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Thomsen TP, Hauggaard-Nielsen H, Gøbel B, Stoholm P, Ahrenfeldt J, Henriksen UB, Müller-Stöver DS. Low temperature circulating fluidized bed gasification and co-gasification of municipal sewage sludge. Part 2: Evaluation of ash materials as phosphorus fertilizer. Waste Manag 2017; 66:145-154. [PMID: 28479087 DOI: 10.1016/j.wasman.2017.04.043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 04/23/2017] [Accepted: 04/26/2017] [Indexed: 06/07/2023]
Abstract
The study is part 2 of 2 in an investigation of gasification and co-gasification of municipal sewage sludge in low temperature gasifiers. In this work, solid residuals from thermal gasification and co-gasification of municipal sewage sludge were investigated for their potential use as fertilizer. Ashes from five different low temperature circulating fluidized bed (LT-CFB) gasification campaigns including two mono-sludge campaigns, two sludge/straw mixed fuels campaigns and a straw reference campaign were compared. Experiments were conducted on two different LT-CFBs with thermal capacities of 100kW and 6MW, respectively. The assessment included: (i) Elemental composition and recovery of key elements and heavy metals; (ii) content of total carbon (C) and total nitrogen (N); (iii) pH; (iv) water extractability of phosphorus after incubation in soil; and (v) plant phosphorus response measured in a pot experiment with the most promising ash material. Co-gasification of straw and sludge in LT-CFB gasifiers produced ashes with a high content of recalcitrant C, phosphorus (P) and potassium (K), a low content of heavy metals (especially cadmium) and an improved plant P availability compared to the mono-sludge ashes, thereby showing the best fertilizer qualities among all assessed materials. It was also found that bottom ashes from the char reactor contained even less heavy metals than cyclone ashes. It is concluded that LT-CFB gasification and co-gasification is a highly effective way to purify and sanitize sewage sludge for subsequent use in agricultural systems.
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Affiliation(s)
- Tobias Pape Thomsen
- Technical University of Denmark, Department of Chemical Engineering, DTU Risø Campus, Technical University of Denmark Building 313, Frederiksborgvej 399, 4000 Roskilde, Denmark.
| | - Henrik Hauggaard-Nielsen
- Roskilde University, Department of Environmental, Social and Spatial Change, 4000 Roskilde, Denmark
| | - Benny Gøbel
- DONG Energy Thermal Power A/S, Nesa Allé 1, 2820 Gentofte, Denmark
| | - Peder Stoholm
- Danish Fluid Bed Technology ApS, Industrivej 38, 4000 Roskilde, Denmark
| | - Jesper Ahrenfeldt
- Technical University of Denmark, Department of Chemical Engineering, DTU Risø Campus, Technical University of Denmark Building 313, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | - Ulrik B Henriksen
- Technical University of Denmark, Department of Chemical Engineering, DTU Risø Campus, Technical University of Denmark Building 313, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | - Dorette Sophie Müller-Stöver
- University of Copenhagen, Department of Plant and Environmental Sciences, Plant and Soil Science, Thorvaldsensvej 40, Frederiksberg, Denmark
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Parés Viader R, Jensen PE, Ottosen LM, Thomsen TP, Ahrenfeldt J, Hauggaard-Nielsen H. Comparison of phosphorus recovery from incineration and gasification sewage sludge ash. Water Sci Technol 2017; 75:1251-1260. [PMID: 28272054 DOI: 10.2166/wst.2016.620] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Incineration of sewage sludge is a common practice in many western countries. Gasification is an attractive option because of its high energy efficiency and flexibility in the usage of the produced gas. However, they both unavoidably produce sewage sludge ashes, a material that is rich in phosphorus, but which is commonly landfilled or used in construction materials. With current uncertainty in phosphate rock supply, phosphorus recovery from sewage sludge ashes has become interesting. In the present work, ashes from incineration and gasification of the same sewage sludge were compared in terms of phosphorus extractability using electrodialytic (ED) methods. The results show that comparable recovery rates of phosphorus were achieved with a single ED step for incineration ashes and a sequential combination of two ED steps for gasification ashes, which was due to a higher influence of iron and/or aluminium in phosphorus solubility for the latter. A product with lower level of metallic impurities and comparable to wet process phosphoric acid was eventually obtained from gasification ashes. Thus, gasification becomes an interesting alternative to incineration also in terms of phosphorus separation.
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Affiliation(s)
- Raimon Parés Viader
- Department of Civil Engineering, Technical University of Denmark, Building 118, 2800 Kongens Lyngby, Denmark E-mail:
| | - Pernille Erland Jensen
- Department of Civil Engineering, Technical University of Denmark, Building 118, 2800 Kongens Lyngby, Denmark E-mail:
| | - Lisbeth M Ottosen
- Department of Civil Engineering, Technical University of Denmark, Building 118, 2800 Kongens Lyngby, Denmark E-mail:
| | - Tobias P Thomsen
- Department of Chemical and Biochemical Engineering, Technical University of Denmark, Building 313, 4000 Roskilde, Denmark
| | - Jesper Ahrenfeldt
- Department of Chemical and Biochemical Engineering, Technical University of Denmark, Building 313, 4000 Roskilde, Denmark
| | - Henrik Hauggaard-Nielsen
- Department of Environmental, Social and Spatial Change, Roskilde University, 4000 Roskilde, Denmark
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Parés Viader R, Jensen PE, Ottosen LM, Ahrenfeldt J, Hauggaard-Nielsen H. Sequential electrodialytic recovery of phosphorus from low-temperature gasification ashes of chemically precipitated sewage sludge. Waste Manag 2017; 60:211-218. [PMID: 27912988 DOI: 10.1016/j.wasman.2016.11.030] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 11/11/2016] [Accepted: 11/21/2016] [Indexed: 06/06/2023]
Abstract
Phosphorus recycling from secondary materials like sewage sludge ashes offers an alternative to mining of phosphates from primary resources and a mean to counteract the current phosphorous rock depletion concern. A separation of P from the bulk ash is normally required, due to its low plant availability and the presence of heavy metals. Previously, more than 80% of P was recovered from incineration sewage sludge ashes using a two-compartment electrodialytic cell. In contrast, the recovery was below 30% for ashes from low-temperature gasification using the same setup. The low recovery was due to a high presence of Al- and Fe(III)-P bindings. In the present study, an electrodialytic process combining sequentially a pair of two-compartment cells allowed a recovery of up to 70% of phosphorus from these ashes. The use of a second cell, where the ash was suspended in an alkaline solution, allowed the P solubilisation from aluminium and ferric phosphates. In addition, P was separated from most metals as they became insoluble under the prevailing chemical environment. The obtained ratio of Al, Fe, Mg and most heavy metals to P was comparable to wet process phosphoric acid. Therefore, this sequential process was found to be suitable to recycle P and potentially use it in the production of common fertilizers like diammonium phosphate.
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Affiliation(s)
- Raimon Parés Viader
- Department of Civil Engineering, Technical University of Denmark, Building 118, 2800 Kongens Lyngby, Denmark.
| | - Pernille Erland Jensen
- Department of Civil Engineering, Technical University of Denmark, Building 118, 2800 Kongens Lyngby, Denmark
| | - Lisbeth M Ottosen
- Department of Civil Engineering, Technical University of Denmark, Building 118, 2800 Kongens Lyngby, Denmark
| | - Jesper Ahrenfeldt
- Department of Chemical and Biochemical Engineering, Technical University of Denmark, Building 313, 4000 Roskilde, Denmark
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Hansen V, Müller-Stöver D, Imparato V, Krogh PH, Jensen LS, Dolmer A, Hauggaard-Nielsen H. The effects of straw or straw-derived gasification biochar applications on soil quality and crop productivity: A farm case study. J Environ Manage 2017; 186:88-95. [PMID: 27815006 DOI: 10.1016/j.jenvman.2016.10.041] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 08/12/2016] [Accepted: 10/19/2016] [Indexed: 06/06/2023]
Abstract
Thermal gasification of straw is a highly efficient technology that produces bioenergy and gasification biochar that can be used as a soil amendment, thereby returning non-renewable nutrients and stable carbon, and securing soil quality and crop productivity. A Danish on-farm field study investigated the impact of traditional straw incorporation vs. straw removal for thermal gasification bioenergy production and the application of straw gasification biochar (GB) on soil quality and crop production. Two rates of GB were applied over three successive years in which the field was cropped with winter wheat (Triticum aestivum L.), winter oilseed rape (Brassica napus L.) and winter wheat, respectively, to assess the potential effects on the soil carbon pool, soil microorganisms, earthworms, soil chemical properties and crop yields. The application of GB did not increase the soil organic carbon content significantly and had no effect on crop yields. The application of straw and GB had a positive effect on the populations of bacteria and protists, but no effect on earthworms. The high rate of GB increased soil exchangeable potassium content and soil pH indicating its potassium bioavailability and liming properties. These results suggest, that recycling GB into agricultural soils has the potential to be developed into a system combining bioenergy generation from agricultural residues and crop production, while maintaining soil quality. However, future studies should be undertaken to assess its long-term effects and to identify the optimum balance between straw removal and biochar application rate.
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Affiliation(s)
- Veronika Hansen
- University of Copenhagen, Department of Plant & Environmental Sciences, Thorvaldsensvej 40, 1821 Frederiksberg, Denmark
| | - Dorette Müller-Stöver
- University of Copenhagen, Department of Plant & Environmental Sciences, Thorvaldsensvej 40, 1821 Frederiksberg, Denmark
| | - Valentina Imparato
- Aarhus University, Department of Environmental Science - Environmental Microbiology & Biotechnology, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | - Paul Henning Krogh
- Aarhus University, Department of Bioscience - Soil Fauna Ecology and Ecotoxicology, Vejlsoevej 25, Silkeborg, Denmark
| | - Lars Stoumann Jensen
- University of Copenhagen, Department of Plant & Environmental Sciences, Thorvaldsensvej 40, 1821 Frederiksberg, Denmark
| | - Anders Dolmer
- Bregentved Estate, Koldinghus Allé 1, 4690 Haslev, Denmark
| | - Henrik Hauggaard-Nielsen
- Roskilde University, Department of People and Technology, Universitetsvej 1, 4000 Roskilde, Denmark.
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Selck H, Adamsen PB, Backhaus T, Banta GT, Bruce PKH, Burton GA, Butts MB, Boegh E, Clague JJ, Dinh KV, Doorn N, Gunnarsson JS, Hauggaard-Nielsen H, Hazlerigg C, Hunka AD, Jensen J, Lin Y, Loureiro S, Miraglia S, Munns WR, Nadim F, Palmqvist A, Rämö RA, Seaby LP, Syberg K, Tangaa SR, Thit A, Windfeld R, Zalewski M, Chapman PM. Assessing and managing multiple risks in a changing world-The Roskilde recommendations. Environ Toxicol Chem 2017; 36:7-16. [PMID: 28024105 PMCID: PMC6130322 DOI: 10.1002/etc.3513] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 02/28/2016] [Accepted: 05/24/2016] [Indexed: 05/24/2023]
Abstract
Roskilde University (Denmark) hosted a November 2015 workshop, Environmental Risk-Assessing and Managing Multiple Risks in a Changing World. This Focus article presents the consensus recommendations of 30 attendees from 9 countries regarding implementation of a common currency (ecosystem services) for holistic environmental risk assessment and management; improvements to risk assessment and management in a complex, human-modified, and changing world; appropriate development of protection goals in a 2-stage process; dealing with societal issues; risk-management information needs; conducting risk assessment of risk management; and development of adaptive and flexible regulatory systems. The authors encourage both cross-disciplinary and interdisciplinary approaches to address their 10 recommendations: 1) adopt ecosystem services as a common currency for risk assessment and management; 2) consider cumulative stressors (chemical and nonchemical) and determine which dominate to best manage and restore ecosystem services; 3) fully integrate risk managers and communities of interest into the risk-assessment process; 4) fully integrate risk assessors and communities of interest into the risk-management process; 5) consider socioeconomics and increased transparency in both risk assessment and risk management; 6) recognize the ethical rights of humans and ecosystems to an adequate level of protection; 7) determine relevant reference conditions and the proper ecological context for assessments in human-modified systems; 8) assess risks and benefits to humans and the ecosystem and consider unintended consequences of management actions; 9) avoid excessive conservatism or possible underprotection resulting from sole reliance on binary, numerical benchmarks; and 10) develop adaptive risk-management and regulatory goals based on ranges of uncertainty. Environ Toxicol Chem 2017;36:7-16. © 2016 SETAC.
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Affiliation(s)
| | | | | | | | | | | | | | - Eva Boegh
- Roskilde University, Roskilde, Denmark
| | - John J Clague
- Simon Fraser University, Burnaby, British Columbia, Canada
| | - Khuong V Dinh
- Technical University of Denmark, Kongens Lyngby, Denmark
| | - Neelke Doorn
- Delft University of Technology, Delft, The Netherlands
| | | | | | - Charles Hazlerigg
- Enviresearch, Newcastle-upon-Tyne, United Kingdom of Great Britain and Northern Ireland
| | | | | | - Yan Lin
- Norwegian Institute for Water Research, Oslo, Norway
| | - Susana Loureiro
- Department of Biology & CESAM, University of Aveiro, Aveiro, Portugal
| | | | - Wayne R Munns
- US Environmental Protection Agency, Narragansett, Rhode Island
| | | | | | | | | | | | | | | | | | - Maciej Zalewski
- European Regional Centre for Ecohydrology (Polish Academy of Sciences), Lodz, Poland
| | - Peter M Chapman
- Chapema Environmental Strategies, North Vancouver, British Columbia, Canada
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Hauggaard-Nielsen H, Lachouani P, Knudsen MT, Ambus P, Boelt B, Gislum R. Corrigendum to "Productivity and carbon footprint of perennial grass-forage legume intercropping strategies with high or low nitrogen fertilizer input" [Sci. Total Environ. 541 (January 2016) pages 1339-1347]. Sci Total Environ 2016; 557-558:917-918. [PMID: 27063726 DOI: 10.1016/j.scitotenv.2016.01.167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Affiliation(s)
- Henrik Hauggaard-Nielsen
- Department of Chemical and Biochemical Engineering, Technical University of Denmark, Kgs. Lyngby, Denmark; Department of Environmental, Social and Spatial Change, Roskilde University, Denmark.
| | - Petra Lachouani
- Department of Chemical and Biochemical Engineering, Technical University of Denmark, Kgs. Lyngby, Denmark; Department of Geosciences and Natural Resource Management, University of Copenhagen, Denmark
| | | | - Per Ambus
- Department of Chemical and Biochemical Engineering, Technical University of Denmark, Kgs. Lyngby, Denmark; Department of Geosciences and Natural Resource Management, University of Copenhagen, Denmark
| | - Birte Boelt
- Department of Agroecology, Aarhus University, Denmark
| | - René Gislum
- Department of Agroecology, Aarhus University, Denmark
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Hauggaard-Nielsen H, Lachouani P, Knudsen MT, Ambus P, Boelt B, Gislum R. Productivity and carbon footprint of perennial grass-forage legume intercropping strategies with high or low nitrogen fertilizer input. Sci Total Environ 2016; 541:1339-1347. [PMID: 26479907 DOI: 10.1016/j.scitotenv.2015.10.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 10/02/2015] [Accepted: 10/04/2015] [Indexed: 06/05/2023]
Abstract
A three-season field experiment was established and repeated twice with spring barley used as cover crop for different perennial grass-legume intercrops followed by a full year pasture cropping and winter wheat after sward incorporation. Two fertilization regimes were applied with plots fertilized with either a high or a low rate of mineral nitrogen (N) fertilizer. Life cycle assessment (LCA) was used to evaluate the carbon footprint (global warming potential) of the grassland management including measured nitrous oxide (N2O) emissions after sward incorporation. Without applying any mineral N fertilizer, the forage legume pure stand, especially red clover, was able to produce about 15 t above ground dry matter ha(-1) year(-1) saving around 325 kg mineral Nfertilizer ha(-1) compared to the cocksfoot and tall fescue grass treatments. The pure stand ryegrass yielded around 3t DM more than red clover in the high fertilizer treatment. Nitrous oxide emissions were highest in the treatments containing legumes. The LCA showed that the low input N systems had markedly lower carbon footprint values than crops from the high N input system with the pure stand legumes without N fertilization having the lowest carbon footprint. Thus, a reduction in N fertilizer application rates in the low input systems offsets increased N2O emissions after forage legume treatments compared to grass plots due to the N fertilizer production-related emissions. When including the subsequent wheat yield in the total aboveground production across the three-season rotation, the pure stand red clover without N application and pure stand ryegrass treatments with the highest N input equalled. The present study illustrate how leguminous biological nitrogen fixation (BNF) represents an important low impact renewable N source without reducing crop yields and thereby farmers earnings.
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Affiliation(s)
- Henrik Hauggaard-Nielsen
- Department of Chemical and Biochemical Engineering, Technical University of Denmark, Kgs. Lyngby, Denmark; Department of Environmental, Social and Spatial Change, Roskilde University, Denmark.
| | - Petra Lachouani
- Department of Chemical and Biochemical Engineering, Technical University of Denmark, Kgs. Lyngby, Denmark; Department of Geosciences and Natural Resource Management, University of Copenhagen, Denmark
| | | | - Per Ambus
- Department of Chemical and Biochemical Engineering, Technical University of Denmark, Kgs. Lyngby, Denmark; Department of Geosciences and Natural Resource Management, University of Copenhagen, Denmark
| | - Birte Boelt
- Department of Agroecology, Aarhus University, Denmark
| | - René Gislum
- Department of Agroecology, Aarhus University, Denmark
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Parés Viader R, Jensen PE, Ottosen LM, Ahrenfeldt J, Hauggaard-Nielsen H. Electrodialytic extraction of phosphorus from ash of low-temperature gasification of sewage sludge. Electrochim Acta 2015. [DOI: 10.1016/j.electacta.2015.05.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Peoples MB, Hauggaard-Nielsen H, Jensen ES. The Potential Environmental Benefits and Risks Derived from Legumes in Rotations. Agronomy Monographs 2015. [DOI: 10.2134/agronmonogr52.c13] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
| | - Henrik Hauggaard-Nielsen
- Biosystems Dep., Risø DTU Natl. Lab. for Sustainable Energy; Technical Univ. of Denmark; Roskilde
| | - Erik S. Jensen
- Dep. of Agriculture, Swedish Univ. of Agricultural Sciences; Alnarp Sweden
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Jensen ES, Bedoussac L, Carlsson G, Journet EP, Justes E, Hauggaard-Nielsen H. Enhancing Yields in Organic Crop Production by Eco-Functional Intensification. ACTA ACUST UNITED AC 2015. [DOI: 10.5539/sar.v4n3p42] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
<p>Organic agriculture faces challenges to enhance food production per unit area and simultaneously reduce the environmental and climate impacts, e.g. nitrate leaching per unit area and greenhouse gas (GHG) emissions per unit mass produced. Eco-functional intensification is suggested as a means to reach these objectives. Eco-functional intensification involves activating more knowledge and refocusing the importance of ecosystem services in agriculture. Organic farmers manage agrobiodiversity by crop rotation (diversification in time). However, sole cropping (SC) of genetically identical plants in organic agriculture may limit resource use efficiency and yield per unit area. Intercropping (IC) of annual grain species, cultivar mixes, perennial grains, or forage species and forestry and annual crops (agroforestry) are examples of spatial crop diversification. Intercropping is based on eco-functional intensification and may enhance production by complementarity in resource use in time and space. Intercropping is based on the ecological principles of competition, facilitation and complementarity, which often increases the efficiency in acquisition and use of resources such as light, water and nutrients compared to sole crops, especially in low-input systems. Here we show that IC of cereals and grain legumes in European arable organic farming systems is an efficient tool for enhancing total grain yields compared to their respective sole crops. Simultaneously, we display how intercropping of cereals and legumes can be used as an efficient tool for weed management and to enhance product quality (i.e. cereal grain protein concentration). We discuss how intercropping contributes to efficient use of soil N sources and minimizes losses of N by nitrate leaching via <em>Ecological Precision Farming</em>. It is concluded that intercropping has a strong potential to increase yield and hereby reduce global climate impacts such as GHG kg<sup>-1</sup> grain. Finally, we discuss likely barriers and lock-in effects for increased use of intercropping in organic farming and suggest a roadmap for innovation and implementation of IC strategies in organic agriculture.</p>
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Kumari KGID, Moldrup P, Paradelo M, Elsgaard L, Hauggaard-Nielsen H, de Jonge LW. Effects of biochar on air and water permeability and colloid and phosphorus leaching in soils from a natural calcium carbonate gradient. J Environ Qual 2014; 43:647-657. [PMID: 25602666 DOI: 10.2134/jeq2013.08.0334] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Application of biochar to agricultural fields to improve soil quality has increased in popularity in recent years, but limited attention is generally paid to existing field conditions before biochar application. This study examined the short-term physicochemical effects of biochar amendment in an agricultural field in Denmark with a calcium carbonate (CaCO) gradient. The field comprised four reference plots and four plots to which biochar (birch wood pyrolyzed at 500°C) was applied at a rate of 20 t ha. Five undisturbed soil columns (10 cm diam., 8 cm height) were sampled from each plot 7 mo after biochar application, and a series of leaching experiments was conducted. The leachate was analyzed for tritium (used as a tracer), colloids, and phosphorus concentration. The results revealed that the presence of CaCO has resulted in marked changes in soil structure (bulk density) and soil chemical properties (e.g., pH and ionic strength), which significantly affected air and water transport and colloid and phosphorous leaching. In denser soils (bulk density, 1.57-1.69 g cm) preferential flow dominated the transport and caused an enhanced movement of air and water, whereas in less dense soils (bulk density, 1.38-1.52 g cm) matrix flow predominated the transport. Compared with reference soils, biochar-amended soils showed slightly lower air permeability and a shorter travel time for 5% of the applied tracer (tritium) to leach through the soil columns. Colloid and phosphorus leaching was observed to be time dependent in soils with low CaCO. Biochar-amended soils showed higher colloid and P release than reference soils. Field-scale variations in total colloid and P leaching reflected clear effects of changes in pH and ionic strength due to the presence of CaCO. There was a linear relationship between colloid and P concentrations in the leachate, suggesting that colloid-facilitated P leaching was the dominant P transport mechanism.
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Martín C, Thomsen MH, Hauggaard-Nielsen H, Belindathomsen A. Wet oxidation pretreatment, enzymatic hydrolysis and simultaneous saccharification and fermentation of clover-ryegrass mixtures. Bioresour Technol 2008; 99:8777-82. [PMID: 18514510 DOI: 10.1016/j.biortech.2008.04.039] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2007] [Revised: 04/07/2008] [Accepted: 04/12/2008] [Indexed: 05/08/2023]
Abstract
The potential of clover (Trifolium repens) and ryegrass (Lolium perenne) mixtures as raw materials for ethanol production was investigated. Wet oxidation, at 175, 185 or 195 degrees C during 10min at two different oxygen pressures and with either addition or no addition of sodium carbonate, was evaluated as pretreatment method for clover-ryegrass mixtures. The enzymatic hydrolysis of cellulose was significantly improved after pretreatment. The highest conversion efficiency, 93.6%, was achieved for the sample pretreated at 195 degrees C, 10min, 1.2MPa and no addition of Na(2)CO(3). For that sample, the overall glucose yield after pretreatment and hydrolysis was 75.5%. No inhibition of cellulose enzymatic conversion by the filtrates was observed. The simultaneous saccharification and fermentation of the pretreated material yielded cellulose conversions of 87.5 and 86.6%, respectively, with Saccharomyces cerevisiae and the filamentous fungus Mucor indicus, and revealed that no addition of nutrients is needed for the fermentation of clover-ryegrass hydrolysates.
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Affiliation(s)
- Carlos Martín
- Department of Chemistry and Chemical Engineering, University of Matanzas, Matanzas 44740, Cuba.
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