The impact of microbial ecology and chemical profile on the enhanced biological phosphorus removal (EBPR) process: A case study of northern wastewater treatment works, Johannesburg
International Journal of Environmental Research and Public Health
Department of Environmental, Water and Earth Sciences, Tshwane University of Technology, Arcadia Campus, Private Bag X680, Pretoria 0001, South Africa; Department of Applied Chemistry, University of Johannesburg, P.O. Box 17011, Doornfontein 2028, South Africa
The impact of polyphosphate-accumulating organism (PAO) and glycogen-accumulating organism (GAO) populations as well as of the chemical profile on the performance of Unit-3 (open elutriation tanks) and Unit-5 (covered elutriation tank) of the City of Johannesburg Northern Wastewater Treatment Works was determined. Physicochemical parameters of wastewater samples were measured using standard methods. Bacterial diversity was determined using 16S rRNA gene amplicon pyrosequencing of the variable region V1-3. Results showed soluble COD concentrations from settled sewage for Unit-3 at 192.8 mg COD/L and for Unit-5 at 214.6 mg COD/L, which increased to 301.8 mg COD/L and 411.6 mg COD/L in the overflow from elutriation tanks and decreased to 170.9 mg COD/L and 256.3 mg COD/L at the division boxes, respectively. Both long-chain volatile fatty acids (heptanoic acid, isobutyric acid, 3-methylbutanoic acid, pentanoic acid, 4-methylpentanoic acid, methylheptanoic acid) and short-chain volatile fatty acids (acetic acid, propionic acid, isobutyric acid) were present within concentration ranges of 17.19 mg/L to 54.98 mg/L and 13.64 mg/L to 87.6 mg/L for Unit 3 and 38.61 mg/L to58.85 mg/L and 21.63 mg/L to 92.39 mg/L for Unit 5, respectively. In the secondary settling tanks, the phosphate-removal efficiency in Unit-5 appeared to be slightly higher (0.08 mg P/L) compared to that of Unit-3 (0.11 mg P/L). The average DO concentrations (2.1 mg/L and 2.2 mg/L) as well as the pH values (pH 7 to pH 7.5) were found to be slightly higher in Unit-5 in the aerobic zones. The high presence of PAOs in the bioreactors (Unit-5: Dechloromonas (14.96%), Acinetobacter (6.3%), Zoogloea (4.72%) in the anaerobic zone and Dechloromonas (22.37 %) in the aerobic zone; Unit-3: Dechloromonas (37.25%) in the anaerobic zone and Dechloromonas (23.97%) in the aerobic zone) confirmed the phosphate-removal efficiencies of both units. Negligible GAOs were found in the aerobic zones (Defluviicoccus spp.: 0.33% for Unit-5 and 0.68% for Unit-3) and in the anaerobic zones (Defluviicoccus: 9.8% for Unit-3). The high microbial diversity and a negligible percentage of GAOs in Unit-5 could contribute to its high phosphate-removal efficiency, although results did not indicate statistically significant differences between the unit with a covered elutriation tank (Unit-5) and that with open elutriation tanks (Unit-3). © 2014 by the authors; licensee MDPI, Basel, Switzerland.
4 methylpentanoic acid; acetic acid; fatty acid; glycogen; heptanoic acid derivative; isobutyric acid; isovaleric acid; methylheptanoic acid; polyphosphate; propionic acid; RNA 16S; unclassified drug; valeric acid; phosphorus; sewage; chemical oxygen demand; concentration (composition); fatty acid; microbial ecology; phosphate; phosphorus; physicochemical property; waste treatment; wastewater; water treatment; 16S RNA gene; Acinetobacter; Africa; article; case study; concentration (parameters); Dechloromonas; Defluviicoccus; enhanced biological phosphorus removal process; gene; glycogen accumulating organism; microbial diversity; microbiological parameters; nonhuman; pH; physical chemistry; polyphosphate accumulating organism; Proteobacteria; pyrosequencing; tank; waste water management; Zoogloea; chemistry; isolation and purification; metabolism; microbial consortium; microbiology; sewage; South Africa; waste management; Gauteng; Johannesburg; South Africa; Microbial Consortia; Phosphorus; Polyphosphates; Sewage; South Africa; Waste Management