1. Streaming Current Detectors

2. What Is It?
On-line monitor that measures net charge density of a water sample
Allows continuous monitoring & control of coagulation process in water & wastewater treatment
Provides effective polymer control in sludge dewatering processes

3. Models
SC2200- base unit (usually used with RM6200 or RC7200 or strip chart recorder)
SC4200- base unit with LCD display, gain and zero capabilities (allows set point to be chosen)
SC5200- base unit with PID controller (allows for automatic control of coagulant dose pumps

4. Chemicals Used with SCD (Coagulants)
Inorganic Salts
Alum
Aluminum Chloride
Poly Aluminum Chloride (PAC)
Ferric Sulfate
Ferric Chloride
Organic Polyelectrolytes (Polymers)

5. Working Description
Net charge density analyzer - measures the amount of free charges left after coagulation dosing and mixing
Reciprocating plunger moves sample past electrodes that measures charge in the form of an induced current in the electrode
Main circuit board amplifies, processes and displays

6. SCD Applications Influent Clarification Wastewater Treatment
Industrial and Municipal Plants
Wastewater Treatment
Sludge Dewatering
Belt Filter Presses
Centrifuge

7. Selling the Benefits of the SCD
Optimization of Coagulant Feed ($$$)
Possible Reduction in Chemical costs
More effective use of Manpower
Decrease frequency of jar testing
Consistent Water Quality
Compliance with environmental regulations
Increase in filter run time
Reduced downtime due to equipment fouling

8. SCD & Influent Clarification
River
Coagulant Feed
Clarifier
Effluent
SCD
Mix Tank
Settling Basin
Pump
Coagulant
Feed
Mix Tank
Sludge Draw Off

9. SCD & Influent Clarification
Chemical is fed to “charge” dirt and particles in the water
Floc settles out in either a clarifier or settling basin
Customer uses jar testing to determine the right concentration of chemical needed for best performance
SCD allows customer to establish a “setpoint” based on the right concentration

10. SCD & Wastewater Treatment
Typical Wastewater Clarification System
Waste Sludge
Wastewater
Inlet
Effluent
Primary
Clarifier
Aeration
Basin
Secondary
Clarifier
Mix Tank
Return Sludge
SCD
Sample
Polymer
Feed

11. SCD and Wastewater Treatment
Same principle applies as to influent clarification. Treatment of Waste stream
Due to higher solids contact, use cyclone separator and/or jet wash
Some wastewater clarifiers do not use coagulant

12. SCD and Waste Treatment (Dewatering- Belt Filter Press)
Typical Belt Filter Press System
Polymer Feed
Belt Filter Press
Thickener
Waste Sludge
Mixer
From
Secondary
Clarifier
or Process
SCD
Sludge
Cake
Sample (Filtrate)

13. SCD and Waste Treatment (Dewatering- Belt Filter Press)
Thickener increases solids percent from 1% to 2-3%
Polymer is added to sludge for coagulation
Sludge is pressed between two tensioned belts and passed over and under rollers
Water, part sludge and residual polymer are tested by sampling filtrate
SCD “setpoint” is based on optimum filtrate charge.
Because of solids content, use cyclone separator and/or jetwash

14. Typical Continuous Bowl Centrifuge

15. SCD and Waste Treatment (Dewatering- Centrifuge)
Two principal elements of a centrifuge are the rotating bowl and the inner screw conveyor
Solids settle due to centrifugal force from bowl rotation
Screw conveyor picks up solids and conveys them to discharge port
Water, part sludge, residual polymer are tested by sampling centrate
Because of solids content, use cyclone separator and/or jetwash

16. SCD and Water Purification (Reverse Osmosis)
Influent
Water
Primary Filter
Intermediate
Processes
SCD
Cartridge
Filter
Coagulant
Feed
Reverse
Osmosis
Units
Permeate

17. SCD and Water Purification (Reverse Osmosis)
Pre-treatment of influent water for RO system
Control coagulant injection feed to minimize over- coagulation that causes fouling of RO membrane
Set point is defined to give slightly negative reading ensuring minor under coagulation condition

18. Competition CHEMTRAC (MODEL 2000XP) HF SCIENTIFIC (MICRO 200 SCM)
NORCROSS, GEORGIA
HF SCIENTIFIC (MICRO 200 SCM)
FORT MYERS, FLORIDA
LECHINTECH (SCD 3000)
STANGER, SOUTH AFRICA

19. What Can we Offer? Demo units available for 30 day trial
Delivery of new units in 2 weeks or less
Trade in for older SCD units

20. SCD and Waste Treatment (Dewatering- Centrifuge)
Typical Centrifuge Dewatering System
Influent
Slurry
Feed
Slurry Discharge
Polymer Feed
SCD