OxyPower HTC™
A unique patented combination of wet oxidation and hydrothermal carbonization (HTC) for converting wet biowaste into useful products.
OxyPower HTC™ is the best way to convert wet biowaste
OxyPower HTC™ combines two established technologies: hydrothermal carbonization (HTC) and wet oxidation, with a compact industrial design. It’s an ideal solution for wet biowaste handling.
Energy efficient
Advanced wet oxidation technology creates the heat energy required by the HTC process. In fact, the wet oxidation process is so powerful it can generate excess heat for auxiliary use.
Multi-purpose hydrochar
The inert hydrochar produced by OxyPower HTC™ can be used as both a biofuel or as a soil improvement product. Or simply stored for future use.
N and P recovery
OxyPower HTC™ simplifies both nitrogen and phosphorus recovery. Nitrogen is extracted from the nitrogen-rich process separated water, and phosphorus is recovered from ash after the incineration of the hydrochar.
What is HTC?
Pyrolysis is the treatment of organic matter at elevated temperatures in oxygen-free conditions. This can be done with water (wet pyrolysis) or without water (dry pyrolysis). Wet pyrolysis is called hydrothermal carbonization (HTC), and is the foundation of the OxyPower HTC™ process. HTC was discovered in 1913 by the German chemist Friedrich Bergius. He was awarded the Nobel Prize in 1931 for this discovery.
What is wet oxidation?
Modern wastewater treatment plants aerate the incoming water causing oxidation, which helps break down biological material, a kind of slow wet oxidation. OxyPower HTC™ applies a very intensive wet oxidation process. This is achieved at a temperature of about 230 °C, which significantly accelerates the oxidation process. The resulting reactions produce heat, which is then used to run the entire OxyPower HTC™ process.
The OxyPower HTC™ process
The OxyPower HTC™ process treats sludge in an HTC reactor for one hour at about 200 °C. An aqueous phase is formed containing inorganic and organic water soluble components and a slurry phase containing particles of hydrochar. The organic content in the aqueous phase is then wet oxidized under pressure at 230 °C, degrading it into CO₂, water, and easily biodegradable organic acids. The resulting chemical reactions release heat, and steam is formed as the pressure is lowered. The steam is recycled and injected at the beginning of the process to heat the sludge before it is fed into the HTC reactor, thus eliminating the need for added external heat.
Vent gases from the process are treated in three steps:
Condensation with water
Scrubbing with alkaline water
Activated carbon treatment
Water separated from the sludge is sent back to the wastewater treatment plant. If the plant has biogas production, it is possible to increase the production with the separated water.
Nitrogen recovery
After OxyPower HTC™ processing, the hydrochar contains large amounts of phosphorus and nitrogen and can be spread directly on arable land, if the threshold limits for undesirable substances are not exceeded. About 60% of the nitrogen in the sludge ends up in the separated water. Nitrogen stripping is an optional stage that can be added to the OxyPower HTC™ plant, allowing for 80–90% nitrogen separation and removal from the process as ammonium sulfate.
Stripping of ammonium nitrogen from process water
The process water contains different types of nitrogen, mainly organic nitrogen and ammonium nitrogen. In the OxyPower HTC™ process, organic nitrogen is converted into ammonium nitrogen. The process can be adjusted to control the conversion rate within certain parameters. The water’s high temperature creates favorable conditions for ammonium stripping. An optional pH-adjustment feature is also available.
Modular design for fast assembly and start-up
OxyPower HTC™ plants are very compact due to the space-efficient direct heat recovery and the self-generating heat functionality, eliminating the need for external heat supply. The processing plants are specially designed for large-scale serial production.
They are constructed as easily transportable prefabricated modules, each individual module the size of 20-foot or 40-foot ISO container, making on-site assembly very easy. A standard OxyPower HTC™ main building, with a capacity of 30,000 tons dewatered sludge per year, requires an area of approximately 250 m2 with a height of 7 m.
Quick facts
OxyPower HTC™
A combination of reliable technical solutions
Debris protection
Large particles are separated by a grate and smaller particles are mechanically desintegrated in a macerator.
Gas scrubbing
The small amounts of gases created by the OxyPower HTC™ process are treated to comply with strict environmental regulations.
Remote control
A high-end DCS (Distributed Control System) allows for remote connectivity, monitoring, and alarms.
Mechanical dewatering
A high-capacity chamber filter press is used for efficient dewatering of the HTC slurry, the same type that is widely used by the mining and food industry.
All kinds of wet biowaste
OxyPower HTC™ is flexible enough to convert almost any type of wet biowaste, both digested and non-digested. Our custom-built lab can analyze your sludge to determine specific characteristics and basic process design data.
Sewage sludge
Biogas digestate
Manure
Food waste
Industrial biosludge
Agricultural residues
Fiber bank sludge
Algae and seaweed
Some kinds of biosludge contain contaminants. The high temperature in the HTC-reactor sterilizes the sludge, destroying pathogens. Heavy metals, chlorinated dioxins, PCBs and other bioaccumulative substances in the sludge are concentrated in the hydrochar.
Hydrochar
Hydrochar is a solid product formed after dewatering slurry from the HTC process. It is sterile, odorless, and storable, with considerably less volume and weight than wet sludge—as much as 80% less—which simplifies handling and transportation. Hydrochar has a dry solid content (DS) of between 55-70%, with a heat value of an average of 10 GJ per ton—about 25% of the heat value of oil.
Hydrochar can be used in a combustion plant designed for waste incineration as biofuel for heat and power production. It can also be used as a biosolid fertilizer or as soil improvement, if the environmental threshold limit values are not exceeded.
Hydrochar properties
Thermally sterilized and odorless
Easy to store
Solid
Can be pelletized