Co-cultivation of microalgae and nitrifiers for higher biomass production and better carbon capture

Significance Statement

Dragoljub Bilanovic and colleagues investigated the co-cultivation of nitrifiers with microalgae as a non-intrusive technique for selective removal of oxygen generated by microalgae. The study is now published in peer-reviewed journal, Bioresource Technology.

According to the researchers, to tackle the challenge of climate change, processes and practices, elimination of all anthropogenic carbon emissions from CO2 must be deployed.  Current biological, chemical and physical processes being developed for carbon capture and storage are expensive to operate even when capturing and storing carbon from concentrated CO2 sources. Photosynthesis was found helpful in reducing CO2 emissions and will not decrease the concentration of the atmospheric CO2.

Microalgae will produce about 280 ton of biomass per hectare per year, which indicate that a hectare microalgal reactor will release > 500 ton CO2 to the atmosphere per year. Microalgal photosynthesis, has been found to be an excellent-natural carbon capture and microalgae biomass.

The authors calculated the oxygen excreted by microalgae into growth medium intentionally to balance the amount of oxygen needed for full oxidation of both ammonia and nitrite to provide N-NO3 for microalgal growth. The research team assumed composition of ammonia oxidizers and nitrite oxidizing to be the same. Nitrifying bacteria use large quantities of oxygen to convert ammonia to nitrate, to avoid unnecessary accumulation of extracellular products, generated by Chlorella and nitrifying bacteria the experiments were terminated at the end of exponential phase. The team immobilized nitrifying bacteria to know how immobilization affects growth and oxygen concentration in mixed culture of suspended C. vulgaris and immobilized nitrifiers.

They observed that a higher chlorophyll concentration, and higher microalgae biomass production in the mixed-culture, which was due to nitrifying bacteria decreasing the local concentration of photosynthetic oxygen at the surface of microalgae cells thereby improving C. vulgaris growth. The lowest chlorophyll concentration was measured in mixed-culture in which the initial [N]/[A B] ratio was 4.20 indicating that the concentration of nitrifiers was sufficient to affect the concentration of dissolved oxygen but not sufficiently high to eliminate oxygen inhibition.

A somewhat smaller chlorophyll concentration was found with immobilized nitrifiers, up to 30% smaller, than with nitrifiers grown in suspended mode. They found biomass and chlorophyll concentration to be significantly higher in cultures where the dissolved oxygen concentration was kept below 9.0μL L-1 this shows microalgae to be more sensitive to oxygen inhibition than currently thought.

The study concluded higher biomass production is the main way to reduce atmospheric CO2. Nitrifiers was able eliminate oxygen inhibition, enabling high levels of CO2 conversion to organic compounds via photosynthesis. The microalgae biomass production method developed in this study can be scaled up into building reactors for removal of CO2 straight from the atmosphere.

About the author

Dr. Mark A. Holland
Professor of Biology, Salisbury University, Salisbury MD, USA.
His interest in the growth of algal/microbial consortiums grows out of a primary interest in microbes as probiotic organisms for plants.  Early work focused on terrestrial plants, especially crop plants and technology developed in his lab gave birth to the biotech company, NewLeaf Symbiotics.
He received his doctoral degree in Horticulture (Breeding and Genetics) from Rutgers University and was a post-doctoral fellow in plant biochemistry at the University of Missouri before joining the faculty of Salisbury University in 1993.

About the author

Prof. Robert ArmonHead of Environmental Microbiology Lab., Faculty of Civil & Environmental Eng. – Faculty of Civil & Environmental Engineering – The Division of Environmental, Water and Agricultural Engineering – Technion, Haifa 32000, Israel.

Education B.Sc and M.Sc. – Hebrew University of Jerusalem, Israel.
D.Sc. –Technion, Israel Institute of Technology, Israel

Post-Doc USA (University of Rhode Island, with Prof. Vic Cabelli) and Canada (University of Quebec, Institute Armand-Frappier, with Prof. Pierre Payment)

Experience 30 years in Environmental Microbiology
Present research/professional specialty: bacteriological well clogging, protozoan parasites, bacteriophages, pathogenic bacteria and biofilms, sol-gel technology and enzymatic activity, photocatalysis, MFC.
Graduate students:   M.Sc. -30,          Ph.D. – 17
Aquatech Innovation Award 2013 (Amsterdam) –Category: “Innovation – not to market yet” Early biofouling detection biosensor from Mekorot National Water: Automated device for the early detection of biofouling potential of RO membranes (together with Dr. Eli Kotzer), (awarded).

Selected publication:
Armon, R., R. Araujo, Y. Kott, F. Lucena and J. Jofre. Bacteriophages of enteric bacteria in drinking water, comparison of their distribution in two countries. Journal of Applied Microbiology, 83:627-633, (1997).
Armon, R., J. Starosvetzky & I. Saad. Sol-Gel As Reaction Matrix For Bacterial Enzymatic Activity. Journal of Sol-gel Science & Technology, 19: 289-292, (2000).
Laor, Y, Zolkov, C. and Armon, R. Immobilizing humic acid in a sol-gel matrix: a new tool to study humic-contaminants sorption interactions. ES&T, 36:1054-1060, (2002).
Baram, D. Starosvetsky, J. Starosvetsky, M. Epshtein, R. Armon and Y. Ein-Eli. Enhanced photo-efficiency of immobilized TiO2 catalyst via intense anodic bias. Electrochemistry Communications, 9(7): 1684-1688, (2007).
Blumberg, I., Starosvetsky, J., Bilanovic, D. and Armon, R. TiO2 P-25 anatase rapid precipitation from water by use of struvite formation. (Journal of Colloid and Interface Science, 336(1), 107-10, 2009).
Zolkov, C., Avnir, D. and Armon, R. Tissue-derived cell growth on hybrid sol-gel films. J. Materials Chemistry, 14: 2200-2205, (2004). (Hot article by Royal Chemistry Society).

Publication– 98
“Environmental aspects of zoonotic diseases” authored by R. Armon & U. Cheruti. 2012, 497 pp., IWA Press (Published February, 2012).
“Environmental Indicators” R. Armon and Osmo Hanninen (Eds.) (Springer, February 2015) 1066 p. Top 25% on Spriger list, 40323 chapters downloads.
Chapters in books-21

About the author

Prof. Dragoljub (Drago) Bilanovic; Center for Environmental, Earth, and Space Studies. Bemidji State University, Bemidji, MN 56601, U.S.A.

Dr. Bilanovic received his degree in chemistry and biochemical engineering from the University of Sarajevo. His Doctor of Science and Master of Science degrees in applied and environmental biotechnology – environmental science are from the Technion, Israel Institute of Technology. His post-graduate studies were at the Forschungszentrum Jülich, Germany.

The objectives of his research are: a) to study the time/space dynamics of chemical species and microbial population(s) in natural and engineered systems of different salinity, and b) to use the generated knowledge to predict and optimize the expression of functions essential for: minimization of pollution, CO2 sequestration, rejuvenation of waters and other natural resources, and the green-sustainable production of food, feed and chemicals.

 Dr. Bilanovic worked as a principal and co-principal investigator, project director, and scientist on twenty projects with the total budget exceeding $3.0 million. These projects were on: photosynthetic CO2 sequestering; flocculation in fresh and saline water; nitrification, denitrification; modeling studies; sol-gel process, bio-polymers and  hydrogels; biotechnology of water, wastewater and solid waste,   and other subjects.

Bilanovic has more than hundred conference and invited presentations, referred publications, consulting reports, and four patents. Three of his paper on microalgae flocculation and CO2 sequestering were quoted over 100 times each. Bilanovic mentored 273 students in 97 undergraduate projects which were in biotechnology, photosynthetic CO2 sequestering, fermentations, and related agro-bio-eco-environmental topics.

Journal Reference

Dragoljub Bilanovic1 ,Mark Holland2, Jeanna Starosvetsky3, Robert Armon3, Co-Cultivation of Microalgae and Nitrifiers for Higher Biomass Production and Better Carbon Capture, Bioresource Technology 220 (2016) 282–288.

Show Affiliations
  1. Center for Environmental, Earth, and Space Studies, Bemidji State University, Bemidji, MN, USA.
  2. Department of Biological Sciences, Salisbury University, Salisbury, MD, USA.
  3. Division of Environmental, Water, and Agriculture Engineering, Faculty of Civil and Environmental Engineering, Technion, Israel Institute of Technology, Haifa 32000, Israel.



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