Amy Lane
Honors Thesis Proposal
Testing of Different Membranes used in Wastewater Treatment Plants
Problem:
In the past few years, people have been trying to create alternate methods to treat wastewater. As
it is now, most typical wastewater treatment plants contain several processes where the water is
treated biologically, and chemically in special cases. The problems with biological systems are
that the system creates large amounts of sludge, consumes large amounts of energy, and has
difficulty removing nitrogen and phosphorous throughout the year, all of which amount to
expensive processes.
An alternate solution to wastewater treatment is to use a hydroponics system to remediate the
water. A hydroponics system is where plants grow in water, instead of soil, where the wastewater
is simply run through the roots of the plants. The plants found in wetlands need more nutrients,
and thrive under nutrient rich conditions such as those found in wastewater. Using wetland plants
in the hydroponics system will aid in the removal of nutrients from the wastewater.
This technology, of using hydroponics systems to clean wastewater was discovered in 1989,
however, it is relatively undeveloped. There are several plants throughout the country that use the
hydroponics technology, yet there is no universal hydroponics design approach due to differences
in climate, wastewater properties, and plants used. Also, it is unknown at this time how
effectively hydroponics systems are to remove trace contaminants trace contaminants present in
wastewaters receiving industrial discharges.
This research will determine the effectiveness of hydroponics systems to remove nitrogen and a
select trace contaminant. Assuming that the removal efficiency of hydroponics systems is
proportional to plant density, a lab-scale system at a representative plant density will be
constructed. Nitrogen removal rates as a function of influent nitrogen concentration will be
determined. A study of the trace contaminants in the wastewater will also be run. The variables of
the system will be the nitrogen and trace contaminant concentration in the inflow of the water.
The plant density, water flow rate, temperature, and system size will all be held constant, in order
to isolate the study of the nitrogen and trace contaminant concentration.
The findings of this research can be used in by industrial hydroponics systems in two ways. First,
if given a certain input nitrogen and contaminant flow, a plant could predict the size of the
hydroponics tank, if using the same plant density. Secondly, a plant could predict the outflow
contaminant concentration of a series of hydroponics tanks by using the removal curve that will
be generated.
Rationale:
This project will incorporate aspects of chemistry, environmental engineering, and biology, in
order to design a hydroponics system and test the input and output levels of the contaminants in
the system. An understanding of hydroponics systems, as well as chemical testing will be
important. In order to accomplish the different goals of this thesis project, a lab scale hydroponics
system will need to be built.
Methodology:
In order to accomplish the goals of this thesis, there will need to be three major facets of the
research completed. First, the growing of a hydroponics system will need to take place for the
testing to take place in. Secondly, the hydroponics system will be tested by using nitrogen rich
water to irrigate the system, and measuring the outflow contaminant levels. A study of these
results will yield a nitrogen removal rate curve for the system, which can be used to predict the
removal rates, for given influent loading, on any hydroponics system, assuming a constant plant
density. If time permits, the third stage of the research will involve the use of a trace contaminant
instead of nitrogen where the removal rates will be determined for various trace contaminants in
the influent.
The goal of this research will be to quantify the nitrogen uptake rates of a hydroponics system as
a function of nitrogen loading. By changing the nitrogen concentration that enters the system, and
measuring the outflow concentration, a removal rate for nitrogen can be established. The
synthetic wastewater used in the system will be modeled after typical wastewater found in
municipal wastewater, and will be spiked with ammonia nitrogen, which is the target contaminant
for this study. The plants used in the system will be similar to the plants found in other
hydroponics systems, which are typically wetland foliage. By closely modeling municipal
wastewater treatment plants that use hydroponics systems, it is hoped that this research will
improve the design of future plants.