Jätevesilietteen energiatehokas käsittely termofiilisesti mädättämällä

Elina Merta, Ari Kangas, Mona Arnold, Charlotta Lund, Risto Saarinen

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

Abstract

The goal of the project was to improve the utilization of sludge in a cost-efficient manner. Thermophilic anaerobic digestion (TAD) is an option to improve the energy efficiency of sewage sludge due to potentially higher biogas yield. TAD also offers other advantages over mesophilic process such as reduction in sludge volume and better hygienic properties of the treated sludge and thus better potential for agricultural utilization. The experimental part of the project focused on the modification of anaerobic digestion process from mesophilic to thermophilic. The aim was to investigate and compare the biogas yield and quality, process loadability, digestate and reject water properties and digestor material durability in the two processes. Basic data on anaerobic digestion was gathered in comparative pilot scale experiments. Loading tests were carried out to determine the maximum loading rate of the digestion processes. In the first set of loading tests, the TAD process produced more biogas than the MAD process. The average total biogas production and unit production in TAD were as high as 1.3 times those of MAD. The biogas unit production started to decrease when the retention time was shorter than 17 (TAD) or 15 (MAD) days. In the second set of loading tests, thickened sludge was let to hydrolyse for ca. two days and the formation of gas bubbles caused flotation. This procedure more than tripled the biogas unit production compared to previous test set, but now both TAD and MAD processes produced similar amounts of methane. Biogas methane content was similar in both reactors throughout the pilot runs. However, the elevated temperature caused increased siloxane concentrations in the gas phase. Also the sulphur concentration in TAD was higher than in MAD. Overall, the sulphur content of the biogas was low in both processes. TAD process hygienized the sludge when the retention time was > 15 days. According to CST measurements (Capillary Suction Time), dewatering properties of thermophilic sludge were inferior and the reject water contained more NH4+-N and CODCr compared to mesophilic sludge. Thermophilic sludge was times more odorous and more volatile organic compounds were released from it. Reactor material tests indicated that thermophilic process caused slightly more corrosion in stainless steel. However, no significant differences between the two processes were observed.
Original languageEnglish
Title of host publicationThe 12th Nordic/NORDIWA Wastewater conference, Conference book
Place of PublicationHelsinki
Pages299-308
Publication statusPublished - 2011
MoE publication typeA4 Article in a conference publication
Event12th Nordic Wastewater Conference - Helsinki, Finland
Duration: 14 Nov 201116 Nov 2011
Conference number: 12

Conference

Conference12th Nordic Wastewater Conference
CountryFinland
CityHelsinki
Period14/11/1116/11/11

Fingerprint

biogas
sludge
loading test
methane
anaerobic digestion
dewatering
durability
gas
energy efficiency
suction
volatile organic compound
bubble
digestion
corrosion
steel
sulfur
water
cost

Keywords

  • Sludge
  • digestion
  • thermophilic
  • biogas
  • trace compounds

Cite this

Merta, E., Kangas, A., Arnold, M., Lund, C., & Saarinen, R. (2011). Jätevesilietteen energiatehokas käsittely termofiilisesti mädättämällä. In The 12th Nordic/NORDIWA Wastewater conference, Conference book (pp. 299-308). Helsinki.
Merta, Elina ; Kangas, Ari ; Arnold, Mona ; Lund, Charlotta ; Saarinen, Risto. / Jätevesilietteen energiatehokas käsittely termofiilisesti mädättämällä. The 12th Nordic/NORDIWA Wastewater conference, Conference book. Helsinki, 2011. pp. 299-308
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title = "J{\"a}tevesilietteen energiatehokas k{\"a}sittely termofiilisesti m{\"a}d{\"a}tt{\"a}m{\"a}ll{\"a}",
abstract = "The goal of the project was to improve the utilization of sludge in a cost-efficient manner. Thermophilic anaerobic digestion (TAD) is an option to improve the energy efficiency of sewage sludge due to potentially higher biogas yield. TAD also offers other advantages over mesophilic process such as reduction in sludge volume and better hygienic properties of the treated sludge and thus better potential for agricultural utilization. The experimental part of the project focused on the modification of anaerobic digestion process from mesophilic to thermophilic. The aim was to investigate and compare the biogas yield and quality, process loadability, digestate and reject water properties and digestor material durability in the two processes. Basic data on anaerobic digestion was gathered in comparative pilot scale experiments. Loading tests were carried out to determine the maximum loading rate of the digestion processes. In the first set of loading tests, the TAD process produced more biogas than the MAD process. The average total biogas production and unit production in TAD were as high as 1.3 times those of MAD. The biogas unit production started to decrease when the retention time was shorter than 17 (TAD) or 15 (MAD) days. In the second set of loading tests, thickened sludge was let to hydrolyse for ca. two days and the formation of gas bubbles caused flotation. This procedure more than tripled the biogas unit production compared to previous test set, but now both TAD and MAD processes produced similar amounts of methane. Biogas methane content was similar in both reactors throughout the pilot runs. However, the elevated temperature caused increased siloxane concentrations in the gas phase. Also the sulphur concentration in TAD was higher than in MAD. Overall, the sulphur content of the biogas was low in both processes. TAD process hygienized the sludge when the retention time was > 15 days. According to CST measurements (Capillary Suction Time), dewatering properties of thermophilic sludge were inferior and the reject water contained more NH4+-N and CODCr compared to mesophilic sludge. Thermophilic sludge was times more odorous and more volatile organic compounds were released from it. Reactor material tests indicated that thermophilic process caused slightly more corrosion in stainless steel. However, no significant differences between the two processes were observed.",
keywords = "Sludge, digestion, thermophilic, biogas, trace compounds",
author = "Elina Merta and Ari Kangas and Mona Arnold and Charlotta Lund and Risto Saarinen",
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Merta, E, Kangas, A, Arnold, M, Lund, C & Saarinen, R 2011, Jätevesilietteen energiatehokas käsittely termofiilisesti mädättämällä. in The 12th Nordic/NORDIWA Wastewater conference, Conference book. Helsinki, pp. 299-308, 12th Nordic Wastewater Conference, Helsinki, Finland, 14/11/11.

Jätevesilietteen energiatehokas käsittely termofiilisesti mädättämällä. / Merta, Elina; Kangas, Ari; Arnold, Mona; Lund, Charlotta; Saarinen, Risto.

The 12th Nordic/NORDIWA Wastewater conference, Conference book. Helsinki, 2011. p. 299-308.

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

TY - GEN

T1 - Jätevesilietteen energiatehokas käsittely termofiilisesti mädättämällä

AU - Merta, Elina

AU - Kangas, Ari

AU - Arnold, Mona

AU - Lund, Charlotta

AU - Saarinen, Risto

N1 - Project code: 30875

PY - 2011

Y1 - 2011

N2 - The goal of the project was to improve the utilization of sludge in a cost-efficient manner. Thermophilic anaerobic digestion (TAD) is an option to improve the energy efficiency of sewage sludge due to potentially higher biogas yield. TAD also offers other advantages over mesophilic process such as reduction in sludge volume and better hygienic properties of the treated sludge and thus better potential for agricultural utilization. The experimental part of the project focused on the modification of anaerobic digestion process from mesophilic to thermophilic. The aim was to investigate and compare the biogas yield and quality, process loadability, digestate and reject water properties and digestor material durability in the two processes. Basic data on anaerobic digestion was gathered in comparative pilot scale experiments. Loading tests were carried out to determine the maximum loading rate of the digestion processes. In the first set of loading tests, the TAD process produced more biogas than the MAD process. The average total biogas production and unit production in TAD were as high as 1.3 times those of MAD. The biogas unit production started to decrease when the retention time was shorter than 17 (TAD) or 15 (MAD) days. In the second set of loading tests, thickened sludge was let to hydrolyse for ca. two days and the formation of gas bubbles caused flotation. This procedure more than tripled the biogas unit production compared to previous test set, but now both TAD and MAD processes produced similar amounts of methane. Biogas methane content was similar in both reactors throughout the pilot runs. However, the elevated temperature caused increased siloxane concentrations in the gas phase. Also the sulphur concentration in TAD was higher than in MAD. Overall, the sulphur content of the biogas was low in both processes. TAD process hygienized the sludge when the retention time was > 15 days. According to CST measurements (Capillary Suction Time), dewatering properties of thermophilic sludge were inferior and the reject water contained more NH4+-N and CODCr compared to mesophilic sludge. Thermophilic sludge was times more odorous and more volatile organic compounds were released from it. Reactor material tests indicated that thermophilic process caused slightly more corrosion in stainless steel. However, no significant differences between the two processes were observed.

AB - The goal of the project was to improve the utilization of sludge in a cost-efficient manner. Thermophilic anaerobic digestion (TAD) is an option to improve the energy efficiency of sewage sludge due to potentially higher biogas yield. TAD also offers other advantages over mesophilic process such as reduction in sludge volume and better hygienic properties of the treated sludge and thus better potential for agricultural utilization. The experimental part of the project focused on the modification of anaerobic digestion process from mesophilic to thermophilic. The aim was to investigate and compare the biogas yield and quality, process loadability, digestate and reject water properties and digestor material durability in the two processes. Basic data on anaerobic digestion was gathered in comparative pilot scale experiments. Loading tests were carried out to determine the maximum loading rate of the digestion processes. In the first set of loading tests, the TAD process produced more biogas than the MAD process. The average total biogas production and unit production in TAD were as high as 1.3 times those of MAD. The biogas unit production started to decrease when the retention time was shorter than 17 (TAD) or 15 (MAD) days. In the second set of loading tests, thickened sludge was let to hydrolyse for ca. two days and the formation of gas bubbles caused flotation. This procedure more than tripled the biogas unit production compared to previous test set, but now both TAD and MAD processes produced similar amounts of methane. Biogas methane content was similar in both reactors throughout the pilot runs. However, the elevated temperature caused increased siloxane concentrations in the gas phase. Also the sulphur concentration in TAD was higher than in MAD. Overall, the sulphur content of the biogas was low in both processes. TAD process hygienized the sludge when the retention time was > 15 days. According to CST measurements (Capillary Suction Time), dewatering properties of thermophilic sludge were inferior and the reject water contained more NH4+-N and CODCr compared to mesophilic sludge. Thermophilic sludge was times more odorous and more volatile organic compounds were released from it. Reactor material tests indicated that thermophilic process caused slightly more corrosion in stainless steel. However, no significant differences between the two processes were observed.

KW - Sludge

KW - digestion

KW - thermophilic

KW - biogas

KW - trace compounds

M3 - Conference article in proceedings

SN - 978-952-5000-84-9

SP - 299

EP - 308

BT - The 12th Nordic/NORDIWA Wastewater conference, Conference book

CY - Helsinki

ER -

Merta E, Kangas A, Arnold M, Lund C, Saarinen R. Jätevesilietteen energiatehokas käsittely termofiilisesti mädättämällä. In The 12th Nordic/NORDIWA Wastewater conference, Conference book. Helsinki. 2011. p. 299-308