Volute Dewatering Press as a New Technology Bill LaPorte, Envirep, Inc. WLaPorte@Envirep.com Rev 11 May 2017
DEWATERING METHODS PLATE AND FRAME PRESSES CENTRIFUGES BELT PRESSES SCREW PRESSES ROTARY / FAN PRESSES VOLUTE THICKENERS & PRESSES
DEWATERING CONSIDERATIONS ECONOMICS CAPITAL COST POWER CAKE MOISTURE / DISPOSAL COSTS SECONDARY (ALSO ECONOMIC) SOLIDS CAPTURE WASH WATER ODORS OPERATOR ATTENTION CAPACITY (LARGE EQUIPMENT)
Screw Presses Archimedes screw inside a porous cylinder Mechanically very simple Minimal maintenance (if designed right) Easy operation Minimal alignment and wear issues Low power consumption Easy automation Performance Cake solids between a bfp and centrifuge Superior Solids Capture
Typical Screw Press Problems If the openings in the casing are too fine casing will clog with solids reducing fluid release Therefore either: Perforations are large (>1/8 or 1/16 ) meaning that the sludge cannot be squeezed to remove moisture leading to wet cake and low solids capture. Other Screw presses are large because most of the openings are clogged. High pressure intermittent washing is required. Wetter cake during the wash cycle. These presses also REQUIRE thickened sludge
What is a Volute Dewatering Press? A SCREW PRESS with a unique de-watering drum Designed to overcome many limitations of other dewatering devices A screw press with a unique sliding ring screen, that is self cleaning NO PLUGGING. A compact, all-in-one device - chemical dosing, flocculation and dewatering.
The Volute Story Developed in Japan in early-mid 90 s by Amcon Inc. and Japan Sewage Works Authority Utilized in Industrial/Agricultural Industries Developed for use in Municipal market in 1995-1998 Currently Patented and being installed across Europe, North America and Asia Over 1100 Installations worldwide 1 st North American Installation, July 2005 at Port Deposit, MD (Now at >70)
Process Description Sludge is fed into a rapid mixing tank and injected with polymer Sludge flows through the mixing tank into a flocculation tank and then drains into the de-watering drum
FLOCCULATION
Process Description Sludge is fed into a rapid mixing tank and injected with polymer Sludge flows through the mixing tank into a flocculation tank and then drains into the de-watering drum In the first part of the drum the sludge is thickened by gravity In the 2 nd section of the dewatering drum the sludge is pressed to form a dry cake Dewatered solids cake is pushed out the end of the screw, supernatant is discharged from the base of the dewatering drum
Dewatering Drum Design The Dewatering Drum design is the critical difference between the Volute Dewatering Press and other screw presses Dewatering Drum is made of a combination of fixed and moving rings around a variable pitch screw conveyor. Conveyor can achieve both thickening and dewatering/pressing of the feed sludge.
Dewatering Drum Components Spacers Moving rings Fixed rings
Dewatering Drum Assembly Flocculated Sludge In Thickening Zone Dewatering Zone Filtrate Pressate (Can be Recycled) Dewatered Cake
Dewatering Drum
DEWATERING DRUM
Dewatering Drum Benefits The moving rings allow very small gaps around the screw to be used without clogging because they don t clog, less open area is needed for dewatering making the dewatering drum very compact compared with other units. The fine gaps allow the sludge to be squeezed without extruding excessive solids The moving rings also CUT INTO THE CAKE allowing BETTER WATER RELEASE
Dewatering Drum Benefits Non-clogging effect allows the unit to deal with oily and fatty sludges Non-clogging means minimal cleaning water Dewatering mechanism is very efficient and requires very little power Volute 7-10 kwh per dry ton of solids BFP ~25-40 kwh per ton of dry solids Centrifuge ~175-250 kwh per ton dry solids
CLEAR FILTRATE
Configuration Dewatering Press Unit is sold as an all-in-one dewatering system Package always includes polymer system (High quality system including progressive cavity pump and polymer flow monitoring) Control panel will control feed pump and conveyor, even if PWT doesn t supply these. Feed pump is controlled by the unit and can include a PID loop to set flow. Thus the entire dewatering system is integrated and works as a single system giving minimal operator issues.
Models 4, 5, 8, 12, 14 screw diameters Units utilize 1-3 dewatering drums Flows from 4-400 GPM Solids Capacities from 20 2100 lbs. d.s./hour Power consumption - <1 to 8 kw
Shinma WWTP - Gunma Prefecture - Japan Approximately 60 miles NW of Tokyo First municipal installation of the Volute Dewatering Press in the world (1995) Run directly from oxidation ditches maximum sludge concentration stability. Runs 24/7 Currently at about 140,000 hours of operation Operator free plant (weekly inspections)
Unit in operation
Cake Solids
Maintenance Weekly - Check chemical supplies and unit performance Monthly - Inspection of motors, pumps, level sensors and other items For optimal performance replace MOVING RINGS in the dewatering section of the dewatering drum casing every 10,000-15,000 hours 1 or 2 people, on site, in about half a day or less. SCREW replacement approx. once every 30,000 hours (depends on abrasiveness of dewatered material) Adds 1 hour to ring replacement
Performance Benefits Can dewater sludges from 0.03%-15% Does not require pre-thickening or storage Can produce very dry solids cake (typically a few % more than a BFP) High solids recovery (>99.%) High quality filtrate Able to deal with greasy/oily sludges AND STRUVITE
Operational Benefits Very low water usage Almost no wash water most service water is for polymer make-up Low odor and noise generation Low operator attendance Unit will operate itself on a timer or PLC Low power consumption Flexible Installation
PILOT DEMONSTRATIONS DEMONSTRATIONS ON-SITE NO COST TO CUSTOMER 5 PILOT UNITS PRESSES AND THICKENERS
CASE HISTORY Chestnut Ridge Area Joint Municipal Authority New Paris, Bedford County, PA
PLANT FLOW DIAGRAM Current average daily flow: 0.5 MGD Design flow: 1.0 MGD Piloted PW Tech Volute Dewatering Press May 2014
ORIGINAL EQUIPMENT
PW TECH VOLUTE DEWATERING PRESS
1.0 Meter BFP with an infeed solids concentration of 3.8 4.0% Hydraulic feed rate approximately 35 gpm Processing approximately 700 lbs d.s./hour Dewatered cake solids averaging 15-16% Estimated Total Connected HP (not including sludge feed pump polymer feed system and discharge conveyor) = 18.5 HP
Purchased Late 2015; installed & operating Spring 2016 PW Tech Model ES-302 with an infeed solids concentration of 3.8 4.0% Hydraulic feed rate approximately 35 gpm Processing approximately 700 lbs d.s./hour Dewatered cake solids averaging 16-18% (pilot test achieved as high as 20% with a 98% Capture Rate at 31 lbs. active polymer/ton d.s.) Estimated Total Connected HP (not including sludge feed pump polymer feed system and discharge conveyor) = 2.0 HP
THANK YOU! Bill LaPorte, Envirep, Inc. Email: WLaPorte@Envirep.com Phone: 717-972-0852