Integrated co-limitation kinetic model for microalgae growth in anaerobically digested municipal sludge centrate

Abstract

Microalgae have a substantial potential as a renewable energy resource, but sustainable microalgae-based bioenergy production has to find an inexpensive water and nutrient resource. Wastewater has been considered as such a resource to reduce environmental impacts and economic burdens of microalgae cultivation. Understanding of microalgae growth kinetics in wastewater is necessary to improve microalgae productivity for successful implementation of the integrated microalgae-wastewater system. This study presents an integrated colimitation kinetic model of microalgae growth in anaerobically digested municipal sludge centrate. Nitrogen (N), dissolved carbon dioxide (CO 2 ) concentrations, light intensity (I), and temperature (T) were selected as major growth factors in the model. The model framework was constructed by combining threshold and multiplicative structures to explain the relationship among these factors. Depending on culture conditions, the integrated model consists of alternative rate expressions for factors selected. These expressions include the Andrews and Monod models for both CO 2 and N, and the Chalker and Muller-Fuega models combined with the Arrhenius equation for light intensity and temperature. The model was calibrated and validated using batch studies with anaerobically digested municipal sludge centrate as wastewater source. Criteria to select the rate expressions considering limitation conditions include NH 4 -N ≤ 150 mg L −1 , aqueous CO 2 ≤ 50 mg L −1 , and light intensity ≤ 90 μmol photon m −2 s −1 . Above these ranges, the rate expressions considering both limitation and inhibition were applied to the model. The model was shown to have a reasonable growth rate prediction of Chlorella sp. under different nutrient levels of the centrate.

Tuning the Solid Retention Time to Boost Microalgal Productivity and Carbon Exploitation in an Industrial Pilot-Scale LED Photobioreactor

“…24,34 It should be mentioned that the protein content of Spirulina is quite variable in the literature, with values ranging from 30% up to 75%, 18,24,34 which is however strongly related to the cultivation system and the biomass productivity. Moreover, it is known that the pigment content is higher under lower irradiances, 22,35 which however do not guarantee high biomass productivity. In fact, in Borella et al, 18 an increase in the incident light intensities corresponded to an increase in biomass productivity, but not in the protein content, while in Chuei Matsudo et al, 24 at the same light intensity, the protein content and productivity reached their maximum value at a lower residence time.…”

Mathematical Model of Closed Microecosystem “Algae – Heterotrophic Bacteria”

“…Начальные условия для системы уравнений (11):  10 14 e -0.5 [20] a параметры рассчитаны на основе данных [16] b параметры рассчитаны на основе данных для P. putida и P. aeruginosa [17] c параметры рассчитаны на основе данных для P. putida [18] Динамика концентраций компонентов МЭС показаны на рисунках 3-5. Также исследовалась замкнутая микроэкосистема состоящая из водоросли Scenedesmus obliquus и гетеротрофных бактерий Pseudomonas sp.…”

Are microbes colimited by multiple resources?

“…At this time, there is limited information about colimitation in other microbial ecosystems, although there are isolated examples in animal microbiomes [39], streams [32,40], groundwater bacteria [41], wastewater sludge [42], and specialized habitats such as hypersaline lakes [43]. This may be because of the difficulty in experimentally assessing even a single resource limitation in these systems.…”