Conference article

Chemical equilibrium model to investigate scaling in moving bed biofilm reactors (MBBR)

Vasan Sivalingam
Department of Process, Energy and Environmental Technology, University of South-Eastern Norway, Norway

Osama Ibrahim
Department of Process, Energy and Environmental Technology, University of South-Eastern Norway, Norway

Sergey Kukankov
Department of Process, Energy and Environmental Technology, University of South-Eastern Norway, Norway

Babafemi Omodara
Department of Process, Energy and Environmental Technology, University of South-Eastern Norway, Norway

Eshetu Janka
Department of Process, Energy and Environmental Technology, University of South-Eastern Norway, Norway

Shuai Wang
Biowater Technology AS, Norway

Carlos Dinamarca
Department of Process, Energy and Environmental Technology, University of South-Eastern Norway, Norway

Hildegunn Haugen
Department of Process, Energy and Environmental Technology, University of South-Eastern Norway, Norway

Rune Bakke
Department of Process, Energy and Environmental Technology, University of South-Eastern Norway, Norway

Download articlehttps://doi.org/10.3384/ecp20170139

Published in: Proceedings of The 60th SIMS Conference on Simulation and Modelling SIMS 2019, August 12-16, Västerås, Sweden

Linköping Electronic Conference Proceedings 170:21, s. 139-144

Show more +

Published: 2020-01-24

ISBN: 978-91-7929-897-5

ISSN: 1650-3686 (print), 1650-3740 (online)

Abstract

Moving bed biofilm reactor (MBBR) is a robust, flexible and compact technology for treatment of medium to high strength wastewater. However, while treating with high concentration of ammonium, phosphorus and metal ions, the biofilm carriers can sink to the bottom of reactors. That leads to less carrier motion, higher energy consumption and deteriorated mass transfer, causing lower process efficiency and increased operational cost. This can be a major operational challenge for certain types of wastewater. In this study, scaling on biofilm carriers in an MBBR reactor treating reject water from anaerobically digested wastewater sludge was investigated. The metal ion concentrations in the reject wastewater were analyzed using microwave plasma-atomic emission spectroscopy (MP-AES). The chemical equilibrium tool Visual MINTEQ was applied to determine the possible mineral precipitates from the measured concentrations and alkalinity. Dry biomass and precipitates from biofilm carriers were digested by a DigiPREP digestion system and element analysis performed using MP-AES for validation. The results show that Fe3+ and Ca2+ had the highest potential to form mineral precipitates and scaling on the biofilm carriers. Hematite, Maghemite, Hydroxyapatite, Geothite and Magnesioferrite were the first predominant forms of precipitates. The saturation indices (SI) of these minerals increased with pH, implying that measures to lower pH may reduce the problem. Digested biomass composition and inorganic solid analysis confirmed that calcium is the major cause for scale formation. Crystal formations in the biofilms were confirmed by optical microscopy images.

Keywords

Visual MINTEQ, scaling, moving bed biofilm reactor, reject water

References

American Public Health Association (APHA). Standard Methods for the Examination of Water and Wastewater, 19th ed. American Public Health Association, American Water Works Association and Water Pollution Control Federation, Washington D.C, 1995.

R. Chand. Struvite forming possibility based on the component concentration in liquid phase of anaerobically digested sludge at varying temperature and pH and phosphorus recovery using acetate and tris buffer solution a case study at aalborg west wastewater treat, International Journal of Recent Scientific Research, 9(7): 28198-28208, 2018.

S. Daneshgar, A. Buttafava, D. Capsoni, A. Callegari, and A. Capodaglio. Impact of pH and ionic molar ratios on phosphorous forms precipitation and recovery from different wastewater sludges. Resources, 7(4): 71, 2018.

X.D. Hao, C.C. Wang, L. Lan, and M. Van Loosdrecht. Struvite formation, analytical methods and effects of pH and Ca2+. Water Science and technology, 58 (8): 1687-1692, 2008.

G. Jia. Nutrient Removal and Recovery by the Precipitation of Magnesium Ammonium Phosphate, Faculty of Engineering, Computer and Mathematical Sciences, The University of Adelaide, Adelaide South Australia, 2014.

J.H. Harker, and J.F.B. Richardson. Chemical Engineering. Butterworth-Heinemann, Oxford, 2013.

M. Piculell. New Dimensions of Moving Bed Biofilm Carriers: Influence of biofilm thickness and control possibilities, Doctoral Thesis. Department of Chemical Engineering, Lund University, Lund, 2016.

R. E. Sharp, R. Vadiveloo, M. Fergen, P. Moncholi, D. Pitt, M. Wank, and R. Latimer. A theoretical and practical evaluation of struvite control and recovery. Water Environment Research, 85(8): 675-686, 2013.

B. Tansel, G. Lunn, and O. Monje. Struvite formation and decomposition characteristics for ammonia and phosphorus recovery: A review of magnesium-ammonia-phosphate interactions. Chemosphere, 194:504-514, 2018.

I. Çelen, J.R. Buchanan, R.T. Burns, R. Bruce Robinson, and D. Raj Raman. Using a chemical equilibrium model to predict amendments required to precipitate phosphorus as struvite in liquid swine manure, Water Research, 41(8):1689-1696, 2007.

I. Çelen, and M.Turker. Chemical equilibrium model of struvite precipitation from anaerobic digester e?uents. Turkish J. Eng. Env. Sci., 34:39 – 48, 2010.

H. Ødegaard. Innovations in wastewater treatment: the moving bed biofilm process. Water Science and Technology, 53(9): 17-33, 2006.

Citations in Crossref