Feasibility of vermicomposting combined with room drying for enhancing the stabilization efficiency of dewatered sludge. (15th April 2022)

• Record Type: Journal Article
• Authors: Huang, Kui; Zhang, Yingying; Xu, Junjie; Guan, Mengxin; Xia, Hui
• Is Part Of: Waste management. Volume 143(2022)
• Page Start: 116
• Page End: 124
• Publication Date: 2022-04-15
• Subjects: Earthworm -- Sludge recycling -- Vermicompost -- Bio-degradation -- Microbial fertilizer; Hazardous wastes -- Periodicals; Refuse and refuse disposal -- Periodicals; 363.728
• DOI: 10.1016/j.wasman.2022.02.026
• Languages: English
• ISSNs: 0956-053X

Abstract

Graphical abstract: Highlights: Vermicomposting combined with room drying for sludge recycling was studied. The fastest decomposition of organic matter was recorded in VD process. Bacterial and eukaryotic numbers were the highest in VD product. The decomposition pathway of sludge was strongly modified by VD process. Dewatered sludge can be stabilized and maturated within 20 days by VD process. Abstract: Vermicomposting is characterized by transforming organic waste into nutrient-rich organic fertilizer through the action of different earthworms and microorganisms. Although vermicomposting can recycle the excess sludge in an eco-friendly manner, the longer stabilization period has limited its industrial application. The present study sought to investigate a novel operation process of vermicomposting combined with room drying (VD) to improve the stabilization efficiency of dewatered sludge. Subsequently, the performance and efficiency of vermicomposting without room drying, room dry without vermicomposting, and VD for sludge stabilization were compared simultaneously. In the VD process, the sludge water content reduced from 60.8% to 1.64%, showing the highest electrical conductivity and lowest organic matter content, making the humus substances abundant in the final product. Moreover, the vermicomposting achieved the highest ammonia and nitrate content in final product. Additionally, the bacterial and eukaryotic abundances in the VD product were significantly higher ( P < 0.01, i.e., 15.6% and 180.7%) than the vermicomposting product. The specific bacterial genus of Glutamicibacter, Chitinibacter, and Acidobacteria was dominated in the VD product. The Partial least squares-Path modeling (PLS-PM) results revealed that the maturity degree in the VD product was significantly associated with microbial component, and the organic form was strongly driven by the change in the physicochemical properties, which was contradictory to vermicomposting model. The study suggests that the VD process could shorten the vermicomposting period by rapidly accelerating the physical, chemical, and biological stabilization of sludge.