What is unique about the Volute Dewatering Press?

The PW Tech Volute Dewatering Press is an improved version of the traditional screw press. The conventional screw press has a screw inside a drum with perforated holes or wedge wire. It requires a high-pressure feed pump and is often shut down to be manually pressure-washed to unclog the drum. The Volute Press has a dewatering drum with fixed and moving rings continuously driven by the screw to provide a self-cleaning action to allow dewatering without plugging up with solids.

Why use a Volute Dewatering Press to dewater sludge?

• High cake solids and capture rates
• Simple, robust, and reliable with minimal moving parts and no high-speed components
• Automated operation requires very little operator attention
• Low power use compared to other types of dewatering equipment
• The low total overall cost of ownership due to low power, labor, and maintenance costs
• Low noise, low odors, small footprint

What types of sludge can the Volute Dewatering Press handle?

The Volute Dewatering Press is designed for dewatering a wide range of sludges, including biological and oily ones, which are known to cause clogging in other dewatering devices. Its self-cleaning mechanism helps handle oily and fatty sludges effectively, making it a suitable option for these applications.

How much sludge can the Volute Dewatering Press dewater?

The amount of sludge that can be dewatered using the Volute Press will depend on a number of factors, including the concentration and nature of the specific sludge, the desired cake solids, the size of the press, and other variables. To get an accurate understanding of capacity and performance, it is recommended to conduct pilot testing using PWTech’s pilot test trailers. This will help determine the best operating parameters and provide valuable data that can be used to make informed decisions about the best course of action.

How much operator time is required?

The Volute Dewatering Press offers automatic, unattended operation and requires little operator attention. The only operator requirement is daily visual inspections and more comprehensive quarterly and yearly inspections.

Where are PW Tech Volute Dewatering Presses made?

The tanks, support frame, polymer feed system, control panel, motors, and other components are made in the U.S., where all the components are assembled and tested before shipment to the job site. The dewatering drum is manufactured in Japan and shipped to the U.S.

How much does it cost to run?

The cost of operation includes power, overhaul costs, labor, and chemicals. These vary significantly for every installation. The following table is a guide with low and high cost/ton of dry solids processed:

Item	Low	High	Unit	Unit Cost	Low-Cost Est	High-Cost Est
Power	5	10	kWh	$0.12/kWh	$0.60	$1.20
Overhaul	2500	1500	Tons/overhaul	$8,000/overhaul	$3.20	$5.33
Chemicals	10	30	#/ton dry solids	$5.00/pound (polymer)	$50.00	$150.00

How much power does the Volute Dewatering Press use compared with other dewatering products?

The Volute Press is an energy-efficient dewatering technology compared to other options like centrifuges or belt filter presses. The Volute Press typically uses about 5 kW hours of power per ton of dry sludge, which is significantly lower compared to the energy consumption of other technologies. Centrifuges and belt filter presses, for example, can require at least 100 kW hours and 50 kW hours of power, respectively, not including additional energy consumed by pre-thickening equipment, wash water pumps, compressors, etc. Therefore, the Volute Press can offer a cost-effective solution in terms of energy consumption, making it a more sustainable and environmentally friendly option.

What chemicals are used with the Volute Dewatering Press?

Approximately 95% of Volute Dewatering Press installations use polymer only. Polymers cause flocculation of the sludge solids to improve dewatering performance. Generally, the amount of polymer used will vary between 10 and 30 lbs/ton of dry solids dewatered, similar to a centrifuge or belt filter press.

How many are installed?

There are approximately 2,000 units installed worldwide and over 200 units in North America and over 35 units in the mid-Atlantic states.

How much maintenance is required?

One of the main benefits of the Volute Dewatering Press is its low maintenance requirements. The main wear component of the press is the moving rings, which are located at the pressure end of the dewatering drum. The lifespan of these rings varies depending on the type of sludge being processed, but they typically last between 10,000 to 15,000 operating hours. As the rings wear, the performance of the press may decrease, but it will still continue to operate and dewater sludge. Replacing the moving rings is a relatively simple process that can be done in a matter of hours per drum. This low maintenance requirement helps keep the cost of operation low and allows the Volute Press to provide long-term, reliable performance.

Is Pilot Testing Available?

PW Tech offers a full range of Volute Press pilot test trailers located in Baltimore, MD. The trailer-mounted system is fully automated and includes all necessary components, such as controls, flow meters, feed pumps, polymer systems, and connection hoses. The pilot test, which lasts for one week, is conducted under the supervision of an experienced PW Tech technician and is designed to evaluate the performance of the Volute Press on the specific sludge, evaluate various polymers, provide operational data, and allow the operators to gain hands-on experience with the equipment. After the test, the results are summarized in a written report, which can be used to inform further decisions and help determine the suitability of the Volute Press for the particular application.

PWTech offers the opportunity to test the Volute Dewatering Press through the use of pilot units before making a full investment. This allows customers to evaluate the performance of the equipment on their specific sludge and gather data to make an informed purchasing decision. By testing the equipment on-site before making a full investment, customers can ensure that the equipment will meet their needs and provide the desired results.

Please contact Envirep if you want additional information or schedule a pilot test at your facility.

By Mike Gillespie, P.E., Envirep

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Envirep is a manufacturer’s representative for manufacturers of equipment used to pump, treat and dispose of wastewater and biosolids. We also represent manufacturers of equipment used to pump, treat, distribute, and store drinking (potable) water. Envirep serves the municipal and industrial water and wastewater market in Pennsylvania, New Jersey, Maryland, Delaware, the District of Columbia, and Virginia.