Achieving low effluent NO3-N and TN concentrations in low influent chemical oxygen demand (COD) to total Kjeldahl nitrogen (TKN) ratio without using external carbon source

• Published in: Chinese journal of oceanology and limnology Vol. 33; no. 4; pp. 1039 - 1052
• Main Authors: Cao, Jiashun, Oleyiblo, Oloche James, Xue, Zhaoxia, Otache, Y. Martins, Feng, Qian
• Format: Journal Article
• Language: English
• Published: Heidelberg Science Press 01.07.2015; Springer Nature B.V
• Subjects: Activated sludge; Anaerobic digestion; Anaerobic processes; Anaerobic treatment; Anoxia; Biological wastewater treatment; Bioreactors; Carbon; Carbon sources; Chemical oxygen demand; Chemistry; computer software; Decay rate; Denitrification; Dissolved oxygen; Earth and Environmental Science; Earth Sciences; Effluents; energy; Energy consumption; Growth rate; Heterotrophic organisms; Heterotrophs; hydrolysis; Influents; Mathematical models; nitrate nitrogen; Nitrogen; Nutrient flow; Nutrient removal; Oceanography; Operating costs; Oxygen; Oxygen requirement; Parameters; Phosphorus; Plug flow; Plugs; Polyphosphates; Saturation; Sludge; Sludge digestion; Wastewater treatment; Wastewater treatment plants; WEST2011; anaerobic anoxic oxic (A; O) process; activated sludge; BioWin AS/AD; ASM2d
• ISSN: 0254-4059; 2096-5508; 1993-5005; 2523-3521
• DOI: 10.1007/s00343-015-4201-z

Two mathematical models were used to optimize the performance of a full-scale biological nutrient removal (BNR) activated treatment plant, a plug-flow bioreactors operated in a 3-stage phoredox process configuration, anaerobic anoxic oxic (A²/O). The ASM2d implemented on the platform of WEST2011 software and the BioWin activated sludge/anaerobic digestion (AS/AD) models were used in this study with the aim of consistently achieving the designed effluent criteria at a low operational cost. Four ASM2d parameters (the reduction factor for denitrification [Formula: see text], the maximum growth rate of heterotrophs (µH), the rate constant for stored polyphosphates in PAOs (q ₚₚ), and the hydrolysis rate constant (k ₕ)) were adjusted. Whereas three BioWin parameters (aerobic decay rate (b H), heterotrophic dissolved oxygen (DO) half saturation (K OA), and Y P/acetic) were adjusted. Calibration of the two models was successful; both models have average relative deviations (ARD) less than 10% for all the output variables. Low effluent concentrations of nitrate nitrogen (N-NO₃), total nitrogen (TN), and total phosphorus (TP) were achieved in a full-scale BNR treatment plant having low influent chemical oxygen demand (COD) to total Kjeldahl nitrogen (TKN) ratio (COD/TKN). The effluent total nitrogen and nitrate nitrogen concentrations were improved by 50% and energy consumption was reduced by approximately 25%, which was accomplished by converting the two-pass aerobic compartment of the plug-flow bioreactor to anoxic reactors and being operated in an alternating mode. Findings in this work are helpful in improving the operation of wastewater treatment plant while eliminating the cost of external carbon source and reducing energy consumption.