Effects of thermal treatment on high solid anaerobic digestion of swine manure: Enhancement assessment and kinetic analysis.

Anaerobic digestion (AD), which is a process for generating biogas, can be applied to the treatment of organic wastes. Owing to its smaller footprint, lower energy consumption, and less digestate, high solid anaerobic digestion (HSAD) has attracted increasing attention. However, its biogas production is poor. In order to improve biogas production and decrease energy consumption, an improved thermal treatment process was proposed. Raw swine manure (>20% solid content) without any dilution was thermally treated at 70±1°C for different retention times, and then its effect on HSAD was investigated via batch AD experiments at 8.9% solid content. Results showed that the main organic components of swine manure hydrolyzed significantly during the thermal treatment, and HSAD's methane production rate was improved by up to 39.5%. Analysis using two kinetic models confirmed that the treatment could increase biodegradable organics (especially the readily biodegradable organics) in swine manure rather than upgrading its hydrolysis rate. It is worth noting that the superimposed first-order kinetics model was firstly applied in AD, and was a good tool to reveal the AD kinetics mechanism of substrates with complex components.

[Aqueous Fingerprint of Printing and Dyeing Wastewater].

Aqueous fingerprint has an advantage to represent the organic components of water samples as compared to traditional parameters such as chemical oxygen demand (COD) and total organic carbon (TOC). Printing and dyeing wastewater is one of the major types of industrial wastewater in China. It is of huge volume and heavy pollution, containing large numbers of luminescent components and being difficult to be degraded. In this study the aqueous fingerprint of printing and dyeing wastewater was investigated with the fluorescent spectrometry. The experimental results showed that there existed two peaks in the aqueous fingerprint of the printing and dyeing wastewater, locating at the excitation/emission wavelength around 230/340 nm and 280/310 nm respectively. The intensity of the excitation/emission wavelength at 230/340 nm was higher than that of 280/310 nm. The locations and intensities of peaks varied within small range. The intensities of the two peaks linearly correlated with coefficient of 0.910 8 and slope of 1.506. The intensity ratio of Peak at 280/310 nm to Peak at 230/340 nm averagely was 0.777, ranging between 0.712 and 0.829. It was found that the aqueous fingerprints of sewage and aniline compounds were significantly different from that of the printing and dyeing wastewater, but the aqueous fingerprints of several types of widely-used dye were similar to that of the printing and dyeing wastewater. Thus dye may be the main luminescent components in the wastewater. The aqueous fingerprint can be used as a novel tool of early warning of waterbodies.

[Mechanism study on the extraction of nonylphenol by ionic liquids in water through IR spectroscopy and quantum chemical calculation].

The interaction mechanism of the typical ionic liquid (IL) 1-methyl-3-butyl imidazolium hexafluorophosphate ([BMIM][PF6]), imidazolium ionic liquid with hydroxyl group and nonylphenol (NP) was studied through infrared (IR) spectroscopy and quantum chemical calculations for density functional theory. The results indicated the hydrogen bonds could not be found in the IR spectra before and after IL [BMIM][PF6] extracting NP while the absorption peaks of the hydroxyl group of the ILs containing hydroxyl group have red shifts after the ILs extracting NP. It could be seen in the theoretical calculation that the cation [BMIM]+ of [BMIM][PF6] has the C--H...O hydrogen bond interaction with NP. The O--H...O type hydrogen bond could also be formed between the cation [C4H9OHIM]+ of the IL with hydroxyl group and NP. It could be concluded through the two mechanism study methods that the strength of hydrogen bond between the IL with hydroxyl group and NP was bigger than the one between the typical IL [BMIM][PF6] and NP, followed by the bigger extraction efficiency of NP by the former, which coincided with the extraction experiment result.