Slant Plate Wastewater Clarifier

M.W. Watermark Slant Plate Wastewater Clarifier Series
When it’s necessary to remove particles from a large volume of water, often the best option is to go with a slant plate wastewater clarifier. M.W. Watermark offers high quality, American-made products that are designed to achieve the ultimate goal of keeping the planet’s water supply safe for generations to come.

The M.W. Watermark Slant Plate Clarifier

Our slant plate wastewater clarifier is one of the most efficient methods available for the removal of solids from process liquid and waste. While there exists a variety of designs for such devices, utilizing inclined plates allows us to pack the widest possible combined plate area into a compact floor space. Plates are placed close together, and settling surfaces are stacked to form a settling area 10 times larger than the total area occupied by the machine.

M.W. Watermark Slant Plate Wastewater Clarifier Series

M.W. Watermark SPC-20 and SPC-40 Skid Mounted Clarifiers with Tanks and Pumps

Click Here to Download Our Slant Plate Clarifier Brochure

Learn More on Our Blog…

“What is a Slant Plate Clarifier?” –  Read more.

“Slant Plate or Dissolved Air Flotation (DAF) Clarifier?” –  Read more.

“Coating Types for Your Industrial Filtration Equipment”Read more.

Need feed pumps, tanks or an electrical control cabinet? M.W. Watermark can supply everything you need for a complete wastewater treatment system.

Does you spec call for a Low Profile Clarifier (LPC) design? We can provide that as well. Just ask!


Product Features

Within our range of slant plate clarifiers, we offer nine standard-sized models, handling between 5 and 400 GPM, a sludge holding capacity between 17 and 960 gallons, and a plate area of between 16 and 1,680 square feet. That large capacity comes at very little cost in terms of floor space; sizes range from 45″ x 23″ to 170″ x 120″, with heights ranging from 51″ to 147″. The machines feature no moving parts, constructed using 1/4″ steel and dye-pen tested welding. Integral flash mixing and flocculation tanks help to increase efficiency, and the entire structure is sandblasted, primed, and painted to provide maximum chemical resistance. Each device comes equipped with 1/4″ thick removable PVC settling plates, dual sludge outlet flanges, sludge sampling ports, and a large side-access hatch to allow for easy maintenance.

M.W. Watermark SPC-20 Slant Plate Clarifier


M.W. Watermark Slant Plate Clarifier - Slant Plate Clarifier – Top View: Showing flash mixing tank, flocculation tank, and inclined plates

Flash Mixing Tank, Flocculation Tank, and Inclined Plates

M.W. Watermark SPC-10 Slant Plate Clarifier - Inclined Plate Clarifier



M.W. Watermark SPC-80 Slant Plate Clarifier - Inclined Plate Clarifier



M.W. Watermark SPC-40 Slant Plate Clarifier - Stainless Steel - Inclined Plate Clarifier

SPC-40 (Stainless Steel)

M.W. Watermark SPC-80 Slant Plate Clarifier - Shown with Optional Mixers - Inclined Plate Clarifier

SPC-80 (Shown with Optional Mixers)

M.W. Watermark Slant Plate Wastewater Clarifier Series - SPC-40 with Tnemec Internal Coating

SPC-40 (Tnemec Chemical-Resistant Internal Coating)

M.W. Watermark Slant Plate Wastewater Clarifier Series; SPC-150 with Enduroliner External Coating

SPC-150 (Enduroliner™ External Coating)

System Design

Fluid is fed into the top of the wastewater clarifier (A) and flows under a baffle to the integral flash mixing tank (B). At this point, a flocculating agent may be added with a PolyMark™ polymer blending system, and is blended with the fluid using an optional high-speed mixer. From the flash mixing tank, the fluid flows over a baffle into the integral flocculation tank (C), which may include an optional low-speed mixer. From here, the fluid flows through the feed channel, between the two plate stacks, and down to a sludge chamber, located at the bottom of the structure. Large particles begin to drop out of suspension as the velocity of the fluid decreases.

M.W. Watermark Slant Plate Clarifier - Inclined Plate Clarifier - Diagrams

As the liquid enters the bottom of the plates and flows between settling plates, it maintains a low velocity, laminar flow profile which allows the suspended solids to settle on the lower plate, then flow downward to the sludge holding tank. While the solids are settling along the plate surfaces, the fluid is gradually heading upward through the plate stacks, over the weirs, and into the discharge trough.

M.W. Watermark Slant Plate Clarifier - Inclined Plate Clarifier - Illustration

Finally, the clarified effluent is discharged through a flanged pipe connection. Through sample ports, operators are able to judge the sludge level, which is periodically pumped into a batch storage tank for further liquid-solid separation via an M.W. Watermark Filter Press and eventual disposal.

Contact M.W. Watermark

To learn more, please contact the M.W. Watermark Sales and Service team.

M.W. Watermark SPC-5 Slant Plate Clarifier - Inclined Plate Clarifier


A-C Flash & Flocculation Tanks
D Influent
E Clean Effluent Liquid
F Modular Laminar Plates
G Thickening Sludge Ports
H Sludge Removal
I Access Hatch
H Sludge Removal
J Baffle
K Overflow Weir
L Waterline


Clarifier Model SPC 5 SPC 10 SPC 20 SPC 40 SPC 80 SPC 150 SPC 200 SPC 300 SPC 400
Design Flow Maximum (GPM) 5 10 20 40 80 150 200 300 400
Flash Tank Mix Volume (gal) 4.4 4.5 38 50 79 110 110 186 186
Flocculation Tank Volume (gal) 6.5 20.5 62 99 189 316 316 742 742
Total Pre-Treatment Vol. (gal) 10.9 25 100 149 268 426 426 928 928
Effluent Piping Connection (Class 150 Flange) 1″ 3″ 4″ 4″ 4″ 6″ 6″ 8″ 8″
Solids Discharge Connection (Class 150 Flange) 1″ 3″ 4″ 4″ 4″ 4″ 4″ 6″ 6″
Sludge Capacity (gallons) 17 42 88 150 275 469 611 834 960
Plate Area (ft2) 16 39 87 160 300 560 868 1,167 1,680
Projected Plate Area (ft2) 9.4 23 50 92 172 321 497 670 964
Empty Shipping Weight (lb) 765 1,400 2,065 3,600 4,800 7,400 11,000 13,200 16,500
Full Operating Weight (lb) 1,325 2,875 5,310 9,000 15,480 22,900 32,760 58,300 60,320
Overall Length 45″ 55.5″ 70″ 87″ 102″ 135″ 163″ 185″ 210″
Overall Width 23″ 44″ 60″ 60″ 73″ 76.5″ 77″ 100″ 100″
Overall Height 51″ 64″ 94″ 104″ 130″ 147″ 147″ 145″ 143″
Design Solids Removal (200ppm influent) 95%+ 95%+ 95%+ 95%+ 95%+ 95%+ 95%+ 95%+ 95%+
Underflow Solids (% by weight) 1-2% 1-2% 1-2% 1-2% 1-2% 1-2% 1-2% 1-2% 1-2%