Polymer Preparation System (ASP)

Overview

MAK Water’s Polymer Preparation System (ASP) is a packaged plant used for automated batching of matured polymer solution from liquid concentrate polymer (C-type) or powder polymer (P-type). The ASP is ideal for mechanical sludge dewatering applications and small to medium water and wastewater treatment processes, including clarification and thickening.

Both the C-type and P-type ASP systems have a mixing tank fitted with a mixer, and a solution storage tank. Both tanks are fitted with level probes used for control purposes. Once the polymer in the tank drops below a certain level, a new preparation cycle is triggered automatically. There are actuated valves on the water inlet, and on the discharge of matured polymer solution between mixing and storage tanks. The P-type has a powder hopper with heated feeder that feeds powder polymer into the mixing tank. The C-type has a feed pump to transfer concentrated liquid polymer from a bulk tank (by others) into the mixing tank. The powder hopper for the P-type is filled manually.

Dewatering Screw Press

MAK Water’s Dewatering Screw Press (DSP) is designed for efficient thickening and dewatering of liquid sludges that emanate from municipal and industrial wastewater treatment processes. Typical applications for wastewater treatment plants include dewatering of thickened or unthickened waste activated sludge (WAS), digested sludge from aerobic or anaerobic processes, and dissolved air flotation (DAF) sludges.

Our Dewatering Screw Press is also suitable for dewatering of liquid sludges from a wide range of industries, including food & beverage, chemical, manufacturing, infrastructure development and resource industries.

For municipal WWTP sludge applications, our sludge Dewatering Screw Press typically produces dewatered sludge cake of 15% to 20% dry solids content. For industrial projects, depending on the specific application, cake of >20% dry solids content is possible.

The ability to dewater WAS directly from the activated sludge process, eliminates the need for an intermediate thickening process, thus offering significant savings in capital and operating costs.

DEWATERING SCREW PRESS EQUIPMENT DESCRIPTION

Liquid sludge is pumped to the Dewatering Screw Press via an external feed pump. The sludge enters the Inlet Chamber, which is fitted with an overflow. Any overflow is directed back to the sludge source tank or process. The Inlet Chamber serves to optimise flow to the other parts of the machine.  

Liquid sludge is discharged from the Inlet Chamber via a V-notch weir into the Flocculation Chamber. Polymer is added into the Flocculation Chamber to aggregate/flocculate sludge solids into flocs. Flocculation occurs where the sludge and polymer are mixed slowly by a vertical paddle mixer. The sludge flocs then flow via an overflow from the Flocculation Chamber into the screw, which is the basic mechanism of the dewatering press.

A screw with a variable pitch helix operates within a cylinder of fixed and moving rings that make up the dewatering drum. The fixed rings form a static structure whereas the moving rings ensure continuous self-cleaning while the screw is in motion. The gap between the fixed and moving rings varies from 0.5 to 0.1 mm.
However, when the screw is in operation, the size of the gaps changes continuously, thus giving a smooth dewatering process. The filtrate that results from the dewatering process as the flocculated sludge is compressed, flows through these gaps into a collection tray located under the machine. The filtrate can gravitate from this tray to the head of works or any other suitable location.

An adjustable pressure plate is mounted at the end of the screw. This allows the already dewatered sludge to be compressed even more to increase the dewatering efficiency, thus producing dewatered sludge cake. The dewatered cake can be discharged from the sludge Dewatering Screw Press into a skip directly, or discharged via a conveyor into a skip for collection & disposal of the dewatered cake.

The Dewatering Screw Press machine is made of 304 stainless steel. The rings are made of 316 stainless steel, and the screw is made of 316L stainless steel with special tungsten surface treatment. This ensures abrasion resistance, sufficient hardness and resistance to wear and tear, and provides the necessary resistance to corrosion for materials which come into contact with aggressive sludges.

Equipment Operation & Control

The Dewatering Screw Press is designed to run in AUTO mode, thus requiring little operator attendance. In AUTO mode the operator can check the status of the equipment and change operational set-points via the HMI touch screen located in the Control Panel.

The Screw motor is fitted with a Variable Speed Drive (VSD) which makes it possible to accelerate or slow down the screw rotational speed for optimal dewatering. The Mixer motor is also fitted with a VSD to allow the operator to optimise flocculation for the best possible dewatering results.

The Dewatering Screw Press can also be operated in full MANUAL mode, where each component can be manually turned on/off via the HMI touch screen.

WendeWolf® Solar Sludge Drying System

MAK Water is the exclusive representative in Australia and New Zealand for the WendeWolf^® Solar Sludge Drying technology which is designed and supplied by German engineering company IST-Anlagenbau GmbH.
The WendeWolf^® sludge drying system was developed in collaboration with the University of Munich, and IST-Anlagenbau has more than 30 years of experience in delivering this technology.
Worldwide there are over 170 WendeWolf^® systems installed at over 100 locations across 11 countries. In Australia there are currently 9 WendeWolf^® Solar Sludge Dryers in operation at 4 locations.

MAK Water provides full design, costing and technical support of the WendeWolf® sludge drying technology, from concept stage through to final project delivery. We provide the complete package that includes design, supply and installation of the WendeWolf® system and associated mechanical and electrical works, as well as design, supply and installation of the greenhouse drying hall(s). All WendeWolf® systems are commissioned by IST-Anlagenbau and supported by MAK Water in Australia and New Zealand. MAK Water also offers refresher training to operators and provides spare parts and servicing to existing sludge drying equipment.

WendeWolf^® Sludge Drying System Overview

The WendeWolf® sludge dryer system includes a tiller & turner machine that processes dewatered sewage sludge cake into a dry granulated product. The WendeWolf® machine is installed inside an enclosed greenhouse building or drying hall. The greenhouse serves to prevent rain from re-wetting the sludge and capture solar radiation to evaporate the moisture from the sludge. The WendeWolf® machine spreads, turns over and breaks up the sludge in the bed, as it transports it along the length of the drying hall. The final granulated product at the end of the drying hall is on average approximately 10 mm in size and can have up to 85% dry solids content. This granulate is suitable for agricultural reuse, as fertilizer, as well as secondary fuel in coal fired power plants or in cement plants.

How does soldar sludge drying work?

• Dewatered sludge cake from as low as 13% dry solids content is brought into the front end of the drying hall in batches or continuously as it is produced. This cake in-loading process can be manual (e.g. tip truck or skip) or automated (e.g. belt or screw conveyor).
• The WendeWolf® machine moves along the length of the drying hall on dwarf walls. It spreads the dewatered cake across the width of the drying hall, turns it over, and transports it along the length of the drying hall. During this process the dewatered cake is transformed into a granular product that can range in dry solids content from around 40% to 85%.
• Captured solar radiation inside the greenhouse causes evaporation of moisture from the sludge bed. The warmer the air is the more water vapour can be transported. The difference between the partial vapour pressure inside the sludge and the ambient air, drives the drying process.
• This process is enhanced by the WendeWolf® machine as it breaks up the sludge, and turns the sludge over to expose moisture-rich sludge to the surface. As the sludge dries and the WendeWolf® machine moves it along the length of the hall, the sludge is transformed from dewatered cake into small granules.
• In order to avoid an equilibrium between the vapour pressure inside and outside the sludge, the humid air has to be evacuated. This is naturally helped by the fact that water vapour is lighter than dry air. Active and passive ventilation systems are used to control the humidity inside the greenhouse. Ventilation fans installed above the sludge bed force warm air onto the sludge bed to drive evaporation. Water vapour is vented through automated roof vent(s) in the greenhouse. Dry and cooler (than inside) air is pulled in from outside the greenhouse along the length on both sides of the hall.
• The WendeWolf® control strategy to maximise evaporation and sludge drying (for operating with only solar radiation) involves the following. Temperature and relative humidity are monitored inside and outside and inside each hall. The Programmable Logic Controller (PLC) calculates the temperature difference and the absolute water content inside and outside for each hall separately. The respective thresholds can be altered.
• Due to seasonal variation in solar radiation, the rate of evaporation varies accordingly. As a result, in order to maintain a granular product with a desired minimum dry solids content, the sludge bed depth in the drying hall varies throughout the year. The throughput of a Solar Sludge Dryer system is therefore expressed on a yearly basis.
• The granular product that is produced at the end of the drying hall, can be removed from the hall in batches or continuously. This out-loading process can be manual (e.g. Mechanical loader) or automated (e.g. conveyor).
• By reducing the moisture in the dewatered cake from 15% dry solids content to 85% dry solids content in the granulate, there is a 78% reduction in wet mass. This mass reduction is directly proportional to savings in transport costs.

What components make up a Solar Sludge Drying system?

A Solar Sludge Drying facility can comprise one or more drying halls. The drying halls can be configured as standalone greenhouses or, two or more drying halls within a single greenhouse.

The WendeWolf® machine is installed inside a drying hall and runs on two dwarf walls that are 11.3m apart and 850 mm high, up to 120m in length. The WendeWolf® solar sludge drying system contains the following mechanical & electrical equipment as standard:

• WendeWolf® machine i.e. tiller and turner assembly
• Control Hardware and Software, including Operation Switchboard and Machine Switchboard
• Festoon system that includes power cable
• Ventilation fans; quantity depends on hall length
• Four (4) safety lanyards with emergency stop pull switches; two (2) on the WendeWolf® machine and one (1) at each entry to the drying hall
• One (1) set of Meteorology Instruments installed inside each drying hall
• Position Labels installed along the length of the drying hall

Common equipment for the complete WendeWolf® Solar Sludge Drying facility include:

• One (1) set of Meteorology Instruments installed outside the drying hall(s)
• Main Switchboard (for power distribution to each WendeWolf® Operation Switchboard, ventilation fans, greenhouse vents and other miscellaneous equipment)

What Process Design considerations are relevant?

The process design and sizing of a Solar Sludge Drying facility is determined by IST – Anlagenbau using modelling or process simulations. Each simulation requires the following inputs:

• Location-specific climate data including Daily Radiation in J/cm², Average Daily Temperature in °C, and Average Daily Relative Humidity in % (data is sourced directly by IST-Anlagenbau)
• Sludge quantities to be treated in tonnes Dry Solids (tDS) per month throughout a year. Specify whether INPUT per month is fixed or variable
• Dewatered sludge cake INPUT in percent Dry Solids (%DS) content
• Dried granulate product OUTPUT in percent Dry Solids (%DS) content. Specify whether OUTPUT target %DS is based on Minimum Monthly %DS or Annual Average %DS
• It is required to store dried granulate product must be stored temporarily inside the drying hall(s), and the required duration for storage
• Is auxiliary heat is available for a heating system to be installed in the hall(s). Heat systems can include, Floor Heating, Hot Air Blowers and Infrared Radiators.
• Selected systems for dewatered cake in-loading and dried granulate product out-loading.
• Requirements for staging of works
• Site constraints

Key features of the WendeWolf® solar drying system

The WendeWolf® machine:

• Control system has pre-set programmes to operate the process. These pre-set programmes are operator adjustable, and by combining these into a sequence, all plant operation is automated.
  • LOADING – used to import and flatten input piles of sludge into the hall, and to spread it across the width of the hall, over a selected length in the hall.
  • TURNING – used to turn over the drying sludge for a selected sludge bed depth, over a selected length in the hall. Turning can occur in both directions; there is no preferred direction.
  • DISPLACING – used to move the sludge for a selected sludge bed depth, over a selected length in the hall. Displacing can occur in both directions.
  • ACCUMULATING – used to accumulate or stockpile dried granulate product
  • CLEARING (optional) – used to remove dried granulate product from the end of hall, where an automated out-loading system is available
• Can operate in Batch mode or Continuous mode without changing the programming.
• Turns over and conveys the sludge homogeneously in one single process along the full width and length of the hall.
• Can handle dewatered cake input piles up to 110 cm high.
• Operates (Turning and Displacing) a sludge bed depth up to 40 cm.
• Can stockpile the dried granulate product up to 80 cm high.
• Does not touch the floor, and therefore does not damage the floor. At start-up the WendeWolf^® machine’s on-board sensors are used to “map” the floor surface. This process determines the minimum operating height from the floor across the width and length of the hall.
• Can be used to “back-mix” dried granulate with wet sludge (as an option if required).
• Uses robust, low wear, easy to maintain, and exchangeable tilling tools.

Watromat® Sludge Dryer

Standard sludge dryer

WATROMAT® batch sludge dryer use dried air to reduce the weight and volume of filter cake sludge. Sludge drying with WATROMAT® batch sludge dryers is ideal for filter cake sludge from small and medium plate and frame filter presses. The filter cake sludge is filled into WATROMAT® drying containers and will be dried with dry air. All WATROMAT® drying containers have integrated tipping systems. Sludge drying with WATROMAT® standard sludge dryer is maintenance-poor and emission-free.

Watromat® Screw Press Dryer

Screw press dryer

WATROMAT® Screw press dryer are tested piped combined dewatering and drying equipment and consisting of: sludge pump, polymer dosing unit, flocculation tank, screw press, screw conveyors, belt dryer and bagging point. WATROMAT® screw press dryer dewater, dry sludge and fill the dry sludge in bags or silos. WATROMAT® screw press dryers operate at low temperatures without emissions and with low maintenance.

Sludge Handling

Dewatering Screw Press (DSP)

MAK Water’s Dewatering Screw Press (DSP) is designed for efficient thickening and dewatering of liquid sludges that emanate from municipal wastewater treatment processes. Typical applications for wastewater treatment plants include dewatering of thickened or unthickened waste activated sludge (WAS), digested sludge from aerobic or anaerobic processes, and dissolved air flotation (DAF) sludges.

Polymer Preparation System (ASP)

MAK Water’s Polymer Preparation System (ASP) is a packaged plant used for automated batching of matured polymer solution from liquid concentrate polymer or powder polymer. The ASP is ideal for mechanical sludge dewatering applications and small to medium water and wastewater treatment processes, including clarification and thickening.

WendeWolf^® Solar Sludge Drying (SSD)

MAK Water is the exclusive representative in Australia and New Zealand for the WendeWolf^® Solar Sludge Drying technology which is designed and supplied by German engineering company IST-Anlagenbau GmbH.  The WendeWolf^® system was developed in collaboration with the University of Munich, and IST-Anlagenbau has more than 30 years of experience in delivering this technology.

Watromat® Sludge Dryer

WATROMAT® batch sludge dryer use dried air to reduce the weight and volume of filter cake sludge. Sludge drying with WATROMAT® batch sludge dryers is ideal for filter cake sludge from small and medium plate and frame filter presses.

Watromat® Screw Press Dryer

WATROMAT® Screw press dryer are tested piped combined dewatering and drying equipment and consisting of: sludge pump, polymer dosing unit, flocculation tank, screw press, screw conveyors, belt dryer and bagging point.