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Batchwise mesophilic anaerobic co-digestion of secondary sludge from pulp and paper industry and municipal sewage sludge
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
2013 (English)In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 33, no 4, 820-824 p.Article in journal (Refereed) Published
Abstract [en]

Residues from forest-industry wastewater-treatment systems are treated as waste at many pulp and paper mills. These organic substances have previously been shown to have potential for production of large quantities of biogas. There is concern, however, that the process would require expensive equipment because of the slow degradation of these substances. Pure non-fibrous sludge from forest industry showed lower specific methane production during mesophilic digestion for 19 days, 53 ± 26 Nml/g of volatile solids as compared to municipal sewage sludge, 84 ± 24 Nml/g of volatile solids. This paper explores the possibility of using anaerobic co-digestion with municipal sewage sludge to enhance the potential of methane production from secondary sludge from a pulp and paper mill. It was seen in a batch anaerobicdigestion operation of 19 days that the specific methane production remained largely the same for municipal sewage sludge when up to 50% of the volatile solids were replaced with forest-industry secondary sludge. It was also shown that the solid residue from anaerobic digestion of the forest-industry sludge should be of suitable quality to use for improving soil quality on lands that are not used for food production.

Place, publisher, year, edition, pages
Elsevier, 2013. Vol. 33, no 4, 820-824 p.
Keyword [en]
Anaerobic digestion
National Category
Energy Engineering
Research subject
Environmental and Energy Systems
Identifiers
URN: urn:nbn:se:kau:diva-26116ISI: 000317798000006PubMedID: 23294534OAI: oai:DiVA.org:kau-26116DiVA: diva2:602359
Projects
SWX-Biogas
Note

Artikel är publicerad som manuskript i Alina Hagelqvists avhandling och heter där Stoica, A. / Batchwise mesophilic anaerobic co-digestion of secondary sludge from pulp industry and municipal sewage sludge / 2013 /

Available from: 2013-02-28 Created: 2013-02-01 Last updated: 2016-06-30Bibliographically approved
In thesis
1. Forest industry sludge as a resource for energy recovery
Open this publication in new window or tab >>Forest industry sludge as a resource for energy recovery
2009 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Forest industries produce large amounts of carbon rich sludges as by-products in their processes. Presently sludge is treated as a poor quality biofuel for co-incineration, some mills treat it solely as a disposal problem. This thesis provides an introduction to production, composition and disposal issues of sludge. It also includes a presentation of strategies for sludge handling.

The main concern with energy recovery from sludge is connected to high content of water (50-80%). Mechanical dewatering is an energy efficient method of decreasing the water content. However, there are limitations to how far sludge can be dewatered mechanically. Thermal dewatering is sometimes required to dewater the sludge beyond these limits, in order to obtain a high quality biofuel for incineration and/or thermal gasification. It is often inefficient, from an energy point of view, to incorporate thermal dewatering in the sludge handling strategy.

An interesting alternative to thermal processes is anaerobic digestion, which is a biological process used for energy recovery. Advantages with anaerobic digestion include biogas production, efficient treatment of sludge with high content of water and potential for nutrients recovery. The process and the kinetics of anaerobic digestion are presented.

The aim of this thesis is to present a method for evaluating different sludge handling strategies from an energy perspective, and to further develop anaerobic digestion as a process for energy recovery from sludge. The thesis is based on two papers. Paper I presents an inclusive approach with focus on energy use and energy recovery in wastewater management, including wastewater treatment and sludge handling. Paper II explores the possibility to enhance biogas production by anaerobic co-digestion of pulp mill sludge with municipal sewage sludge.

Place, publisher, year, edition, pages
Karlstad: Karlstad University, 2009. 27 p.
Series
Karlstad University Studies, ISSN 1403-8099 ; 2009:26
National Category
Energy Engineering
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-3872 (URN)978-91-7063-249-5 (ISBN)
Distributor:
Fakulteten för teknik- och naturvetenskap
Presentation
2009-05-20, Karlstad, 13:15 (Swedish)
Supervisors
Available from: 2009-05-04 Created: 2009-03-25 Last updated: 2016-06-30Bibliographically approved
2. Sludge from pulp and paper mills for biogas production: Strategies to improve energy performance in wastewater treatment and sludge management
Open this publication in new window or tab >>Sludge from pulp and paper mills for biogas production: Strategies to improve energy performance in wastewater treatment and sludge management
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The production of pulp and paper is associated with the generation of large quantities of wastewater that has to be purified to avoid severe pollution of the environment. Wastewater purification in pulp and paper mills combines sedimentation, biological treatment, chemical precipitation, flotation and anaerobic treatment, and the specific combination of techniques is determined by the local conditions. Wastewater treatment generates large volumes of sludge that after dewatering can be incinerated and thus used for bio-energy production. Sludge is currently viewed as biofuel of poor quality due to its high water content, and some mills treat it solely as a disposal problem.

Two strategies have been identified as feasible options to improve the energy efficiency of sludge management. One is drying using multi-effect evaporation followed by incineration. The other is anaerobic digestion of the wet sludge to produce methane.

This thesis explores the energy balances of sludge management strategies in pulp and paper mills with special focus on anaerobic digestion. The first part consists of a system analysis, used to evaluate some wastewater treatment processes and sludge management, and the second part of empirical studies of anaerobic digestion of pulp and paper mill sludge. It was shown that the use of energy for aeration in aerobic biological treatment should be kept to the minimum required for acceptable quality of the processed water. Additional aeration for reduction of the generated sludge will only result in reduced energy generation in a subsequent methane generation stage. In the second part of the thesis, it is shown that anaerobic digestion is a feasible option for sludge management as it leads to production of high value biogas. Co-digestion with grass silage, cow/pig manure or municipal sewage sludge should then be used to counteract the low nitrogen content of pulp and paper mill sludge.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2013. 46 p.
Series
Karlstad University Studies, ISSN 1403-8099 ; 2013:9
Keyword
anaerobic digestion, pulp and paper mill sludge, methane production, energy efficient sludge management
National Category
Energy Engineering
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-26171 (URN)978-91-7063-484-0 (ISBN)
Public defence
2013-03-15, Nyquistsalen, 9C 203, Karlstads universitet, Universitetsgatan 2, Karlstad, 09:15 (Swedish)
Opponent
Supervisors
Available from: 2013-02-28 Created: 2013-02-04 Last updated: 2016-06-30Bibliographically approved

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PubMedhttp://dx.doi.org/10.1016/j.wasman.2012.11.002

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