Algae oil is an interesting sustainable feedstock for biodiesel manufacturing. It is an alternative to popular feedstocks, like soybean, canola and palm. Ultrasonication improves the extraction of oil from the algae cells and the conversion to biodiesel.

In comparison to traditional oil-seed crops, algae yields much more oil per acre. While soybean typically produces less than 50 gallon of oil per acre and rapeseed generates less than 130 gallon per acre, algae can yield up to 10,000 gallons per acre. In particular diatoms and green algae are good sources for the production of biodiesel.

Like other plants, algae stores energy in the form of lipids. There are various methods for extracting the oils, such as pressing, hexane solvent wash and ultrasonic extraction.

Ultrasonic Extraction of Algae Oil

Intense sonication of liquids generates sound waves that propagate into the liquid media resulting in alternating high-pressure and low-pressure cycles. During the low-pressure cycle, high-intensity small vacuum bubbles are created in the liquid. When the bubbles attain a certain size, they collapse violently during a high-pressure cycle. This is called cavitation. During the implosion very high pressures and high speed liquid jets are produced locally. The resulting shear forces break the cell structure mechanically and improve material transfer. This effect supports the extraction of lipids from algae.

 
The table below shows typical power requirements for various volume flows. The ultrasonic system is generally integrated inline. The ultrasonication reactor can be easily retrofitted into existing facilities, improving algae extraction.

Ultrasonic Preparation for Cold Pressing of Algae Oil

In particular for the purpose of pressing, good control of the cell disruption is required, to avoid an unhindered release of all intracellular products including cell debris, or product denaturation. By breaking the cell structure, more lipids stored inside the cells can be released by the application of outside pressure.

Ultrasonic Solvent Extraction of Algae Oil

The high pressure cycles of the ultrasonic waves support the diffusion of solvents, such as hexane into the cell structure. As ultrasound breaks the cell wall mechanically by the cavitation shear forces, it facilitates the transfer of lipids from the cell into the solvent. After the oil dissolved in the cyclohexane the pulp/tissue is filtered out. The solution is distilled to separate the oil from the hexane. For the sonication of flammable liquids or solvents in hazardous environments Hielscher offers FM and ATEX-certified ultrasonication systems, such as the UIP1000-Exd.

Ultrasonic Enzymatic Extraction of Algae Oil

Strong synergetic effects can be observed when combining enzymatic treatment with sonication. The cavitation assists the enzymes in the penetration of the tissue, resulting in faster extraction and higher yields. In this case water acts as a solvent and the enzymes degrade the cell walls.

Biodiesel from Algae Oil

Click here to read more about ultrasonication in biodiesel manufacturing.

Ultrasonic Algae Oil Processing From Pilot Scale to Production

We recommend pilot scale trials e.g. using 1kW systems. This will show the general effects and improvement for your particular process stream. All results can be scaled up linear to large process streams. We will be glad to discuss your process with you and to recommend further steps.

Mid-Size and Large-Scale Ultrasonicators for Industrial Biodiesel Production

Hielscher Ultrasonics supplies industrial-grade mid-size as well as large scale industrial ultrasonic processors for the efficient production of biodiesel at any volume. All system can be used to improve transesterification of any kind of feedstocks including algae oil, vegetable oils, animal fats, waste oils etc.
Since Hielscher portfolio covers ultrasonic systems for any production capacity, we can offer the ideal solution for both small producers and large companies. Ultrasonic biodiesel conversion can be operated as batch or as continuous inline process. The installation and operation is simple, safe and gives reliably high outputs of superior biodiesel quality.
Below you will find recommended reactor setups for a range of production rates.