AS-H Belt Thickener

Using gravity to thicken dilute sludge and slurries, the Alfa Laval AS-H belt thickener is suitable for all municipal or industrial flocculated sludges – particularly those from biological and activated sludge processes. Low energy and polymer consumption and trouble-free operation give important reductions in both cost and hassle for wastewater management.

Alfa Laval Ashbrook gravity belt thickener

Numerous advantages of the AS-H Belt Thickener for flocculated sludge thickening

  • Lower sludge disposal costs resulting from superior thickening
  • Low energy use and polymer consumption
  • Lower labor cost and cost of change, thanks to minimal need for operator attention and maintenance
  • Optional totally-enclosed, low-odor unit with easy access for better safety and work environment
  • Robust and simple design allows for easy adjustment and reliable operation
Designed for high throughput rates and high product solids content, the Alfa Laval AS-H belt thickener is considered the industry standard for removal of liquid from a solid-liquid suspension/sludge. With a simple design the sludge thickener has a small footprint and is suitable for both indoor and outdoor installation in your effluent treatment plant.

How it works

The sludge thickener works on the principle of separating liquid from solids by gravity drainage through a slowly rolling belt cloth. It uses a sludge polymer mixing valve with an adjustable lever arm to ensure sufficient turbulent sludge/polymer mixing.

After this, the ramp feeding section delivers a consistent load across the filtration area to maximize sludge thickening performance.

A sludge retention tank, also known as the flocculation chamber, is filled from the bottom and then rises up over a weir to ensure even distribution onto the belt. Sludge ploughs force the sludge into lanes, which allows free water to run through the belt where sludge is not present, thus enhancing the thickening process. Sludge ploughs can be lifted to allow for removal of debris such as rags etc.


Achieve 2% or more additional dry solids from your belt filter press or gravity belt thickener

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When placed ahead of an existing belt filter press or gravity belt thickener, the Orege SLGTM sludge pre-treatment system changes the rheology of your sludge so that it releases water more freely. Its small footprint means it can likely fit in your existing facility. Alfa Laval has an exclusive agreement to supply Orege in greenfield and brownfield applications.

Reduce your sludge management expenses by:

- Increasing final cake dryness by 2% or more and reducing hauling volumes

- Reducing polymer use

- Increasing belt filter press / gravity belt thickener throughput

Learn more about the Orege SLGTM system

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Lab and pilot testing for municipal and industrial water and wastewater

Alfa Laval has a full testing lab to determine the best solution for achieving the sludge thickening and dewatering results you need. Pilot testing also available.

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Solutions for the Circular Economy

More and more wastewater treatment plants are discovering the benefits of a circular, holistic approach to wastewater treatment. Cost savings, reduced environmental impact and new income streams from recovered resources are but a few. Every wastewater treatment plant is unique and has its own set of challenges and opportunities. With our expertise in processing and our broad range of products, we can support your shift to a circular resource flow. Regardless of whether you are a contractor, designer or plant operator we can help you find the optimum solution for your specific project.

10 top tips for Alfa Laval AS-H Belt Thickeners

Have an Alfa Laval AS-H Belt Thickener? Here are some top tips to help ensure that your equipment continues to perform at peak sludge thickening performance.

Alfa Laval Ashbrook gravity belt thickener

How can we help?

With industry-leading wastewater technology and expertise based on the experience from thousands of installations, we can help analyze your unique situation and select the optimal equipment model, configuration and services for your needs and budget. Get in touch by reaching out directly to the local contact for your area or submitting a general inquiry on the contact form. 

Request a quote

Submit your process information to receive an estimated price range for this application.  (Please note that this will be a budget estimate only. A firm quotation will require more detailed process parameters.)

Submit a budget quote request


Local contacts

Chuck Shaw
Regional Sales Manager – Water Separation Sales – Midwest
Phone: (317) 345-5512
Coverage area:  IA, IL, IN, KS, KY, MI, MN, MO, ND, NE, OH, SD, TN, WI


Jose Carpio
Director of Sales – Water & Wastewater
Phone: (804) 852-9340
Coverage Area: CT, DE, MA, MD, ME, NH, NJ, NY, PA, RI, VT, WV


Roger McKinney
Regional Sales Manager – Water Separation Sales – Northwest
Phone: (559) 317-8551
Coverage area: WA, OR, ID, MT, WY, CO, NM


Marc Arquit
Regional Sales Manager – Water Separation Sales – South
Phone: (713) 882-1286
Coverage area:  AR, LA, MS, TX, OK

Mark Schlitzkus
Regional Sales Manager – Water Separation Sales – Southeast
Phone: (713) 906-0505
Coverage area:  AL, DC, FL, GA, NC, SC, VA


Marc Perratore
Regional Sales Manager – Water Separation Sales – Southwest
Phone: (201) 388-8393
Coverage area: CA, NV, AZ, UT


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