Butterfly Valves for Wastewater Treatment Systems

Introduction: The Harsh Reality of Wastewater

Wastewater treatment is one of the most demanding environments for flow control equipment. Valves face:

• Abrasive solids (sand, grit)

• Corrosive chemicals (chlorine, ozone, ferric chloride)

• Fibrous materials (rags, wipes)

• Hydrogen sulfide gas (H2S – accelerates corrosion)

Butterfly valves are the industry standard for wastewater due to their compact design, cost-effectiveness, and reliable shutoff. However, selecting the wrong materials leads to rapid failure and unplanned downtime.

This guide covers butterfly valve selection for each stage of wastewater treatment, with specific recommendations for Kinko valves and AT/AW series actuators.

Part 1: Wastewater Treatment Stages & Valve Requirements

Part 2: Material Selection for Wastewater

Disc Materials

Kinko recommendation: 316 stainless steel disc for most wastewater applications. Super duplex for high-chloride or marine-adjacent plants.

Seat Materials

Kinko recommendation: EPDM for 90% of wastewater lines. PTFE for chemical dosing stations. Viton for aggressive industrial waste.

Body Materials

Part 3: Common Wastewater Applications

1. Influent (Headworks)

Conditions: Raw sewage with sand, grit, rags, wipes.

Requirements:

• Full lug type (allows removal of downstream piping for cleaning)

• EPDM seat (resists abrasion and chemicals)

• 316 stainless steel disc

Recommended Kinko valve: Kinko lug type, DN100-DN600, 316 disc, EPDM seat.

Actuator recommendation: Kinko AT-DA pneumatic (double-acting) for frequent backwashing cycles.

2. Aeration Basin Air Lines

Conditions: Clean compressed air, continuous operation, high cycle counts.

Requirements:

• Lightweight wafer design

• Very high cycle life (valves open/close every few minutes)

• Fast actuation speed

Recommended Kinko valve: Kinko wafer type, DN50-DN300, aluminum disc (lightweight), EPDM seat.

Actuator recommendation: Kinko AT series pneumatic (rack and pinion). Cycle life exceeding 500,000 cycles. Double-acting for air lines.

3. Sludge Lines (Primary and Secondary)

Conditions: Thick, abrasive, slow-moving sludge. High solids content.

Requirements:

• Larger bore (reduce velocity and abrasion)

• Full lug type for rodding access

• Harder disc coating (nylon or ceramic)

Recommended Kinko valve: Kinko lug type, DN150-DN400, nylon-coated ductile iron disc, EPDM seat.

Actuator recommendation: Kinko AW series scotch yoke for high break torque. Sludge tends to solidify around the disc when stagnant.

4. Chemical Dosing (Chlorine, Ferric Chloride, Polymer)

Conditions: Highly corrosive chemicals, low flow rates, precise dosing.

Requirements:

• PTFE seat (chemical resistance)

• Stainless steel or super duplex disc

• Modulating control for precise chemical feed

Recommended Kinko valve: Kinko wafer type, DN25-DN100, PTFE seat, 316 stainless steel disc.

Actuator recommendation: Kinko electric actuator with 4-20mA modulating control. For hazardous chlorine areas, use Kinko AT-SR with ATEX certification.

5. Effluent Discharge

Conditions: Clean treated water, low pressure, large diameters.

Requirements:

• Low cost (clean service)

• Wafer design acceptable

• EPDM seat sufficient

Recommended Kinko valve: Kinko wafer type, DN200-DN800, ductile iron disc with nylon coating, EPDM seat.

Actuator recommendation: Kinko electric actuator (on/off) or Kinko AT pneumatic depending on control system preference.

Part 4: Actuator Selection for Wastewater

Special wastewater actuator features to specify:

• IP67 or IP68 enclosure (flood-prone pits and manholes)

• Corrosion-resistant coating (epoxy or nickel plating)

• Manual override (for power outage or maintenance)

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Part 5: Common Failure Modes in Wastewater

Part 6: Kinko Wastewater Valve Packages

Part 7: Maintenance Schedule for Wastewater Valves

For Kinko actuators in wastewater:

• Monthly: Check air filter bowls (drain water).

• Annually (AT series): Replace piston seals if cycle count exceeds 100,000.

• Annually (AW series): Inspect scotch yoke bushing for wear.

Conclusion: Wastewater Demands the Right Valve

Wastewater treatment is unforgiving. The wrong butterfly valve fails within months. The right valve—with proper materials and actuator—runs for years with minimal maintenance.

Kinko recommendations by application:

Ivan (Mobile:+86-18968769287)
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Website： www.kinko-flow.com
ZHEJIANG KINKO FLUID EQUIPMENT CO.,LTD