Seditank System – Grit and Plastic Removal

Description

The Drycake Seditank: Revolutionizing Food Waste Processing and Anaerobic Digestion

Efficient management of food waste is a critical component of sustainable practices in industries ranging from food processing to renewable energy production. A significant challenge in this arena is the presence of contaminants such as grit and plastics in organic waste streams used to feed the anaerobic digestion facilities. These contaminants can cause severe operational issues, including increased maintenance costs, reduced efficiency in anaerobic digesters, and contamination of final products. The Drycake Seditank is designed to be used to further clean-up the organic output (pulp) from any depackaging or other pre-processing equipment to address these challenges head-on. Whether installed downstream of Drycake’s own Twister Depackager, or retrofitted to another machine, the Seditank offers a reliable and effective solution for separating unwanted materials from food waste before it enters the anaerobic digestion process.

What is the Drycake Seditank?

The Drycake Seditank is an advanced food waste plastic and grit separator that ensures the smooth operation of downstream processes by removing both grit and plastics before the waste reaches critical equipment such as anaerobic digesters. This machine is designed to be highly effective and versatile, capable of handling various types of food waste while minimizing downtime and protecting essential components like piping, heat exchangers, and pumps from abrasive damage.

How Does the Seditank Work?

The Seditank operates based on the simple yet effective principles of sedimentation and flotation. Here’s a breakdown of its operation: 

1. Inlet and Initial Separation: 

• Food waste, in the form of an “organic soup” from organic waste pre-processing “Depackaging” is introduced into the Seditank through a top inlet using an augur lift or pumping system. 
• The mixture enters a large rectangular tank, where the first step of separation begins.

2. Grit Removal: 

• As the waste settles in the tank, heavier materials like sand, grit, glass, and other inert particles naturally fall to the bottom, forming a sediment layer. 

• A horizontal screw located at the bottom of the tank continuously moves this grit into a collection hopper. 

• An inclined screw then extracts the grit from the unit, ensuring that the remaining organic material is free of these heavy contaminants. 

3. Plastics and Floatables Removal: 

• Simultaneously, lighter contaminants, including plastics and other floating materials, are removed using a low-pressure air diffusion bubbler system. The airflow is low and avoids odour. 

• This system gently agitates the mixture, encouraging floatables to rise to the surface, where they are skimmed off by a paddle scraper. 

• The skimmed material is collected in a trap and transferred to a hopper for further treatment or disposal. 

4. Final Output: 

• The cleaned organic slurry, now free of both grit and plastics, exits the tank through an outlet and is ready to be pumped to the biogas reactor or other processing units. 

The Drycake Depackager organic outlet and the Seditank/ Plastifloat unit are used in sequence to provide a full organic waste separation system.

The Importance of Grit and Plastics Removal

Grit Removal

Grit, composed of sand, glass, and similar materials, poses a significant risk to anaerobic digesters. This abrasive material can cause severe wear and tear on biogas reactors, leading to frequent maintenance and costly repairs. Additionally, grit can build-up, clog and damage piping, heat exchangers, and pumps. Many digester tanks need to be decommissioned and the accumulated sludge removed by a specialist contractor further disrupting operations. By effectively removing grit, the Seditank not only protects equipment but also enhances the overall efficiency of the digestion process.

The Seditank provides a very short ROI when used to prevent or reduce downtime due to digester grit cleaning. However, the avoidance of grit build-up in digester tanks provides additional cost savings preserving internal tank piping, improving heat exchanger efficiency and extends the life of pumps.

Plastics and Microplastics

Plastics, including microplastics, are another major concern in food waste streams. These materials can increase the viscosity of the biogas reactor contents, slowing down the digestion process and reducing overall efficiency. Moreover, the presence of plastics in the final digestate raises environmental concerns, particularly when this material is used as fertilizer. The Seditank’s ability to remove plastics before they enter the digestion process is crucial in maintaining the integrity of the final product and ensuring compliance with environmental standards.

If for example even as little as 0.05% of plastic is left in the pulp without a Seditank, at a throughput of 10tph, that’s 50kg of micro and nano scale plastic particles per daily 10 hour shift that scientists estimate will be un-degraded for about 450 years.

That’s up to 20 tonnes per month of inert material going into a digester tank, dead space within the digester that will proportionately degrade the efficiency of the reaction.

The Seditank works for all digester feed requirements up to 12% w/w above which the higher viscosity of the pulp prevents the plastic from rising to the surface of the tank from which it is mechanically removed.

Metal Contamination

In cases where the depackaging or separation system grinds metals into tiny pieces, these contaminants must also be removed to prevent issues in fertilizer production. The Seditank is capable of handling this, ensuring that the final output is free from harmful metal contaminants.

Performance and Efficiency

The Drycake Seditank is engineered for high performance and efficiency, with key features that make it an essential tool for food waste management:

• Washing Efficiency: Achieves a washing efficiency of organic matter of 90% or greater.
• Grit Removal: Offers a grit removal efficiency of 95% or greater.
• Floatable Matter Reduction: Reduces floating matter, including plastics, by 97%.
• Grit Dryness: Ensures 90% dryness of the captured grit, making disposal easier and more cost-effective.
• High Reliability: Built with durable materials and designed for long-term use with minimal maintenance.
• Compact Design: The Seditank’s compact footprint allows it to be easily installed in a variety of settings, from food processing plants to waste management facilities.

System Configuration and Customization

The Seditank can be configured as a complete stand-alone unit and integrated with any screening system to enhance its capabilities. It’s also customizable to meet specific plant requirements, making it a versatile solution for a wide range of applications.

Environmental and Commercial Benefits

Advancing the Circular Economy

By efficiently removing contaminants from food waste, the Seditank plays a crucial role in promoting a circular economy. The system’s ability to separate plastics and grit supports the recycling of these materials, reducing the need for virgin resources and minimizing overall waste generation.

Reducing Operational Costs

The Seditank’s high-efficiency separation process not only protects critical equipment from damage but also reduces the need for frequent maintenance, leading to significant cost savings. Additionally, the clean, contaminant-free organic slurry produced by the Seditank can be directly used in anaerobic digesters, improving the efficiency of biogas production and further lowering operational costs.

Enhancing Product Quality

For industries involved in the production of biogas or organic fertilizers, the quality of the input material is crucial. The Seditank ensures that the organic material fed into these processes is free from harmful contaminants, resulting in a higher quality end product that meets or exceeds industry standards.

Conclusion

The Drycake Seditank represents a significant advancement in food waste management technology. By effectively separating grit, plastics, and other contaminants from organic waste, the Seditank enhances the efficiency of anaerobic digestion processes and supports the production of high-quality biogas and organic fertilizers. Its robust design, high efficiency, and environmental benefits make it an invaluable tool for industries committed to sustainable waste management.

Investing in the Seditank is a clear demonstration of a commitment to sustainability and responsible waste management. As the demand for effective food waste recycling solutions continues to grow, the Seditank stands out as a reliable, innovative, and eco-friendly option that not only protects critical equipment but also contributes to a greener, more sustainable future.

Contact DRYCAKE for more information on how the Seditank can benefit your operations.