Bioremediation of Polluted Water via Algal Biofilm Systems

Team: Darren Fillmore, Tyanna Doran, Isaac Trejo, and Aaron Burt

Sponsor: WesTech

Background

Rotary Algae Biofilm Reactors (RABRs):

  • Emerging technology in wastewater treatment.
  • Rotating cylinder in wastewater enables algae to form a biofilm
  • Yields more biomass than traditional planktonic algal growth

HTL Aqueous Phase (HTL-AQ) Challenges:

  • Toxicity, typically from hydrocarbons, requires additional processing to neutralize.
  • Contains valuable nutrients, notably nitrogen and phosphorus.

Methods

  • Grow algae in four sets of three RABRs & Planktonic Ponds at concentrations 0%, 20%, 30%, and 40% of HTL-AQ.
  • Water samples were taken at the beginning and end.
  • At the end of the week 7, algae was collected to obtain the dry weight of the biomass.
  • Quantified total nitrogen and phosphorus data using Hach Kits.

Results

Control RABR – Initial Conditions

Control RABR – Initial Conditions

Control RABR – Week 9 Conditions

Control RABR – Week 9 Conditions

Initial Conditions

Initial Conditions
Initial Conditions

Week 9 Conditions

Week 9 Conditions
Week 9 Conditions

Figure 1. Algal growth in planktonic state and RABRs. Each row has the following concentration percent values of HTL-AP from top to bottom: 0%, 20%, 30%, 40%.

pH Change in RABRs Over Feedings
pH Change in Planktonic Ponds Over Feedings

Figure 2. Average pH of water in RABRs and planktonic algae growth ponds over feedings.

Statistical Analysis

Figure 3.

Figure 3. The Average Biomass Mass (g) – x̄, and Standard Deviation (g) – σ, for each trial. Only one data point in the 20% HTL-AP RABRs was found to be an outlier.

Equations

Equation 1:

Equation 1

Equation 2:

Equation 2

Equation 3:

Equation 3

Equation 4:

Equation 4
Figure 4.

Figure 4. Expected biofilm assimilation capacity at a given toxin concentration. The control RABR represents an HTL-AP stream treated with DOWEX ion exchange resin.

The use of DOWEX to remove all toxic phenol and heterocyclic nitrogen compounds reduces design size by a factor of 6.3.

The use of DOWEX to remove all toxic phenol and heterocyclic nitrogen compounds reduces design size by a factor of 6.3.

Sources

[1] Algae Biofilm Reactors. Chapter 6, in: Biofilm Reactors Manual of Practice (MOP 35), 2nd ed., 2025. Water Environment Federation. J. Boltz, R. C. Sims, B. Hill [Eds).

[2] Chen, P. H.; Venegas Jimenez, J. L.; Rowland, S. M.; Quinn, J. C.; Laurens, L. M. L. Nutrient Recycle from Algae Hydrothermal Liquefaction Aqueous Phase through a Novel Selective Remediation Approach. Algal Research 2020, 46, 101776. https://doi.org/10.1016/j.algal.2019.101776.