Bioremediation of Nickel with Chlorella Vulgaris and Chlorella Pyrenoidosa

Overview

The purpose of this study was to compare the abilities of the microalgae strains Chlorella Pyrenoidosa and Chlorella Vulgaris to absorb various concentrations of nickel to evaluate their potential for bioremediation of contaminated water. It was hypothesized that there would be no significant difference between the two species' ability to absorb nickel, and no difference in removal efficiency would occur as concentrations changed within the range of the study. Three r eplicates were carried out under constant light and temperature conditions. Algae was grown in UTEX protose medium with nickel concentrations of 4 8 and 12μg/mL over 12 days. Final nickel concentrations were determined using a nickel assay, after which the interference of the growth medium was accounted for. The percentage of nickel removal was then divided by the optical density at 750nm wavelength (OD750) of the algae in each trail to account for differing algae masses. The hypothesis was rejected. Data s howed a significant difference between the absorption effectiveness of C. pyrenoidosa and C. Vulgaris (P=.002<.05), with C. pyrenoidosa removing nickel more effectively in each concentration, which could be attributed to its larger size. However, no stati stically significant difference existed between the absorption effectiveness of the algae at different concentrations (P=.06) or in how the two species reacted to increasing concentrations (P=.1). Ohio Designing and Testing UAV Propellers with Serrated Trailing and Leading Edges Inspired by Nocturnal Owl Flight to Reduce Noise and Improve Aerodynamic Performance Justice Arai University School, Chagrin Falls, OH Drones are infamous for their noise, and unfortunately, growing usage of UAVs across disciplines have increased noise pollution to negatively impact human health and the environment. Owls are known for their silent flight, with fringes at the trailing edges and leading edges of their feathers mitigating turbulent eddies and vortices, and thus, noise. This feature was implemented in a biomimetic propeller design for this project, observing the effects of each feature in question individually, as well as in conjunction to observe trailing - edge and leading-edge serration interaction. One control and five modified propellers with serrations were designed and 3D printed by the author, each possessing equal parameters. The trailing-edge fringes of the modified propellers were triangular with a height to wavelength ratio of 1:3. The leading -edge serrations had a 1:1 height-to-base ratio. The thrust and SPL at seven different speeds were recorded from 4000 RPM to 10000 RPM at 1000 RPM increments. Propellers that had both trailing-edge and leading-edge serrations were able to reduce noise at all RPMs, with a maximum of a 3.1 dBA reduction. Frequency analysis also revealed that noise levels by the control propellers were the greatest across the middle frequencies. Additionally, these modified propellers that possessed both features were able to increase thrust by 17.9%, a considerable improvement from last year’s designs that were tested. This project proved that propellers with biomimetic features can reduce noise pollution and energy consumption, in hopes of a more sustainable, noise-free future.