Impacts of seasonal variation on volatile fatty acids production of food waste anaerobic fermentation.

This study aims to investigate the influence of seasonal variations on Volatile fatty acids (VFAs) production from food waste (FW) and to quantify their impact. Results of batch experiments with external pH control indicated that the properties of FW exhibited significant seasonal variations and were markedly different from kitchen waste (KW). The spring group demonstrated the highest VFA concentration and VFA/SCOD, at 31.24 g COD/L and 92.20 % respectively, which were 1.22 and 1.27 times higher than those observed in the summer season. The combined proportion of acetic acid and butyric acid accounted for 81.10 % of the total VFAs in spring, suggesting the highest applicability to the carbon source. The VFA content of all seasonal groups in descending order was butyric acid, propionic acid and acetic acid. Carbohydrates, along with spicy and citrusy substances, promoted the conversion of total VFA and butyric acid, while proteins and lipids favored the production of acetic acid and propionic acid.

New insight into transformation of tetracycline in presence of Mn(II): Oxidation versus photolysis.

Tetracycline (TC) and Mn(II) is a common antibiotic and metal ion respectively. Nevertheless, literatures involving in the effects of Mn(II) on TC transformation are still insufficient. In this study, the kinetic experiment, spectral analysis, complexation experiment and electrochemical analysis, theoretical calculation and products detection were carried out to probe into oxidation and photolysis of TC with Mn(II). Mn(II) greatly accelerated TC oxidation, preferably tending to complex with TC at O10 - O12 or O2 - O3 site. There were a TC-Mn(II)/TC-Mn(III) redox couple and electron transfer process. Conversely, Mn(II) inhibited photolysis of TC. The photolysis of excited TC could compete with energy dissipation reactions. The electron transfer and complexation reaction easily made excited TC energy transfer, thus slowing down photolysis process. During the TC transformation, the intensity of functional groups was significantly decreased. Simultaneously, the degradation pathways mainly included eight reactions. It is a very interesting and probably overlooked phenomenon, which identifies new transformation of TC with Mn(II). This study helps to further understand fate and environmental behavior of antibiotics and metal ion.

Magnesite driven the complementary effects of core fungi by optimizing the physicochemical parameters in pig manure composting.

The effects of magnesite (MS) on fungi communities and the core fungi complementarity during pig manure (PM) composting were explored. Different dosage of MS [0% (T1), 2.5% (T2), 5% (T3), 7.5% (T4) and 10% (T5)] as amendments mixed with PM for 42 days composting. The results showed the dominant of phyla were Ascomycota (78.87%), Neocallimastigomycota (41.40%), Basidiomycota (30.81%) and Aphelidiomycota (29.44%). From day 7 to 42, the abundance of Ascomycota and Aphelidiomycota were increased from 7.75% to 42.41% to 57.27%-78.87% and 0-0.70% to 11.73%-29.44% among all treatments. Nevertheless, the phyla abundance of Neocallimastigomycota and Basidiomycota decreased from day 7 to 42. The co-occurrence network indicated that the high additive amendment could enhance the core fungi complementarity effects capacity. The 10% MS addition was a promisable candidate to optimum fungal communities, and causing a better compost quality. This study illustrated the potential and fungi communities changing of MS as additives in composting.