Microbial pathways of nitrogen removal in aerobic granular sludge treating domestic wastewater

2017 ◽  
Vol 92 (7) ◽  
pp. 1756-1765 ◽  
Author(s):  
Lorena B Guimarães ◽  
Melissa P Mezzari ◽  
Gilberto C Daudt ◽  
Rejane HR da Costa
2015 ◽  
Vol 71 (7) ◽  
pp. 1040-1046 ◽  
Author(s):  
J. Wagner ◽  
L. B. Guimarães ◽  
T. R. V. Akaboci ◽  
R. H. R. Costa

This study evaluated aerobic granulation and nitrogen removal via assimilation, nitrification, and denitrification of a system fed with real domestic wastewater. The granulation process was complete after 160 days of operation. The mature granules had an almost spherical structure, an average size of 473.0 μm, and a good settling ability (SVI30 of 75.6 mL g−1). Ammonium assimilation for cell growth varied between 3.5 and 64.6% during reactor start-up. After granule formation, assimilation accounted for less than 5% and nitrogen was mainly removed by partial nitrification up to nitrite, followed by denitrification via nitrite. Average efficiencies of 86.6% for nitrification, 59.5% for denitrification, and 60.5% for total nitrogen were obtained in this period. The assimilation ability of the mature granules grown on domestic wastewater was lower than the commonly reported results obtained for synthetic granules.


2020 ◽  
Vol 58 (5A) ◽  
pp. 64
Author(s):  
Ngoc-Thuy Vu ◽  
Khac-Uan Do

Grey domestic wastewater from septic tank contains high nitrogen content and low C/N ratio. Therefore, the aerobic biological treatment is often not effective for ammonium and nitrogen removal. The aim of this work was to study the performance of nitrogen removal and production of aerobic granular sludge using biochar produced from coffee husk pyrolyzed at 350oC as biocarrier. It was performed under the lab-scale SBR systems. Low C/N ratio domestic wastewater was used for this work. Coffee husk biochar (CFH 350) was added into the systems at different dosage. As a result, the biochar made from coffee husk pyrolyzed at low temperature promoted the adhesion of sludge onto biochar surface. The particles size of biochar played an important role for adsorption and adhesion capacity of activated sludge on biochar. The growth rate of bacterial sludge was accelerated and higher than control sample when biochar was used with biochar dose of 15 g/L. Though nitrification rate was improved as the bacterial sludge was accelerated, however, at initial stage, the removal efficiency of COD and total nitrogen was not as high as compare to traditional activated aerobic sludge system.


Author(s):  
Sara Toja Ortega ◽  
Mario Pronk ◽  
Merle K. de Kreuk

Abstract Complex substrates, like proteins, carbohydrates, and lipids, are major components of domestic wastewater, and yet their degradation in biofilm-based wastewater treatment technologies, such as aerobic granular sludge (AGS), is not well understood. Hydrolysis is considered the rate-limiting step in the bioconversion of complex substrates, and as such, it will impact the utilization of a large wastewater COD (chemical oxygen demand) fraction by the biofilms or granules. To study the hydrolysis of complex substrates within these types of biomass, this paper investigates the anaerobic activity of major hydrolytic enzymes in the different sludge fractions of a full-scale AGS reactor. Chromogenic substrates were used under fully mixed anaerobic conditions to determine lipase, protease, α-glucosidase, and β-glucosidase activities in large granules (>1 mm in diameter), small granules (0.2–1 mm), flocculent sludge (0.045–0.2 mm), and bulk liquid. Furthermore, composition and hydrolytic activity of influent wastewater samples were determined. Our results showed an overcapacity of the sludge to hydrolyze wastewater soluble and colloidal polymeric substrates. The highest specific hydrolytic activity was associated with the flocculent sludge fraction (1.5–7.5 times that of large and smaller granules), in agreement with its large available surface area. However, the biomass in the full-scale reactor consisted of 84% large granules, making the large granules account for 55–68% of the total hydrolytic activity potential in the reactor. These observations shine a new light on the contribution of large granules to the conversion of polymeric COD and suggest that large granules can hydrolyze a significant amount of this influent fraction. The anaerobic removal of polymeric soluble and colloidal substrates could clarify the stable granule formation that is observed in full-scale installations, even when those are fed with complex wastewaters. Key points • Large and small granules contain >70% of the hydrolysis potential in an AGS reactor. • Flocculent sludge has high hydrolytic activity but constitutes <10% VS in AGS. • AGS has an overcapacity to hydrolyze complex substrates in domestic wastewater. Graphical abstract


2016 ◽  
Vol 44 (5) ◽  
pp. 525-531 ◽  
Author(s):  
Shuo Wang ◽  
Qianqian Yang ◽  
Wenxin Shi ◽  
Shuili Yu ◽  
Yan Wang ◽  
...  

2019 ◽  
Vol 84 ◽  
pp. 144-154 ◽  
Author(s):  
Quan Yuan ◽  
Hui Gong ◽  
Hao Xi ◽  
Heng Xu ◽  
Zhengyu Jin ◽  
...  

2020 ◽  
Vol 305 ◽  
pp. 122961 ◽  
Author(s):  
Riccardo Campo ◽  
Sara Sguanci ◽  
Simone Caffaz ◽  
Lorenzo Mazzoli ◽  
Matteo Ramazzotti ◽  
...  

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