Description

Information
This photobioreactor is designed to be used by the Spirulina grower who wishes to grow Spirulina for his or her own consumption but also some extra for family and friends. It will work to grow other microalgae too.

During optimal growth conditions, you can harvest over 100-gram fresh Spirulina per day. Every change in surface height in centimeters corresponds to 0.29 Liter. So if you wish to grow all you can increase the volume up to 35 liter.

Photobioreactor function and design
The photobioreactor is built out of an outer transparent 200 mm column, with a spherical bottom, and an inner 150 mm transparent column. The inner column has an open bottom ending circa 15 cm above the outer columns spherical bottom. In the upper part of the inner column, there are also openings to enable the culture to move out into the outer column space. These openings are placed so that they will be underneath the culture surface to suck the culture down. The culture moves upwards inside the inner 150 mm column and down in between the inner and outer (200 mm) column.

The photobioreactor has an airlift driven circulation which enables an even exposure of the culture to the outside light. This circulation enables optimal mixing and a switching of direct light to deep culture darkness, just what the Spirulina grows best from (in pond or “raceway” cultures only the top 1-2 cm of the culture surface is exposed to the light and often by a too strong light – this will not happen here as the culture is switched over and over before this can occur).

The starting point of the circulation is from a gas stone (50 mm in diameter). This gas stone separates and spreads out the inlet gas (air) into small fine bubbles. Small bubbles have a larger total surface area compared to larger bubbles. This increases the gas to liquid transfer of CO2 and thereby enables a better culture growth. As the small bubbles leave the gas stone, they continue their path upwards inside the transparent 150 mm tube. As the bobbles go upwards, they cause a drag that pulls the culture upwards. The lifting motion moves the culture towards and to the top of the photobioreactor. There the culture can pass out to the outer column through three large 50 mm holes in the inner column. These three holes sit just underneath the top surface. As the bubbles pull the culture upwards the drag causes the culture on the outside of the inner column to be pulled downwards. This sucks (and also pushes) the culture from the inner column out into the space between the inner and outer columns. Together with the culture many of the small bubbles will also be sucked down. These bubbles will thereby stay in the culture longer and this prolonged time will increase the gas exchange even more. As the gas exchange from the bubbles, into the culture is prolonged, more CO2 can pass into the culture and the Spirulina will grow even better. As the culture moves down between the outside of the inner column (150 mm) and the inside of the outer column (200 mm) to the bottom the circle is completed and the whole rotation will start again. This way the culture will both have a great gas exchange (air to water mixing) and an even light exposure.
By regulating the gas flow, you can control the circulation and mixing time of the culture. A thin and new culture requires less mixing than a dense culture. Even though not regulated on the air pump, the pump pulls less electricity (25 W) the lower the flow is set. The lower the flow the less the air pump also sounds (40 dB). The photobioreactor sounds much less than the air pump.
Since there are four outlets on the accompanying outlet valve you can add three extra reactors to run on the same air pump. These outlets can be opened and closed as wished.
An option to the control tubing and valves is to totally bypass and not use them (check valve, gas regulator valve and four outlet valve) with the 13 mm tubing direct from the air pump to the photobioreactor. This would increase the airflow (maximum pressure 0.025 MPa), but you cannot control it since there is no check valve (only allows gas and liquid to go from and not into the air pump) possible culture or water moving backward could destroy the air pump.

Harvesting and maintenance
The tap at the bottom of the photobioreactor enables you to easily harvest the culture. The tap outlet fits a garden house (13 mm) which can be used to lead the outlet culture to a suitable area to filter the culture.
To replace the culture there is a 13 mm nipple on the top that is connected to a small 13 mm tubing with a stop at the end. The stop keeps this opening sealed from letting gas in and out. It will also stop other things such as insects to get in (the photobioreactor can be kept fully closed and ran sterile if started and ran right). By replacing the stop with a funnel or the short tubing with a hose you can easily fill the photobioreactor with a new medium or water.

Washing and cleaning the photobioreactor
When you wish to wash the photobioreactor you will open the top lid and lift out the inner column out of the inner column. Then you can wash the parts separately and then assemble the photobioreactor again. You cannot wash the reactor with naphtha, acid or alcohol detergents since these will make the transparent plastic turn white. Test on a small surface first before you continue if you are unsure. Normal detergents for the dishes work fine but use soft brushes (see more beneath in “Photobioreactor materials”).

Photobioreactor material
All steel parts, except the white holder, are made out of 316L aka 1.4404 aka A4 steel. This is corrosive resistant to the high salinity spills from the reactor. Since polycarbonate glass is made out of Bisphenol-A (aka BPA, the hormone disturbing chemical) the reactor is instead made out of the little more soft but harmless Poly(methyl methacrylate) (PMMA) also called acrylic plastic/glass. It is used in dental care and Bisphenol-A free. However, it cannot stand alcohols or oil-based (naphtha) detergents. So, if you wish to sterilize the reactor we recommend to use a steamer, chlorine or hydroxide peroxide (H2O2). Not a high concentration of chlorine or H2O2 is needed but you need to have circulation on for at least one hour to enable all parts to be reached. Carefully wash away the chlorine or H2O2 by adding clean water and then a new medium before finally adding the culture. If chloroform or H2O2 is used, all of it needs to be washed away. Even the smallest traces of it can kill a Spirulina culture. Since PMMA is a bit softer than other polycarbonates wash with softer tools to avoid scratching.

Full photobioreactor (product) component list
– Inner 150 mm column attached with the top lid (1100 mm)
– Outer 200 mm column with a sphere in the end (1300 mm)
– Other holding structures made from three 300×300 mm PMMA plates and 8 mm rods, screws, screw-nuts, washers, and an adjustable column holder. The lower part sticks out 100 mm and can be fastened into various surfaces (extra screws, screw-nuts, washers and lock washers comes is enclosed for this).
– Air pump (Flow: 30 Liter/minute / 1800 Liter/h, 25W, 220-240 V – with US and EU hole in the wall connection, 0.025 MPa, 40 dB)
– 13 mm tubing for the inlet (3 m) of gas into the photobioreactor, the outlet of gas (3 m) from the photobioreactor, and also availability to have an extra CO2 inlet (3 m) into the photobioreactor via a three-way connection with a replaceable stop on one side. The two later comes in one piece for you to cut as you like.
– 4 mm silicone tubing (5 m) for replacement of the inner reactor tubing and other replacements
– 4 valve connection – for connection 3 more photobioreactors to the air pump
– Check valve / One-way valve – to protect the air pump in case culture would move via the gas inlet out of the photobioreactor
– Gas flow regulator – to enable full gas to low or no flow into the photobioreactor.
– Extra screws, screw-nuts, washers, and lock washers to replace possible lost ones.

Shipment and delivery time
The photobioreactor will be delivered well packed and protected. If it isn’t delivered directly to your doorstep you will be notified when you can collect it at a service point. You will be able to track it.
Delivery time will vary but is circa 5 working days within Europe and 2 weeks to the rest of the world.

About HealthAlgae
HealthAlgae is a Swedish company producing clean Spirulina for human and animal consumption. As an extra service, we also help you who wish to grow Spirulina at home. From us, you can also order Spirulina cultures, full complete Spirulina nutrient mediums, information and other that can help you grow your own Spirulina, from small to large scale.

Thank you and great Spirulina or crop cultivation!

 

And remember,

You can always ask us for tips and help. We want this to work for you so we are glad to help. Just send us an email at “order – at – healthalgae dot com”

 

HealthAlgae return policy:

HealthAlgae accepts returns within 2 weeks of receiving your order.

 

HealthAlgae refund policy:

HealthAlgae gives refunds when we cannot help you in regard to your order or if you are dissatisfied with your purchase. We will try to make as much as possible for you to succeed.