Removing H2S contamination in biogas produced from animal wastes
Cuong H Pham1, Surinder Saggar2, Peter Berben2, Kevin Tate2
1Landcare Research, Private Bag 11052, Palmerston North 4442, New Zealand on secondment from Ministry of Agriculture and Rural Development, National Institute of Animal Sciences, Hanoi 10000, Vietnam
2Landcare Research, Private Bag 11052, Palmerston North 4442, New Zealand
ABSTRACT
Animal wastes have been widely used to produce biogas in developing countries including Vietnam. However, hydrogen sulphide (H2S) contamination in this biogas limits its use for cooking only because, when used for power generation, it corrodes the metallic components of engines or gas burners. Thus, large quantities of this biogas (up to 51%) are released to the atmosphere. The main objective of this 2-year LEARN Postdoctoral project is to reduce and mitigate greenhouse and other gas emissions from animal waste produced from in-house cow manure management. This involves the following two components of research: (i) purification of biogas and (ii), treating digestate/effluent to develop a technology for application in the efficient management and use of biogas system in Vietnam and other developing countries.
For the first part of this research, we selected the following locally available iron-rich soils varying in iron contents for removing H2S: Acidic sandy brown soil, Typic sandy brown soil, Black iron-sand, Typic orthic allophanic soil, Orthic podzol soil, Orthic brown soil and Iron rust and Raw sand to purify biogas for use in power generation. The preliminary results of H2S removal with Acidic sandy brown soil indicated that H2S removal (%) declined with increasing feeding time from 15 minutes to 240 minutes irrespective of the retention time. But with a longer retention time of 25 min, >80% H2S was removed over 240 min feeding period. These results suggest that the locally available iron-sand has the potential to purify biogas produced from animal waste. Further testing of other iron-sands is now underway to determine how effective the most efficient materials are for future use by the farmers.