Energetic enhancement of thermal assistance in the cooling stage of biodrying by stimulating microbial degradation. (15th April 2019)

• Record Type: Journal Article
• Authors: Ma, Jiao; Zhang, Lei; Mu, Lan; Zhu, Kongyun; Li, Aimin
• Is Part Of: Waste management. Volume 89(2019)
• Page Start: 165
• Page End: 176
• Publication Date: 2019-04-15
• Subjects: Bulking agent -- Conventional biodrying -- Cooling stage -- Energetic enhancement -- Thermally assisted biodrying; Hazardous wastes -- Periodicals; Refuse and refuse disposal -- Periodicals; 363.728
• DOI: 10.1016/j.wasman.2019.04.004
• Languages: English
• ISSNs: 0956-053X

Abstract

Graphical abstract: Highlights: Thermal assistance enhanced water removal and biodegradation in cooling stage; Enzymes were stimulated for organics degradation, especially for lignocelluloses; Small amounts of thermal heat (<25%) efficiently upgraded conventional processes; Thermal assistance consumed less external energy than further thermal drying. Abstract: In this study, thermal assistance was employed in the cooling stage of conventional biodrying. The results indicated that thermal assistance greatly enhanced water removal with improved vapor-carrying capacity of air-flow, and rapidly decreased moisture contents (MCs) from 45.15% to 49.42% to 15.20–25.85% in 6 days, which were much lower than those of conventional biodrying (CB, 34.90–40.85%). More importantly, a synergistic enhancement of physical and biological effects was observed in thermally assisted biodrying (TB) in terms of stimulated enzymes activity and microbial metabolism (higher oxygen uptake rate and degradation coefficient k). Among the degraded organics, lignocellulose was noted to be important for bio-heat generation in cooling stages, especially for straw as bulking agent. Heat balance results suggested that small fractions of thermal heat (19.76–24.73%) were required to upgrade CB processes for water evaporation with higher energy efficiency. Based on economic viability analysis and with consideration of the further drying for CB products, thermally assisted biodrying presented more economic benefits with less investment and shorter payback period. This research provided an efficient engineering approach to upgrade the cooling stage of conventional biodrying with low external heat cost.