Anaerobic digestion trials with HTC process water
Hydrothermal carbonization (HTC) is a process where elevated temperature and pressure is used in order to convert biomass to hydrochar, a coal-like substance with good dewatering properties and many potential uses. HTC can be used to treat digestate from anaerobic digestion, but the process water th...
Main Author: | |
---|---|
Format: | Others |
Language: | English |
Published: |
Uppsala universitet, Institutionen för geovetenskaper
2017
|
Subjects: | |
Online Access: | http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-325289 |
id |
ndltd-UPSALLA1-oai-DiVA.org-uu-325289 |
---|---|
record_format |
oai_dc |
spelling |
ndltd-UPSALLA1-oai-DiVA.org-uu-3252892017-06-23T05:29:44ZAnaerobic digestion trials with HTC process waterengRötningsförsök med HTC processvattenNilsson, ErikUppsala universitet, Institutionen för geovetenskaper2017anaerobic digestionHTCprocess waterhydrocharAMPTSBMPprimary sludgedigestaterötningHTCprocessvattenbiokolAMPTSBMPprimärslamrötningsslamOther Engineering and Technologies not elsewhere specifiedÖvrig annan teknikHydrothermal carbonization (HTC) is a process where elevated temperature and pressure is used in order to convert biomass to hydrochar, a coal-like substance with good dewatering properties and many potential uses. HTC can be used to treat digestate from anaerobic digestion, but the process water that remains after the hydrochar has been recovered needs to be treated further in the wastewater treatment plant. In order to make HTC more competitive compared to other sludge treatments it is important to find a good use for the process water. The main objective of this master thesis was to investigate the effects of recirculating HTC process water to the anaerobic digestion. To achieve the objective, both theoretical calculations and experimental trials were performed. The experimental trials were conducted with an Automatic Methane Potential Test System (AMPTS II) in order to investigate the anaerobic digestion in laboratory scale. In the first trial, three substrates, process water, hydrochar, and primary sludge were tested for their biochemical methane potential (BMP). All substrates were mixed with inoculum. Process water had a BMP of 335 ± 10 % NmL/gvs (normalized CH4 production in mL per g added VS (volatile solids)), hydrochar had BMP of 150 ± 5 % NmL/gvs, and primary sludge had a BMP of 343 ± 2 % NmL/gvs. The methane production was almost the same for process water as for primary sludge i.e. no inhibitory effects could be seen when process water was mixed with only inoculum. In the second trial, a more realistic scenario was tested where process water was co-digested with primary sludge at different ratios. The results from the second trial were not statistically reliable and therefore cannot be used on their own to determine with certainty if the process water could have an inhibitory effect in a full-scale anaerobic digester. However, the combined results from both trials indicate that it is unlikely that the process water would have an inhibitory effect. The possible increase in methane yield, if the digestate from a biogas facility was treated in full-scale implementation of the HTC process, was calculated theoretically. The produced process water would have the capacity to increase the methane production with approximately 10 % for a biogas facility. For the calculations, the BMP for process water was assumed to be 335 NmL/gvs and no synergetic effects was considered. Student thesisinfo:eu-repo/semantics/bachelorThesistexthttp://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-325289UPTEC W, 1401-5765 ; 17008application/pdfinfo:eu-repo/semantics/openAccess |
collection |
NDLTD |
language |
English |
format |
Others
|
sources |
NDLTD |
topic |
anaerobic digestion HTC process water hydrochar AMPTS BMP primary sludge digestate rötning HTC processvatten biokol AMPTS BMP primärslam rötningsslam Other Engineering and Technologies not elsewhere specified Övrig annan teknik |
spellingShingle |
anaerobic digestion HTC process water hydrochar AMPTS BMP primary sludge digestate rötning HTC processvatten biokol AMPTS BMP primärslam rötningsslam Other Engineering and Technologies not elsewhere specified Övrig annan teknik Nilsson, Erik Anaerobic digestion trials with HTC process water |
description |
Hydrothermal carbonization (HTC) is a process where elevated temperature and pressure is used in order to convert biomass to hydrochar, a coal-like substance with good dewatering properties and many potential uses. HTC can be used to treat digestate from anaerobic digestion, but the process water that remains after the hydrochar has been recovered needs to be treated further in the wastewater treatment plant. In order to make HTC more competitive compared to other sludge treatments it is important to find a good use for the process water. The main objective of this master thesis was to investigate the effects of recirculating HTC process water to the anaerobic digestion. To achieve the objective, both theoretical calculations and experimental trials were performed. The experimental trials were conducted with an Automatic Methane Potential Test System (AMPTS II) in order to investigate the anaerobic digestion in laboratory scale. In the first trial, three substrates, process water, hydrochar, and primary sludge were tested for their biochemical methane potential (BMP). All substrates were mixed with inoculum. Process water had a BMP of 335 ± 10 % NmL/gvs (normalized CH4 production in mL per g added VS (volatile solids)), hydrochar had BMP of 150 ± 5 % NmL/gvs, and primary sludge had a BMP of 343 ± 2 % NmL/gvs. The methane production was almost the same for process water as for primary sludge i.e. no inhibitory effects could be seen when process water was mixed with only inoculum. In the second trial, a more realistic scenario was tested where process water was co-digested with primary sludge at different ratios. The results from the second trial were not statistically reliable and therefore cannot be used on their own to determine with certainty if the process water could have an inhibitory effect in a full-scale anaerobic digester. However, the combined results from both trials indicate that it is unlikely that the process water would have an inhibitory effect. The possible increase in methane yield, if the digestate from a biogas facility was treated in full-scale implementation of the HTC process, was calculated theoretically. The produced process water would have the capacity to increase the methane production with approximately 10 % for a biogas facility. For the calculations, the BMP for process water was assumed to be 335 NmL/gvs and no synergetic effects was considered. |
author |
Nilsson, Erik |
author_facet |
Nilsson, Erik |
author_sort |
Nilsson, Erik |
title |
Anaerobic digestion trials with HTC process water |
title_short |
Anaerobic digestion trials with HTC process water |
title_full |
Anaerobic digestion trials with HTC process water |
title_fullStr |
Anaerobic digestion trials with HTC process water |
title_full_unstemmed |
Anaerobic digestion trials with HTC process water |
title_sort |
anaerobic digestion trials with htc process water |
publisher |
Uppsala universitet, Institutionen för geovetenskaper |
publishDate |
2017 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-325289 |
work_keys_str_mv |
AT nilssonerik anaerobicdigestiontrialswithhtcprocesswater AT nilssonerik rotningsforsokmedhtcprocessvatten |
_version_ |
1718462384247406592 |