Introduction
Welcome to MAK Water’s guide to selecting the right sludge dewatering process for your wastewater treatment requirements. Dealing with sludge can be a significant challenge for industry and municipalities alike. Fortunately, advancements in dewatering technology have made it possible to efficiently and economically separate water from sludge, making it easier to handle and dispose of the dewatered solids.
In this blog post, we will delve into the various sludge dewatering methods available on the market and we will demonstrate that the Dewatering Screw Press (DSP) is the obvious solution for numerous applications. The Dewatering Screw Press has drastically changed the conventional approach to sludge dewatering, surpassing traditional dewatering methods in terms of performance, cost-effectiveness, and environmental sustainability. Join us as we explore the selection process and discover why the Dewatering Screw Press is the game-changer you’ve been searching for.
Understanding Sludge Dewatering
Sludge, a by-product of wastewater treatment processes, consists of water and solid materials. Sludge dewatering aims to reduce the volume of sludge to handle and lower disposal costs. Additionally, it minimises the environmental impact by decreasing the amount of sludge sent to landfills or other disposal routes with environmental impact.
Several factors must be considered when choosing a sludge dewatering process, including:
1. Type of Sludge:
Different industries generate diverse types of sludge with varying characteristics. Municipal waste activated sludge (WAS), aerobically digested WAS, anaerobically digested sludge, water treatment chemical sludge, industrial sludge, and biological sludge, to name a few, each have unique properties that can influence the dewatering process selection. Sludge concentration is commonly characterised by percent dry solids (%DS) where 1% DS = 10 g/L of solids. The sludge type and composition will determine the best type of dewatering technology to consider.
2. Polymer Optimisation and Polymer Preparation Systems
In order to dewater sludge, it is critically important to flocculate the solids in the liquid sludge using a polymer, before it is directed into the dewatering machine. The better the flocculation, the better the dewatering process will perform. Different types of sludges require different types of polymers to flocculate effectively. Polymers are available as powder or liquid emulsion (or concentrate). A polymer preparation system is required to make the polymer down to a solution that provides the best flocculation performance. It is prudent to carry out jar testing on sample sludges to find the best performing polymer. Polymer use is a significant input cost in sludge dewatering, and while the key driver is typically the lowest moisture content in dewatered cake content, the right polymer can save on operating costs.
Waste water in the flocculation stage
3. Dryness Requirements:
The dryness that can be achieved for the dewatered cake, depends on the type of sludge and its composition, the polymer type and flocculation that is achievable, and the dewatering technology used. The desired final dryness of the dewatered cake plays a crucial role in determining the appropriate dewatering method. Some applications require a higher dryness level than others, depending on their intended use or disposal. In general > 12%DS is considered to be “spadable” cake, where liquid sludge has been converted through flocculation and dewatering to no longer contain “free” water and is a non-free flowing material.
4. Throughput Capacity:
The volume and mass of sludge to be dewatered influences the required capacity of the dewatering equipment. Matching the throughput capacity with the equipment’s capabilities ensures an efficient dewatering process. The design for dewatering machines considers the volume and mass throughput as typically measured in m3/h and kg/h respectively.
5. Cake Storage:
Consideration should be given to how the dewatered cake is stored before offsite removal & disposal. For low throughputs, a simple skip bin may suffice. In instances of high throughput or odorous cakes, you may want to consider enclosed auto filling, self-levelling containment with odourous air extraction systems to minimise operator input and mitigate complaints from neighbours.
6. Washwater requirements:
All sludge dewatering technologies require washwater to clean or wash the mechanical components of machine when it is in operation, or when it shuts down. Some systems require vast quantities of washwater, while other require very little washwater. In addition to considering washwater supply (quality and quantity), the subsequent capture and treatment of the fouled water that is discharged following the washing process, must be considered when selecting a dewatering technology.
7. Footprint and Space Constraints:
Available space and footprint limitations may impact the choice of dewatering technology. A sludge dewatering facility typically houses not only the dewatering machine(s) but also the polymer preparation system, cake outloading system and cake storage system. Depending on the dewatering technology some systems require more space than others, especially when high capacity cake storage is required to minimise operational input/disposal frequency.
8. Operating Costs:
Sustainability and operational costs are essential considerations for any sludge dewatering facility. The main operating costs are associated with polymer consumption, power draw, maintenance and operator input. Selecting the right polymer is key to lowering operating costs. Selecting dewatering equipment with low energy consumption can significantly impact long-term operational expenses. Some dewatering systems require specialised maintenance that can only be carried out by the manufacturer, and sometimes this needs to be done offsite resulting in long equipment down-time. Such systems can have high operating costs dominated by high maintenance costs. When considering a dewatering machine, the lowest maintenance costs usually result when maintenance can be carried out onsite by an operator, with minimal equipment downtime. Dewatering equipment that requires minimal operational input is preferable to reduce overall operating costs for the dewatering facility.
Sludge Dewatering Technologies
Before exploring MAK Water’s Dewatering Screw Press, let’s briefly review some conventional sludge dewatering technologies:
1. Belt Filter Press (BFP):
The Belt Filter Press 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, BFPs have certain limitations, including high energy consumption, very high washwater consumption, frequent maintenance, and limited dewatering efficiency for certain types of sludge.
2. 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.
3. 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.
The Dewatering Screw Press Advantage
MAK Water’s Dewatering Screw Press offers stand-out features and benefits, 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.
Dewatering Screw Press Model DSP-403
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 in the long run. 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.
Applications of the Dewatering Screw Press
The adaptability and efficiency of the Dewatering Screw Press make it suitable for a wide range of applications:
1. 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.
2. 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.
Conclusion
Choosing the right sludge dewatering process is critical for effective water treatment, reduced disposal costs, and environmental sustainability. MAK Water’s Dewatering Screw Press stands as a testament to our commitment to providing innovative solutions for your specific needs.
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.
We have a trial dewatering screw press available for hire/pilot anywhere in Australia, along with specialist chemical expertise to help you select the optimal polymer to use with your sludge.
At MAK Water, we are passionate about delivering cutting-edge technology that drives efficiency and supports our clients’ sustainability goals. Our Dewatering Screw Press demonstrates our commitment to excellence in the water treatment industry. For more information on our Dewatering Screw Press solutions please don’t hesitate to contact us.
Case Studies
Follow this link to our Case Studies library to discover real MAK Water customer success stories with our Dewatering Screw Press and other sludge handling technologies.