DOI: https://doi.org/10.15368/theses.2015.119
Available at: https://digitalcommons.calpoly.edu/theses/1477
Date of Award
6-2015
Degree Name
MS in Civil and Environmental Engineering
Department/Program
Civil and Environmental Engineering
Advisor
Nirupam Pal
Abstract
Effects of commercially available bacterial products were investigated on two common recreational pool contaminants: sunscreen and cyanuric acid (CYA). Microbial products developed by BiOWiSH Technologies, Inc. were tested for enhancing mechanical filtration and water clarification in bench-scale bioreactors, with conditions mimicking those of recreational pool water. Bacterial consortia included proprietary mixes of Bacillus, Lactobacillus and Pseudomonas, and other genera of bacteria. BiOWiSH products are either fermented on a solid substrate consisting of rice bran and soy meal, or they are mixed with a soluble diluent. Twenty-nine BiOWiSH products were tested throughout forty experiments.
Experiments were carried out to determine both the efficacy of BiOWiSH products for turbidity reduction and the mechanism by which BiOWiSH removes sunscreen from solution. In trials without mechanical filtration, the only product which showed a reduction in turbidity relative to the control, albeit inconsistently, was the solid substrate version of BiOWiSH Aqua FOGTM (Thai FOG). Experiments on BiOWiSH coupled with mechanical filtration showed a 79% average reduction of turbidity in the first 24 hrs. BiOWiSH products containing solid substrate, both active and abiotic, showed an average turbidity reduction of 90% in the first 24 hrs. In the same timeframe, soluble BiOWiSH products showed a 79% average reduction in turbidity. Thus, the solid v substrate provided an additional 11% reduction in turbidity over soluble products and un-amended mechanical filtration. Through experimentation and scanning electron microscopy, it was concluded that the primary mechanism of clarification by the solid substrate is adsorption of sunscreen to the substrate surface.
Further experiments were performed in anaerobic and aerobic environments to determine whether BiOWiSH products can remove cyanuric acid from solution through adsorption or biodegradation. Two measurement methods, turbidimetric and HPLC (high performance liquid chromatography) were used to independently quantify CYA. A reverse-phase HPLC method was developed which utilizes a phosphate buffer and methanol for the separation of cyanuric acid from nitrate and other chemical species. The solid BiOWiSH Aqua FOG product (prod. in Thailand) interfered with the turbidimetric analysis, showing false decreases in CYA. Using HPLC, there was no measureable biodegradation or adsorption of CYA by BiOWiSH products in these bench-scale tests. Significant systematic error in the HPLC analysis prevented conclusive findings; therefore, the ability of BiOWiSH products to reduce CYA from solution remains inconclusive.