Acidogenic fermentation of chicken manure (CM) for production and recovery of volatile fatty acids (VFA) is an interesting biological waste-to-value approach compared to benchmark organic waste management strategies. Considering the wide range of high value applications of VFA, a semi-continuous immersed anaerobic membrane bioreactor (AnMBR) was applied to boost VFA productivity and yield, while reducing downstream processing stages assisting the recovery of VFA. In this regard, the effect of parameters such as pH and organic loading rates (OLR) on the overall bioconversion and filtration performance was investigated. Thermal-shocked CM was applied both as inoculum and substrate. A very high VFA yield (0.90 g-VFA/g-VS) was obtained in the treatment with no pH control (~8.2) at an OLR of 2 g-VS/(L·d), presenting 24% higher yield compared to that of the controlled pH. Batch assays further demonstrated the enhanced hydrolysis and acidogenesis activities at weak alkaline conditions. A long-term (78 days) fermentation and filtration was successfully performed, where stable membrane filtration performance was experienced for about 50 days under high-solid (suspended solid of 37–45 g/L) and high flux (20 L/(m²·h)) conditions. Results suggest that AnMBR of CM is a feasible and promising process for VFA production and recovery.

Applying microbial organic fertilizer (MOF) effectively improves soil tilth and microbial diversity. However, there were few studies about the changes incurred in the physicochemical properties and bacterial diversity in the farmland of North China at a large-scale following MOF application. This study aimed to investigate the soil physicochemical properties and bacterial community following MOF application. A total of 910 t MOF was used on 173 hectares of degraded soil, and the results indicated increased nutrients in the top plough layer. Compared to controls, the treated samples had significant higher organic matter, total nitrogen, available phosphorus, potassium, and hydrolyzed nitrogen (p < 0.05). Furthermore, MOF application also induced a slight increase in the soil bacterial richness, but a significant decrease in the evenness was observed, where Firmicutes, Actinobacteria, and Bacteroidetes were enriched in the treated group, with Bacillus and Arthrobacter being the dominant genera, accounting for 0.291 and 0.136, respectively. Similarly, an increase in the proportion of Pseudomonas and Psychrobacillus was also observed at up to 0.038 and 0.034, respectively. The MOF treatment improved complex carbon metabolism and nitrogen reduction functions, inhibiting nitrogen oxidation as represented by nitrification. Redundancy and correlation analyses showed that total nitrogen, available phosphorus, and pH were the main factors driving the soil microbial community. This study concluded that MOF application could improve the soil’s physicochemical properties and enhance the abundance and function of soil microbes, which is an effective method for improving the soil tilth and ecology of farmland in north China.

Erythromycin is one of the most commonly used macrolide antibiotics. However, its pollution of the ecosystem is a significant risk to human health worldwide. Currently, there are no effective and environmentally friendly methods to resolve this issue. Although erythromycin esterase B (EreB) specifically degrades erythromycin, its non-recyclability and fragility limit the large-scale application of this enzyme. In this work, palygorskite was selected as a carrier for enzyme immobilization. The enzyme was attached to palygorskite via a crosslinking reaction to construct an effective erythromycin-degradation material (i.e., EreB@modified palygorskite), which was characterized using FT-IR, SEM, XRD, and Brunauer–Emmett–Teller techniques. The results suggested the successful modification of the material and the loading of the enzyme. The immobilized enzyme had a higher stability over varying temperatures (25–65 °C) and pH values (6.5–10.0) than the free enzyme, and the maximum rate of reaction (V_max) and the turnover number (k_cat) of the enzyme increased to 0.01 mM min⁻¹ and 169 min⁻¹, respectively, according to the enzyme-kinetics measurements. The EreB@modified palygorskite maintained about 45% of its activity after 10 cycles, and degraded erythromycin in polluted water to 20 mg L⁻¹ within 300 min. These results indicate that EreB could serve as an effective immobilizing carrier for erythromycin degradation at the industrial scale.

Erythromycin fermentation residue (EFR) is difficult to dispose of due to its high content of macrolide erythromycin. An alternative economic method was proposed in this study for erythromycin elimination in EFR through volatile fatty acid (VFA) production via an anaerobic digestion process. Different parameters were applied to evaluate the effects on energy recovery of VFA together with erythromycin elimination from EFR through batch assays under mesophilic conditions. Results demonstrated that anaerobic digestion technology for VFA production can significantly enhance erythromycin elimination in EFR. The highest removal efficiency of 86.7–87.5% was obtained at conditions of controlled pH at 11.0, with erythromycin decreasing from an initial 100.2 to 12.6–14.0 mg/L. Additionally, controlled pH during the digestion process was reported to positively improve VFA yield to a maximum of 1.04 g-COD/g-VS than the adjustment of initial pH (0.46 g-COD/g-VS). Metabolic analysis alongside high-throughput sequence analysis further demonstrated the high hydrolysis and acidogenesis activities of EFR during the VFA accumulation process. Dominate enzymes EC:3.2.1.40, EC:6.2.1.3, EC:4.1.2.14, EC:2.7.2.1, and EC:1.1.1.27 well balanced the whole process from organic to VFA at pH controlled 11.0. The current study provided a new feasible choice for the economical treatment of antibiotic fermentation residues due to the tolerable antibiotic removal efficiency and satisfactory VFA yield.