[Applications of biofilm in environmental pollution control and the related challenges].

Biofilm has been used in environmental pollution control in recent years due to its characteristics of adsorption and biodegradation. Beyond the success of its utilization in wastewater treatment, biofilm technique has high application value in the remediation of heavy metals and organic pollutants in soils. With the extensive attention and research of emerging pollutants such as microplastics and antibiotic resistance genes (ARGs), the pivotal role of biofilm can not be overlooked.

Numerical study of hydrodynamic characteristics in a moving bed biofilm reactor.

The moving bed biofilm reactor (MBBR) has certain advantages, such as high wastewater treatment efficiency, low maintenance and operating costs, and simple operation. It has emerged as a valuable option for small decentralized facilities. The filling ratio, aeration mode and aeration intensity are the main factors that affect the performance of MBBRs in wastewater treatment.

Fouling behaviors are different at various negative potentials in electrochemical anaerobic membrane bioreactors with conductive ceramic membranes.

Membrane fouling remains a critical challenge to the practical application of anaerobic membrane bioreactor (AnMBR). To address this challenge, a conductive ceramic membrane was prepared for fouling control in AnMBR. By using the conductive membranes, the anti-fouling performances were enhanced about 3 times at potentials below -1.

Sustainable synthesis of novel carbon microwires for the modification of a Ti mesh anode in bioelectrochemical systems.

Herein, an effective method was developed to integrate carbon microwires on Ti mesh (denoted as CM/TiM) to fabricate high-performance anodes with long-time stability in microbial fuel cell. CM/TiM was synthesized by colonizing filamentous fungi on the bread modified Ti mesh followed by carbonization, which could convert the attached mycelium into carbon microwires (denoted as CM). Benefiting from the biocompatibility and 3D interlaced structure of carbon microwires, the biomass accumulation (1027 ± 83 μg cm) of CM/TiM have been significantly improved nearly 3 folds, thus the fabricated CM/TiM demonstrated 2-fold higher current density (12.

Pd-PEPPSI-IPent Promoted Deactivated Amination of Aryl Chlorides with Amines under Aerobic Conditions.

We report herein a highly efficient Pd-catalyzed amination by "bulky-yet-flexible" Pd-PEPPSI-IPent complexes. The relationship between the N-heterocyclic carbenes (NHCs) structure and catalytic properties was discussed. Sterically hindered (hetero)aryl chlorides and a variety of aliphatic and aromatic amines can be applied in this cross-coupling, which smoothly proceeded to provide desired products.

[Bacterial quorum sensing: Cooperation and cheating].

Quorum sensing (QS), a cell-to-cell communication, regulates a variety of social beha-viors, such as biofilm formation, public goods produce and gene horizontal transfer of bacteria. In the process of quorum sensing, public goods could be utilized by any members in the population, which was termed as cooperation. Notably, public goods also could be shared by the individuals who could not produce them, which was termed as cheating.

A common evolutionary pathway for maintaining quorum sensing in Pseudomonas aeruginosa.

In the bacterium Pseudomonas aeruginosa, the synthesis and secretion of extracellular protease is a typical cooperative behavior regulated by quorum sensing. However, this type of cooperative behavior is easily exploited by other individuals who do not synthesize public goods, which is known as the "tragedy of the commons". Here P.

Nitrogen Source Stabilization of Quorum Sensing in the Pseudomonas aeruginosa Bioaugmentation Strain SD-1.

SD-1 is efficient at degrading aromatic compounds and can therefore contribute to the bioremediation of wastewater. uses quorum sensing (QS) to regulate the production of numerous secreted "public goods." In wastewater bioaugmentation applications, there are myriad nitrogen sources, and we queried whether various nitrogen sources impact the stabilities of both QS and the bacterial populations.

Flexible Steric Bulky Bis(Imino)acenaphthene (BIAN)-Supported N-Heterocyclic Carbene Palladium Precatalysts: Catalytic Application in Buchwald-Hartwig Amination in Air.

To achieve efficient palladium-catalyzed cross-coupling reaction under mild reaction conditions with the flexible steric bulk strategy, a series of Pd-PEPPSI (PEPPSI: pyridine-enhanced precatalyst preparation, stabilization, and initiation) complexes C1-C6 were synthesized and characterized, in which unsymmetric flexible steric bulk was introduced on the N-aryl of ancenaphthyl skeleton. These well-defined palladium complexes were found to be excellent precatalysts for Buchwald-Hartwig amination of aryl chlorides with amines in air. The electronic effect of the Pd-PEPPSI complexes and the effect of ancillary pyridine ligands were evaluated, among which complex C3 exhibited the most efficiency.

Control of the pollution of antibiotic resistance genes in soils by quorum sensing inhibition.

To investigate whether pollution from antibiotic resistance genes (ARGs) could be affected by bacterial quorum sensing, the oxytetracycline (OTC)-containing manure was fertilized to establish the ARG-polluted soil environment. Under long-term OTC stress, substantial ARGs in the range from 10 to 10 RG/16S rRNA (resistance genes/16S rRNA) were detected in the antibiotics control (AC) group, in which OTC-containing manure was fertilized. Meanwhile, 10 RG/16S rRNA was detected in biological control (BC) group, in which non-OTC-containing manure was fertilized.

Bulky α-diimine palladium complexes: highly efficient for direct C-H bond arylation of heteroarenes under aerobic conditions.

Through the strategy to enhance the bulkiness on both the backbone and the N-aryl moieties, we designed and synthesized a type of bulky α-diimine palladium complex (i.e., {[Ar-N[double bond, length as m-dash]C(R)-C(R)[double bond, length as m-dash]N-Ar]PdCl2, (Ar = 2-benzhydryl-4,6-dimethylphenyl)}, C1, R = H; C2, R = An; C3, R = Ph).

Effect of migration and transformation of iron on the endogenous reduction of H2S in anaerobic landfill.

Hydrogen sulfide (H2S) is a major odor in landfill gas and needs urgent treatment. In this study, the effect of migration and transformation of iron on the endogenous reduction of H2S was investigated in two simulated landfills. The results showed that the H2S emission concentration from the landfill cover of conventional anaerobic landfill (CL) and anaerobic landfill with leachate recirculation (RL) could reach 19.

Could humic acid relieve the biochemical toxicities and DNA damage caused by nickel and deltamethrin in earthworms (Eisenia foetida)?

The aim of the study was to determine whether humic acid (HA) prevented gene and biochemical toxic effects in earthworms (Eisenia foetida) exposed to nickel and deltamethrin (at 100 and 1 mg kg(-1), respectively) in soil. Cellular- and molecular-level toxic effects of nickel and deltamethrin in earthworms were evaluated by measuring damage to lipid membranes and DNA and the production of protein carbonyls over 42 days of exposure. Nickel and deltamethrin induced significant levels of oxidative stress in earthworms, increasing the production of peroxidation products (malondialdehyde and protein carbonyls) and increasing the comet assay tail DNA% (determined by single-cell gel electrophoresis).

Effect from low-level exposure of oxytetracycline on abundance of tetracycline resistance genes in arable soils.

To evaluate the effect from low-level exposure of antibiotics on the abundance of antibiotic resistance genes, unpolluted arable soils were treated with oxytetracycline (OTC)-containing manure, with OTC (0, 2, 20, or 70 μg kg(-1)) added every 2 weeks on 10 occasions. Six tetracycline resistance genes [TRGs-tet(A), tet(L), tet(M), tet(Q), tet(O), and tet(W)] and the 16S ribosomal RNA (rRNA) gene were monitored using real-time quantitative polymerase chain reaction. The relative abundance of tet(A), tet(L), tet(M), and tet(Q) genes in soil increased 10-1000 times after application of OTC-containing manure.

Characteristics of H2S emission from aged refuse after excavation exposure.

Hydrogen sulfide (H2S(g)) emission from landfills is a widespread problem, especially when aged refuse is excavated. H2S(g) emission from aged refuse exposed to air was investigated and the results showed that large amounts of H2S(g) can be released, especially in the first few hours after excavation, when H2S(g) concentrations in air near refuse could reach 2.00 mg m(-3).

Sulfide oxidation and nitrate reduction for potential mitigation of H2S in landfills.

Because H2S emitted by landfill sites has seriously endangered human health, its removal is urgent. H2S removal by use of an autotrophic denitrification landfill biocover has been reported. In this process, nitrate-reducing and sulfide-oxidizing bacteria use a reduced sulfur source as electron donor when reducing nitrate to nitrogen gas and oxidizing sulfur compounds to sulfate.

Water state changes during the composting of kitchen waste.

Changes in water states during the composting of kitchen waste were determined. Three experiments, R(55), R(60), and R(65), with different initial moisture contents, 55%, 60%, and 65%, respectively, were performed. Three water states, entrapped water (EW), capillary water (CW), and multiple-molecular-layer water (MMLW), were monitored during the experiments.

Evidence for existence of quorum sensing in a bioaugmented system by acylated homoserine lactone-dependent quorum quenching.

The introduction of a gene, strain, or microbial consortium into an indigenous bacterial population is known as bioaugmentation. This technique has been proposed as an effective strategy for accelerating and enhancing the removal of recalcitrant and toxic compounds during wastewater treatment. In this study, three types of reactors were used to test whether quorum sensing plays an important role in bioaugmented systems.

Bioaccessibility and health risk of heavy metals in ash from the incineration of different e-waste residues.

Ash from incinerated e-waste dismantling residues (EDR) may cause significant health risks to people through ingestion, inhalation, and dermal contact exposure pathways. Ashes of four classified e-waste types generated by an incineration plant in Zhejiang, China were collected. Total contents and the bioaccessibilities of Cd, Cu, Ni, Pb, and Zn in ashes were measured to provide crucial information to evaluate the health risks for incinerator workers and children living in vicinity.

Aerobic degradation study of three fluoroanilines and microbial community analysis: the effects of increased fluorine substitution.

The fate of fluorinated compounds in the environment, especially polyfluorinated aromatics, is a matter of great concern. In this work, 4-Fluoroaniline (4-FA), 2,4-Difluoroanilines (2,4-DFA), and 2,3,4-Trifluoroanilines (2,3,4-TFA), were chosen as the target pollutants to study their biodegradability under aerobic conditions. The required enriched time of the mixed bacterial culture for degrading 4-FA, 2,4-DFA, and 2,3,4-TFA was 26, 51, and 165 days, respectively, which suggested that the longer enrichment time was required with the increase of fluorine substitution.

Effects of added polyacrylamide on changes in water states during the composting of kitchen waste.

The effects of adding polyacrylamide (PAM), to attempt to delay the loss of capillary water and achieve a better level of organic matter humification, in the composting of kitchen waste were evaluated. Four treatments, with initial moisture content of 60 % were used: 0.1 % PAM added before the start of composting (R1), 0.

A new method for rapid construction of a Pseudomonas sp. HF-1 bioaugmented system: accelerating acylated homoserine lactones secretion by pH regulation.

Pseudomonas sp. HF-1 bioaugmented systems were operated to treat tobacco wastewater under pH 5.5 for three cycles and pH 8.

Impact of MSWI bottom ash codisposed with MSW on landfill stabilization with different operational modes.

The aim of the study was to investigate the impact of municipal solid waste incinerator (MSWI) bottom ash (BA) codisposed with municipal solid waste (MSW) on landfill stabilization according to the leachate quality in terms of organic matter and nitrogen contents. Six simulated landfills, that is, three conventional and three recirculated, were employed with different ratios of MSWI BA to MSW. The results depicted that, after 275-day operation, the ratio of MSWI BA to fresh refuse of 1 : 10 (V : V) in the landfill was still not enough to provide sufficient acid-neutralizing capacity for a high organic matter composition of MSW over 45.

Reduction of heavy metals in residues from the dismantling of waste electrical and electronic equipment before incineration.

Residues disposal from the dismantling of waste electrical and electronic equipment are challenging because of the large waste volumes, degradation-resistance, low density and high heavy metal content. Incineration is advantageous for treating these residues but high heavy metal contents may exist in incinerator input and output streams. We have developed and studied a specialized heavy metal reduction process, which includes sieving and washing for treating residues before incineration.

Role of iron in H(2)S emission behavior during the decomposition of biodegradable substrates in landfill.

Hydrogen sulfide (H2S) is regarded as a major odor causing compound in landfill gas that may lead to adverse environmental and health effects. In this study, the potential role of iron in the entire life cycle of H2S production and emission was investigated during the decomposition of biodegradable substrates in the landfilled refuse. The results showed that the quantity of H2S emission decreased about 95% when Fe(OH)3 was present in the biodegradable sulfur-containing substrates.