressive cavity pumps are well-suited for chemical dosing applications due to their pulsation-free flow and ability to handle corrosive or abrasive chemicals.

2. Chemical Dosing > Water Treatment > typical process flow
Coagulation removes dirt
and other particles
suspended in water. Alum
and other chemicals are
added to water to form tiny
sticky particles called "floc"
which attract the dirt
particles. The combined
weight of the dirt and the
alum (floc) become heavy
enough to sink to the bottom
during sedimentation.

3. • Coagulants (flocculants)
 Ferric sulphate
 Aluminium sulphate (Alum) – AI2SO4
 Ferric chloride - FeCI3
• pH adjustments
 Magnesium hydroxide - Mg(OH)2
 Lime slurry
 Sulphuric acid – H2SO4
 Hydrochloric acid – HCI
• Disinfection
 Sodium hypochlorite – NaOCI
• Dechlorination
 Sodium Bisulphite NaHSO3
Chemical Dosing > Water Treatment

4. • Disinfection types
 Ultraviolet
 Ozone
 Chlorination (most common)
 Gas chlorination is declining
 Upcoming liquid chlorination
NaOCI
But: unlike gaseous chlorine and UV
systems sodium hypochlorite require
the use of metering pumps to
complete the injection system
Chemical Dosing > Water Treatment > Disinfection

5. • Sodium hypochlorite has been used for the
disinfection of drinking water or water systems.
• Advantages of Sodium hypochlorite vs
chloride gas
o The use of chlorine-based disinfectants
in domestic water, although
widespread, has led to some
controversy due to the formation of
small quantities of harmful byproducts
such as chloroform
o Additionally, transport and handling
safety concerns have directed public
opinion towards the use of sodium
hypochlorite rather than chlorine gas in
water treatment, which represents a
significant market expansion potential
Chemical Dosing > Water Treatment > NaOCI

6. • Sodium hypochlorite is commonly used as a
biocide in industrial applications to control slime
and bacteria formation in water systems used at
power plants, pulp and paper mills, etc. in
solutions typically of 10%-15% by weight.
• Sodium hypochlorite is a strong oxidizer,
• oxidation reactions are corrosive, solutions burn
skin and cause eye damage, in particular, when
used in concentrated forms
• Corrosive
• pH 11 – 13
• Concentration
• Typically 12,5% in water treatment
• Household bleach is 5%
Chemical Dosing > Water Treatment > NaOCI

7. • NaOCI is always decomposing due to:
• UV light
• If pH below 12 decomposition increase
• Increase of temperature, increase of
decomposition
• Concentration NAOCI
Chemical Dosing > Water Treatment > NaOCI >
Decomposition

8. • Not be handled in equipment or piping systems
containing stainless steel, aluminium, carbon steel
or other common metals
Chemical Dosing > Drinking Water Treatment > NaOCI >
Materials

9. • Standard seal is single,
• SIC/SIC
• Viton
• Titanium metal parts
• Offer quench if user does not accept
crystallization
• Seal casing Titanium
Chemical Dosing > Water Treatment > NaOCI > Sealing

10. • decomposition:
Salt will crystallize on, piping, valves, seal
faces, rotors, etc.
• Guideline
keep suction piping short
use slopes
Chemical Dosing > Water Treatment > NaOCI > Guidelines

11. Chemical Dosing > Water Treatment > NaOCI > Pump sizes
MD BN
0005-24 025-12
0015-24 025-24
003-12 05-12
003-24 1-6L
006-12
006-24
012-12
012-24
025-6L
025-12T
05-6LT

12. Advantages
• accurate metering with minimum pulsation
• low-pulsation – pulsation dampners not needed
• low pulsation means that smaller pipe diameters
possible on longer distances
• low pulsation - flow meters give accurate
readings
• higher pressure applications possible with accurate
flow control
• vapour locking is not a problem
• changing viscosities are not an issue: from easily
flowable to highly viscous products
Chemical Dosing > PC Pump Advantages

13. Advantages
• direction of rotation and thus delivery flow
reversible
• flexible installation including horizontal or vertical
• Good high self-priming, even with air or gas-liquid
mixtures of up to 8.5 mWS
• corrosive and abrasive products can be handled
.
Chemical Dosing > PC pump features

14. • NaOCl gassing in the chamber –
GASLOCK
Gaslock or vapor lock is when a pump
fills with vapor or gas cause the pump to
stop pumping. A diaphragm pump must
build enough pressure and vacuum
inside the diaphragm chamber to open
and close check valves inside the pump.
When to much vapor, the vapor is
compressed and cannot build enough
pressure to actuate the check valves
causing vapor locking.
• External gas bypass systems required
• Pulsations – require dampeners
• Slip and backflow in valves
• Valves require maintenance – salt
crystallization
Chemical Dosing > Diaphragm vs PCP > overview

15. Design differences:
• No ball valves to block or vapour lock
• PCP are virtually pulsation free
A note on “Repeatability” and “Variance”
• Reciprocating Pumps are Accurate over Long Time Measurements
• Progressive Cavity Pumps are Also Accurate over Short Time Period Measurements
Chemical Dosing > Diaphragm vs PCP > overview

16. Vertical pumps for
barrel emptying.
Suction lift possible
MDF
Open hopper pumps for
handling non flow able
pasty product MDT
For flow able products of
low to high viscosity
Wobble pump - low cost option
MD range options
Chemical Dosing > pumping solutions

17. Details – MD range:
Chemical Dosing > pumping solutions
:
• Virtually pulsation free flow, no need to install pulsation
dampers
• Self priming and does not gas lock
• Low NPSH R, can perform suction lifts
• Variable frequency drive VFD for accurate control
• Flow rate 0.1 l/hr upwards and pressures up to 24 bar
• Temperatures up to 150°C (higher by design)
• No limitations for viscosity
• API 675 accuracy and repeatability capable,
repeatable accuracy <1.0% fluctuation

18. seepex Wobble Pumps – Group W
Range W
• short, compact design with directly flange-mounted
drive
• flexible stator
• rotating unit with only one joint
• rapid replacement of the conveying elements due
to simple pump design
• Suitable for fluids of all viscosities, even containing
solids
• capacities: up to 10 m³/h
• pressures: up to 4 bar
Chemical Dosing > pumping solutions

19. ccw
cw
Chemical Dosing > installation options

20. Body-Internals-Stator Max
Liquid Materials Seal RPM
NaOCl B4-T4-RO T-1 500
(Sodium Hypochlorite) RCH 1000 Titanium
Disinfection Titanium
EPDM
NaOH A6-A7-RO MG-1 500
(Sodium Hydroxide) SS316 Q1Q1EGG
pH Adjustment EPDM
Chemical Dosing > Application Guidelines

21. Max
Liquid Materials Seal RPM
NaHSO3 A6-A7-F9 MG-1 400
(Sodium Bisulphite) SS316 Q1Q1PGG
Dechlorination HNBR
Mg(OH)2 A6-A7-FO MG-1 400
(Magnesium Hydroxide) SS316 Q1Q1PGG
pH Adjustments NBR
Chemical Dosing > Application Guidelines

22. Max
Liquid Materials Seal RPM
Al2SO4 A6-A7-F9 MG-1 400
(Aluminum Sulphate, Alum) SS316 Q1Q1PGG
Flocculant HNBR
FeCl3 B4-T4-FO T-1 400
(Ferric Chloride) RCH1000 Titanium
Flocculant Titanium
NBR
Chemical Dosing > Application Guidelines

23. Max
Liquid Materials Seal RPM
H2SO4 B4-C4-HO MG-1 400
(Sulphuric Acid) RCH1000 Q1Q1VMM
pH Adjustments Titanium
Viton
HCl B4-C4-RO MG-1 400
(Hydrochloric Acid) RCH1000 Q1Q1EMM
pH Adjustments Titanium
EPDM
Chemical Dosing > Application Guidelines

24. Max
Liquid Materials Seal RPM
Na2CO3 A6-A7-FO MG-1 400
(Sodium Carbonate, Soda Ash) Q1Q1VGG
pH Adjustments
NH4OH A6-A7-RO MG-1 400
(Ammonium Hydroxide, Aqua Ammonia) Q1Q1EGG
pH Adjustments, enhances chlorine disinfecting residuals
Chemical Dosing > Application Guidelines

25. chemical dosing
• Custom made skid with control panel
• Pump specified for hypochlorite dosing
• optional equipment
 chlorine concentration meter
 discharge pressure display
Chemical Dosing > system design

26. NaOCl dosing at Water Treatment
plant in USA
• 19 pumps in use
• MD pump range
• Titanium internal parts
• EPDM elastomer
Chemical Dosing > applications > NAOCI

27. seepex website

28. Hydrochloric acid (HCI) dosing
• BN range pump
• Halar-coated cast iron pump
• Variable pump speed controlled by
conductivity probe and inverter
• 99% accuracy
Chemical Dosing > applications > Hydrochloric acid HCI

29. Pumps of range MD 012-24
Conveying product:
Polymer solution
Conveying capacity:
30-15 l/h (0.13 -0.66 USGPM)
Pressure:
Max. 24 bar (360PSI)
Temperature:
20°C (68°F)
Chemical Dosing > applications > Polymer solution

30. Pumps of range BN 2-6L
Conveying product:
Flocculant solution
Conveying capacity:
300-1500 l/h
Pressure:
2 bar
Temperature:
20-30°C
Chemical Dosing > applications > Polymer solution

31. Polymer preparation and dosing at Chenbei - China
Chemical Dosing > applications > Polymer Preparation

32. Polymer preparation and dosing unit at Shaoxing
Chemical Dosing > applications > Polymer Preparation

33. Lime slurry dosing pump
BN 10-12
Chemical Dosing > applications > Lime slurry

34. Poly Aluminium Chloride
dosing pump
Chemical Dosing > applications > Poly Aluminium
Chloride