Preincubation and vermicomposting of divergent biosolids exhibit vice versa multielements stoichiometry and earthworm physiology

Muhammad Bilal Khan; Xiaoqiang Cui; Ghulam Jilani; Yan Ting; Afsheen Zehra; Yasir Hamid; Bilal Hussain; Lin Tang; Xiaoe Yang; Zhenli He

doi:10.1016/j.jenvman.2019.04.116

Preincubation and vermicomposting of divergent biosolids exhibit vice versa multielements stoichiometry and earthworm physiology

J Environ Manage. 2019 Aug 1:243:144-156. doi: 10.1016/j.jenvman.2019.04.116. Epub 2019 May 16.

Authors

Affiliations

¹ Ministry of Education Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China.
² Institute of Soil Science, PMAS, Arid Agriculture University Rawapindi, 46300, Pakistan.
³ Ministry of Education Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China; Department of Botany, Federal Urdu University of Arts, Science and Technology, Karachi, Pakistan.
⁴ Ministry of Education Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China. Electronic address: xeyang@zju.edu.cn.
⁵ Soil and Water Science Department, Indian River Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Fort Pierce, FL, 34945, USA.

PMID: 31100659
DOI: 10.1016/j.jenvman.2019.04.116

Abstract

Sewage sludge and kitchen refuse are ubiquitously mounting wastes with high organic load, which if reprocessed they could salvage the environment. Reckoned with this certitude, an incubating study was initiated on sequential preincubation of sewage sludge with kitchen waste in 100:0, 70:30, 50:50, and 30:70 ratios for 16 days ensued by vermicomposting of 30 days using Eisenia fetida. Concentration of heavy metals (Cd, Cr, Cu, Mn, Pb, and Zn) in the biosolid mixtures increased during preincubation but reduced progressively through vermicomposting due to bioaccumulation of these metals in the earthworm tissues. Earthworm growth parameters data reflected that sewage sludge and kitchen waste mixture with 70:30 ratio increased the number of cocoons (10.6%), biomass (8.2%), growth rate (8.3%), reproduction rate (12.2%), and decreased their mean mortality rate (80.1%) as compared to that in sole sewage sludge (control). Results of chemical analysis and SEM/EDS imaging, showed that alkalinity, organic carbon, C/N ratio, organic matter and concentration of trace elements (Cd, Cr, Cu, Mn, Pb, and Zn) reduced while macronutrients (N, P, K, Ca and Mg) increased in the final vermicompost as compared to that in initial mixtures. The FT-IR analysis also revealed that various biochemical functional groups underwent biodegradation during combined preincubation-vermicomposting. Bioaccumulation factor (BAF) of all trace elements in the earthworm tissues was higher with 70:30 ratio of substrates, with the trend of Cd > Zn > Cu > Mn > Pb > Cr. Hence, this study concludes that combined preincubation-vermicomposting is the most efficient and ecofriendly technique for biodegradation, stabilization, and conversion of sewage sludge and kitchen waste into organic fertilizer. The nutrient rich vermicompost can be safely used as horticultural substrate and soil conditioner for efficient management of degraded soils. Finally, combined preincubation-vermicomposting is a sustainable system of recycling the sewage sludge along with kitchen waste.

Keywords: Bioaccumulation; FT-IR; Heavy metals; Kitchen waste; Sewage sludge; Vermicomposting.

MeSH terms

Animals
Metals, Heavy*
Oligochaeta*
Sewage
Soil
Spectroscopy, Fourier Transform Infrared

Substances

Metals, Heavy
Sewage
Soil