Raw FT-ICR MS Data from Anaerobic Digesters at Food Waste Treatment Plants (FWTPs)

Sample collection: Sludge samples were collected from 7 representative full-scale, two-stage digesters located in Beijing (BJ), Guangyuan (GY), Hangzhou (HZ), Liaocheng (LC), Quanzhou (QZ), Shenyang (SY), Shenzhen (SZ) across China. The cities BJ, LC, and SY belong to North China, while GY, HZ, QZ and SZ are in South China, regions traditionally distinguished by their culture, diet, habits, and customs. Sample pretreatment: These samples were collected from the effluent of primary digestion (PD) and secondary digestion (SD) at the end-stage of a feed cycle. At least 250 mL sample was taken from each digester and then shipped on dry ice to the lab. Upon arrival, the samples were separated into aliquots, specifically prepared for analysis of physicochemical parameters and DOM. For liquid sample analysis, the samples were centrifuged at 7000 rpm (5752 rcf) for 10 minutes and the supernatant was filtered with 0.22 μm Millipore membrane. These samples were stored short-term in fridge (<14 days). Owing to high organic contents in the DOM samples, all the DOM samples were diluted 10 times before filtering and other treatment. Solid phase extraction (SPE) for DOM preparation was performed using solid phase extraction columns (HyperSepTM retain PEP 60 mg, Thermo Scientific) with balanced retention of polar and non-polar analytes. FT-ICR MS analysis: The analysis of DOM was conducted using a 7T Bruker solariX FT-ICR MS in negative ion mode with the ESI source and a krypton lamp, following a previous protocol61 with minor adjustments. The nebulizer gas (N2) was adjusted to 2.0 bar and maintained at 400°C to ensure complete vaporization of the samples injected at a rate of 20 μL/h. The operating capillary voltage was -1500 V, and the end plate voltage was -500 V. Ion accumulation and flight times to the analyzer were optimized to 0.02 s and 0.8 s, respectively. We collected 200 coadded scans of broadband spectra in the 54-20000 m/z range and the mass resolution set to ~320000 at 400 m/z. The sodium trifluoroacetate (NaTFA) was used as a quality control sample within the mass range of 112-2968 m/z, achieving a mass accuracy of ≤ 0.5 ppm through calibration. Data documentation: The dataset consists of 14 XML files generated from FT-ICR MS analyses. Each file represents a DOM sample collected from one of seven full-scale food waste treatment plants (FWTPs) located in different cities. The naming convention follows the format: City_Process, where: City is represented by a two-letter abbreviation (e.g., BJ for Beijing, LC for Liaocheng, etc.)；Process indicates the digestion stage, with PD for primary digestion and SD for secondary digestion. For example, BJ_PD refers to the DOM sample from the primary digestion process at the FWTP in Beijing, while BJ_SD refers to the corresponding sample from the secondary digestion stage. The complete list of samples includes: BJ_PD, BJ_SD; LC_PD, LC_SD; SY_PD, SY_SD; GY_PD, GY_SD; HZ_PD, HZ_SD; QZ_PD, QZ_SD; SZ_PD, SZ_SD.