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Olsson, J., Forkman, T., Gentili, F., Zambrano, J., Schwede, S., Nehrenheim, E. & Thorin, E. (2018). Anaerobic co-digestion of sludge and microalgae grown inmunicipal wastewater: A feasibility study. Water Science and Technology, 77(3), 682-694
Open this publication in new window or tab >>Anaerobic co-digestion of sludge and microalgae grown inmunicipal wastewater: A feasibility study
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2018 (English)In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 77, no 3, p. 682-694Article in journal (Refereed) Published
Abstract [en]

In this study a natural mix of microalgae grown in wastewater of municipal character was co-digested with sewage sludge in mesophilic conditions, in both batch and semi-continuous modes. The semicontinuous experiment was divided into two periods with OLR 1 (Organic Loading Rate) of 2.4 kg VS m3 d-1 and HRT1 (Hydraulic Retention Time) of 15 days, and OLR2 of 3.5 kg VS m3 d-1 and HRT2 of 10 days respectively. Results showed stable conditions during both periods. The methane yield was reduced when adding microalgae (from 200 ± 25 NmL CH4 g VSin-1 , to 168±22 NmL CH4 g VSin-1). VS reduction was also decreased by 51%. This low digestability was confirmed in the anaerobic batch test. However, adding microalgae improved the dewaterability of the digested sludge. The high heavy metals content in the microalgae resulted in a high heavy metals content in the digestate, making it more difficult to reuse the digestate as fertilizer on arable land. The heavy metals are thought to originate from the flue gas used as a CO2 source during the microalgae cultivation. Therefore the implementation of CO2 mitigation via algal cultivation requires careful consideration regarding thesource of the CO2-rich gas.

Keywords
Biogas, dewaterability, Gompertz model, mesophilic, semi-continuous study, waste activated sludge
National Category
Renewable Bioenergy Research Water Engineering
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-37381 (URN)10.2166/wst.2017.583 (DOI)000424765000013 ()29431713 (PubMedID)2-s2.0-85042218057 (Scopus ID)
Projects
MAASICA-projektet
Funder
Knowledge Foundation
Available from: 2017-12-04 Created: 2017-12-04 Last updated: 2019-06-18Bibliographically approved
Thorin, E., Olsson, J., Schwede, S. & Nehrenheim, E. (2018). Co-digestion of sewage sludge and microalgae: Biogas production investigations. Applied Energy, 227, 64-72
Open this publication in new window or tab >>Co-digestion of sewage sludge and microalgae: Biogas production investigations
2018 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 227, p. 64-72Article in journal (Refereed) Published
Abstract [en]

In municipal wastewater treatment plants (WWTPs), algae could be utilised for cleaning the water and, at thesame time, produce a biomass that can be used for energy. Through anaerobic digestion, microalgae can contributeto biogas production when co-digested with sewage sludge. In this paper, previous published results onthe co-digestion of sewage sludge and microalgae are summarised and reviewed, and any remaining knowledgegaps are identified. The batch tests currently documented in literature mostly concern digestion under mesophilicconditions, and studies investigating thermophilic conditions are less common. The average biochemicalmethane potential (BMP) for 29 different mixtures co-digested under mesophilic conditions is 317 ± 101 N cm3CH4 gVS−1 while the result for 12 different mixtures investigated under thermophilic conditions is a BMP of318 ± 60 N cm3 CH4 gVS−1. An evaluation of the heat required for increasing the temperature from mesophilicto thermophilic conditions shows that increased methane production under thermophilic conditions can beenough to create a positive energy balance. For a full-scale WWTP, using thermophilic digestion on sludge, or acombination of sludge and microalgae could therefore be of interest. This is dependent on the demands onsanitation of the sludge and the possibilities for heat recovery.Most of the mesophilic investigations indicate a synergetic effect for co-digestion, with enhancements of up toalmost 70%. However, the results are uncertain since the standard deviations for some of the BMP tests are in thesame order of magnitude as the identified enhancement. Neither of the presented publications provide an understandingof the basic mechanisms that led to higher or lower BMP when microalgae were mixed with wastewatersludge. We, therefore, call for care to be taken when assuming any effects related to the specification ofsubstrates. Microalgae and wastewater sludge have several similarities, and the specific results of BMP in themixtures relate more to the specifics of the respective materials than the materials themselves.Investigations into semi-continuous processes of co-digestion of microalgae and sludge are scarce. The yieldsfor three co-digestion studies show high variation, with an average of 293 ± 112 N cm3 gVSin−1. The availableresults show strong potential for co-digestion of sewage sludge and microalgae. Further investigations are requiredto identify optimal conditions for biogas production, and analysis of microalgae implementation onwastewater treatment at a system level is also needed to identify the total mass balance of substrate and nutrientrecovery.

Keywords
Biomass Wastewater treatment Batch Continuous BMP Anaerobic digestion
National Category
Other Engineering and Technologies not elsewhere specified
Identifiers
urn:nbn:se:mdh:diva-37578 (URN)10.1016/j.apenergy.2017.08.085 (DOI)000445987200007 ()2-s2.0-85028066228 (Scopus ID)
Projects
MAASICA
Funder
Knowledge Foundation
Available from: 2017-12-27 Created: 2017-12-27 Last updated: 2018-12-18Bibliographically approved
Olsson, J., Schwede, S., Nehrenheim, E. & Thorin, E. (2018). Microalgae as biological treatment for municipal wastewater - Effects on the sludge handling in a treatment plant. Water Science and Technology, 78(3), 644-654
Open this publication in new window or tab >>Microalgae as biological treatment for municipal wastewater - Effects on the sludge handling in a treatment plant
2018 (English)In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, ISSN 0273-1223, Vol. 78, no 3, p. 644-654Article in journal (Refereed) Published
Abstract [en]

A mix of microalgae and bacteria was cultivated on pre-sedimented municipal wastewater in a continuous operated microalgae-activated sludge process. The excess material from the process was co-digested with primary sludge in mesophilic and thermophilic conditions in semi-continuous mode (5 L digesters). Two reference digesters (5 L digesters) fed with waste-activated sludge (WAS) and primary sludge were operated in parallel. The methane yield was slightly reduced (≈10%) when the microalgal-bacterial substrate was used in place of the WAS in thermophilic conditions, but remained approximately similar in mesophilic conditions. The uptake of heavy metals was higher with the microalgal-bacterial substrate in comparison to the WAS, which resulted in higher levels of heavy metals in the digestates. The addition of microalgal-bacterial substrate enhanced the dewaterability in thermophilic conditions. Finally, excess heat can be recovered in both mesophilic and thermophilic conditions. 

Place, publisher, year, edition, pages
IWA Publishing, 2018
Keywords
Dewaterability, Heat balance, Heavy metals, Microalgae, Semi-continuous study, Waste activated sludge, Algae, Anaerobic digestion, Biological water treatment, Microorganisms, Wastewater treatment, Micro-algae, Semi-continuous, Waste activated sludges, Activated sludge process, Bacteria (microorganisms)
National Category
Water Engineering
Identifiers
urn:nbn:se:mdh:diva-41017 (URN)10.2166/wst.2018.334 (DOI)000445518100018 ()30208005 (PubMedID)2-s2.0-85053616456 (Scopus ID)
Available from: 2018-09-27 Created: 2018-09-27 Last updated: 2019-06-18Bibliographically approved
Nõlvak, H., Truu, M., Oopkaup, K., Kanger, K., Krustok, I., Nehrenheim, E. & Truu, J. (2018). Reduction of antibiotic resistome and integron-integrase genes in laboratory-scale photobioreactors treating municipal wastewater. Water Research, 142, 363-372
Open this publication in new window or tab >>Reduction of antibiotic resistome and integron-integrase genes in laboratory-scale photobioreactors treating municipal wastewater
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2018 (English)In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 142, p. 363-372Article in journal (Refereed) Published
Abstract [en]

Wastewater treatment systems receiving municipal wastewater are major dissemination nodes of antibiotic resistance genes (ARGs) between anthropogenic and natural environments. This study examined the fate of antibiotic resistome and class 1–3 integron-integrase genes in photobioreactors that were treating municipal wastewater diluted (70/30) with lake or tap water for the algal biomass production. A combined approach of metagenomic and quantitative (qPCR) analysis was undertaken. Municipal wastewater treatment in the photobioreactors led to reduced antibiotic resistome proportion, number of ARG subtypes, and abundances of individual ARGs in the bacterial community. The ARGs and intI1 gene abundances and relative abundances in the discharges of the photobioreactors were either comparable or lower than the respective values in the effluents of conventional wastewater treatment plants. The reduction of the resistome proved to be strongly related to the changes in the bacterial community composition during the wastewater treatment process as it was responding to rising pH levels caused by intense algal growth. Several bacterial genera (e.g., Azoarcus, Dechloromonas, and Sulfuritalea) were recognized as potential hosts of multiple antibiotic resistance types. Although the lake water contributed a diverse and abundant resistome and intI genes profile to the treatment system, it proved to be considerably more beneficial for wastewater dilution than the tap water. The diversity (number of detected resistance types and subtypes) and proportion of the antibiotic resistome, the amount of plasmid borne integron-integrase gene reads, and the abundances and relative abundances of the majority of quantified ARGs (aadA, sul1, tetQ, tetW, qnrS, ermB, blaOXA2-type) and intI1 gene as well as the amount of multi-resistance determinants were significantly lower in the discharges of photobioreactors where lake water was used to dilute wastewater.

Place, publisher, year, edition, pages
Elsevier Ltd, 2018
Keywords
Antibiotic resistome, Integron-integrase genes, Photobioreactors, Wastewater treatment
National Category
Civil Engineering
Identifiers
urn:nbn:se:mdh:diva-40233 (URN)10.1016/j.watres.2018.06.014 (DOI)000440125800036 ()29908464 (PubMedID)2-s2.0-85049317608 (Scopus ID)
Available from: 2018-07-12 Created: 2018-07-12 Last updated: 2018-10-16Bibliographically approved
Kanders, L., Beier, M., Nogueira, R. & Nehrenheim, E. (2018). Sinks and sources of anammox bacteria in a wastewater treatment plant - screening with qPCR. Water Science and Technology, 78(2), 441-451
Open this publication in new window or tab >>Sinks and sources of anammox bacteria in a wastewater treatment plant - screening with qPCR
2018 (English)In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 78, no 2, p. 441-451Article in journal (Refereed) Published
Abstract [en]

The deammonification process, which includes nitritation and anammox bacteria, is an energyefficient nitrogen removal process. Starting up an anammox process in a wastewater treatment plant (WWTP) is still widely believed to require external seeding of anammox bacteria. To demonstrate the principle of a non-seeded anammox start-up, anammox bacteria in potential sources must be quantified. In this study, seven digesters, their substrates and reject water were sampled and quantitative polymerase chain reaction (qPCR) was used to quantify both total and viable anammox bacteria. The results show that mesophilic digesters fed with nitrifying sludge (with high sludge ages) can be classified as a reliable source of anammox bacteria. Sludge hygienization and dewatering of digestate reduce the amount of anammox bacteria by one to two orders of magnitude and can be considered as a sink. The sampled reject waters contained on average >4.0 × 104 copies mL1 and the majority of these cells (>87%) were viable cells. Furthermore, plants with side-stream anammox treatment appear to have higher overall quantities of anammox bacteria than those without such treatment. The present study contributes to the development of sustainable strategies for both startup of anammox reactors and the possibility of improving microbial management in WWTPs.

Place, publisher, year, edition, pages
IWA Publishing, 2018
Keywords
Anaerobic ammonium oxidizing bacteria (anammox), Digestion, Full-scale, QPCR, Reject water treatment, Start-up strategy, Anaerobic digestion, Bacteria, Nitrogen removal, Polymerase chain reaction, Seed, Sewage pumping plants, Sludge digestion, Water treatment, Water treatment plants, ANAMMOX, Reject water treatments, Wastewater treatment
National Category
Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-40740 (URN)10.2166/wst.2018.318 (DOI)000445517400020 ()30101779 (PubMedID)2-s2.0-85052107611 (Scopus ID)
Available from: 2018-09-07 Created: 2018-09-07 Last updated: 2019-08-15Bibliographically approved
Thorin, E., Olsson, J., Schwede, S. & Nehrenheim, E. (2017). Biogas from Co-digestion of Sewage Sludge and Microalgae. In: Energy Procedia: . Paper presented at The 8th International Conference on Applied Energy – ICAE2016 (pp. 1037-1042). , 105
Open this publication in new window or tab >>Biogas from Co-digestion of Sewage Sludge and Microalgae
2017 (English)In: Energy Procedia, 2017, Vol. 105, p. 1037-1042Conference paper, Published paper (Refereed)
Abstract [en]

Microalgae cultivated in waste water could contribute to increased biomass production at municipal waste watertreatment plants. The biomass could be utilized for biogas production when co-digested with sewage sludge. In thispaper previous published results on co-digestion of sewage sludge and microalgae are summarized and remainingknowledge gaps are identified. The available batch tests in literature mostly concern digestion at mesophilicconditions. Some of those tests indicate a synergetic effect for the co-digestion. Investigations at thermophilicconditions and of semi-continuous processes are scarce. The available results show good possibilities for co-digestionof sewage sludge and microalgae. Further investigations are needed to find optimal conditions for biogas production.

Keywords
biomass; waste water treatement; batch; continous; BMP; anaerobic digestion
National Category
Other Engineering and Technologies not elsewhere specified
Identifiers
urn:nbn:se:mdh:diva-37579 (URN)10.1016/j.egypro.2017.03.449 (DOI)000404967901020 ()2-s2.0-85020740140 (Scopus ID)
Conference
The 8th International Conference on Applied Energy – ICAE2016
Projects
MAASICA
Funder
Knowledge Foundation
Available from: 2017-12-27 Created: 2017-12-27 Last updated: 2018-07-25Bibliographically approved
Olsson, J., Schwede, S., Nehrenheim, E. & Thorin, E. (2017). Co-digestion of microalgae, grown on municipal wastewater, and primary sewage sludge–: Pilot study in thermophilic and mesophilic conditions. In: : . Paper presented at The 15th World Conference on Anaerobic Digestion, Beijing, China, October 17-20, 2017.
Open this publication in new window or tab >>Co-digestion of microalgae, grown on municipal wastewater, and primary sewage sludge–: Pilot study in thermophilic and mesophilic conditions
2017 (English)Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

The most common biological treatment in a municipal waste water today is the activated sludge process (ASP). A possible substitution of the ASP could be the utilization of microalgae for the reduction and/or transformation of nutrients. The produced algal biomass can be converted to biofuel by anaerobic digestion. In the present study, co-digestion of primary sludge and microalgae are studied in semi-continuous tests at mesophilic and thermophilic conditions. Two reactors fed by waste activated sludge and primary sludge are used as reference. The results show that thermophilic digestion of microalgae and primary sludge is less attractive since the methane yield is approximately the same as the mesophilic digestion. In mesophilic conditions the results are approximately the same in the two pilot reactors and also comparable with the mesophilic full-scale digesters in Västerås, Sweden.

Keywords
Anaerobic digestion, waste activated sludge, biogas, continuous, microalgae based activated sludge process
National Category
Other Engineering and Technologies not elsewhere specified
Identifiers
urn:nbn:se:mdh:diva-37587 (URN)
Conference
The 15th World Conference on Anaerobic Digestion, Beijing, China, October 17-20, 2017
Funder
Knowledge Foundation
Available from: 2017-12-27 Created: 2017-12-27 Last updated: 2018-03-07Bibliographically approved
Anbalagan, A., Schwede, S., Lindberg, C.-F. & Nehrenheim, E. (2017). Continuous microalgae-activated sludge flocs for remediation of municipal wastewater under low temperature. In: Peter Van der Steen (Ed.), : . Paper presented at 1st IWA Conference on Algal Technologies for Wastewater Treatment and Resource Recovery (pp. 1-8).
Open this publication in new window or tab >>Continuous microalgae-activated sludge flocs for remediation of municipal wastewater under low temperature
2017 (English)In: / [ed] Peter Van der Steen, 2017, p. 1-8Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

The operational performance of indigenous microalgae-activated sludge was evaluated regarding the nutrient removal efficiency using raw wastewater collected from Västerås wastewater treatment plant, Sweden at limited artificial surface lighting (290 μmol m-1 sec-1) and Nordic wastewater conditions (13°C). Additionally, the oxygen production and consumption, biomass concentration and its settling was evaluated during the symbiotic algal-bacterial interaction. The results confirmed oxygenic organic compound removal (COD removal of 65-94%) at higher (31-45 d) and lower (13-18 d) sludge retention time (SRT). Also, a complete removal of ammonium throughout the process and partial nitrite-nitrate removal at all SRTs (total nitrogen removal of 41- 62%) were observed. Likewise, a partial phosphorus (P)removal was observed in the effluent which provides an opportunity to capture free P fromthe effluent for recovery as fertiliser. Further, the microalgal growth was slower due to lightor inorganic carbon limitation or ammonium repression caused by higher internal recirculationas observed from ammonium and nitrite-nitrate levels in the PBR. Most importantly, effectivePBR biomass concentration based nutrient removal and relative sludge recirculation have tobe considered in the PBR design to avoid light limitation and activate symbiosis.

Keywords
Indigenous microalgae-activated sludge, Lighting, Nordic wastewater condition; Sludge retention time; Sludge recirculation
National Category
Environmental Engineering
Research subject
Biotechnology/Chemical Engineering
Identifiers
urn:nbn:se:mdh:diva-38020 (URN)
Conference
1st IWA Conference on Algal Technologies for Wastewater Treatment and Resource Recovery
Available from: 2018-01-12 Created: 2018-01-12 Last updated: 2018-05-07Bibliographically approved
Anbalagan, A., Toledo-Cervantes, A., Posadas, E., Rojo, E. M., Lebrero, R., González-Sánchez, A., . . . Muñoz, R. (2017). Continuous photosynthetic abatement of CO2 and volatile organic compounds from exhaust gas coupled to wastewater treatment: Evaluation of tubular algal-bacterial photobioreactor. Journal of CO2 Utilization, 21, 353-359
Open this publication in new window or tab >>Continuous photosynthetic abatement of CO2 and volatile organic compounds from exhaust gas coupled to wastewater treatment: Evaluation of tubular algal-bacterial photobioreactor
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2017 (English)In: Journal of CO2 Utilization, ISSN 2212-9820, E-ISSN 2212-9839, Vol. 21, p. 353-359Article in journal (Refereed) Published
Abstract [en]

The continuous abatement of CO2 and toluene from the exhaust gas by an indigenous microalgal-bacterial consortium was investigated in a pilot tubular photobioreactor interconnected to an absorption column using diluted centrate in seawater as a free nutrient source. The removal efficiency of CO2 and toluene was maximised in the vertical absorption column by identifying an optimum liquid to gas (L/G) ratio of 15. The photobioreactor supported steady-state nitrogen and phosphorus removals of 91 ± 2% and 95 ± 4% using 15% diluted centrate at 14 and 7 d of hydraulic retention time (HRT), respectively. A decrease in the removal efficiencies of nitrogen (36 ± 5%) and phosphorus (58 ± 10%) was recorded when using 30% diluted centrate at 7 d of HRT. The volumetric biomass productivities obtained at an HRT of 7 d accounted for 42 ± 11 and 80 ± 3 mg TSS L-1 d-1 using 15 and 30% centrate, respectively. Stable CO2 (76 ± 7%) and toluene removals (89 ± 5%) were achieved at an L/G ratio of 15 regardless of the HRT or centrate dilution. Hence, this study demonstrated the potential of algal-bacterial systems for the continuous removal of CO2 and volatile organic compounds from exhaust gas coupled with the simultaneous treatment of centrate. 

Place, publisher, year, edition, pages
Elsevier Ltd, 2017
National Category
Water Treatment Renewable Bioenergy Research
Identifiers
urn:nbn:se:mdh:diva-36676 (URN)10.1016/j.jcou.2017.07.016 (DOI)000411443200040 ()2-s2.0-85029771500 (Scopus ID)
Available from: 2017-10-06 Created: 2017-10-06 Last updated: 2018-05-07Bibliographically approved
Jonfelt, C., Zambrano, J., Lindblom, E. & Nehrenheim, E. (2017). Key parameters for modelling Anammox process with N2O emissions. In: French Federation of Biotechnology - Bioreactors Symposium 2017: Innovative approaches in bioreactors design and operation. Paper presented at French Federation of Biotechnology - Bioreactors Symposium 2017, Innovative approaches in bioreactors design and operation University Lille, May 15th-16th 2017, Villeneuve d'Ascq, France. France
Open this publication in new window or tab >>Key parameters for modelling Anammox process with N2O emissions
2017 (English)In: French Federation of Biotechnology - Bioreactors Symposium 2017: Innovative approaches in bioreactors design and operation, France, 2017Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

In this paper, a sensitivity analysis and a calibration were applied to a recent published model used to replicate N2O emissions in an Anammox process of a moving-bed biofilm reactor (MBBR). The model used in this study was designed to replicate a one-stage nitrification-Anammox system in a MBBR at Hammarby-Sjöstad pilot plant (Stockholm, Sweden), whichtreats of anaerobic digestion liquor. The aeration was intermittently (45/15 minutes - on/off). During the aeration, a 1.5 mg/L DO set-point was set. Three main measurements wereobtained: NH4 in water, N2O in both water and gas phase.The sensitivity analysis was done via the one-at-a-time method, where one parameter at a timeis changed (in our case, 10%) from its nominal value and the model output is quantified. Next,the most sensitive parameters were used in the model calibration. Results indicate that the biofilm porosity (η [-]), biofilm density (ρ [gTS/m3]), maximum biofilmthickness (Lmax [mm]) and boundary layer thickness of the biofilm (L0 [μm]) were the mostsensitive parameters of the model. These parameters performed the model calibration.

Place, publisher, year, edition, pages
France: , 2017
Keywords
ASMN, denitrification, greenhouse gases, sensitivity analysis
National Category
Bioprocess Technology
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-35272 (URN)
Conference
French Federation of Biotechnology - Bioreactors Symposium 2017, Innovative approaches in bioreactors design and operation University Lille, May 15th-16th 2017, Villeneuve d'Ascq, France
Projects
CONAN
Funder
VINNOVA, 2015-02422
Available from: 2017-05-01 Created: 2017-05-01 Last updated: 2018-09-19Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-3311-9465

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