Understanding the Differences Between

Dewatering Pumps,

Pump Styles

Sewage Pumps,

and Grinder Pumps.

Presented by: Darren Meyers, P.E.Zoeller Pump Company

Why Do We Pump?

Pumping gives us options

• We’re not constrained by gravity.

• We can avoid greater costs.• Larger construction costs• Larger pump costs

• We gain control!

Wastewater Defined

• Sewage– Raw Wastewater (including solids) from toilettes &

drains

• Effluent– Wastewater (mostly liquid) which has passed through

a septic tank

• Groundwater (o.k.- so it’s not wastewater)– Mostly clean, but may contain some silt

Three Keys toTrouble-Free Pump Operation

1. Proper Selection• Picking the right pump for the job

2. Correct Installation• Clean, safe, organized

3. Periodic Maintenance• Keeping a pump in top shape

One Size Does NOT Fit All!

Pumps have been designed according to specific needs.

Each style has a particular application.

Choosing the correct pump style is as critical as choosing the correct pump size.

Most Common Pumps for Wastewater Installers

• Sump / Effluent / Dewatering• Little or no solids

• Sewage Ejectors• Varying solids passing capabilities

• Grinders• Solids environment

Dewatering / Effluent Pumps

Dewatering pumps are designed to move liquid which is mostly solids free

• Groundwater– Sump applications

• Effluent– Onsite dosing applications

Dewatering Pump Characteristics

• Little to no solids handling capability

• Sometimes none• Sometimes up to ¾”

• Typically smaller pipes (1” to 2”)

• Higher head pressures• Lower flow rates

Sump Pumps

• Intended for use in groundwater removal applications.

• Often contain an integral side switch.

• May be partially above and below the waterline

Effluent Pumps

• Intended to pump septic tank effluent.

• Does not have any integral switch

• Must be kept below the waterline• Corrosive gasses build up in a septic

environment

Effluent Turbine Pumps

Turbine pumps are designed and built very differently than centrifugals.

• These pumps have no solids handling capabilities.

• Units consist of a motor end and an impeller end.

• Replacement ends, motor or impeller, are typically available and simple to change out.

Sewage Pumps

a.k.a. – Sewage Ejector, Non-Clog

Sewage pumps are designed to pump whole solids from a basin to some other location

• Gravity sewer• Septic tank

Sewage Pump Characteristics

• Designed to handle solids• 2” solids or greater

• Larger pipes (greater than 2”)• Lower head pressures• Higher flow rates

Grinder Pumps

Grinder pumps come in two styles:– Centrifugal– Progressing Cavity

Grinder pumps chop and grind raw sewage into little bits to more easily move it through a piping network.

Centrifugal Grinders• Curves are similar to large effluent

pumps

• Use standard impellers to move the sewage slurry after chopping it.

• Used most frequently in:– Sites just downhill from a gravity sewer– Problematic sites where sewage pumps

may clog• Prisons, nursing homes, schools, etc.

Progressing Cavity Grinders• Produce very high heads and

relatively small flows.

• Use a “corkscrew” type action to lift ground-up sewage

• Use most frequently in:– Applications requiring very high

pressures– Pressure sewer networks

• High heads/low flows are ideal for networks with large numbers of units.

Pumping into a Septic Tank

• Sewage pumps are appropriate• Transfer whole solids

• Do not use grinders to pump into septic tanks.• Solids are ground too finely to settle out.

Pump Sizing in Two Slides!• Static Head – Actual elevation change

• Friction Head – Loss due to frictional resistance between water and pipe

• Operating Head – Pressure required in some systems (LPP, Pressure Dist., etc.)

Static Head + Friction Head + Operating Head

= Total Dynamic Head (TDH)

Size Based On Pump Curve

Pump Curves are easily accessible for any pump on the market.

Find where the calculated TDH and the desired flow intersect on the graph. Select a curve which crosses close to but above this point.

Always try to stay toward the middle of the curve, as this is where the pump is most efficient.

Thank You for Your Attention