I have two paper already published and two coming out soon that would help answer this question. Several other papers of mine on ion exchange properties of algae and cyanobacteria dating right back to 1982 are also relevant.

Ritchie RJ (2010). Modelling Photosynthetically Active Radiation and Maximum Potential Gross Photosynthesis. Photosynthetica 48: 596-609.

Ritchie RJ (2012). The Ammonia Transport, Retention and Futile Cycling Problem in Cyanobacteria. (Published in Microbial Ecology DOI 10.1007/s00248-012-0111-1).

Thanks for the info. I have lloked through these papers. They seem to be refering to one cell and the modeling of the chemistry of a specific pollutant or substrate going into the cell. Cyanobacterial mats are highly complex systems with many microniches: from supersaturation of oxygen to anaeroby within 5mm. light gradients, pH gradient, sulfide gradient an others. I was wondering if there is any information or calculation that can teach how much m^2 of a cyanobacterial biofilm is needed to remove X% of pollutant Y from m^3 water in one hour (or something like that).

Trying to get a figure for the metabolic rate of an algal mat is not easy at all. For example photosynthesis of green algal mats can be measured quite reliably with a PAM but only a specialised PAM machines give reliable data on Cyanobacteria. I have a paper submitted to Photochemistry and Photobiology on using a PAM on photosynthetic bacteria but it is not accepted yet. Meauring PS bacterial activity in situ in an algal mat would require a special type of PAM using infrared light. For other studies look at the stromatolite literature and some of Kuhn's work. Work on sewage pond benthos might also be useful.

you asked how much can be cleaned in a given volume of water ? This will depend entirely on how long the residence time of the water is , if it is rushing by a mat it is a different condition as when the water is in contact with the mat for days.. so it is the physical contact and secondly it depends which pollutants you want to remove from the water, as each degradation rate is compound specific.. and if the pollutant gets degraded ro metabolized, if this is the case then it would also be dependant on the water temperature and as the temperature influences metabolic rate, you could go on.. therefore the question if far too broad. Margarete Kalin

Hi,

Thanks for your answers. I did my PhD on microbial mats and even published few papers about photosynthesis in mats and polished the light-dark shift method for photosynthesis. I am not sure a PAM would give a real good estimate of that in Cyanobacterial and this is due to the Muller reaction of water-water cycle. Anyway, I am aware that the question is broad. I was hoping a debate could develop over this subject. Let's assume a running river. Let's assume that all river bed is full with microbial mats and let's assume COD level of ca. 100 and ammonia level of ca. 40 (ppm). How much microbial mat surface area would 1 liter of this water would have to see in order to get to 10 ppm of these pollutants?

There is a new paper out regarding biomining of gold via microbial mats. But there the idea is the physical attachment of gold particles to the EPS. I was wondering about the metabolic rate and uptake of mats. Are they producers or consumers? Are they producers or consumers in which stage of their growth? How about day and night? What about fully anaerobic biofilms? Who would be more efficient in bioremediating water?

I would love to hear your thoughts.