Proof Of Concept
design of the filter
While meeting with algae cultivation experts this summer, we were able to gain inspiration for the large-scale
growth of our recombinant Chlamydomonas. Our model incorporates this information by utilizing the general shape
and function of a photobioreactor. In an effort to prioritize sustainability, we also felt that an important
device specification is the minimization of externally powered facets of our system. Thus, to keep our algae
mobile and oxygenated, we required a system to allow movement without a power source. A Tesla valve leverages a
cyclone shape to encourage single-direction flow without the use of an energy input.
In general, hydrocyclone
technology can be described as the application of centrifugal forces derived from the natural flow of water in a
conical vessel to separate particles in mixtures based on individual densities. Through this method, it is
possible to filter a pure column of the original liquid in a vertical outflow column. Initial modeling of our
device was performed with On Shape CAD design tools to generate 2D sketches and 3D printed plastic vinyl models
which can be used for advanced testing.
In order to separate small (10um) cells from our experimental filtrate, we adapted the use of these
hydrocyclones. Drawing from the concept of separating small particles with centrifugal force, the utilization of
hydrocyclones enables a simplified method of purifying treated water reservoirs in small batches for the express
purpose of modeling large-scale filtration processes. In particular, removing Chlamydomonas reinhardtii from
treated water posed an issue, as the design of our experiments incorporates direct application and growth of
recombineered microbes in drinking water. Calculations based around the partition curve allowed for accurate
measurements of flow rate ratios and approximate height and circumferential dimensions, which provided an
estimate for the partition number at particle sizes from 5um to 24um. While additional testing and supplemental
simulations are required to confirm separation of post-treatment Chlamy, we are confident that this design will
effectively remove the remaining live cell contaminants, and deliver filtered drinking water free from arsenic
contamination.
The final product filter will be based on the use of non-degradable non-reactive plastic polymers, PVC, and
clear tubing. Initial constructs require filters to be designed for general public health safety as well as the
proper drainage of engineered microbes to minimize leakage or contamination into the environment. A closed
filter system with both pre and post filtration testing will confirm removal of potential contaminants and
cellular debris. Theoretically, this model will situate directly into water well extraction plumbing, and
provide direct treatment of contaminated groundwater reservoirs. After multiple rounds of filtration, a final
test or inspection will confirm safety of drinkable water.
This concept was particularly difficult to model; determining simple and replicable methods of completely
removing Chlamy is difficult due to the nature of its size. Instead, natural processes were analyzed and
inspiration for the concept of the hydrocyclone was derived from the centrifugal separation of materials and the
guided size separation of particles found in ribbed shark stomachs. These two ideas were found in our final
design, yet it required significant research and calculations to determine the lower limit of the size of
particles which can be effectively filtered. While the range does permit groundwater and chlamy to be filtered,
it does not completely remove all contaminants in a single round, and there will likely be a requirement for
multiple filtration steps or repeated cycles to be run in order to reach a complete filtration of Chlamy. We aim
to improve upon this complication by improving the filtration capacity so as to minimize the time, water, and
energy consumed in the process. Another potential point of improvement revolves around the accurate and rapid
detection of Chlamy post-treatment. Hematocytometry is currently the most accurate and repeatable method of
testing for Chlamy contaminants, and it is another future focus to increase the screening methods to quickly
check for contaminants.