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Performance of biofilm reactors for polluted source water pretreatment is usually limited under low-temperature stress in cold winter, and two biofilm reactors were built up for studying performance promotion and spatial distribution of functional bacteria. Experimental results showed that unstable but enhanced pollutants removal was observed in biofilm reactors under low-temperature stress of 8.6 ± 1.8 °C. Proteobacteria was dominant as functional bacteria for nitrogen and organics removal with the maximum relative abundance (RA) values of 30.7–51.7%. Gammaproteobacteria and Alphaproteobacteria were dominant at any spatial locations in blank ESM reactor with RA of 22.8–28.6% and 10.9–14.6%, respectively. The pre-cultured bacteria affected the bacterial distribution under low-temperature stress. Gammaproteobacteria with RA of 14.5% were dominant in the end and Alphaproteobacteria dominant in other locations in precoated ESM reactor with RAs of 12.5–12.9%. Biofilm systems faced the potential risks including Cyanobacteria (0.9–18.62%) and potential bacterial pathogens (PBP) (10.05–12.43%) under low-temperature stress. Fortunately, potential cyanotoxins production genus Planktothrix of Cyanobacteria was gradually decreased and hardly observed at the end of reactors.

This study evaluated nitrogen removal characteristics in a biofilm system for recirculating aquaculture wastewater treatment with different carriers and aeration modes under salinity condit...

The operation performance of biofilm system is limited by the oligotrophic quality of source water, especially the bioavailable organics. In this study, two lab-scale biofilm reactors (R1 and R2) feeding different organic carbon sources (OCS) were built up using sediment in drinking water source as bacterial source. Experimental results showed that sediment in biofilm systems enhanced the NH4 +-N removal performance. Using ethanol as OCS was more beneficial to the removal of NH4 +-N with ammonia removal efficiency (ARE) of 87.0 ± 5.4%, which was higher and more stable than that of glucose with ARE of 83.9 ± 13.3%. Organic carbon source changed the bacterial structure in biofilm systems. The dominant phyla in biofilm under ethanol condition were Proteobacteria, Bacteroidetes and Firmicutes with relative abundances (RA) of 29.1%, 32.7% and 22.0%, respectively. The dominant phyla in biofilm exposure to glucose was Proteobacteria with an RA of 63.4%. At genus level, Nitrospira, Lachnospiraceae, Arcobacter and Hyphomicrobium were dominant under ethanol condition (R1) with the total relative abundance of 20.5%. Sphaerotilus was the dominant genus under glucose condition (R2) with RA of 33.72%. These dominant bacteria were basically having the ability for the removal of nitrogen and organic matter.

The growth and accumulation of functional bacteria were limited due to the deficiency of substrates in biofilm reactors for source water pretreatment. In this study, pre-cultured biofilm (PCB) formed on different carriers was used to treat oligotrophic source water, and the kinetic characteristics and bacterial structures was evaluated under realistic conditions. Experimental results showed that PCB formed under substrate-enhanced conditions decreased substrate affinity of biofilm, but effectively improved the operation performance of biofilm reactors. In particularly, biofilm formed on elastic stereo media had the lowest apparent half-saturation coefficient (Ks) for substrates, which was more easily to accommodate oligotrophic niche. Interestingly, biodiversity of biofilm was obviously increased after long-term exposure to oligotrophic niche, and decreased functional bacteria were replaced by others with similar function. Basically, Proteobacteria and Planctomycetes were dominant in biofilm samples under both substrate-enhanced and oligotrophic conditions.

This study investigated the performance and microbial communities of denitrifying biofilms on polyurethane foam coupled with various solid carbon sources of acid- and alkali-pretreated rice straw and rice husk. Results showed that acid and alkali-pretreated rice straw both had higher TOC release rates (0.041–0.685 mg g−1 day−1) than those of rice husk (0.019–0.160 mg g−1 day−1) over a month, while acid pretreatment of rice husk and rice straw had a much higher organics release rate than that of alkali pretreatment and non-pretreatment, respectively. Acid-pretreated rice straw achieved the most efficient TN removal performance (82.06 ± 3.65%) with the lower occurrences of NH4+-N during denitrification than that of alkali-pretreated rice straw (80.05 ± 4.12%) over more than a month operation. However, alkali pretreatment of rice husk demonstrated much more significantly efficient TN removal efficiency (80.39 ± 2.1%) than did acid pretreatment (69.59 ± 13.43%). MiSeq sequencing analysis showed that the four biofilm samples attached on polyurethane foam with the addition of pretreated rice straw or rice husk had a range of 13–15 differentially abundant phylum and 81–123 differentially abundant genera in comparison with biofilm without extra solid carbon sources, and a higher TN removal efficiency demonstrated more types of differentially abundant genera.

CH3NH3PbI3 is one of the most widely studied and most promising photoelectric conversion materials for large-scale application. However, once it is discharged into the aquatic environment, it will release a variety of lethal substances to the aquatic organisms. Herein, two typical aquatic pollution indicators, Scenedesmus obliquus (a typical phytoplankton) and Daphnia magna (a typical zooplankton), were used to assess the acute effects of CH3NH3PbI3 perovskite on aquatic organisms. The results showed that, when the initial CH3NH3PbI3 perovskite level (CPL) was 40 mg L−1 or higher, the growth of S. obliquus would be remarkably inhibited with significant decreases of chlorophyll content and protein content. And when the CPL was over 5 mg L−1, the survival of D. magna would be notably threatened. Specifically, the 72 h EC-50 of CH3NH3PbI3 perovskite to S. obliquus was calculated as 37.21 mg L−1, and the 24 h LC-50 of this perovskite to D. magna adults and neonates were calculated as 37.53 mg L−1 and 18.55 mg L−1, respectively. Moreover, remarkably solution pH declination and large amounts of lead bio-accumulation was observed in the both acute experiments, which could be the main reasons causing the above acute effects. Considering the strong acute effects of these CH3NH3PbI3 perovskite materials and their attractive application prospect, more attentions should be paid on their harmness to the environment.

In this study, a photoautotrophic hydrogen production of Chlorella pyrenoidosa was presented, with NaHCO 3 (10 mM) instead of organic carbon and DCMU addition (10 μM) instead of sulfur-deprivation. The results showed that the algal O 2 evolution was significantly inhibited by DCMU, and the earlier it was added the more serious the inhibition was. Overall, when DCMU was added within 9 h after illumination, the relative O 2 concentrations could be regarded as anaerobic ( 2 photoproduction was also influenced by DCMU addition time, but with opposite trend to the O 2 evolution. In summary, the highest H 2 production occurred when DCMU was injected at 9 h, being fourfold of that in sulfur-deprived TAP medium (93.86 mL L −1 vs 23.12 mL L −1 ). Further study suggested that the higher H 2 productivity might be mainly due to a relatively higher PSII photochemical activity.

In this work, we coated carbon nanotubes (CNT) supported Pt catalyst by conductive carbon layers (labelled as Pt/CNT@C) and the catalyst was further functionalized by surface oxidation (denoted as Pt/CNT@Oxi-C). The textural properties of the catalysts were extensively characterized and liquid phase catalytic hydrogenation reduction of Cu2+ was conducted. Results showed that Pt particles of Pt/CNT@C and Pt/CNT@Oxi-C were completely embedded beneath carbon overcoatings. Furthermore, contrary to Pt/CNT no CO chemisorption was observed on both Pt/CNT@C and Pt/CNT@Oxi-C, indicative of the absence of exposed Pt particles in carbon-coated Pt/CNT. Effective Cu2+ reduction and metallic Cu deposition by catalytic hydrogenation were achieved on catalyst surface. Surface oxidation of Pt/CNT@C resulted in increased surface wetting and functionality content, leading to noticeable enhancement in catalytic activity for Cu2+ reduction. Additionally, Cu2+ reduction on Pt/CNT@Oxi-C proceeded through the Langmuir-Hinshelwood model, suggesting that the reduction of Cu2+ adsorbed on catalyst surface was the rate-determining step. Carbonization of overcoatings exhibited a volcano-type relationship between carbonization temperature and catalytic activity of Pt/CNT@C for Cu2+ reduction. As for catalyst reuse, Pt/CNT lost 92 % of initial activity after five consecutive reaction cycles, whereas Pt/CNT@Oxi-C maintained a high catalytic activity without remarkable deactivation.