Wastewater Treatment Lagoons
The City of Logan Wastewater Treatment Lagoons will not meet future requirements for water quality under current design and operation conditions. Wastewater systems across the state of Utah that utilize lagoons also will not meet future standards. There is a need to understand current lagoon performance with regard to nutrient removal, primarily phosphorus and nitrogen, and what can be done to improve the quality of waters leaving lagoon systems. Improvements in the design and operation of existing lagoon systems for wastewater treatment my be possible based on an understanding of behavior and fate of nutrients with regard to algal growth and recycle within a lagoon system as affected by changes in temperature, nutrient composition, and pH (see Figure 1).
Benefits to State:
The ability to re-design lagoon systems and change operation parameters to improve treatment with regard to phosphorus and nitrogen through the application of algae biotechnology will enable other communities in Utah to utilize this technology for the treatment of waters and wastewaters at costs that are significantly lower than alternative technologies.
Study Area(s): City of Logan Wastewater Reclamation Facility that treats the wastewater of six towns, including Logan, Hyde Park, Smithfield, North Logan, Nibley, and Hyrum.
Areas Benefited: All areas of the state of Utah that utilize ponds or lagoons for the treatment of wastewater that includes Northern and Southern Utah.
Findings. The average percentage phosphorus removal is only 23% (from 5.2 to 4.0 mg/L) (Figure 2), and future standards will require 50% removal or more. Nitrogen removal is near 100% in the warmer weather, but poor in the colder weather, and nitrogen loss occurs by volatilization of ammonia as the pH is increased through growth of algae within the lagoon system.
Results: The AggieAir autonomous, multispectral remote sensing platform, developed at the Utah Water Research Laboratory, was used to obtain data on algae distribution across the Logan Lagoon system (Figure 4). Results indicate non-uniform distribution and low concentrations of algae within ponds comprising the Lagoon system. The uneven distribution of algae is due to the lack of mixing within each pond. Engineered mixing is required in order to improve algae growth and distribution, and simultaneous phosphorus and nitrogen uptake.
Work Plan FY09/FY10
- Monitoring Lagoon System through seasonal changes.
- Evaluate changes in design and operation through raceway bioreactors at laboratory and pilot scales.
Presentation: Sustainable Production of Biofuels from Algae. Institute of Biological Engineering 2009 Annual Conference, California (March). IBE wiki site: http://openwetware.org/wiki/Institute_of_Biological_Engineering
Figure 1. Logan Lagoon treatment system of seven ponds for a flow of 15 million gallons per day (MGD). Parallel ponds include A1/B1 and A2/B2 while Ponds C, D, and E are sequential, and retention time is 60-90 days.
Figure 2. Phosphorus concentrations in the Logan Lagoon System.
Figure 3. Nitrogen concentrations in the Logan Lagoon Systems.
Figure 4. Algae (as total suspended solids or TSS).