Available at: https://digitalcommons.calpoly.edu/theses/1325
Date of Award
MS in Civil and Environmental Engineering
Civil and Environmental Engineering
Various bacterial products from BiOWiSHTM Technologies have been tested in dairy wastewater experiments to determine the bacterial mixes’ ability for enhanced degradation of biochemical oxygen demand (BOD), solids, and nitrate concentrations. The dairy wastewater was augmented with various bacterial composition obtained from BiOWiSHTM. The bacterial mixes experimented were US Aqua, Thai Aqua, BMT, Osprey, Fruit Wash, KLB, LCM1, and MDG. Method development was a crucial process to optimize and test the effects of the BiOWiSHTM Technologies bacterial mixes.
After 5 experiments, the BOD tests showed that for some of the tests, the redosage of bacteria helped further drive the BOD concentrations to be lower than the control. With redose, the samples reduced BOD by 10 – 55% to samples that were not redosed. Although the redose adds supplemental BOD initially, the addition showed that in some cases, the bacterial sample BOD is lower than without any redose.
For the solids testing, different solids tests showed either conclusive impacts of bioaugmentation or no effect. For the total solids (TS) and total suspended solids (TSS) tests, both showed about a 10% decrease or increase in solids throughout the experiments. The smaller solids components, volatile suspended solids (VSS), did demonstrate that the bacterial mixes reduced organic suspended solids more than the control. The bioaugmented samples reduced the VSS organic material by 5 – 15% compared to the control with BiOWiSHTM.
Particle size distribution (PSD) tests provided a breakdown of which particle sizes were increasing and decreasing. Those samples bioaugmented with BiOWiSHTM showed that smaller particles (0.7 µm pore size) were getting assimilated by the bacteria which produced more bacteria (larger pore sizes of 5 µm). After the bacteria ran out of food, the sequentially smaller pore size (2.5 µm) increased while the smaller pore sizes (1.6 µm and 0.7 µm) remained low. The rate limiting step was determined to be 1.6 – 2.5 µm where the control’s zero rate constant was +1.4 mg/L-day whereas the USA and TA was -1.1 mg/L-day and -1.4 mg/L-day respectively. Thus, the BiOWiSHTM samples decreased TSS in smaller pore size filters by about 10 – 20% more than the control.
Ion chromatography (IC) measured that nitrate levels were clearly reduced by 30 – 50% adding the BiOWiSHTM bacteria compared to the control. Therefore, the additional bacteria further denitrified the nitrate (NO3-) than if no BiOWiSHTM was added. Denitrification experiments were performed for pure Bacillus spores, KLB, that showed a 90% decrease of NO3- to the control.
Keywords: bioaugmentation, BiOWiSHTM, BOD, dairy wastewater, dissolved solids, ion chromatography, nitrate, particle size distribution, redose, suspended solids, total solids, volatile suspended solids