Effect of aeration strategy on moisture removal in bio-drying process with auto-controlled aeration system

Abstract

Moisture removal during bio-drying with an auto-controlled aeration system was investigated under four combined aeration strategies for a set range on exhaust gas temperature and air-flow direction. The exhaust gas temperature was kept stable within the set range by varying the air-flow rate under upward aeration, although there was a horizontal temperature gradient in the waste layer, irrespective of air-flow direction. This aeration system enhanced drying performance such that 74.7% of initial moisture weight was removed for 14 days, on average. Moreover, inversion of the air-flow direction induced as much uniformity of the vertical moisture distribution as turning the waste matrix. We evaluated moisture removal in the bio-drying process in terms of performance and efficiency and confirmed that the air-flow rate significantly affected both indicators. To achieve rapid and efficient moisture removal during bio-drying, it is important to control the air-flow rate in response to the exhaust gas temperature to fully utilize metabolic heat for evaporation.

Keywords:

• Bio-drying
• aeration strategy
• moisture removal
• auto-controlled aeration system
• mechanically sorted residue

Declaration of interest statement

We have no conflicts of interest to disclose.

Additional information

Funding

This work was supported by the Korea Ministry of Environment (MOE) under Grant 2018001570001; and the Korea Ministry of Trade, Industry and Energy (MOTIE) under Grant 20153010102020.