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Gao, Qiuju
Publications (10 of 10) Show all publications
Gao, Q., Blum, K. M., Gago-Ferrero, P., Wiberg, K., Ahrens, L. & Andersson, P. L. (2019). Impact of on-site wastewater infiltration systems on organic contaminants in groundwater and recipient waters. Science of the Total Environment, 651, 1670-1679
Open this publication in new window or tab >>Impact of on-site wastewater infiltration systems on organic contaminants in groundwater and recipient waters
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2019 (English)In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 651, p. 1670-1679Article in journal (Refereed) Published
Abstract [en]

On-site sewage treatment facilities, particularly septic systems combined with soil infiltration, can be an important source of emerging organic contaminants in groundwater and surface water and thus represent a significant source of environmental and human exposure. Two infiltration systems in Åre municipality, Sweden, were examined to assess the occurrence of contaminants in groundwater and their fate and transport during infiltration. Groundwater samples, recipient surface water samples, and wastewater samples from septic tanks were collected from 2016 to 2017 covering all climatological seasons. These samples were analysed for a total of 103 contaminants, including pharmaceuticals, personal care products, organic phosphorus flame-retardants, plasticisers, perfluoroalkyl substances, and food additives. Fourteen of 103 contaminants showed 100% detection frequency in groundwater at concentrations in the low ng L−1 to low μg L−1 range. Of the compounds analysed, tris(2‑butoxyethyl) phosphate, sucralose, caffeine, and benzophenone showed high abundancy with maximum concentrations in the μg L−1 range. The data were normalised for dilution using chloride and sucralose as commonly applied tracers; however, the level of sucralose decreased significantly during infiltration and it is thus suboptimal as a sewage water tracer. Large differences between the two infiltration sites were observed in detection frequencies and concentrations in groundwater, which could be attributed to the system design and the contaminant's migration time from release to sampling point. Seasonal variation was observed for selected chemicals, and the more hydrophobic chemicals showed a higher tendency for attenuation, indicating sorption as a major retention mechanism. A moderate environmental risk to aquatic organisms was estimated in adjacent surface water for galaxolide, tris(1‑chloro‑2‑propyl) phosphate, and tris(2‑butoxyethyl) phosphate. Due to this site-dependency and potential environmental risks, further studies are needed on infiltration systems in different settings and on alternative treatment techniques to reduce the contaminant discharge from on-site sewage treatment facilities.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Micropollutants, Environmental fate, Pharmaceuticals and personal care products, Drain field, Leach field, Decentralised wastewater treatment system
National Category
Environmental Sciences Oceanography, Hydrology and Water Resources
Identifiers
urn:nbn:se:umu:diva-154019 (URN)10.1016/j.scitotenv.2018.10.016 (DOI)000450551600003 ()30317168 (PubMedID)
Funder
Swedish Research Council Formas, RedMic (216 - 2012-2101)Swedish Agency for Marine and Water Management, 907-2017
Available from: 2018-12-20 Created: 2018-12-20 Last updated: 2018-12-20Bibliographically approved
Blum, K. M., Haglund, P., Gao, Q., Ahrens, L., Gros, M., Wiberg, K. & Andersson, P. L. (2018). Mass fluxes per capita of organic contaminants from on-site sewage treatment facilities. Chemosphere (201), 864-873
Open this publication in new window or tab >>Mass fluxes per capita of organic contaminants from on-site sewage treatment facilities
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2018 (English)In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, no 201, p. 864-873Article in journal (Other academic) Published
Abstract [en]

This study is the first attempt to quantify environmental fluxes per capita of organic contaminants discharged from on-site sewage treatment facilities (OSSFs) in affected recipients. Five sites were monitored around the River Fyris in Sweden: three mainly affected by OSSFs and two mainly affected by municipal sewage treatment plants (STPs). Gas chromatography-mass spectrometry was used to determine environmental concentrations of 30 anthropogenic contaminants, including organophosphorus compounds, rubber and plastic additives, UV stabilizers, fragrances, surfactant ingredients and polycyclic aromatic hydrocarbons. Uni- and multivariate statistical analysis of the most frequently detected contaminants showed that median fluxes per capita of tris(1,3-dichloro-2-propyl) phosphate, tris(1-chloro-2-propyl) phosphate, tris(2-chloroethyl) phosphate, and n-butylbenzene sulfonamide were similar at OSSF and STP sites, but the mass fluxes per capita of tris-(2-butoxyethyl) phosphate, 2-(methylthio)benzothiazole, and galaxolide, were significantly lower (~2 to 3-fold) at OSSF sites than at STP sites (Mann-Whitney, α = 0.05). Differences between these sites were larger in samples collected in summer and autumn than in samples collected in winter. Deviations likely originated from differences in treatment technology and distances between source and sampling sites. Further studies are needed to characterize mass fluxes per capita of contaminants in waters that directly receive discharges from OSSFs.

Keywords
Decentralized wastewater treatment systems, environmental load, surface water, diffuse sources, GC×GC-HRMS
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:umu:diva-144259 (URN)10.1016/j.chemosphere.2018.03.058 (DOI)000430895300095 ()29567470 (PubMedID)
Available from: 2018-01-29 Created: 2018-01-29 Last updated: 2019-04-09Bibliographically approved
Edo Gimenez, M., Skoglund, N., Gao, Q., Persson, P.-E. & Jansson, S. (2017). Fate of metals and emissions of organic pollutants from torrefaction of waste wood, MSW, and RDF. Waste Management, 68, 646-652
Open this publication in new window or tab >>Fate of metals and emissions of organic pollutants from torrefaction of waste wood, MSW, and RDF
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2017 (English)In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 68, p. 646-652Article in journal (Refereed) Published
Abstract [en]

Torrefaction of municipal solid waste (MSW), refuse-derived fuel (RDF), and demolition and construction wood (DC) was performed at 220°C and a residence time of 90 min in a bench-scale reactor. The levels of toxic polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) contained in emission from the torrefaction process were evaluated. In addition, main ash-forming elements and trace metals in the raw feedstock and char were determined. The use of MSW in fuel blends with DC resulted in lower PCDD and PCDF emissions after torrefaction, compared with the RDF blends. The migration of chlorine from the feedstock to the gas phase reduces the chlorine content of the char which may reduce the risk of alkali chloride-corrosion in char combustion. However, trace metals catalytically active in the formation of PCDD and PCDF remain in the char, thereby may promote PCDD and PCDF formation during subsequent char combustion for energy recovery; this formation is less extensive than when the feedstock is used.

Place, publisher, year, edition, pages
Oxford: Elsevier, 2017
Keywords
Fuel upgrading, PCDD, PCDF, Thermochemical conversion
National Category
Organic Chemistry Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-127415 (URN)10.1016/j.wasman.2017.06.017 (DOI)000413126300065 ()28633911 (PubMedID)
Projects
Bio4Energy
Note

Originally included in thesis in manuscript form.

Available from: 2016-11-10 Created: 2016-11-10 Last updated: 2019-09-02Bibliographically approved
Gao, Q., Edo, M., Larsson, S. H., Collina, E., Rudolfsson, M., Gallina, M., . . . Jansson, S. (2017). Formation of PCDDs and PCDFs in the torrefaction of biomass with different chemical composition. Journal of Analytical and Applied Pyrolysis, 123, 126-133
Open this publication in new window or tab >>Formation of PCDDs and PCDFs in the torrefaction of biomass with different chemical composition
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2017 (English)In: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 123, p. 126-133Article in journal (Refereed) Published
Abstract [en]

Torrefaction is a thermal pre-treatment technology used to refine biomass, mainly for energy production purposes. However, there is currently a lack of information on the potential formation of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in the torrefaction process. In this study, torrefaction was conducted using five different types of feedstock: stemwood, bark, wood from a discarded telephone pole, cassava stems and particle board. The feedstock as well as the torrefied biomass (chars) and the volatiles (non-condensable and condensable) generated during torrefaction were analyzed for PCDDs and PCDFs. PCDD concentrations in the torrefaction products were about 2-5 fold of those in the feedstocks. Torrefaction of particle board resulted in extensive formation of PCDDs (7200 ng kg(-1)) compared to the other four feedstocks (13-27 ng kg(-1)). Examination of the homologue profiles suggested that the observed PCDDs in the torrefaction products partly originated from new formation and partly physical transformation from volatilization and re-condensation of PCDDs present in the feedstock. Dechlorination of highly chlorinated compounds (HpCDD and OCDD) in the feedstock to form less chlorinated PCDDs was also observed. Compared to PCDDs, the net formation of PCDFs in the torrefaction process was low, except for the telephone pole sample, for which a dramatic increase (44-fold) of PCDFs was observed. PCDDs and PCDFs were mainly retained in the chars, accounting for 76-96% and 39-74% of the total concentration, respectively. It was also found that the highly chlorinated congeners tended to be retained in the chars, whereas the less chlorinated ones were predominantly volatilized into the gas phase.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2017
Keywords
Polychlorinated dibenzo-p-dioxin, Polychlorinated dibenzofuran, Persistent organic pollutant, ermochemical conversion, Lignocellulosic biomass
National Category
Chemical Process Engineering
Identifiers
urn:nbn:se:umu:diva-133480 (URN)10.1016/j.jaap.2016.12.015 (DOI)000394064200015 ()
Projects
Bio4Energy
Available from: 2017-04-11 Created: 2017-04-11 Last updated: 2019-09-02Bibliographically approved
Matsakas, L., Gao, Q., Jansson, S., Rova, U. & Christakopoulos, P. (2017). Green conversion of municipal solid wastes into fuels and chemicals. Electronic Journal of Biotechnology, 26, Article ID 4.
Open this publication in new window or tab >>Green conversion of municipal solid wastes into fuels and chemicals
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2017 (English)In: Electronic Journal of Biotechnology, ISSN 0717-3458, E-ISSN 0717-3458, Vol. 26, article id 4Article, review/survey (Refereed) Published
Abstract [en]

Presently, the society is facing a serious challenge for the effective management of the increasing amount of produced municipal solid wastes. The accumulated waste has caused a series of environmental problems such as uncontrolled release of greenhouse gases. Moreover, the increasing amount of wastes has resulted in a shortage of areas available for waste disposal, resulting in a nonsustainable waste management. These problems led to serious public concerns, which in turn resulted in political actions aiming to reduce the amount of wastes reaching the environment. These actions aim to promote sustainable waste management solutions. The main objective of these policies is to promote the recycling of municipal solid waste and the conversion of waste to energy and valuable chemicals. These conversions can be performed using either biological (e.g., anaerobic digestion) or thermochemical processes (e.g., pyrolysis). Research efforts during the last years have been fruitful, and many publications demonstrated the effective conversation of municipal solid waste to energy and chemicals. These processes are discussed in the current review article together with the change of the waste policy that was implemented in the EU during the last years. 

Keywords
Anaerobic digestion, Biogas, Conversion of waste to energy, Environmental problems, Ethanol, sification, Hydrogen, Public concerns, Pyrolysis, Uncontrolled release of greenhouse gases, Waste sposal
National Category
Environmental Management
Identifiers
urn:nbn:se:umu:diva-133759 (URN)10.1016/j.ejbt.2017.01.004 (DOI)000397905100012 ()
Available from: 2017-05-03 Created: 2017-05-03 Last updated: 2018-06-09Bibliographically approved
Gao, Q. (2016). Dioxins and dioxin-like compounds in thermochemical conversion of biomass: formation, distribution and fingerprints. (Doctoral dissertation). Umeå: Umeå University
Open this publication in new window or tab >>Dioxins and dioxin-like compounds in thermochemical conversion of biomass: formation, distribution and fingerprints
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In the transition to a sustainable energy supply there is an increasing need to use biomass for replacement of fossil fuel. A key challenge is to utilize biomass conversion technologies in an environmentally sound manner. Important aspects are to minimize potential formation of persistent organic pollutants (POPs) such as dioxins and dioxin-like compounds.

This thesis involves studies of formation characteristics of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and naphthalenes (PCNs) in microwave-assisted pyrolysis (MAP) and torrefaction using biomass as feedstock. The research focuses are on their levels, distributions, fingerprints (homologue profiles and isomer patterns) and the underlying formation pathways. The study also included efforts to optimize methods for extracting chlorinated aromatic compounds from thermally treated biomass. The overall objective was to contribute better understanding on the formation of dioxins and dioxin-like compounds in low temperature thermal processes.

The main findings include the following:

  • Pressurized liquid extraction (PLE) is applicable for simultaneous extraction of PCDDs, PCDFs, PCNs, polychlorinated phenols and benzenes from thermally treated wood. The choice of solvent for PLE is critical, and the extraction efficiency depends on the degrees of biomass carbonization.
  • In MAP experiments PCDDs, PCDFs and PCNs were predominantly found in pyrolysis oils, while in torrefaction experiments they were mainly retained in solid chars with minor fractions in volatiles. In both cases, highly chlorinated congeners with low volatility tended to retain on particles whereas the less chlorinated congeners tended to volatize into the gas phase.
  • Isomer patterns of PCDDs, PCDFs and PCNs generated in MAP were more selective than those reported in combustion processes. The presence of isomers with low thermodynamic stability suggests that the pathway of POPs formation in MAP may be governed not only by thermodynamic stabilities but also by kinetic factors.
  • Formation of PCDDs, PCDFs and PCNs depends not only on the chlorine contents in biomass but also the presence of metal catalysts and organic/metal-based preservatives.

Overall, the results provide information on the formation characteristics of PCDDs, PCDFs and PCNs in MAP and torrefaction. The obtained knowledge is useful regarding management and utilization of thermally treated biomass with minimum environmental impact.

Place, publisher, year, edition, pages
Umeå: Umeå University, 2016. p. 72
Keywords
Polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, polychlorinated naphthalenes, PCDD, PCDF, PCN, persistent organic pollutants, torrefaction, pyrolysis
National Category
Organic Chemistry
Identifiers
urn:nbn:se:umu:diva-118861 (URN)978-91-7601-451-6 (ISBN)
Public defence
2016-04-29, KBC-huset, KB3A9, Umeå universitet, Umeå, 10:00 (English)
Opponent
Supervisors
Available from: 2016-04-08 Created: 2016-04-05 Last updated: 2018-06-07Bibliographically approved
Gao, Q., Cieplik, M. K., Budarin, V. L., Gronnow, M. & Jansson, S. (2016). Mechanistic evaluation of polychlorinated dibenzo-p-dioxin, dibenzofuran and naphthalene isomer fingerprints in microwave pyrolysis of biomass. Chemosphere, 150, 168-175
Open this publication in new window or tab >>Mechanistic evaluation of polychlorinated dibenzo-p-dioxin, dibenzofuran and naphthalene isomer fingerprints in microwave pyrolysis of biomass
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2016 (English)In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 150, p. 168-175Article in journal (Refereed) Published
Abstract [en]

Isomer distribution patterns of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and naphthalenes (PCNs) were investigated in microwave-assisted pyrolysis (MAP) products of woody biomass. The feedstocks included bark and impregnated wood. The results indicated that isomer distributions in MAP are more selective compared to those reported from wood burning and waste incineration. Favored formation of 4-MoCDF and highly selective chlorine substitution at the 2,4-position observed during MAP suggested a preferred formation pathway of PCDFs involving (chloro)phenol precursors followed by subsequent chlorination. The PCDD distribution was dominated by isomers typically formed from chlorophenol condensation at relatively low temperature. The PCN isomer distributions showed a tendency for sequential chlorination from non-substituted naphthalene at successive positions. The presence of isomers such as 1-MoCDD, 4-MoCDF, 1,2,3-TriCN with low thermodynamic stability indicates that kinetic factors may be important in the MAP process.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
PCDD, PCDF, Dioxin-like compounds, PCN, Persistent organic pollutants, Biomass thermochemical conversion
National Category
Organic Chemistry Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-118908 (URN)10.1016/j.chemosphere.2016.02.031 (DOI)000372765100022 ()26901473 (PubMedID)
Projects
Bio4Energy
Available from: 2016-04-06 Created: 2016-04-06 Last updated: 2019-09-02Bibliographically approved
Gao, Q., Budarin, V. L., Cieplik, M., Gronnow, M. & Jansson, S. (2016). PCDDs, PCDFs and PCNs in products of microwave-assisted pyrolysis of woody biomass: Distribution among solid, liquid and gaseous phases and effects of material composition. Chemosphere, 145, 193-199
Open this publication in new window or tab >>PCDDs, PCDFs and PCNs in products of microwave-assisted pyrolysis of woody biomass: Distribution among solid, liquid and gaseous phases and effects of material composition
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2016 (English)In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 145, p. 193-199Article in journal (Refereed) Published
Abstract [en]

Microwave-assisted pyrolysis (MAP) of lignocellulosic biomass is a technique that could potentially be used to produce and upgrade renewable energy carriers. However, there is no available information about the formation of dioxins and other organic pollutants in MAP treatment of woody biomass. In this study, MAP experiments were conducted in lab-scale using virgin softwood, bark, and impregnated wood as feedstocks. The non-condensable gas, liquid (fractionated into aqueous and oil phases), and char fractions generated during pyrolysis were collected and analysed for polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and naphthalenes (PCNs). The concentrations of PCDDs, PCDFs and PCNs in the pyrolysis products ranged from 0.52 to 43.7 ng kg(-1). All investigated compound groups were most abundant in the oil fraction, accounting for up to 68% (w/w) of the total concentrations. The highest PCDD, PCDF and PCN concentrations were found from the pyrolysis of bark, which has relatively high contents of chlorine and mineral matter, followed by impregnated wood, which contains organic and metal-based preservatives. The homologue profiles of all three compound groups were dominated by the less chlorinated homologues. The homologue abundance decreased as the degree of chlorination increased. This trend was observed for all three feedstocks.

Keywords
Polychlorinated dibenzo-p-dioxins, Polychlorinated dibenzofurans, Polychlorinated naphthalenes, Persistent organic pollutants, Thermochemical conversion, Lignocellulosic biomass
National Category
Organic Chemistry
Identifiers
urn:nbn:se:umu:diva-117388 (URN)10.1016/j.chemosphere.2015.11.110 (DOI)000369196300025 ()26688256 (PubMedID)
Projects
Bio4Energy
Available from: 2016-03-29 Created: 2016-02-29 Last updated: 2019-09-02Bibliographically approved
Gao, Q., Haglund, P., Pommer, L. & Jansson, S. (2015). Evaluation of solvent for pressurized liquid extraction of PCDD, PCDF, PCN, PCBz, PCPh and PAH in torrefied woody biomass. Fuel, 154, 52-58
Open this publication in new window or tab >>Evaluation of solvent for pressurized liquid extraction of PCDD, PCDF, PCN, PCBz, PCPh and PAH in torrefied woody biomass
2015 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 154, p. 52-58Article in journal (Refereed) Published
Abstract [en]

Biomass torrefaction for sustainable energy production has gained an increasing interest. However, there is a lack of information on the thermal formation of persistent organic pollutants such as dioxins in the torrefied solid product. In this paper, we investigated the applicability of pressurized liquid extraction (PLE) for simultaneous extraction of a number of polychlorinated planar aromatic compounds from torrefied wood. The targeted compounds included polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), naphthalenes (PCNs), benzenes (PCBz), phenols (PCPhs) and PAHs. PLE tests were conducted on torrefied and non-torrefied (i.e. raw) eucalyptus wood chips using 5 single solvents (n-hexane, toluene, dichloromethane, acetone and methanol) and a mixture of n-hexane/toluene (1:1, v/v). The performance of each solvent was evaluated in terms of recoveries of spiked internal standards and the amount of co-extracted sample matrix. High polarity solvents such as methanol and acetone resulted in poor recoveries from torrefied wood for most of the target compounds, probably due to the high co-extraction of thermally degraded lignocellulosic compounds. Raw wood was less solvent-dependent and comparable results were obtained for polar and non-polar solvents. Toluene showed the best performance of the investigated solvents, with average recoveries of 79 +/- 14% and 66 +/- 9% for raw and torrefied wood, respectively. The method was validated using pentachlorophenol-tainted spruce wood chips. The proposed PLE method was compared to the traditional Soxhlet method. Results show that PLE gave equivalent or better extraction for all target compounds.

Keywords
Persistent organic pollutants, PLE, Dioxin, Solvent effect, Torrefaction
National Category
Organic Chemistry
Identifiers
urn:nbn:se:umu:diva-103714 (URN)10.1016/j.fuel.2015.03.068 (DOI)000353893200007 ()
Funder
Bio4Energy
Available from: 2015-06-11 Created: 2015-05-28 Last updated: 2019-04-09Bibliographically approved
Gao, Q., Edo, M., Larsson, S. H., Collina, E., Rudolfsson, M., Gallina, M. & Jansson, S.Physical transformation and formation of PCDDs and PCDFs in torrefaction of biomass with different chemical composition.
Open this publication in new window or tab >>Physical transformation and formation of PCDDs and PCDFs in torrefaction of biomass with different chemical composition
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(English)Manuscript (preprint) (Other academic)
National Category
Organic Chemistry
Identifiers
urn:nbn:se:umu:diva-118910 (URN)
Available from: 2016-04-06 Created: 2016-04-06 Last updated: 2018-06-07
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