The '''internal circulation reactor''' ('''IC reactor''') is a form of anaerobic digester. It is primarily designed to treat wastewater. The IC reactor is an evolution of the UASB and EGSB digestion systems. The IC reactor is essentially two vertical UASB reactors in series, providing a larger height-to-diameter ratio, and decreasing footprint. The main feature of an IC reactor is its gas-driven internal circulation system, which retains biomass within the column until digestion, instead of having an external vessel for re-circulation.<ref>{{Cite journal |last=Cui |first=Pengyi |last2=Zhou |first2=Xuefei |last3=Zhang |first3=Yalei |date=2011-01-01 |title=The Feasibility Study of Cotton Pulp Wastewater Treatment with IC Anaerobic Reactor |url=https://www.sciencedirect.com/science/article/pii/S1878029611009303 |journal=Procedia Environmental Sciences |series=2011 2nd International Conference on Challenges in Environmental Science and Computer Engineering (CESCE 2011) |volume=11 |pages=686–692 |doi=10.1016/j.proenv.2011.12.107 |issn=1878-0296|doi-access=free }}</ref> Because of this retention, ICs typically produce biogas with a high concentration of methane (~80%), and can process waste 3-5 times faster than typical UASB reactors.<ref>{{Cite journal |last=van Lier |first=Jules B. |last2=Rebac |first2=Salih |last3=Lettinga |first3=Gatze |date=1997-05-01 |title=High-rate anaerobic wastewater treatment under psychrophilic and thermophilic conditions |url=https://doi.org/10.2166/wst.1997.0383 |journal=Water Science and Technology |volume=35 |issue=10 |pages=199–206 |doi=10.2166/wst.1997.0383 |issn=0273-1223|url-access=subscription }}</ref><ref>{{Cite journal |last=Jiang |first=Jiankai |last2=Wu |first2=Jing |last3=Zhang |first3=Jinbai |last4=Poncin |first4=Souhila |last5=Li |first5=Huai Z. |date=2014-03-01 |title=Multiscale hydrodynamic investigation to intensify the biogas production in upflow anaerobic reactors |url=https://www.sciencedirect.com/science/article/pii/S0960852413019196 |journal=Bioresource Technology |volume=155 |pages=1–7 |doi=10.1016/j.biortech.2013.12.079 |issn=0960-8524|url-access=subscription }}</ref>
The IC reactor typically comes as part of a series of anaerobic digestion system where it is preceded by thermal hydrolysis, acidogenesis, and acetogenesis, with high methanogenic activity in the IC reactor being an indicator of its efficiency.<ref>{{Cite journal |last=Chen |first=Ye |last2=Cheng |first2=Jay J. |last3=Creamer |first3=Kurt S. |date=2008-07-01 |title=Inhibition of anaerobic digestion process: A review |url=https://www.sciencedirect.com/science/article/pii/S0960852407001563 |journal=Bioresource Technology |volume=99 |issue=10 |pages=4044–4064 |doi=10.1016/j.biortech.2007.01.057 |issn=0960-8524|url-access=subscription }}</ref><ref>{{Cite journal |last=Hao |first=Li-Ping |last2=Lü |first2=Fan |last3=Li |first3=Lei |last4=Shao |first4=Li-Ming |last5=He |first5=Pin-Jing |date=2012-12-01 |title=Shift of pathways during initiation of thermophilic methanogenesis at different initial pH |url=https://www.sciencedirect.com/science/article/pii/S0960852411018189 |journal=Bioresource Technology |series=Advances in Biological Waste Treatment and Bioconversion Technologies |volume=126 |pages=418–424 |doi=10.1016/j.biortech.2011.12.072 |issn=0960-8524|url-access=subscription }}</ref> Effluent leaving the IC reactor may require further aerobic treatment to reduce biochemical (BOD) and chemical oxygen demand (COD) to levels consistent with local legislation.<ref>{{Cite journal |last=Seghezzo |first=Lucas |last2=Zeeman |first2=Grietje |last3=van Lier |first3=Jules B. |last4=Hamelers |first4=H.V.M. |last5=Lettinga |first5=Gatze |date=September 1998 |title=A review: The anaerobic treatment of sewage in UASB and EGSB reactors |url=https://doi.org/10.1016/s0960-8524(98)00046-7 |journal=Bioresource Technology |volume=65 |issue=3 |pages=175–190 |doi=10.1016/s0960-8524(98)00046-7 |issn=0960-8524|url-access=subscription }}</ref>
== See also == * Anaerobic digester types
== References == {{Reflist}}
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Category:Anaerobic digester types
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