| Description |
Biological nutrient removal using microorganisms is a crucial part of wastewater treatment that allows for nutrient removal with minimal use of expensive chemicals. A study was performed between May 22, 2023 to August 18, 2023 on the impact of aeration on the nitrification, denitrification, and luxury uptake of phosphorus in the oxidation ditch at Central Davis Sewer District. Thirty-five samples were collected and tested in 5 different locations. The results were plotted to distinguish trends between aeration rate and nutrient removal between 3 key nutrients: ammonia, nitrate, and orthophosphorus. The plotted ammonia figures revealed that as the aeration increased, the concentration of ammonia within the ditch decreased. This is consistent with the nitrification process where the hydrogen is cleaved and replaced with oxygen to produce nitrates. As more oxygen is introduced, more nitrification will occur. Furthermore, the nitrate concentration reacts inversely to the ammonia concentration. As the aeration increases, an elevated nitrate concentration is observed in the ditch. For the removal of these two nutrients, lowering the ditch aeration to 0.6 mg/L of DO saw good removal. However, operating below this threshold or above 1 mg/L cause ammonia values to spike above 10 mg/L or to be removed entirely which is detrimental to disinfection later in the treatment process. Meanwhile, the impact of aeration on orthophosphorus removal was not as clear-cut. The variability of phosphorus concentration was lowered while step testing was performed. Comparing the ambient temperatures to the phosphorus values revealed that temperature may contribute more to phosphorus removal than aeration. Furthermore, due to the similarities in phosphorus and ammonia trends, ammonia may serve as a good control variable when trying to remove phosphorus. |
