title: Organic matter humification in vermifiltration process for domestic sewage sludge treatment by excitation-emission matrix fluorescence and Fourier transform infrared spectroscopy.
abstract: Performance of a conventional biofilter (BF) and two vermifilters (VFs, different heights) containing earthworms was investigated for domestic sewage sludge (DWS) treatment. Humic-acid like (HAL) fraction isolated from the influent sludge (IS) and effluent sludge of BF (ESBF) and VFs (ESVFs) were determined the elemental and functional composition, and structural characteristics using various analytical approaches. Results showed that performance of DWS treatment in the VFs was preferable to that in the BF. With respect to IS-HAL and ESBF-HAL, ESVFs-HAL had low C, H and N contents and C/O ratio, and high O, carboxyl and phenolic OH group contents, and C/N, C/H and E4/E6 ratios, and large molecular weight. The excitation-emission (Ex/Em) matrix spectra revealed that an additional peak was found at Ex/Em wavelength pairs of 345/435 nm in ESVFs-HAL. Further, Fourier transform infrared spectra showed that vermifiltration led to the loss of aliphatic materials and carbohydrates, and the enrichment of carbonyl and phenolic OH groups in HAL fractions. Additionally, the increase in VF height seemed to accelerate humification degree of organic matter in the effluent sludge. In summary, vermifiltration is alternate technology for transformation of organic matter into humic substances, and thus improves quality of DWS as soil organic fertilizer.
authors: State Key Laboratory of Pollution Control and Resources Reuse, The National Engineering Research Center for Urban Pollution Control, Key Laboratory of Yangtze River Water Environment, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China.
authors: Xiaowei
authors: X
authors: Li
authors: Meiyan
authors: M
authors: Xing
authors: Jian
authors: J
authors: Yang
authors: Limin
authors: L
authors: Zhao
authors: Xiaohu
authors: X
authors: Dai
mesh_terms: D000818:Animals; D005374:Filtration / Q000379:methods; D006812:Humic Substances; D009835:Oligochaeta; D012722:Sewage; D013050:Spectrometry, Fluorescence; D017550:Spectroscopy, Fourier Transform Infrared; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D006812:Humic Substances; D012722:Sewage
keywords: ANOVA; BF; BOD(5); COD; DWS; E4/E6 ratio; EEM; EEWPs; ES; ESBF; ESBF-HAL; ESVF; ESVF-HAL; Excitation–emission (Ex/Em) matrix fluorescent spectra; FRI; FT-IR; Fourier transform infrared; Fourier transform infrared spectra; GFC; HAL; Humic acid; IS; IS-HAL; PEGs; SEM; SFI; SS; Sludge reduction and stabilization; UV; VF; VSS; Vermifiltration; WWTPs; analysis of variance; biofilter; chemical oxygen demand; domestic sewage sludge; effluent sludge; effluent sludge of biofilter; effluent sludge of vermifilter; excitation/emission wavelength pairs; excitation–emission matrix; five day carbonaceous biochemical oxygen demand; fluorescence regional integration; gel filtration chromatography; humic acid-like; humic acid-like fraction extracted from effluent sludge of biofilter; humic acid-like fraction extracted from effluent sludge of vermifilter; humic acid-like fraction extracted from influent sludge; influent sludge; polyethylene glycols; ratio of absorbances at 465nm and 665nm; scanning electron microscopy; specific fluorescence intensity; suspended solid; ultraviolet; vermifilter; volatile suspended solid; wastewater treatment plants