Treatment of manure methane emissions in a full-scale biofilter by microbial oxidation

Résumé fourni par la source

• Methane emissions from a tent-covered pig manure tank were collected and treated in a biofilter. • The biofilter was 400 m 2 and consisted of a gas distribution layer and a compost layer. • Of the loaded CH 4 , 93% was removed, equivalent to an annual reduction of 39 tons of CH 4. • CH 4 was oxidised in the gas distribution layer and the deep part of the filter. • The CO 2 shadow price for reducing one ton of CO 2 equivalent was 9.90 €. Efficient collection and treatment of methane (CH 4 ) from a pig manure tank was demonstrated in a full-scale biofilter designed for optimal biological CH 4 oxidation. The 400 m 2 biofilter consisted of a gas distribution layer and a compost-based oxidation layer. The biofilter removed on average 93 ± 6.5 % of the CH 4 loaded to the biofilter, corresponding to an annual reduction of 39 tons of CH 4 . The CH 4 load to the biofilter was lowest during early spring (0.5 kg h −1 ), when a small amount of manure was stored in the tank and the air temperature was reduced, and highest during summer (12.9 kg h −1 ), when the air temperature was high and the tank contained more manure. The biofilter CH 4 oxidation rate ranged between 32 and 650 g CH 4 m −2 d –1 , with the maximum rate observed in August when the biofilter load was at its highest (774 g CH 4 m −2 d –1 ). Most of the time, CH 4 was completely oxidised in the gas distribution layer and the deepest part of the biofilter. When the CH 4 load exceeded 9 kg h −1 , oxidation efficiency decreased to below 90 %. The optimal CH 4 oxidation temperature of the CH 4 oxidising community was 50 °C, which is close to the annual average temperature of 49 ± 1.7 °C. With a CO 2 shadow price of 9.90 € for reducing one ton of CO 2 equivalent, the biofilter was revealed as a cost-efficient mitigation technology for reducing CH 4 emissions from manure storage tanks.

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