Influence of moisture content on chicken manure stabilization during microbial agent-enhanced composting.

Moisture content (MC) influences substance transformation during composting and the function of exogenous microbial agents. Unsuitable MC could cause leaching, nutrient loss, and secondary contamination. In this study, chicken manure composting with varied MC (45-61%) was conducted under functional microbial agent inoculation to explore the optimum condition for composting and the potential mechanism. Due to the enhanced decomposing, nitrosation, and nitrification effect lead by the functional microorganism, treatment with the optimal MC (53%) exhibited the highest composting temperature (61 °C) and longest high-temperature period (15 days), achieving a final carbon-nitrogen ratio (C/N), humic acids and fulvic acids ratio (HA/FA), and NH4+-N/NO3--N at 19.20, 2.00, and 0.93, respectively. After composting, the total nitrogen (TN) increased by 13.01-22.10% in the treatments with microbial agent inoculation compared with original stack, while it decreased by 7.76% in control. The highest nutrient (5.63%, 5.63-14.20% higher than the other composts) and better product safety (11.43-23.58% higher seed germination than others) were observed in treatment with MC at 53%, exceeding the Chinese national standard for organic fertilizer. Obviously, under optimum MC, microbial agent augmentation lead to high quality and safe compost products after a short composting period (25 days) without any leaching, which suggested an efficient way to promote the recycling and recovery of husbandry waste.

Succession and diversity of microbial communities in landfills with depths and ages and its association with dissolved organic matter and heavy metals.

Landfill is an important method for the treatment of municipal solid wastes. Microbes play a central role in the biodegradation and stabilization of organic matter during landfill; however, the succession of microbial communities in landfills and their association with organic matter still remain unclear. This study investigated the succession and diversity of microorganisms in landfill depending on different depths and ages as well as its association with dissolved organic matter (DOM) and heavy metals. The results showed that the actinobacterial diversity and richness were high compared to bacteria in young landfill cells. The diversity and richness of bacteria and actinobacterial were the highest in the middle layer in the intermediate and old landfill cells. Firmicutes, Proteobacteria, and Actinobacteria were the most dominant phyla. Firmicutes were mainly affected by the humification degree, and the aromatic and protein-like substance content of the landfill-derived DOM. The phylum Proteobacteria was greatly affected by the lipid and humic-like substances content of the landfill-derived DOM, while the distribution of Actinobacteria was regulated by both aromatic and humic-like substances. The effect of dissolved heavy metals on the microbial distribution in landfill differed for the metals Cr, Ni, Pb, Mn, Cu, Zn, and Cd. Siderophile elements (Cr, Ni, and Pb) were necessary trace elements for Proteobacteria and Actinobacteria, and promoted their growth. Oxyphilic element (Mn) was an important factor promoting the growth of Actinobacteria. However, no apparent relationship was found between sulfurophile elements (Cu, Zn, and Cd) and microorganisms.

Light and Magnetic Dual-Responsive Pickering Emulsion Micro-Reactors.

Emulsion droplets can serve as ideal compartments for reactions. In fact, in many cases, the chemical reactions are supposed to be triggered at a desired position and time without change of the system environment. Here, we present a type of light and magnetic dual-responsive Pickering emulsion microreactor by coadsorption of light-sensitive titania (TiO2) and super paramagnetic iron oxide (Fe3O4) nanoparticles at the oil-water interface of emulsion droplets. The droplets encapsulating different reactants in advance can be driven close to each other by an external magnetic field, and then the chemical reaction is triggered by UV illumination due to the contact of the isolated reactants as a result of droplet coalescence. An insight into the incorporation of hydrophobic TiO2 and hydrophilic Fe3O4 nanoparticles simultaneously at the emulsion interface is achieved. On the basis of that, an account is given of the coalescence mechanism of the Pickering emulsion microreactors. Our work not only provides a novel Pickering emulsion microreactor platform for triggering chemical reactions in a nonintrusive and well-controlled way but also opens a promising avenue to construct multifunctional Pickering emulsions by assembly of versatile building block nanoparticles at the interface of emulsion droplets.