Jiti Zhou

Bacterial community compositions of coking wastewater treatment plants in steel industry revealed by Illumina high-throughput sequencing

In this study, Illumina high-throughput sequencing was used to reveal the community structures of nine coking wastewater treatment plants (CWWTPs) in China for the first time. The sludge systems exhibited a similar community composition at each taxonomic level. Compared to previous studies, some of the core genera in municipal wastewater treatment plants such as Zoogloea, Prosthecobacter and Gp6 were detected as minor species. Thiobacillus (20.83%), Comamonas (6.58%), Thauera (4.02%), Azoarcus (7.78%) and Rhodoplanes (1.42%) were the dominant genera shared by at least six CWWTPs. The percentages of autotrophic ammonia-oxidizing bacteria and nitrite-oxidizing bacteria were unexpectedly low, which were verified by both real-time PCR and fluorescence in situ hybridization analyses. Hierarchical clustering and canonical correspondence analysis indicated that operation mode, flow rate and temperature might be the key factors in community formation. This study provides new insights into our understanding of microbial community compositions and structures of CWWTPs.

Azo dye decolorization by a new fungal isolate, Penicillium sp. QQ and fungal-bacterial cocultures.

A new azo dyes-decolorizing fungi strain QQ was isolated from activated sludge. It was identified as Penicillium sp. based on 26S rRNA gene sequence analysis. The study indicated that strain QQ could aerobically decolorize Reactive Brilliant Red X-3B by the way of bioadsorption, and nutrient-poor medium was more beneficial for adsorption. Decolorization rate was inversely proportional to the size of mycelial pellets. The optimum pH was observed at 4 or 5 for X-3B decolorization. There was still 70% color removal when salinity increased to 6%. By contrast with aerobic decolorization, the degradation of azo dyes occurred under anaerobic conditions, and some azo dyes could be absolutely decolorized. Furthermore, the decolorization of azo dyes by fungal-bacterial cocultures was investigated. The results demonstrated that strain QQ and Sphingomonas xenophaga QYY cocultures performed better than any single strain did. Weak acidity conditions and the presence of small amount of surfactant could enhance the ability of consortium to decolorize azo dyes.

Adsorption behavior of Azo Dye C. I. Acid Red 14 in aqueous solution on surface soils

Azo dyes have received considerable attention because of their association with various human health problems. The aim of the investigation is to determine the adsorption behavior of azo dyes in aqueous solution on DG06, GSE17200, and GSE17201 soils using C. I. Acid Red 14 (AR14) as example. The experimental results indicate that the Freundlich model expresses the adsorption isotherm better than the Langmuir model and the pseudo-second-order model achieves adsorption of AR14 on the three soils well. Based on the pseudo-second-order model, the adsorption thermodynamic of AR14 on DG06 soil have been studied and the thermodynamics parameter of deltaG0 is determined and deltaG0 value shows the adsorption process of AR14 on DG06 is mainly physical in nature. Furthermore, the effects of temperature, pH and salinity (NaCl) on adsorption have been investigated. The decrease in pH or the increase in salinity enhances the adsorption of AR14 by DG06, GSE17200, and GSE17201.

Heterogeneous Fenton-like catalytic removal of p-nitrophenol in water using acid-activated fly ash

The use of nitric-acid-activated fly ash (AFA), as heterogeneous Fenton-like catalyst for p-nitrophenol (p-NP) removal from water, was investigated. The physicochemical characteristics of AFA were better than those of raw fly ash (RFA). Under experimental conditions of pH 1.5-5.1, H(2)O(2) dosage 83.3-333 mgL(-1), AFA loaded 5.0-20 gL(-1), and temperature 298-348 K, the p-NP removal rate increased with the increase of H(2)O(2) dosage, AFA loaded and temperature. The highest removal rate (98%) was observed at pH 2.0 when H(2)O(2) dosage 166.5 mgL(-1), AFA loaded 10 gL(-1) and temperature 298 K. However, good p-NP removal efficiency (98.8%) could still be achieved under milder pH (5.1) conditions when enough reaction time (14 h) was applied. The leached iron concentration increased with decrease in pH and with increase in reaction time. The homogenous catalysis caused by leached iron was negligible. The less reaction time and higher AFA load could be selected flexibly for catalytic stability and reusability in actual application. The probable heterogeneous catalytic mechanisms were proposed.

Cr(VI) reduction and Cr(III) immobilization by Acinetobacter sp. HK-1 with the assistance of a novel quinone/graphene oxide composite.

Cr(VI) biotreatment has attracted a substantial amount of interest due to its cost effectiveness and environmental friendliness. However, the slow Cr(VI) bioreduction rate and the formed organo-Cr(III) in solution are bottlenecks for biotechnology application. In this study, a novel strain, Acinetobacter sp. HK-1, capable of reducing Cr(VI) and immobilizing Cr(III) was isolated. Under optimal conditions, the Cr(VI) reduction rate could reach 3.82 mg h(-1) g cell(-1). To improve the Cr(VI) reduction rate, two quinone/graphene oxide composites (Q-GOs) were first prepared via a one-step covalent chemical reaction. The results showed that 2-amino-3-chloro-1,4-naphthoquinone-GO (NQ-GO) exhibited a better catalytic performance in Cr(VI) reduction compared to 2-aminoanthraquinone-GO. Specifically, in the presence of 50 mg L(-1) NQ-GO, a Cr(VI) removal rate of 190 mg h(-1) g cell(-1), which was the highest rate obtained, was achieved. The increased Cr(VI) reduction rate is mainly the result of NQ-GO significantly increasing the Cr(VI) reduction activity of cell membrane proteins containing dominant Cr(VI) reductases. X-ray photoelectron spectroscopy analysis found that Cr(VI) was reduced to insoluble Cr(III), which was immobilized by glycolipids secreted by strain HK-1. These findings indicate that the application of strain HK-1 and NQ-GO is a promising strategy for enhancing the treatment of Cr(VI)-containing wastewater.

Enhancement of nitroaromatic compounds anaerobic biotransformation using a novel immobilized redox mediator prepared by electropolymerization

Functionalized polypyrrole (PPy) composites were prepared by incorporation of a model redox mediator, anthraquinonedisulphonate (AQDS), as doping anion during the electropolymerization of pyrrole (Py) monomer on active carbon felt (ACF) electrode. Then, the resulting composite, ACF/PPy/AQDS as a novel immobilized redox mediator for catalyzing anaerobic biotransformation of the model nitroaromatic compounds (NACs), such as nitrobenzene (NB), 2,4- and 2,6-dinitrotoluene (DNT), were investigated in detail. The results showed that ACF/PPy/AQDS exhibited good catalytic activity and stability, and its addition effectively accelerated the NACs anaerobic reduction to the corresponding amino compounds. In order to estimate the relationship between community dynamics and the function of immobilized redox mediator, a combined method based on fingerprints (ribosomal intergenic spacer analysis, RISA) and 16S rRNA gene sequencing was used. The results indicated that the existence of ACF/PPy/AQDS made the potent AQDS-reducing bacteria keeping predominant in the catalytic systems. Based on the results above, it can be concluded that this novel immobilized redox mediator is feasible and potentially useful to enhance NACs anaerobic reduction.

Application of low intensity ultrasound to enhance the activity of anammox microbial consortium for nitrogen removal.

In this study, effect of low intensity ultrasound on the activity of anammox microbial consortium for nitrogen removal was investigated through batch experiments at the same irradiation frequency of 25 kHz. Total nitrogen removal rate increased by about 25.5% when ultrasound intensity of 0.3 w cm(-2) was applied at an optimal irradiation time of 4 min, and further experiments demonstrated that this effect could last for about 6 days. Analysis of extracellular polymeric substances indicated that the maximum increase of carbohydrate, protein and total extracellular substances was obtained on the first day after ultrasound, which was 28.8%, 30.5% and 29.7%, respectively. As the time prolonged, the production rate of extracellular carbohydrate, protein decreased gradually. Transmission electron microscopy observation demonstrated that ultrasounded cell wall of anammox microbial consortium became thinner resulting in increased release of extracellular substances. The results suggested that application of low intensity ultrasound may enhance the activity of anammox microbial consortium and ultimately the potential for nitrogen removal.

Dynamics of microbial community for X-3B wastewater decolorization coping with high-salt and metal ions conditions

In this study, decolorization of Reactive Brilliant Red X-3B wastewater by the biological process coping with high salinity and metal ions conditions was investigated, and 16S rDNA based fingerprint technique was used to investigate microbial population dynamics. Results of sequencing batch tests showed that the microbial community could keep efficient with high concentration of dye (1100 mg L(-1)), salt (150 g L(-1) NaCl) and some metal ions such as Mg(2+), Ca(2+) (1-10 mmol L(-1)) and Pb(2+) (1 mmol L(-1)). 16S rDNA-based molecular analysis techniques demonstrated that the microbial community shifted during the acclimatization process affected by salt or metal ions. Some stains similar to Bacillus, Sedimentibacter, Pseudomonas, Clostridiales, Streptomyces and some uncultured clones acted for the dynamic succession, supposed as potential decolorization bacteria. This study provided insights on the decolorization capability and the population dynamic shifts during decolorization process of azo dye wastewater coping with salt and metal ions.

Microbial synthesis of Pd/Fe3O4, Au/Fe3O4 and PdAu/Fe3O4 nanocomposites for catalytic reduction of nitroaromatic compounds

Magnetically recoverable noble metal nanoparticles are promising catalysts for chemical reactions. However, the chemical synthesis of these nanocatalysts generally causes environmental concern due to usage of toxic chemicals under extreme conditions. Here, Pd/Fe3O4, Au/Fe3O4 and PdAu/Fe3O4 nanocomposites are biosynthesized under ambient and physiological conditions by Shewanella oneidensis MR-1. Microbial cells firstly transform akaganeite into magnetite, which then serves as support for the further synthesis of Pd, Au and PdAu nanoparticles from respective precursor salts. Surface-bound cellular components and exopolysaccharides not only function as shape-directing agent to convert some Fe3O4 nanoparticles to nanorods, but also participate in the formation of PdAu alloy nanoparticles on magnetite. All these three kinds of magnetic nanocomposites can catalyze the reduction of 4-nitrophenol and some other nitroaromatic compounds by NaBH4. PdAu/Fe3O4 demonstrates higher catalytic activity than Pd/Fe3O4 and Au/Fe3O4. Moreover, the magnetic nanocomposites can be easily recovered through magnetic decantation after catalysis reaction. PdAu/Fe3O4 can be reused in at least eight successive cycles of 4-nitrophenol reduction. The biosynthesis approach presented here does not require harmful agents or rigorous conditions and thus provides facile and environmentally benign choice for the preparation of magnetic noble metal nanocatalysts.

Performance and microbial community dynamics in bioaugmented aerated filter reactor treating with coking wastewater

In this study, zeolite-biological aerated filters (Z-BAFs) bioaugmented by free and magnetically immobilized cells of Arthrobacter sp. W1 were designed to treat coking wastewater containing high concentrations of phenol and naphthalene along with carbazole (CA), dibenzofuran (DBF), and dibenzothiophene (DBT). All treatments were carried out for a period of 100days and the data indicated that bioaugmented Z-BAFs with magnetically immobilized cells was most efficient for treating coking wastewaters. Illumina high-throughput sequencing was used to reveal the microbial community structures of Z-BAFs. Both bioaugmentation treatments could accelerate the shift of the bacterial community structures. The introduced strain W1 remained dominant in the bioaugmented Z-BAFs with magnetically immobilized cells, indicating both strain W1 and the indigenous degrading bacteria played the most significant role in the treatment. Overall, bioaugmented Z-BAF with magnetically immobilized cells can be used to efficiently degrade phenol, naphthalene, CA, DBF, and DBT in coking wastewater.