Algal turfs in an ATS environment are highly productive, removing nutrients and CO2, increasing O2 , and elevating pH.

Given strong current, surge or wave action, sunlight and regular grazing, or harvest, algal turfs can be highly efficient at capturing solar energy. Most individual cells of algal turfs are photosynthetic; however, the high level of efficiency of algal turfs is also partly the result of mixing: flowing water, forced against cells by surge, greatly increases chemical exchange. Photosynthesis in most higher plant and planktonic algal cells is biochemically inhibited in full sunlight, especially at high temperatures. Algal turfs in ATS systems are not photo or temperature inhibited.

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Fig. 1
Phosphorus removalas function of loading; comparison of ATS with managed marshland

Because of the back and forth swashing of filaments in wave surge, individual cells in an ATS receive flashing light and no cells are fully shaded by others. The typical problem of terrestrial plants: water loss, stomata closure and CO2 cut off does not occur. As measured by oxygen release, there is no inhibition in ATS even in full tropical summer sun at mid day. A very high proportion of light energy captured is transferred to chemical storage as added biomass.

Recent research published in the Journal of Phycology (2013) shows that the manipulation of the screen substrate can significantly improve both water purification performance and biomass production.

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Fig. 2
This diagram shows the significant improvement in ATS performance obtained by using a more complex basal screen (3-D) as compared to the standard 2-D screen. It also shows that both temperature and light are important elements of ATS performance.