Design and Evaluation of Rotating Algal Biofilm Reactors for Closed-Loop Engineering

Team: Abie Meek, Joshua Wintch, Tyler Wallentine, Crobin Romney, Peter Jeppesen

Sponsor: WesTech-Inc.

I. Abstract

Goal: Create valuable algae bioproducts from wastewater processing that contains at least 15% lipids, reduce the wastewater nitrogen concentration to less than 200 mg/L, and reduce the phosphorus wastewater concentration to less than 20 mg/L.

Approach: Use a two-stage rotation algae biofilm reactor (RABR) system to treat wastewater and produce algae biomass.

Results: A 2 stage system improves lipid concentration in the biomass as well as decreases nitrogen concentrations and phosphorus concentrations in system exit stream

II. Introduction

  • Rotating algae biofilm reactors (RABRs) show potential promise in processing wastewater.1
  • RABRs'productscan be used to create profitable products, such as biodiesel. 2
  • Many bioproducts, including biodiesel, require a feedstock with high lipid content. 2
  • This project receives materials and gives support to the RABR project at the Central Valley Water Reclamation Facility (CVWRF) in Salt Lake City.
RABR Project: Previous iteration
RABR Project: Current iteration

Figure 1 –Images of pilot-scale RABR project at CVWRF. Left: Previous iteration, Right: Current iteration

III. Methods

Design, build, and test three different 2 - stage RABR systems to maximize algae production. The 3 types designed are:

  1. BatchReactor
  2. ContinuousFlowReactor
  3. ReverseFlowReactor
RABR example diagrams
Mini RABR

Figure 2. Design and image of RABR systems used in experiment

IV. Results

Percent Lipid

Figure 3 –Results of percent lipids of biomass produced by each RABR system suggesting that a longer HRT yields higher lipid concentrations.

Average Nitrogen Concentrations
Average Phosphorus Concentrations

Figure 4 –Results of the nitrogen and phosphorus concentrations of the individual RABR systems.

V. Conclusions

  • The collected data supports that 2 stage systems are capable of improved lipid concentration in biomass. The data also shows an improvement inwater contaminantsdecrease in exit water stream.
  • Future research could be applied to greater in-depth quantification ofspecific rate improvements. Improved system refinement and up-scaling of 2-stage systems will continue to show the validity of the researched designs

VI. References

[1] ValchevD,RibarovaI.AReviewontheReliabilityandtheReadinessLevelofMicroalgae‐BasedNutrientRecoveryTechnologiesforSecondaryTreatedEffluentinMunicipalWastewaterTreatmentPlants.Process(2022).

[2] Griffiths,M.J.,&Harrison,S.T.L.(2009).Lipidproductivityasakeycharacteristicforchoosingalgalspeciesforbiodieselproduction.JournalofAppliedPhycology,21(5),493–507.