Flocculation followed by centrifugation is the one to achieve your need

You can try and sieve your algae through 10micron? 20micron? sieve (depend on the size of your algae) followed by centrifugation..

Best is sieving the algae through net and centrifuge..

Could you please describe in more details your algae because I performed in former time a large scale cultivation of algae two times (Aquaculture) and (Carboys).

Another question what is your purpose of this cultivation, do you interested in endo- and exo-metabolites or something else??

I am working on macroalgae and thats why we dont need for sieving bt 4 ur case it could be benificial....we are looking for agar and other components specially one with antioxidant properties..

I suggest use of a continuous centrifuge; at least for use in research

Depend on the algal species it will changes. let me know on which sps r u working

I cultured two Nostoc species in big bottles. I need high biomass for HPLC.

I worked in Libratory of Finland in cyanobacteria group. I learned a good method for harvesting the algae from Ludmila.

After disconnecting the filter of air from each big bottle, you should wait for 30 minutes, if you were lucky most of the biomass will be participate. So you can withdraw the medium, except the biomass that is participating. We didn’t use the big centrifuge; we used a very tall tube that covered with a rubber, so we crashed all of the biomass from wall of big bottles.

It was a very good method, but you should be patient.

For most purposes Jayachuandru's answer is correct. Flocculation wiith a cationic polymer and then centrifugation. For the volumes you are working with you could try either a continuous centrifuge or one with 500 ml bottles.

I suggest filtration through cheese cloth

we use ultra-filtration method to separate the cells from the media. so far that it gives us the best result in term of dewatering purpose, the cells still intact and the viability reaching more than 80%. When re-innoculate they will grow again

Allow your algae broth to settle overnight. Next day you will see cells settled, decant the supernatant and use concentrated cell mass for centrifuge. If you want to do it fast may add any flocculating agent like alum. If want to fully dry algae then you may subject the concentrated biomass to spray drying provided the choice of compound in algae is resistant to heat. If you want to use filtration under vacuum then see that you have enough surface area available but you will be able to use filter cloth only once or twice.

You have got a lot of useful answers, I can add not much new to these... The harvesting method really depends on the species/strain. Sedimentation is not working in some cases, especially for certain cyanobacteria. For collecting large biomass we use centrifugation or - when it is not possible - filtration by plankton nets.

Good luck!

The most generic method is the use of crossflow microfiltration. Filtration does depended on size but more on the quality of the microalagea. This is scalable from 500 ml upto tonnes of water to be processes. We have a range of rigs that can do this upto 1 tonne.. For 25 litres we use a small micorfiltration rig that can concetrate upto 100 times the origanal material. the rig constis of a 25 litre vessle connectect to a pump and a hollow fibre membrane module (0.4 m2 membrane area) this can concentrate the cells in about 30-1h mins. The only problems are 1.) that some algae cannot withstand the action of the centrifugal pump (flajellates) and a dying or nutrient limited culture produce extracellular carbohydrates that foul the membrane so slow down filtartion rate. The best way to removal media componants is by diafiltration (washing the concentrated cells with water/buffer). We use this method to desalt or wash the algea prior to disruption or drying.

first of all thanks to all for your beneficial suggestions...i will try the techniques suggested by you people.at present i am doing mass cultivation of Chlorella vulgaris ,when i did 500ml to 1000ml culture after centrifugation it took more than three days to get dry algae cells by lyophilization. i need plenty of algae biomass to carryout my estimation studies. then i have started my large scale cultivation process. still lot to ask and know from you guys.thanks...

Hi Vidya,

Harvesting technique depends upon the species you are tackling with. For example, Scenedesmus has natural tendency to settle down, if you leave it as such overnight. Otherwise, you can use chelating agents like ferric chloride. If you dont want to add any chemicals, then you can just change the pH of the medium. Large volume of cultures can be easily separated by these techniques. In acidic conditions separation will be quicker, however, selection of the basic pH wont bring any harm to the biological properties of the algae. Hope, this will help you Vidya.

Hi Vidya,

As Archana indicated the species type will have bearing on how simple your separation process can be, also the addition of additional chemicals will not be needed which can effect your next down stream process. With that said filtration techniques will be a process that can be used across all micro algae species. If retention of extracellular components are not an important for the following step using a 10-100 kDa RC ultra filter will work best and minimize membrane fouling. Scalability can range from bench top to large commercial scales. Concentrations can be as high as 90% wet weight with the right set-up. http://www.youtube.com/watch?v=phIJDQZ86sk&feature=plcp .

Hope all goes well in your endeavor! Jason

http://www.youtube.com/watch?v=phIJDQZ86sk&feature=plcp

Hi Vidya, as all the members suggested, sedimentation or floculation with cationic flocculant as aluminium oxide followed by centrifugation process. In the case of filtration you need to put attention about size of your microalga to select the membrane filtration size.

Please go through my paper. in Google type. mass cultivation of botryococcus braunii- you will get the answer for this

I would suggest that in case of microalgae especially chlorella and chlamydomonas species, bring down the pH to 5 or around 5. Then add alum in the concentration around 0.3125 g/L. Shake and rotate the volume well for about 2-3 minutes or say 120-130 rotations and then leave it for few hours. It will settle . But you have to check and ensure that the pH stays around 5 for a longer time. However it may vary from strain to strain as well as may depend on weather conditions.

Sorry for posting here....

I need small quantities of dried microalgae (chlorella or similar) .

We are not interested in production processes, we want to work on oil recovery. So we need dried microalgae in order to test new processes for the intesification of oil recovery yield .

Someone can help me and provide us with around 100g of dried microalgae?

Thanks.

Hello All,

I have an updated video using a crossflow set-up with larger volumes of algae being concentrated to high solids with no chemicals added.

Enjoy!

http://www.youtube.com/watch?v=H45hhvgv6Vg