A mathematical model for carbon fixation and nutrient removal by an algal photobioreactor

Abstract

A comprehensive mathematical modeling method for chlorella vulgaris (Cv) has been developed to assess the influence of nutrient concentration (N = 28-207 and P = 6-8 mg L-1) and UV irradiation intensity (I = 100-250 μE) at feed gas CO 2 concentrations (C c,g) of 0.04-5 %. The model encompasses gas-to-liquid mass transfer, algal uptake of carbon dioxide (C d), nutrient removal efficiency (RE for N and P with reference to total nitrogen TN and total phosphorus TP), and the growth biokinetics of Cv with reference to the specific growth rate µ in d-1). The model was validated using experimental data on the Cv species growth in an externally illuminated photobioreactor (PBR). The fitted parameters of the model were found to be in good agreement with experimental data obtained over the range of cultivation conditions explored. The mathematical model accurately reproduced the dynamic profiles of the algal biomass and nutrient (TN and TP) concentrations, and light attenuation at different input C c,g values. The proposed model may therefore be used for predicting algal growth and nutrient RE for this algal species, permitting both process optimization and scale-up.

Impact of CO2 concentration and ambient conditions on microalgal growth and nutrient removal from wastewater by a photobioreactor

“…4) than Period #4 (the mild season) for the MIMA strain in particular. The results are comparable to values reported in the literature (Gonçalves et al, 2016;Tang et al, 2011) The decreased bio-fixation efficiency at higher C c,g values has been attributed to diminution of the photosynthetic action of the selected microorganisms (Al Ketife et al, 2016;Znad et al, 2018b) as a consequence of the reduced pH and CO 2 mass transfer, the latter pertaining to the relatively slow rate of hydrolysis of CO 2 to H 2 CO 3 (Silva and Pirt, 1984;Sung et al, 1999). In the current study the introduction of CO 2 temporarily marginally depressed the pH, to 8.2± 0.1 for SP.PL and 6.8± 0.2 for MIMA, with recovery to the normal operational range of 8.6-9.6 (8.9± 0.2 on average) and 6.8-7.5 (7.2± 0.1 on average) for the two respective cultures taking up to 7 hrs.…”

Enhancement of CO2 biofixation and lipid production by Chlorella vulgaris using coloured polypropylene film

“…The Chlorella vulgaris (Cv) algal strain (CCAP 211/11B, CS-42) was used as described previously [21,22]. Experiments were conducted in 350 mL cylindrical glass columns (ID = 4 cm), each with a 250 mL working volume.…”

“…TP RE for CT W and CT N were similar at 92% and 90% respectively. P removal is impacted more than N removal by pH via abiotic precipitation, although assimilation by algae remains the primary P removal mechanism [21]. The CT W filtered spectrum contains a wide variety of wavelengths, peaking at 413 nm, that can significantly enhance Cv growth and so nutrient uptake.…”

Analysis of the Emergent Climate Change Mitigation Technologies

“…In this scenario, the CO 2 is provided by an existing industrial stream, as well as for the nutrient elements. There has been increasing interests on the use of microalgae growing technology for both bio fixation of carbon dioxide from flue gases [ 36 , 37 , 38 , 39 , 40 , 41 ] and removal of nutrients from wastewater [ 40 , 41 , 42 , 43 , 44 ]. Another consideration that needs to be done is related with the kind of light energy provided to the microalgae growing system.…”