Microbial community shift in a suspended stuffing biological reactor with pre-attached aerobic denitrifier.

Bioaugmentation is substantially determined by pre-attached communities in biological stuffing systems. However, the inevitable changes of microbial community shift occurred between pre-attached microorganisms on stuffing material and other existing communities in wastewater. Targeting at nitrogen removal in aerobic denitrification reactors, biological augmentation was built by polyurethane supporting material and aerobic denitrification bacteria of Pseudomonas stutzeri strains were primarily colonized. The total nitrogen removal reached a high efficiency of 77 ± 6%, resulting from a relative high nitrate removal (90%) and a low nitrite production of 24 mg l-1. The nitrate removal was kept 10% higher using preattached strains than that using wastewater communities. During the bioaugmentation process, abundant bacteria related to nitrogen removal were evolutively enriched to compete with preattached Pseudomonas stutzeri. The most abundant bacteria growing up in the biofilm belonged to various Classes of Proteobacteria Phylum. A noticeable nitrite production with a relative low TN removal efficiency occurred when Brucella sp. and Brevundimonas sp. were simultaneously enriched in place of Pseudomonas, because Brevundimonas also accumulated nitrite during denitrification under an aerobic condition. The results indicated that pre-attached denitrifiers in comprehensive communities on stuffing material can be established for the efficient nitrogen and COD removal in aerobic denitrification reactors.

Synergetic Effect of Ultrasound, the Heterogeneous Fenton Reaction and Photocatalysis by TiO2 Loaded on Nickel Foam on the Degradation of Pollutants.

The synergistic effect of ultrasound, the heterogeneous Fenton reaction and photocatalysis was studied using a nickel foam (NF)-supporting TiO2 system and rhodamine B (RhB) as a target. The NF-supporting TiO2 system was prepared by depositing TiO2 on the skeleton of NF repeatedly and then calcining it. To optimize the conditions and parameters, the catalytic activity was tested in four systems (ultrasound alone (US), nickel foam (NF), US/NF and NF/US/H2O2). The optimal conditions were fixed at 0.1 g/mL NF, initial 5.00 mg/L RhB, 300 W ultrasonic power, pH = 3 and 5.00 mg/L H2O2. The effects of the dissolution of nickel from NF and quenching of the Fenton reaction were studied on degradation efficiency. When the heterogeneous Fenton reaction is combined with TiO2-photocatalysis, the pollutant removal efficiency is enhanced significantly. Through this synergistic effect, 22% and 80% acetochlor was degraded within 10 min and 80 min, respectively.

The antibacterial activity of ceramsite coated by silver nanoparticles in micropore.

In the present study, ceramsite was combined with silver nanoparticles (AgNPs) to fabricate a new nanocomposite for water disinfection. The ceramsite was prepared by fly ash, straw ash, and cement. AgNPs were synthesized using polyvinylpyrrolidone (PVP) as the capping agent. The nanocomposite was prepared by self-aggregation of AgNPs on the surface of the ceramsite. AgNPs capped with PVP can form a thin film on the surface of micropore in ceramsite. The nanocomposite can inhibit bacteria growth and induce damage of the cell membrane of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Therefore, the nanocomposite is a new material which can be used for disinfection in drinking water.

Study on the adsorption of bacteria in ceramsite and their synergetic effect on adsorption of heavy metals.

In this paper, heavy metal adsorption by ceramsite with or without Bacillus subtilis (B. subtilis) immobilization was studied, and the synergetic effect of ceramsite and bacteria was discussed in detail. To investigate the roles of the micro-pore structure of ceramsite and bacteria in removing heavy metals, the amount of bacteria immobilized on the ceramsite was determined and the effect of pH was evaluated. It was found that the immobilization of B. subtilis on the ceramsite was attributed to the electrostatic attraction and covalent bond. The scanning electron microscopy results revealed that, with the presence of ceramsite, there was the conglutination of B. subtilis cells due to the cell outer membrane dissolving. In addition, the B. subtilis immobilized ceramsite showed a different adsorption capacity for different heavy metals, with the adsorption capacity ranking of La(3+) > Cu(2+) > Mg(2+) > Na(+).