Algae are the oldest photosynthetic (containing chlorophyll) organisms dating back to 3.8 billion years ago.
Although they are one of the most beneficial organisms in the world
with regards to the production of Oxygen, you don’t want them in your (swimming) pool, drinking-or process water systems.
There exists a large amount of different algae species, estimated at >300.000 of which only approximately 30.000 have been studied.
Concentrations can be from hundreds up to millions of cells per milliliter.
They are eukaryotic and range from unicellular micro algae to multicellular macro algae (like seaweed).
Therefore, diversity is wide and classification is difficult:
One possible classification can be done by their pigmentation:
- green (Chlorophceae)
- brown (Phaeophyceae), of which length can be more than 30meter
- red (Rhodophyceae), causing the “red tide” (ex. UAE-2009)
- blue-green algae, which are in fact microcystin (toxin) producing prokaryotic cyanobacteria
- black by pigmentation in the mucilaginous cell-walls
- Yellow-green (Xanthophyta -Tribophyta)
Some are free floating while others form filaments that attach to the wall.
In general, for cultivation, algae need a combination of:
- light (they are photosynthetic species)
- nitrogen (nitrate, ammonia, urea…)
- minerals (potassium, magnesium, sodium, calcium, phosphate, sulfate…)
- trace elements (aluminum, zinc, copper, iron,…)
This in combination with fresh or salt water or at least an aquatic environment. As with bacteria, tropical temperatures are optimal (15-35°C).
Algae convert light energy into chemical energy and consume CO2 from the atmosphere (C02 sequestration) to release Oxygen.
Although (micro)algal biomass is currently considered as a product for the future (for biomedical, biological, food and industrial products), they are not welcome uncontrolled and at places such as:
- (fishing)ponds. Algae growth results in Ph fluctuation or acid-base (CO2/HCO3) imbalance and can become toxic
- industrial settings
- power plants
- cooling towers
- irrigation and rainwater reservoirs
- piping systems
- agricultural drip-feed installations (due to slime formation and possible blockages)
The effects of algae growth can vary from merely undesired to detrimental for industry, health or recreational reasons.
Further reading :
In the media(en) : Blue-Green algae in Brugge (Belgium)