Unlocking Efficiency: The Dewatering Screw Press - Your Ultimate Sludge Dewatering Solution

Dealing with sludge can be a significant challenge for industry and municipalities alike. Fortunately, advancements in modern sludge dewatering technology have made it possible to efficiently and economically separate water from sludge, making sludge disposal easier and more cost-effective.

The Dewatering Screw Press has drastically changed the conventional approach to sludge dewatering, surpassing traditional dewatering methods in performance, operating cost savings, and environmental sustainability.

Understanding Sludge Dewatering

Sludge, a by-product of water and wastewater treatment processes, consists of water and solid materials. Sludge dewatering reduces the volume of sludge for easier handling and lowers disposal costs. It also minimises environmental impact by reducing landfill waste.

What is the best method for sludge dewatering?

Key factors to consider when selecting the best sludge dewatering process include:

1. Type of Sludge
   Different industries generate different sludge types: municipal waste activated sludge (WAS), digested sludge, water treatment sludge, industrial sludge and biological sludge. Each sludge type affects dewatering equipment selection. Sludge concentration is measured in percent dry solids (%DS).
2. Polymer Optimisation
   Flocculation is essential for effective sludge dewatering. The right polymer selection and dose are vital for flocculation in order to maximise cake dryness and minimize operating costs. Jar testing is required to select the optimal polymer.
3. Dryness Requirements
   How dry should dewatered sludge be? Dewatered sludge is generally referred to as dewatered cake or cake. The required cake dryness depends on sludge type and disposal method. Generally, cake >12%DS is considered “spadable” or easy to handle.
4. Throughput Capacity
   How much sludge needs dewatering? Select sludge dewatering equipment sized to match your site’s capacity requirements. Equipment sizing is determined by the hydraulic loading or mass loading or both.
5. Cake Storage
   Consider how to store dewatered cake for offsite removal. For large volumes, enclosed storage with odour control may be needed.
6. Washwater Requirements
   All sludge dewatering machines need washwater for cleaning. Factor in supply volume and quality, and treatment and discharge of fouled washwater when choosing equipment.
7. Footprint and Space
   Site space can limit equipment choice. Dewatering Screw Presses have a compact footprint compared to many other dewatering technologies.
8. Operating Costs
   Key costs include polymer use, energy consumption, maintenance, and labour. Choosing a dewatering screw press with low power use and simple maintenance helps lower total costs.

How to choose the right sludge dewatering equipment

Conventional sludge dewatering technologies have a long history of use however these have some limitations.

Belt Filter

The Belt Filter (BF) is a widely used dewatering technology with a long operational history in the market. It utilises two porous belts to squeeze and remove water from the sludge. Despite being prevalent, BFs have certain limitations, including high energy consumption, very high washwater consumption, frequent maintenance, and limited dewatering efficiency for certain types of sludge.

Centrifuge Dewatering

Centrifuges employ centrifugal force to separate water from the sludge. Due to the high speed of operation, vibration must be considered in the civil design which can impact capital costs. Centrifuges typically produce high cake dryness, but have high power draw and can be costly to operate and maintain and may not be the best option for sludge with low solids content.

Plate and Frame Filter Press

This method involves pressing the sludge between filtering plates to separate water from solids. Filter presses are typically best suited to sludges that contain high % of inert solids and for sludges with high concentration of solids. Filter presses are not economical to dewater low concentration sludges. Filter presses operate in batch-mode which may not suit all applications. Due to the nature of operation, filter presses typically require elevated installation to allow for dewatered cake to drop into a bin or bunker for further handling.

How does a Dewatering Screw Press work?

Liquid sludge enters the Inlet Chamber, with overflow returned to the source. Polymer is added in the Flocculation Chamber, where a paddle mixer generates larger flocs before the flocculated sludge moves into the screw press.

A variable pitch screw pushes flocculated sludge through self-cleaning rings with adjustable gaps, separating water as filtrate that drains to a collection tray. As the sludge moves along the length of the screw shaft, and filtrate is removed, the sludge concentration is increased. An adjustable pressure plate at the end of the screw shaft provides compression to generate dewatered cake, which is discharged to a skip or conveyor.

Why choose a Dewatering Screw Press?

The Dewatering Screw Press has become a popular choice for sludge dewatering, outperforming traditional methods in several crucial aspects.

1. High Dewatering Efficiency
   The Dewatering Screw Press is engineered to achieve high dewatering efficiency even with sludge that has a low solids content. It offers single-step dewatering from as low as 0.2% dry solids content to typically 15-20%DS cake. Its continuous operation ensures consistent performance, allowing for optimal moisture removal from the sludge.
2. Versatility
   One of the standout features of the Dewatering Screw Press is its versatility. It can effectively handle various types of sludge, making it an ideal choice for applications in both municipal and industrial settings.
3. Reduced Footprint
   Compared to conventional dewatering methods, the Dewatering Screw Press has a compact design that requires less space. Its small footprint allows it to fit seamlessly into existing wastewater treatment facilities without the need for extensive modifications.
4. Lower Energy Consumption
   The energy-efficient design of the Dewatering Screw Press translates to cost savings. The reduced energy consumption contributes to the sustainability goals of municipalities, water authorities and industries.
5. Low Maintenance Requirements
   Maintenance costs can be a significant factor in the operational expenses of a wastewater treatment facility. The Dewatering Screw Press is designed for minimal maintenance, reducing downtime and ensuring continuous operation. All maintenance can be carried out by the site’s operational staff.
6. Automatic Operation and Control
   MAK Water’s Dewatering Screw Press models come equipped with advanced automation and control systems. This automation ensures ease of operation, real-time monitoring, and precise adjustment of the dewatering process parameters.

What applications can the Dewatering Screw Press be used for?

The adaptability and efficiency of the Dewatering Screw Press make it suitable for a wide range of applications.

Municipal Wastewater Treatment

In municipal wastewater treatment plants, the Dewatering Screw Press effectively handles the dewatering of thickened or unthickened waste activated sludge (WAS) and digested sludge from aerobic or anaerobic processes.

Industrial Wastewater Treatment

Various industries, such as food processing, chemical manufacturing, and pulp and paper, generate wastewater with sludge. Many industries employ a dissolved air floatation (DAF) process to remove solids from the waste stream. The resultant thickened float of DAF sludge is often difficult to handle. The Dewatering Screw Press provides an ideal solution for efficiently treating DAF sludge and dewatering many different types of industrial sludges.

How MAK Water can help

Choosing the right sludge dewatering process is critical for effective wastewater treatment, reduced disposal costs, and environmental sustainability. At MAK Water we're passionate about delivering cutting-edge technology that drives efficiency and supports our clients’ sustainability goals.

With its high dewatering efficiency, versatility, reduced footprint, lower energy consumption, and automatic operation, the Dewatering Screw Press offers a comprehensive and sustainable solution for various industries and municipal wastewater treatment plants.

MAK Water has a trial Dewatering Screw Press available for hire/pilot testing anywhere in Australia. Our specialist chemical experts are ready to help you select the optimal polymer to use with your sludge.

Contact us for more information or to request a trial.