Anaerobic co-digestion of sludge and microalgae grown inmunicipal wastewater: A feasibility study

Anaerobic co-digestion of sludge and microalgae grown inmunicipal wastewater : A feasibility study

In this study a natural mix of microalgae grown in wastewater of municipal character was co-digested with sewage sludge in mesophilic conditions, in both batch and semi-continuous modes. The semicontinuous experiment was divided into two periods with OLR 1 (Organic Loading Rate) of 2.4 kg VS m3 d-1 and HRT1 (Hydraulic Retention Time) of 15 days, and OLR2 of 3.5 kg VS m3 d-1 and HRT2 of 10 days respectively. Results showed stable conditions during both periods. The methane yield was reduced when adding microalgae (from 200 ± 25 NmL CH4 g VSin-1 , to 168±22 NmL CH4 g VSin-1). VS reduction was also decreased by 51%. This low digestability was confirmed in the anaerobic batch test. However, adding microalgae improved the dewaterability of the digested sludge. The high heavy metals content in the microalgae resulted in a high heavy metals content in the digestate, making it more difficult to reuse the digestate as fertilizer on arable land. The heavy metals are thought to originate from the flue gas used as a CO2 source during the microalgae cultivation. Therefore the implementation of CO2 mitigation via algal cultivation requires careful consideration regarding thesource of the CO2-rich gas.

Forkman, T.Swedish University of Agricultural Sciences,Sveriges lantbruksuniversitet,Institutionen för energi och teknik,Department of Energy and Technology,Swedish University of Agricultural Sciences, Sweden (author)
Gentili, FrancescoSwedish University of Agricultural Sciences,Sveriges lantbruksuniversitet,Institutionen för vilt, fisk och miljö,Department of Wildlife, Fish and Environmental Studies,Swedish University of Agricultural Sciences, Sweden(Swepub:slu)46816 (author)
Zambrano, JesúsMälardalens högskola,Framtidens energi(Swepub:mdh)jzo01 (author)
Schwede, SebastianMälardalens högskola,Framtidens energi(Swepub:mdh)sse02 (author)
Nehrenheim, Emma,1979-Mälardalens högskola,Framtidens energi(Swepub:mdh)enm02 (author)
Thorin, Eva,1967-Mälardalens högskola,Framtidens energi(Swepub:mdh)etn01 (author)
Mälardalens högskolaFramtidens energi (creator_code:org_t)
Sveriges lantbruksuniversitet

In:Water Science and Technology: IWA Publishing77:3, s. 682-6940273-12231996-9732

By the author/editor: Olsson, Jesper, ...; Forkman, T.; Gentili, Frances ...; Zambrano, Jesús; Schwede, Sebasti ...; Nehrenheim, Emma ...; show more...; Thorin, Eva, 196 ...; show less...

About the subject

AGRICULTURAL SCIENCES: AGRICULTURAL SCI ...; and Other Agricultur ...; and Renewable Bioene ...

ENGINEERING AND TECHNOLOGY: ENGINEERING AND ...; and Civil Engineerin ...; and Water Engineerin ...

By the university: Mälardalen University; Swedish University of Agricultural Sciences

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