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Circular ClarifiersMonroe Environmental offers nearly every circular

clarifier design preferred by engineers and plant

operators for municipal and industrial applications.

We will evaluate existing clarifiers and recommend

improvements to influent and effluent geometry,

feedwell /EDI design, weir and launder geometry,

skimming and scum baffles, sludge removal

systems, and drive equipment, as well as a variety

of site-specific design requirements.

Clarifier Designs & ServicesNew, rebuild, and retrofit

Primary, secondary, or tertiary treatment

� Standard scraper

� Spiral scraper

� Hydraulic suction tube header

� Hydraulic suction riser pipes

Solids-Contact/Flocculating

Thickeners

Municipal water and wastewater treatment

Industrial waste and process water treatment

20 ft. diameter Primary Clarifier at a WWTP

46 ft. diameter self-supporting Circular Clarifier for separating blast furnace scrubber fines from wastewater at a steel processing plant

46 ft. diameter stainless steel Circular Clarifier fully assembled in Monroe shop

50 ft. diameter Circular Clarifier during final assembly

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Clarifier RebuildsRebuilding and replacing the internals of

a concrete or steel tank clarifier is a quick,

cost-effective solution versus constructing

an entirely new system. The clarifier tanks

often maintain a suitable operating condi-

tion while the skimmer arm, center well,

drive assembly, and sludge rakes corrode

and wear beyond an acceptable level. In

this case, a Monroe Environmental Clarifier

Rebuild is the perfect solution to restore the

clarifier to its peak operating performance

level, ensuring several decades of future use.

Exact replacement

Modified designs to improve

performance or maintenance capabilities

Variety of construction materials and

coatings available

New Clarifier internals completely assembled in Monroe shop

Existing 55 ft. diameter Scraper Clarifier at chemical manufacturing plant

Installation of new internals as well as drive, bridge, and walkway

Secondary Clarifier before rebuild at a 25 MGD WWTP

Secondary Clarifier operating after just a three day installation

130 ft. Clarifier rakes fully assembled in Monroe shop prior to shipment

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Circular Clarifier Designs

Influent

SludgeDischarge

Effluent

Bridge SupportedDrive Assembly Inlet Well

Scum Baffle

Scum Outlet

Scum Box withBeach Plate

Bridge and Walkway

PerimeterWalkway

Skimmer Arm

Sludge Well

Concrete Floor

Imbedded Steel Channel

Sludge Rake

Steel Wall

Primary ClarifierMonroe Environmental’s

primary circular clarifiers

are designed to receive raw

wastewater after it has been

pre-screened to remove large

objects and grit. This primary

sedimentation tank will produce

a homogeneous liquid capable

of being treated biologically and

a sludge that can be separately

treated or processed.

Secondary ClarifierMonroe Environmental’s

secondary circular clarifiers

for wastewater are designed

to provide a high quality

effluent suitable for discharge

to the environment or further

treatment.

The Monroe Environmental

secondary clarifier effectively

separates the biological floc

and colloidal solids to produce

wastewater with very low

levels of organic material and

suspended matter.

Solids Contact Clarifier

This clarifier combines

the functions of chemical

treatment, mixing, flocculation,

and sedimentation.

This clarifier may be used

for lime softening, colorant

removal, and removal of

magnesium and iron.

The solids-contact clarifier

employs several radial

collection and outlet launders.

Bridge and Walkway InfluentColumn SupportedDrive Assembly

Inlet Well

Scum Baffle

Effluent

Sludge SuctionTube/Header

Concrete Wall and Floor

Influent

PerimeterWalkway

Scum Box withBeach Plate

Scum Outlet

Suction TubeCounter Weight

SludgeDischarge

Skimmer Arm

Walkway

PerimeterWalkway

Influent

Sludge Rake

Effluent

Radial Launders

Sludge Discharge

Imbedded Steel Channel

Rake and Turbine Drive Assembly

Draft Tube

Turbine

Sludge Well

BafflesReaction Well

Concrete Floor

FlocculationZone

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Mechanism Support — Bridge supported or

center column supported clarifiers and thickeners

are available.

Influent — Center feed or peripheral feed,

energy-dissipating inlet and flocculating feed well

are available.

Sludge Removal Systems

Standard scraper

Spiral scraper

Hydraulic suction tube header

Hydraulic suction riser pipes

Skimming Systems — Floating scum and other

material can be removed by a traditional rotating

skimmer arm and scum removal box or by a

ducking skimmer that feeds a radial scum trough.

A scum baffle prevents floating matter from

entering the effluent launder.

Launder — Inboard, outboard, or radial

launders available for effluent collection.

Weirs — A V-notch adjustable weir will be

designed to ensure steady overflow rates, even

in windy conditions. FRP, stainless steel, and other

materials can be used for weir construction.

Walkways, Railing, & Stairways — Designed

and built according to OSHA and API standards.

Drives — Monroe Environmental uses only the

highest quality drives that are conservatively

selected to handle even the most demanding loads.

Fabricated steel precision gear

Cast iron worm gear

Clarifier Features

Skimmer, scum baffle, and launder components18 ft. steel tank Circular Clarifier for an industrial steel manufacturer fully assembled in Monroe shop

The unique design of the Monroe 3-axis pivoting scum wiper blade ensures constant contact with the scum beach, ensuring the highest scum removal efficiency possible.

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Project: Replacement of (4) 250 ft. Diameter Primary Clarifiers

Existing 250 ft. diameter clarifiers help treat an average of 707 million gallons per day at the Detroit WWTP, with capacity to treat over 1 billion gallons per day during peak flows

City of Detroit Saves Millions of Dollars on WWTP Upgrades

ChallengeThe City of Detroit WWTP needed to upgrade

(4) of its 250 ft. primary clarifiers. The plant

decided to replace the internal components with

a combination of mild, coated steel and non-

corrosive stainless steel members. The project

included converting the sludge rakes to higher

efficiency spiral scrapers and rehabilitating exist-

ing drive units, as well as replacing influent wells,

column supports, weirs, baffles, and launders.

Due to the size of the clarifiers and the amount

of steel involved, the budget estimate for the

clarifier components and accompanying work

was roughly $9,000,000.

SolutionMonroe was the successful low-bidder and

was awarded the project. The city saved several

millions of dollars on the total price of the clarifier

equipment, with Monroe’s contract totaling

approximately $5,000,000. Engineering submit-

tals including new spiral scraper rake designs,

structural analysis, and related drawings were

approved in the 3rd quarter of 2011 and the

fabrication of the equipment began shortly there-

after. The project is scheduled to be completed

in 2013.

New stainless steel skimming mechanisms, weirs, baffles, and launders during installation

Case Study