Thesis published:  Duckweed Uptake of Phosphorus and Five Pharmaceuticals:  Microcosm and Wastewater Lagoon Studies

(plus new job started at WesTech Engineering, Inc.)

Duckweed Research: Presentations and Posters

Water Environment Association of Utah (WEAU)--Fall 2008 Conference Poster
"Laboratory Experiment for the Evaluation of Duckweed as a Cost-Effective Technology for Management of Nutrients and Emerging Contaminants in Municipal Wastewater Systems"

WEAU--April 2009 Conference Presentation
"Ecological Engineering That Uses Duckweed to Remove Phosphorus and Nitrogen from Wastewater"

Slides prepared for Wellsville City proposing duckweed treatment and showing Boulder City, NV, project details--Summer 2009 Slides (never presented, information only)
"Presentation for Wellsville City showing Boulder City NV equipment and results"

WEAU--Fall 2009 Poster co-produced with Maureen Kesaano
"Understanding Duckweed Systems from Harvest to Disposal"

Spring Runoff Conference (Utah State University)--April 2009 Presentation--First Place
"Using Duckweed to Remove Phosphorus and Improve Water Quality"

WEAU--Fall 2010 Conference Presentation
"A Theoretical duckweed System for Removing Phosphorus from Logan City Wastewater and How it Compares with an Algae System"

USU Environmental Engineering Seminar--Spring 2011 Presentation
"A duckweed system for removing phosphorus from Wellsville City wastewater"

1st International Conference of Duckweed Research and Applications--October 2011
"Understanding a duckweed system in a temperate climate from harvest to disposal"

1st International Conference of Duckweed Research and Applications--October 2011 (co-presenter with Dr. Louis Landesman from Virginia State University)
"Modeling the growth of duckweed populations"

WEAU--Fall 2011 Conference Presentation
"What duckweed does for lagoons"

Thesis Defense--April 17, 2012
"Duckweed uptake of phosphorus and pharmaceuticals from wastewater in Wellsville City (UT)"

DRAFT: Stirring (occasionally) Gets Rid of Aphids and Improves L. minor Productivity

Observation: occasionally stirring the water surface: #1 gets rid of aphids and #2 promotes L. minor species.

Background: I built a dissolved oxygen probe shaker to keep the probes moving in the otherwise slow-moving water column. After running the shaker for several months, I noticed that L. minor duckweed species accumulated around the probe; unlike W. borealis species which out-competed the L. minor species in un-stirred parts of the reactor (i.e. parts with no probe and no disturbance to the water surface). Later when my plants became infested with aphids I noticed that there were no aphids on the plants closes to the probes.

Hypothesis: By gently disturbing the water surface every two minutes then 1) I will promote L. minor species and prevent W. borealis species from taking over the reactors. 2) I will eliminate the aphids.

Results: I replaced the dissolved oxygen probe(s) with larger objects in order to disturb the entire water surface in two cells (0.167 m^2 each) with no disturbance in the third cell (i.e. the control). In less than a week, the L. minor plants re-established themselves and competed with the W. borealis species (prior to installing the larger "disturbing objects" the W. borealis species had already begun out-competing the L. minor species. This mean that when one looks at the water surface they would notice that 90% of the surface area was occupied by Wolffia plants and only 10% by Lemna plants).

In addition, the aphids went away!!! The aphids were always slothful to begin with and would hardly ever be seen moving around on the duckweed mat. I guess they prefer a more sedentary environment than an occasionally turbulent one.