Managing Microalgae at the Pilot Scale

Transcription

1 Managing Microalgae at the Pilot Scale 7 th Algae Biomass Summit October 1 st, :30 PM Schonna R. Manning, Ph.D. Research Associate

2 Introduction Applied Phycology *water proteins lipids + CO 2 carbs biomass fertilizers O 2 nutraceuticals inorganic fertilizer ash fuel specialty chemicals CO 2 + H 2 O + γ O 2

3 Introduction Applied Phycology Sustainable, large-scale algaculture requires many considerations Detail product(s) Select strain(s) Optimize culturing conditions Scale up cultures Optimize productivity Product accumulation

4 Introduction Applied Phycology Top 25 Cultures UTEX# Genus Species 1648 Selenastrum capricornutum 1185 Neochloris oleoabundans 572. Botryococcus braunii 2505 Haematococcus pluvialis 2441 Botryococcus braunii 999 Dunaliella tertiolecta 2340 Spirulina platensis 2164 Nannochloropsis oculata 2714 Chlorella vulgaris 572 Botryococcus braunii 1237 Scenedesmus dimorphus 1644 Dunaliella salina 2308 Skeletonema costatum 1926 Spirulina platensis 987 Isochrysis galbana 259 Chlorella vulgaris 2658 Chaetoceros gracilis 2054 Thalassiosira sp Microcystis aeruginosa 26 Chlorella vulgaris 640 Phaeodactylum tricornutum 2307 Isochrysis aff. galbana 2342 Spirulina maxima 2629 Botryococcus sudeticus 395 Chlorella vulgaris Every strain is unique.

5 Optimizing Growth Economical Feedstocks Large-scale cultivation requires inexpensive sources of nutrients. Nitrogen Phosphorus Potassium Calcium Magnesium Iron Sulfur Trace minerals Other supplements? Buffers? B3N Bold's 3N medium mm N 8.82 P 1.72 K 2.15 Ca 0.17 N:P 5.13 A B C D E F G H 50 µein/m 2 /s, 32 C, 16 h:8 h light:dark cycle, constant aeration with 1.5% CO 2 enrichment

6 Optimizing Growth Economical Feedstocks Minimum inputs were evaluated. 25 Polyculture Millions of cells/ml B3N Low N-P-K Hours post-inoculation 50 µein/m 2 /s, 32 C, 16 h:8 h light:dark cycle, constant aeration with 1.5% CO 2 enrichment

7 Optimizing Growth Economical Feedstocks Nutrient concentrations were optimized Polyculture High N-P-K Millions of cells/ml B3N Hours post-inoculation 50 µein/m 2 /s, 32 C, 16 h:8 h light:dark cycle, constant aeration with 1.5% CO 2 enrichment

8 Optimizing Growth Economical Feedstocks Nutrient concentrations were optimized Polyculture High N-P-K Millions of cells/ml B3N Hours post-inoculation More than 10 agricultural-grade formulations have been developed for the growth of cyanobacteria and microalgae. 50 µein/m 2 /s, 32 C, 16 h:8 h light:dark cycle, constant aeration with 1.5% CO 2 enrichment

9 Optimizing Growth Kinetics Polyculture (32 C) Nutrition and growth rates are highly variable among species of algae, as well as their optimal culturing conditions. Temperature Light intensity Aeration CO 2 enrichment Mixing Millions of cells/ml Millions of cells/ml Days post-inoculation Polyculture (18 C) Days post-inoculation 50 µein/m 2 /s, 32 C, 16 h:8 h light:dark cycle, constant aeration with 1.5% CO 2 enrichment (n = 10)

10 Optimizing Growth Kinetics Growth curves are used to predict trends in cultures. Measure growth rates Define target culture density Determine harvesting frequency 50 µein/m 2 /s, 32 C, 16 h:8 h light:dark cycle, constant aeration with 1.5% CO 2 enrichment (n = 10)

11 Optimizing Growth Productivity Consider the following: a culture that doubles once per day the culture has a maximum density of 1 g/l a culture facility that holds 100 L

12 Optimizing Growth Productivity Routine harvesting was initiated once cultures reached the targeted density. Daily Harvesting

13 Scaling Up Emergent Problems Scaling cultures up to larger and larger volumes has emergent problems. economy of scale Mini-ponds at AzCATI, Mesa, AZ axenic cultures control Cultures are dynamic and must be managed.

14 Scaling Up Emergent Problems Scaling up production usually results in economy of scale. Medium-scale pond at AzCATI, Mesa, AZ However, culture growth rate and maximum obtainable density are lower than in smaller volumes due to the inability to control light, temperature, and competing organisms.

15 Scaling Up Emergent Problems Contamination is expected. Other algae Grazers Fungi Bacteria Can mitigate contamination in closed systems.

16 Pilot-Scale Cultivation Improving Productivity UTEX began working with AlgEternal and Georg Fischer Piping Systems to optimize the productivity of microalgae in Vertical Growth Modules. Closed-loop design Compatible with GM algae Modular construction AlgEternal Headquarters in Weimar, Texas Units operate independently to minimize cross-contamination and culture crashing events

17 Pilot-Scale Cultivation Improving Productivity Can achieve sustained growth and higher areal productivity in vertical tubular photobioreactors. Areal Productivity = grams of ash-free dry biomass per unit area unit time (g/m 2 day) A vertical cultivation system can hold more volume on the same footprint. 1 m 1 m

18 Pilot-Scale Cultivation Improving Productivity Medium-scale photobioreactors at the UT Algae Culturing Facility and Welch Greenhouse.

19 Pilot-Scale Cultivation Improving Productivity N Experimental photobioreactor array at the UT Algae Culturing Facility.

20 Monitoring Cultures Analysis of Biochemical Contents Cultures are monitored for the presence and abundance of desirable compounds. A freshwater diatom, Surirella ovalis UTEX# FD318, as viewed at 1000X with DIC (A), chlorophyll autofluorescence (B), and Nile Red fluorescence (C). Photo credit : D. Nobles Algal extracts were examined using TLC for the rapid screening of lipid content.

21 Growing Forward Sustainable production of microalgal biomass is possible: strain selection optimization of growth conditions use of economical resources culture management Vertical photobioreactors improve areal productivity: mitigation of emergent problems optimization of reactor geometry

22 Acknowledgements UTEX is grateful to the University of Texas College of Natural Sciences, the UT Algae Culturing Facility, AlgEternal Technologies, and to Georg Fischer Piping Systems for providing piping and other support for this project. Thank You