A secret of high-rate mass transfer in anammox granular sludge : "lung-like breathing"

The granulation of anaerobic ammonium oxidation (Anammox) biomass can play a key role in developing stable and high-rate working of anammox process. It is important to know the working mechanism of anammox granular sludge (AnGS) for the optimization of reactor performance. In this study, a “lung-like breathing” determinator was invented to investigate the working behavior of AnGS in the bioreactor. The results showed that the AnGS had a regular expansion and contraction phenomenon, which was called “lung-like breathing”. With the biological loading rate (BLR) at 0.114 kg-N/(kg-VSS·d), the expansion and contraction amplitude (ExCA) was 1.29 ± 0.05%, and the expansion and contraction frequency (ExCF) was 39.3 ± 1.6 times/h. The AnGS cultivated in a bioreactor with higher nitrogen removal rate (NRR) was found to have the higher ExCA and ExCF when determinated at the same BLR, and the “lung-like breathing” behavior of one type of AnGS was revealed to bear a significantly (p < 0.05) positive correlation with the specific anammox activity (SAA). The mass transfer flux from “lung-like breathing” was far greater than that from molecular diffusion, which was regarded as a vital mechanism for the AnGS to demonstrate its high activity. These findings provided theoretical basis and technical parameters for the optimization of anammox nitrogen removal process.This research was financially supported by the National Natural Science Foundation of China (51578484) and Research Funds for Central Universities (2017xzzx010-03). Major Scientific and Technological Specialized Project of Zhejiang Province (2015C03013) was also be highly appreciated

Phosphate removal from aqueous solutions by nanoscale zero-valent iron

<div><p>In this study, nanoscale zero-valent iron (NZVI) was synthesized by conventional liquid-phase chemical reduction methods without a support material and then characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effect of NZVI particles on phosphate removal from aqueous solutions was examined. The results showed that the phosphate removal efficiency increased from 34.49% to 87.01% as the dosage of nanoscale iron particles increased from 100 to 600 mg L⁻¹ with an initial phosphate concentration of 10 mg L⁻¹, and the phosphate removal efficiency decreased from 72.89% to 51.39% as the initial phosphate concentration increased from 10 to 90 mg L⁻¹, with 400 mg L⁻¹ NZVI. Phosphate removal efficiencies of 99.41% and 95.09% were achieved at pH values of 2 and 4, respectively, with an initial phosphate concentration of 20 mg L⁻¹ and 400 mg L⁻¹ NZVI. The use of NZVI particles synthesized in a carboxymethyl cellulose (CMC)–water solution significantly enhanced phosphate removal from an aqueous solution compared with the use of NZVI synthesized in an ethanol–water solution. NZVI particles achieved 71.34% phosphate removal, which was remarkably higher than that of microscale zero-valent iron (MZVI) particles (16.35%) with 10 mg L⁻¹ of phosphate and 400 mg L⁻¹ iron. Based on the removal mechanism analysis performed in this study, we recommend that phosphate removal be accomplished by simultaneous adsorption and chemical precipitation. The XRD patterns of the NZVI before and after the reactions indicated the formation of crystalline vivianite (Fe₃(PO₄)₂·8H₂O) during the procedure.</p></div

The anammox process at typical feast-famine states : reactor performance, sludge activity and microbial community

Anaerobic ammonium oxidation (Anammox) is a chemolithotrophic bioprocess which has been widely applied in the treatment of different concentrations of ammonium-containing wastewaters. However, there is less attention on the problem that the instantaneous growth rate (or metabolic rate) and equilibrium growth rate were un-synchronous for anammox bacteria due to their long generation time and self-immobilization of the granular sludge which could lead to the inaccurate estimation. In this study, the anammox process was firstly divided to four typical feast-famine (starvation, satiation, tolerance and poison) states based on the combination of both off-site and in-situ anammox reaction kinetics. Then, four respective lab-scale bioreactors were operated at each state for over a year to achieve stable anammox performance. The results showed that the nitrogen removal rates of bioreactors were 0.53, 2.24, 9.30 and 12.96 kg N/(m³·d); and the specific anammox activities of granular sludge were 188.94 (48%), 313.29 (79%), 397.50 (100%) and 198.60 (50%) mg N/(g VSS·d) which could reflect the reactivity of each feast-famine state. The stable microbial communities of bioreactors were cultured and analyzed, whose species diversity went down with the decrease of Shannon and ACE index. The relative abundance of anammox bacteria increased from 11% to 57% from starvation to poison state. Candidatus Brocadia/Nitrospira, Candidatus Kuenenia and Brocadiaceae unclassified were revealed to be the distinctive functional bacteria, which could serve as the indicator of each state. The setting up of the typical feast-famine states could be regarded as the landmark to help the design, control and optimization of anammox process.This research was financially supported by the National Natural Science Foundation of China (51578484 and 51778563) and Research Funds for Central Universities (2017xzzx010-03). Major Scientific and Technological Specialized Project of Zhejiang Province (2015C03013) and Key Research and Development program of Zhejiang Province (2018C03031) were also gratefully thanked

Characteristics of microbial communities and their correlation with environmental substrates and sediment type in the gas-bearing formation of Hangzhou Bay, China

Shallow gas is a kind of natural gas buried in shallow strata, generally, with methane as the main component, endowing it a potential energy resource while also a potential risk to the safety of ground engineering and environment. Microbial activity is usually regarded as an important driving force to generate shallow gas via metabolizing the environmental substrates. Therefore, the research on the microbial communities will be helpful to reveal the distribution of shallow gas in the gas-bearing formation. In this study, 30 sediment samples below the seabed in Hangzhou Bay (China) from depths of 1.5 m to 55 m were collected to investigate their microbial community, environmental characteristics and sediment type (clay or sand). It turned out that the presence of shallow gas had a good correlation with the distribution of archaea rather than bacteria, with the dominant microbe of Bathyarchaeota, Thaumarchaeota, and Euryarchaeota in the formation. Methanosarcinaceae and ANME-1a with the capacity of methane metabolism occupied high proportions. The correlation analysis and redundancy analysis (RDA) suggested that ammonium was a key environmental substrate to indicate the microbial community in the formation. The sediment type was proposed to shape environmental substrates in the formation, thus further affecting the microbial communities. The clay strata were demonstrated to have an important role in the generation and distribution of shallow gas, and more attention should be paid in terms of its resource discovery and engineering safety assessment.Published versio

Advances in the Application of Perovskite Materials

Nowadays, the soar of photovoltaic performance of perovskite solar cells has set off a fever in the study of metal halide perovskite materials. The excellent optoelectronic properties and defect tolerance feature allow metal halide perovskite to be employed in a wide variety of applications. This article provides a holistic review over the current progress and future prospects of metal halide perovskite materials in representative promising applications, including traditional optoelectronic devices (solar cells, light-emitting diodes, photodetectors, lasers), and cutting-edge technologies in terms of neuromorphic devices (artificial synapses and memristors) and pressure-induced emission. This review highlights the fundamentals, the current progress and the remaining challenges for each application, aiming to provide a comprehensive overview of the development status and a navigation of future research for metal halide perovskite materials and devices.Funding Agencies|National Key Research and Development Program of China [2022YFB3803300]; open research fund of Songshan Lake Materials Laboratory [2021SLABFK02]; National Natural Science Foundation of China [21961160720]</p