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Closing the Loop by Combining UASB Reactor and Reactive Bed Filetr Technology for wastewater Treatment: Modelling and Practical Approaches
KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A laboratory-scale upflow anaerobic sludge blanket (UASB) reactor followed by a packed bed reactor (PBR) filled with Sorbulite® in the lower part and Polonite® in the upper part was used to treat household wastewater in a 50-week experiment. A model was developed to describe the performance of the UASB reactor, including mass transfer through the film around anaerobic granules, intra-particle diffusion and bioconversion of the substrate. In a second model, a numerical expression describing the kinetics occurring in the granules was developed. It includes the resistances through which the substrate passes before biotransformation. These expressions were then linked to governing equations for the UASB reactor in order to describe degradation of the substrate, biomass growth (active and inactive), and variation in granule size over time. A third model was developed to describe the profile of the phosphorus (P) concentration throughout the PBR. In a first attempt, the analytical and numerical model was applied to data taken from previous studies in which UASB reactors were used to treat sugarcane mill wastewater and slaughterhouse wastewater. The results showed good agreement between observed and simulated results. Sensitivity analysis showed that diffusion coefficient and yield were important parameters in the UASB reactor model.The laboratory bench-scale experiment revealed that the combined UASB-PBR system efficiently treated the residential wastewater. Phosphorus, BOD7 and pathogenic bacteria all showed average removal of 99%, while total nitrogen showed a moderate reduction in the system (40%). Application of the numerical solution model to the experimental UASB reactor used resulted in good agreement between simulated and experimental values. Regarding the PBR, the model developed successfully predicted P removal. For both models, the capability and sensitivity analyses identified important parameters. A treatment system aiming to close the loop is suggested based on sequential UASB and PBR with biogas collection, nutrient recycling via sludge and filter media and elimination of pathogenic organisms.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. , xvi, 50 p.
Series
TRITA-LWR. PHD, ISSN 1650-8602 ; 2016:02
Keyword [en]
Bench-scale experiment, Modelling, Polonite, Sorbulite, UASB, Wastewater
National Category
Environmental Engineering
Research subject
Land and Water Resources Engineering
Identifiers
URN: urn:nbn:se:kth:diva-182990ISBN: 978-91-7595-878-1 (print)OAI: oai:DiVA.org:kth-182990DiVA: diva2:906336
Public defence
2016-03-18, Sal V1, Teknikringen 76, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20160226

Available from: 2016-02-26 Created: 2016-02-24 Last updated: 2016-02-26Bibliographically approved
List of papers
1. A model to predict the behavior of UASB reactors
Open this publication in new window or tab >>A model to predict the behavior of UASB reactors
2013 (English)In: International Journal of Environmental Research, ISSN 1735-6865, E-ISSN 2008-2304, Vol. 7, no 3, 705-714 p.Article in journal (Refereed) Published
Abstract [en]

A model describing the main processes occurring in the UASB reactor was developed; in order to maintain simplicity and applicability of the model, only the fundamental aspects were considered. In the model, the reactor is divided in several well-stirred reactors coupled in series and it comprises substrate degradation, biomass growth and the reactions that take place within the granules. The important contribution of the paper is the development of a model taking into account the mass transfer through the film around the granules, the intra-particle diffusion, and the degradation reaction. The model enables the determination of the removal efficiency of the substrate and the increase of both the height of the sludge bed and the granule size with time. The simulated results of an experimental UASB reactor treating sugar-cane mill wastewater were found to be in good agreement with the performance of the reactor. The sensitivity analysis shows that the performance of the reactor is determined by several parameters. The most important parameters are: the bioconversion rate, the mass transfer coefficient in the film, the intra-particle diffusivity, the volumetric fraction of biomass in the reactor, and the number of CSTR considered. These parameters should therefore be carefully determined. The model could be a useful tool in the optimization and development of UASB reactors.

Keyword
CSTR, Kinetic, Simulation, UASB, Wastewater
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-133846 (URN)000319952600009 ()2-s2.0-84882252637 (Scopus ID)
Note

QC 20131112

Available from: 2013-11-12 Created: 2013-11-11 Last updated: 2017-12-06Bibliographically approved
2. A model to describe the performance of the UASB reactor
Open this publication in new window or tab >>A model to describe the performance of the UASB reactor
2014 (English)In: Biodegradation, ISSN 0923-9820, E-ISSN 1572-9729, Vol. 25, no 2, 239-251 p.Article in journal (Refereed) Published
Abstract [en]

A dynamic model to describe the performance of the Upflow Anaerobic Sludge Blanket (UASB) reactor was developed. It includes dispersion, advection, and reaction terms, as well as the resistances through which the substrate passes before its biotransformation. The UASB reactor is viewed as several continuous stirred tank reactors connected in series. The good agreement between experimental and simulated results shows that the model is able to predict the performance of the UASB reactor (i.e. substrate concentration, biomass concentration, granule size, and height of the sludge bed).

Keyword
CSTR, Kinetic, Model, UASB, Wastewater
National Category
Microbiology
Identifiers
urn:nbn:se:kth:diva-144112 (URN)10.1007/s10532-013-9656-z (DOI)000332797600007 ()2-s2.0-84895786597 (Scopus ID)
Note

QC 20140414

Available from: 2014-04-14 Created: 2014-04-10 Last updated: 2017-12-05Bibliographically approved
3. Sequential UASB and dual media packed-bed reactors for domestic wastewater treatment - Experiment and simulation
Open this publication in new window or tab >>Sequential UASB and dual media packed-bed reactors for domestic wastewater treatment - Experiment and simulation
2016 (English)In: Water Science and Technology, ISSN 0273-1223, Vol. 73, no 12, 2959-2970 p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
IWA Publishing, 2016
Keyword
nite, Sorbulite, Simulation, UASB, Wastewater
National Category
Environmental Engineering
Identifiers
urn:nbn:se:kth:diva-182987 (URN)10.2166/wst.2016.162 (DOI)000378546200015 ()2-s2.0-84975815567 (Scopus ID)
Note

QC 20160226

Available from: 2016-02-24 Created: 2016-02-24 Last updated: 2016-12-08Bibliographically approved
4. Phosphorus removal from UASB reactor effluent by reactive media filtration
Open this publication in new window or tab >>Phosphorus removal from UASB reactor effluent by reactive media filtration
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The phosphorus (P) and BOD7 removal performance of an upflow packed bed reactor (PBR) filled with two reactive filter media was studied over 50 weeks. The lower one-fifth of the reactor was filled with calcium-silicate-hydrate (Sorbulite®) and the upper four-fifths with calcium-silicate (Polonite®). A laboratory-scale upflow anaerobic sludge bed reactor (UASB) delivered wastewater to the PBR. A model was developed to describe the gradient in P concentration change in the reactor, based on reaction kinetics. The reaction terms were assumed to follow the Langmuir isotherm, based on results obtained in a batch test. First, a comparison was made between experimental and simulated results. The capability of the model to forecast P removal capacity was then tested for three hypothetical cases: (i) reactor filled with Sorbulite and Polonite, (ii) reactor filled with only Sorbulite and (iii) reactor filled with only Polonite. Finally, a sensitivity analysis was performed for the main parameters in the model. The results showed that average removal of P and BOD7 from the UASB effluent was 98% and 90%, respectively. The starting pH of the dual-medium effluent was 12.2 and decreased gradually over time to 11.1. The simulation both overestimated and underestimated mean measured P removal, but was within the range of maximum and minimum measured values. The hypothetical cases revealed that most P was removed by Polonite due to calcium phosphate precipitation. The removal capacity of the two filter materials and their layer height in the reactor were the most sensitive parameters in the simulation.

Keyword
Filter media, Polonite, simulation, Sorbulite, wastewater
National Category
Environmental Engineering
Identifiers
urn:nbn:se:kth:diva-182989 (URN)
Note

QS 2016

Available from: 2016-02-24 Created: 2016-02-24 Last updated: 2016-02-26Bibliographically approved

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