Congratulations to Kaitlyn Sniffen who has just published a manuscript titled “Influence of scale on biomass growth and nutrient removal in an algal-bacterial leachate treatment system” in Environmental Science and Technology. This study explores the suitability of using kinetic data garnered from small scale experiments for modeling photobioreactor performance at larger (pilot or production) scales. We illustrate that this unfortunately common practice is often innapropriate, particularly when drastic differences in scales or reactor design exist. I appreciate Kaitie giving me the opportunity to contribute to her project!

PDFs (manuscript and supplemental material) and journal links can be found on my Publications page or through the journal.

Influence of scale on biomass growth and nutrient removal in an algal-bacterial leachate treatment system
Kaitlyn D. Sniffen, Jacob R. Price, Christopher M. Sales, and Mira S. Olson. 2017. Environ. Sci. Technol. doi:10.1021/acs.est.7b03975

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Abstract
Data collected from experiments conducted at a flask scale are regularly used as input data for life cycle assessments and techno-economic analyses for predicting the potential productivities of large scale commercial facilities. This study measures and compares nitrogen removal and biomass growth rates in treatment systems that utilize an algae-bacteria consortium to remediate landfill leachate at three scales: small (0.25L), mid (100L) and large (1000L). The mid- and large-scale vessels were run for 52 consecutive weeks as semi-batch reactors under variable environmental conditions. The small-scale experiments were conducted in flasks as batch experiments under controlled environmental conditions. Kolomogov-Smirnov statistical tests, which compare the distributions of entire data sets, were used to determine if the ammonia removal, total nitrogen removal, and biomass growth rates at each scale were statistically different. Results from the Kolmogov-Smirnov comparison indicate that there is a significant difference between all rates determined in the large-scale vessels compared to those in the small-scale vessels. These results suggest that small-scale experiments may not be appropriate as input data in predictive analyses of full scale algal processes. The accumulation of nitrite and nitrate within the reactor, observed midway through the experimental process, is attributed to high relative abundances of ammonia- and nitrite-oxidizing bacteria, identified via metagenomic analysis.