Anaerobic Digestion

Anaerobic digestion is an environmentally friendly and effective method of treating biodegradable waste matter. Microorganisms break down the material in the absence of oxygen, creating a significant reduction in the organic load.

Sewage Sludge

Produced during the wastewater treatment process, processing and disposing of sewage sludge is a major money and energy sink. Thermophilic sludge digestion solves this problem by producing energy and reducing disposal costs.

Application

Smart sludge processing can change a sewage treatment plant (STP) from an energy consumer into an energy plant. This sustainable sludge treatment consists of dewatering and digesting the sludge, resulting in the production of biogas, while reducing the total volume of sludge.

The biogas produced can be used as a renewable source of heat and electricity, but it can also be upgraded into green gas. The heat produced by this method is partly used to achieve a neutral heat balance, which means it fits in perfectly with the idea of the STP as an energy-neutral or energy-positive plant.

Process

Thermophilic sludge digestion is a sustainable technology that eliminates pathogens and allows for a high loaded system, making the system more compact than other techniques. Digesting the sludge at a higher temperature causes it to decompose at a faster rate, which means this method generates more energy from the same amount of sludge than mesophilic digestion, as well as releasing more nutrients.

Mixing and heating system

Thanks to our proprietary mixing and heating system, DigestMix®, maintenance and inspections are made easy. The system is located outside the tank and does not require an external heat exchanger. The application and placement of DigestMix® is project-specific and serves to optimise energy and heat transfer, while ensuring optimal mixing and preventing floating layers.

Advantages

  • Thermophilic sludge digestion is a robust and reliable technique that:
  • Yields more biogas than conventional techniques
  • Decomposes organic matter at a higher rate
  • Allows for a higher nutrient-recovery rate
  • Has proven satisfying digestate dewatering
  • Uses a more compact system than mesophilic sludge digestion
  • Can be retrofitted on existing systems
  • Lowers sludge processing costs
  • Eliminates pathogens
  • Has a mixing and heating system with low operating costs

Manure Products

Whether the aim is drainable water, maximum phosphate removal or nitrogen recovery for fertilisers, manure digestion is always the first step. Not just because the resulting biogas allows for energy-neutral manure processing, but also because the leftover manure is homogeneous and will release more nutrients.

Thermophilic Digestion

At a temperature between 50 and 54°C, thermophilic digestion allows for a quick decomposition process, which keeps the digester tank smaller. In addition, thermophilic digestion produces validated manure, which can be exported without requiring additional intermediate steps. If thermophilic digestion is not possible, mesophilic digestion is the best alternative.

DigestMix®

To digest the manure, we use DigestMix®, a proprietary heating and mixing system, requiring no additional components in the digester. Maintenance can be carried out at all times, because the digester tank does not need to be opened, helping you save money.

Energy

The production of biogas is key to manure digestion. The gas can be upgraded to natural gas, which can be fed into the natural gas network, and can also be used in a Combined Heat and Power (CHP) system to produce electricity and heat. In addition, biogas can be used in Central Heating systems.

Projects

Manure digestion projects range from 10,000 to 500,000 m3 per year, from cattle to chicken manure, from the Netherlands to South Africa, and from Mexico to Japan. Major cattle and pig farmers have started digestion projects to make their business more profitable – industrial-scale systems are installed for the digestion of all local manure and co-digestion projects are built.

Poultry Manure

There’s a range of known complications when it comes to digesting chicken manure, from overly dry manure and grit contamination to excess nitrogen levels. As a result, people tend to forget that chicken manure contains biogas potential and useful nutrients. Due to the worldwide increase in the consumption of chicken and eggs, there is an abundance of chicken manure, which is why we need a process to digest this waste.

Poul-AR®

Poul-AR® is the premier system for pre-processing chicken manure. The system mixes manure and digestate from the digester, removing grit and other contaminants from the manure and extracting nitrogen. The end product is then easily fed into a (thermophilic) manure digester.

Mono-digestion

With the Poul-AR® system, chicken manure can be mono-digested, requiring no other manure or co-products, which makes it perfect for major poultry farms or poultry farm clusters. The Poul-AR® can also be used to significantly increase the proportion of chicken manure fed into a co-fermenter, for instance. Besides, chicken manure is comparable to corn in terms of biogas production, so it can bring considerable economic and ecological benefits.

Digestate Treatment

After the digestion of manure and agricultural products, a residual fraction called digestate remains. Typically, digestate cannot be used as a fertiliser without further treatment and it is usually separated into a thick and a thin fraction via different separation techniques.

The phosphate-rich thick fraction can be dried and processed, whereas the thin fraction contains high levels of organic pollutants and high nitrogen concentrations. We extract the nitrogen using AMFER® technology, after which the thin fraction can be processed into dischargeable or even reusable water.

Process

Thanks to smart aeration control and internal recirculation, SBR-NAS® technology allows for the efficient aerobic removal of 98% of all nitrogen and other organic pollutants. In addition, the aeration control enables shortcut N-removal, which means this technology consumes considerably less energy than conventional systems. Using ultra filtration membrane, the last remaining pollutants are extracted, leaving you with drainable water.

Advantages

With the SBR-NAS® system, you can stop disposing your thin digestate, and simply drain it into surface water or the sewerage system. This makes it possible to produce liquid fraction all year long, which is beneficial with regard to storage. SBR-NAS® requires less surface area and a lower energy and chemical consumption compared to conventional techniques.