A comprehensive comparison of microbial communities between aerobic granular sludge and flocculent sludge for nutrient removal in full-scale wastewater treatment plants.

Understanding the microbial community structure of sludge is crucial for improving the design, operation and optimisation of full-scale wastewater treatment plants (WWTPs). This study aimed to have a comprehensive comparison of microbial communities between aerobic granular sludge and flocculent sludge from two full-scale sequential batch reactors-based WWTPs with nutrient removal for the first time. To better understand key functional bacteria such as polyphosphate accumulating bacteria (PAOs), competitive bacteria such as glycogen accumulating bacteria (GAOs) and nitrifying bacteria for both nitrogen and phosphorus removal, another two full-scale WWTPs with only carbon (C) removal and C and nitrogen (N) removal were compared too. It was found that the richness and diversity of the microbial population in sludge increased with pollutant removal from only C, C and N, to C,N, P removal. For C, N P removal, granule structure led to a more diverse and rich microbial community structure than flocculent structure. Although more abundant nitrifying bacteria were enriched in granular sludge than flocculent sludge, the abundance of total putative PAOs was equivalent. However, the most typical putative PAOs such as Tetrasphaera and Candidatus Accumulibacter seemed to be more correlated with biological phosphorus removal performance, which might be more proper to be used as an indication for P removal potential. The higher abundance of GAOs in flocculent sludge with better phosphorus removal performance might suggest that further investigation is needed to understand the functions of GAOs. In addition, the equivalent abundances of PAOs in the WWTPs with only C removal and with C, N, and P removal, respectively, indicate that many newly reported putative PAOs might not contribute to P removal. This study provides insight into the microbial communities and functional bacteria in aerobic granular sludge and flocculent sludge in full-scale SBRs, which can provide microbes-informed optimisation of reactor operation for better nutrient removal.

An oil-absorbing resin with a simple polymerization system with benzyl methacrylate as a functional monomer.

To solve the problem of the low absorbency of oil-absorbing resins, oil-absorbing resins (PAMs) were fabricated in this study by introducing commercially available benzyl methacrylate (BZMA) as a functional monomer copolymerized with stearyl methacrylate (SMA) and butyl acrylate (BA). The internal network structure of the PAMs expanded more easily when absorbing oils or organic solvents after introducing rigid groups of the benzene ring by an uncomplex polymerization process, which provided the oil-absorbing resin with good absorbency. The reagents were all commercially available, and there was no other pretreatment or posttreatment process. Then, the optimum parameters for the monomer feed ratio, water/oil mass ratio, and concentrations of initiator, stabilizer and crosslinker were studied. Simultaneously, the reusability, oil retention and thermal stability of PAMs were investigated in this article. The PAMs swelled in various oils and organic solvents (the values of oil absorbency were 44.52, 56.13, 25.54, 28.21, 32.85, 24.56, 14.17, 15.02 and 29.07 g g-1 for CCl4, CHCl3, CH2Cl2, benzene, toluene, xylene, n-hexane, 0# diesel oil and 93# gasoline, respectively) and displayed good oil absorbency, which met the absorption requirements for common oils or organic solvents.

Adsorption properties of ß-cyclodextrin modified hydrogel for methylene blue.

With the development of dye and printing, production wastewater has become one of the most primary pollution sources of water and soil pollution. Most of the dyes are toxic substances, which have the "three-way" effect of carcinogenic, teratogenic and mutagenic. Therefore, it is a very difficult but significant issue to deal with the dye in the wastewater. Here, we report a study on low-cost, high-capacity hydrogels that remove water-soluble dyes. The hydrogel is prepared by crosslinking the ß-cyclodextrin and functional monomer: acrylamido and 2-acrylamide-2-methylpropane sulfonic acid by aqueous solution polymerization, meanwhile, alkaline hydrolysis is also an important step for adsorption performance. After alkaline hydrolysis, the amide and sulfonic groups in the hydrogel were converted into carboxylate and sulfonate, which was beneficial to the adsorption of cationic dyes. This polymer could remove 96.58% methylene blue (400 mg/L) and only requires 0.02 wt%. Its maximum adsorption capacity for methylene blue could reach 2638.22 mg/g under equilibrium condition. It is the most powerful adsorbent used to treat dye wastewater, according to the report. It also provides some references for hydrogel treatment of dye wastewater.

High crosslinked sodium carboxyl methylstarch-g-poly (acrylic acid-co-acrylamide) resin for heavy metal adsorption: its characteristics and mechanisms.

A lower expansive heavy metal adsorbent, high crosslinked sodium carboxyl methylstarch-g-poly (acrylic acid-co-acrylamide) resin (HCAA), has been prepared by enhancing the crosslinking degree of the traditional water-absorbing polymer under the graft copolymerization reaction. Further heavy metal adsorption experiments, morphology analysis, and structure characteristic observations indicate that HCAA resin has an excellent heavy metal adsorption properties for Cr3+, Cu2+, Ni2+, and Zn2+ of 80.08, 158.07, 155.71, and 137.15 mg/g, respectively. The nanoholes in network structures of HCAA resin expanding in solution provide an effective diffusion and exchange channels for heavy metal ions and Na+. The adsorption process of HCAA containing -COONa is attributed to ion exchange process, and its essence is to form the coordination bond with heavy metals. The adsorption capacity differences of -COO- have been explained by using the coordination chemistry theory. In addition, the adsorption selectivity of an expansive adsorbent containing -COONa are heavy metals > H2O >> Na+. Our research puts forward an insight that increasing the crosslinker content on the basis of the traditional super absorbent resin can obtain a lower expansive adsorbent to heavy metal pollutants.

Preparation of ion exchange resin using soluble starch and acrylamide by graft polymerization and hydrolysis.

Based on soluble starch and acrylamide by performing graft polymerization in aqueous solution and hydrolysis step, a low-cost ion exchange resin has been synthesized to remove the heavy metal ions of Cr3+ and Ni2+. The hydrolysis progresses by adding NaOH to convert -CONH2 to -COONa, and the adsorption experiments confirmed that the functional group to adsorb heavy metals is -COO-, rather than -CONH2. During the determination of heavy metal adsorption, the Na+ concentration diffused by SR-16 into the solution was also analysed to investigate the ion exchange process. The composition and morphology of SR-16 was characterized by FT-IR, SEM, elemental analyser and EDS, and the results showed that SR-16 has an excellent adsorption capacity to the removal of heavy metal pollution; the adsorption mechanism of SR-16 could be explained by ion exchange progress with -COONa attached on the network structure.

Excessive precipitation of CaCO3 as aragonite in a continuous aerobic granular sludge reactor.

A hybrid airlift reactor was adopted to retain aerobic granules in the reactor successfully for continuous operation. It was found that aerobic granules maintained excellent physical structure stability in the continuous-flow reactor with reactor performance as good as batch operation. However, flocs appeared after batch operation was switched to continuous operation, and chemical oxygen demand (COD) in the wastewater was thus removed by co-existed granules and flocs in the reactor. Furthermore, excessive precipitation of CaCO3 as needled shaped aragonite in the continuous aerobic granular sludge reactor was observed, which led to the further enhancement of settling ability of granules with sludge volume index (SVI) reduction from 32 to 2 ml g(-1) but specific oxygen utilization rate (SOUR) decrease from 61 to 23 mg O2 g(-1) MLVSS h(-1). Thus, apart from the physical structure stability, bioactivity stability of granules should be also considered as an important parameter to evaluate the continuous operation of aerobic granular sludge. Furthermore, the decrease in granule polysaccharide content implied that protein was more important for aragonite precipitation. The excessive aragonite precipitation in the continuous-flow reactor could be due to the competition between flocs and granules. In addition, the degradation of polysaccharide in aerobic granules under a continuous-flow mode may also contribute to excessive aragonite precipitation.

[Isolation and identification of a methanogen from the high temperature oil reservoir water].

To explore new microbial resources in deep subsurface oil reservoirs, strain DL-7 was isolated with Hungate technology from oil reservoir water sampled from Dagang oilfield, China. Physiological and biochemical examinations showed that H2/CO2 is the unique substrate of the strain, which cannot metabolize formate, methanol, trimethylamine, acetate and other secondary alcohols. The optimum growth conditions were further identified to be 60 degrees C, pH 7.0-7.5 and 0.25% NaCl. Moreover, the strain cannot grow without yeast extract. Analysis of its 16S rRNA sequence indicated that a similarity of 99.7% presents between the strain and the model species M. marburgensis DSM2133T (X15364).

[Isolation and identification of a thermophilic anaerobic bacterium].

OBJECTIVE: To find new microbial resources from a high-temperature oil reservoir. METHODS: Strain HL-3 was isolated by Hungate Anaerobic Technique from oil reservoir water sampled from Dagang oilfield, China. Through physiological, biochemical and phylogenetic analysis, the strain HL-3 was classified. RESULTS: Cells were Gram-positive. The temperature range for growth was 40 degrees C-75 degrees C (optimum at 60 degrees C) and the pH range was 5.0-8.0 (optimum at 6.5). The isolate could grow in the presence of 0%-3.2% NaCl (optimum at 0.25%). Glucose, ribose, mannose, xylose and cellobiose could be metabolized. Metabolites of glucose were ethanol, acetate, CO2 and trace amount of propionate and butanol. The G + C content of DNA was 33.9 mol%. Based on 16S rRNA studies,strain HL-3 was most close to T. uzonensis DSM 18761T (EF530067) with 98.8% similarity and to T. sulfurigignens DSM 17917T (AF234164) with the 98.1% similarity. Strain HL-3 tolerated to high sulfite (0. 1mol/L) ions and extremely high concentration of thiosulfate (0.8 mol/L). When the concentration of thiosulfate was higher than 0.075 mol/L, the cell would generate S element granular. The presence of H2S gas was detected inside of space at the top of serum bottle. Strain HL-3 together with T. uzonensis DSM 18761T differed greatly in toleration of thiosulfate and sulfite. The toleration of strain HL-3 to thiosulfate and sulfite was most close to T. sulfurigignens DSM 17917T (AF234164). In addition, strain HL-3 to metabolite thiosulfate and sulfite was also similar with T. sulfurigignens DSM 17917T (AF234164). However, it differs largely from both of them to metabolize glucose. CONCLUSION: Therefore, strain HL-3 may be a new spieces of the Thermoanaerobacter, and the definitive classification positioning is still awaiting for further verified with the method of determination of whole-genome DNA-DNA similarity