Characteristics of bacterial populations in an industrial scale petrochemical wastewater treatment plant: Composition, function and their association with environmental factors.

The efficiency of petrochemical wastewater biological treatment is dependent upon complex bacterial communities. A well understanding of the structure and function of bacterial community and their association with environmental variables is essential for the elucidation of contaminant removal mechanisms and optimization of wastewater treatment processes. In this study, the bacterial communities and metabolic functions in the primary hydrolysis acidification unit (PHAU), cyclic activated sludge system (CASS), secondary hydrolysis acidification unit (SHAU), and biological aerated filter (BAF) of a petrochemical wastewater treatment plant (WWTP) were studied via Illumina high-throughput sequencing. The correlations between bacterial community and environmental variables were also investigated. The phylum Proteobacteria, Planctomycetes, Chloroflexi, Acidobacteria and Bacteroidetes were dominant in the petroleum WWTP. The bacterial communities varied with wastewater characteristics and operational parameters, as a result of the differences in biosystems functions. Phylogenetic analysis showed that the genes involved in the degradation of benzoate, nitrotoluene and aminobenzoate degradation were abundant in PHAU, and the genes related to the degradation of benzoate, aminobenzoate, chloroalkane, chloroalkene, caprolactam, naphthalene and toluene were abundant in CASS, SHAU and BAF. The Redundancy analysis (RDA) suggested that biochemical oxygen demand (BOD5), NH4+-N and total nitrogen concentrations exhibited significant impacts in shaping the structure of bacterial community. Variance partitioning analysis (VPA) showed that 18.6% of the community variance was related to wastewater characteristics, higher than operational parameters of 4.5%. These results provide insight into microbial community structure and metabolic function during petrochemical wastewater treatment, and discern the relationships between bacterial community and environmental variables, which can provide basic data and a theoretical analysis of the design and operation optimization in petrochemical WWTP.

Rapid granulation using calcium sulfate and polymers for refractory wastewater treatment in up-flow anaerobic sludge blanket reactor.

Long start-up period and slow granulation are major restraints in up-flow anaerobic sludge blanket (UASB) reactors for the treatment of refractory wastewater. In this study, Calcium sulfate (CaSO4), CaSO4/guar gum (GG), and CaSO4/cationic polyacrylamide (CPAM) were used to enhance granulation during the treatment of phenolic wastewaters in UASB reactors. Use of CaSO4, CaSO4/GG, and CaSO4/CPAM increased formation of granules (>0.25 mm) by 7%, 21% and 40%, respectively, after 90 days in comparison with the control. Use of CaSO4/GG and CaSO4/CPAM at an organic loading rate of 2.89 kg chemical oxygen demand (COD) m-3 d-1 increased the COD removal efficiency by 9% and 3%, respectively, in comparison with the control (75%). The CaSO4 enhanced the granulation rate as nuclei and the subsequent dissolution of CaSO4 improves the activity of methanogens. Polymers facilitated bacteria adhesion and improved the diversity of phenols-degrading bacteria. This study describes a new method for rapid granulation in UASB reactors when treating toxic and refractory wastewaters.

Catalytic Ozonation of Nitrobenzene by Manganese-Based Y Zeolites.

Catalytic ozonation process (COP) is considered as a cost-efficient technology for the treatment of refractory chemical wastewaters. The catalyst performance plays an important role for the treatment efficiency. The present study investigated efficiencies and mechanisms of manganese (Mn)-based Y zeolites in COPs for removing nitrobenzene from water. The catalysts of Mn/NaY and Mn/USY were prepared by incipient wetness impregnation, while Mn-USY was obtained by hydrothermal synthesis. Mn-USY contained a greater ratio of Mn2+ than Mn/NaY, and Mn/USY. Mn oxides loaded on Y zeolites promoted the COP efficiencies. Mn/NaY increased total organic carbon removal in COP by 7.3% compared to NaY, while Mn/USY and Mn-USY increased 11.5 and 15.8%, respectively, relative to USY in COP. Multivalent Mn oxides (Mn2+, Mn3+, and Mn4+) were highly dispersed on the surface of NaY or USY, and function as catalytic active sites, increasing mineralization. Mn-USY showed the highest total organic carbon removal (44.3%) in COP among the three catalysts, because Mn-USY had a higher ratio of Mn2+ to the total Mn oxides on the surface than Mn/NaY and Mn/USY and the catalytic effects from intercorrelations between Mn oxides and mesoporous surface structures. The hydroxyl radicals and superoxide radicals governed oxidations in COP using Mn-USY. Nitrobenzene was oxidized to polyhydroxy phenol, polyhydroxy nitrophenol, and p-benzoquinone. The intermediates were then oxidized to small organic acids and ultimately carbon dioxide and water. This study demonstrates the potential of Y zeolites used in COP for the treatment of refractory chemical wastewaters.

Bioreactor performance using biochar and its effect on aerobic granulation.

The effects that rice husk (biochar-rh), rice bran (biochar-rb) and walnut shell (biochar-ws) biochar had on aerobic granulation and reactor performance during the treatment of petroleum wastewater have been investigated. The different biochars reduced aerobic granulation time by 15 days compared with the control and also increased resistance to shock loading. The average COD and TN removal increased by 3.2%-5.1% and 10%-13%, respectively. Bacteria having functional metabolisms associated with the treatment of petroleum wastewaters were enriched in granular sludge that contained biochars. The reactor containing biochar-rb was the most stable and removed the most nutrients. The reactor containing biochar-rh had the largest initial granule size. This study provides insights into how the physicochemical properties of different biochars influence aerobic granular sludge systems.

A char-clay composite catalyst derived from spent bleaching earth for efficient ozonation of recalcitrants in water.

Catalytic ozonation is an efficient process that can be utilized to degrade recalcitrant organics. Char-clay composite derived from refinery spent bleaching earth (SBE) is an economical and readily available catalyst that can be used during the ozonation treatment of recalcitrants in wastewater. Four catalysts of SBE-N2-650, SBE-N2-850, SBE-O2-650, and SBE-O2-850 were prepared by heating the SBE at 650 and 850 °C under N2 or O2 conditions. High surface OH sites in the SBE-N2-650 and SBE-O2-650 relative to the SBE-N2-850 and SBE-O2-850 resulted in an increase in catalytic activity. Additional carbon (C), that existed in the SBE-N2-650 and SBE-N2-850, had a positive effect on catalytic activity. The SBE-N2-650 exhibited the highest activity among those prepared catalysts. During catalytic ozonation, the SBE-N2-650 increased the mineralization rate of benzoic acid by 36% when compared with single ozonation. Molecular ozone was decomposed at the surface active sites on SBE-N2-650, generating active •OH, •O2-, or 1O2 species. Gas and liquid products having calorific values that are generated during SBE-N2-650 preparation can be further utilized. This study introduces a potential use of SBE for the ozonation treatment of recalcitrant wastewaters.

Catalytic Ozonation of Recalcitrant Organic Chemicals in Water Using Vanadium Oxides Loaded ZSM-5 Zeolites.

The discharge of wastewater having recalcitrant chemical compositions can have significant and adverse environmental effects. The present study investigates the application of a catalytic ozonation treatment for the removal of recalcitrant organic chemicals (ROCs) from the water. Novel catalytic materials using vanadium (V) oxides deposited onto the surface of NaZSM-5 zeolites (V/ZSM) were found to be highly efficient for this purpose. The highly-dispersed V oxides (V4+ and V5+) and Si-OH-Al framework structures were determined to promote the surface reaction and generation of hydroxyl radicals. The constructed V1/ZSM450 (0.7 wt% of V loading and 450°C of calcination) exhibited the highest activity among the developed catalyst compositions. The V1/ZSM450-COP increased the mineralization rate of nitrobenzene and benzoic acid by 50 and 41% in comparison to single ozonation. This study demonstrates the enhanced potential of V/ZSM catalysts used with catalytic ozonation process (COP) for the treatment of chemical wastewaters.

Degradation of guar in an up-flow anaerobic sludge blanket reactor: Impacts of salinity on performance robustness, granulation and microbial community.

Guar is extensively used during shale gas exploitation and is a major component in the flowback water. The viscosity of guar has adverse effects for the treatment of flowback water. This study investigated the degradation of guar at different salinities with an up-flow anaerobic sludge blanket (UASB) reactor. The effects of salinity on guar degradation, granular characteristics and microbial community were also studied. Results showed that more than 79% of guar was removed at hydraulic retention time (HRT) of 10 h, even at a concentration of 10000 mg L-1 of NaCl. Increasing salinity decreased granular size and hydrophobicity, but improved the secretion of EPS (especially for protein). Low salt condition 2500 mg L-1 presented faster degradation rate of guar. Salinity resulted in insignificant difference on bacterial community, but decreased the abundance of methanogens. Bacteroides, Prolixibacter and Pelolinea are essential genera in guar degradation. The results demonstrated the potential of UASB in the treatment of flowback water.

The first complete mitochondrial genome sequence of the korean endemic catfish Silurus microdorsalis (Actinopteri, Siluriformes, Siluridae).

The Silurus microdorsalis is known as Korean endemic slender catfish. Despite its value as a biological resource, there is no complete mitochondrial genome sequence. The complete mitochondrial genome consisted of 16,524 bp including 22 transfer RNA (tRNAs), 2 ribosomal RNA (rRNAs), 13 protein-coding genes (PCGs), and A + T rich region. The overall base composition of S. microdorsalis was A + T: 56.1%, C + G: 43.9%, apparently with slight AT bias. Phylogenetic relationship showed that S. microdorsalis was closely related to Silurus glanis.

Characterization of aerobic granular sludge used for the treatment of petroleum wastewater.

The application of aerobic granular sludge (AGS) is a promising biological method for wastewater treatment. In the present study, the AGS method was used for the treatment of petroleum wastewater. The granulation process and organic/nitrogen compound removal efficiencies were determined and correlated with the microbiological communities. Granulation of the aerobic sludge occurred after 35 days of operation. The compacted granules had a diameter of 0.46-0.9 mm. Extracellular polymeric substances (EPS) contents increased as granulation progressed and reached 128 mg/g·VSS. The granulated sludge efficiently reduced COD by 95% and petroleum compound contents by 90%. NH4+-N and TN removal were inefficient due to the inhibition of nitrobacteria and denitrificans, but were significantly improved by the addition of glucose. The microorganisms in the granules capable of degrading petroleum chemicals consisted of the genera Propioniciclava, Micropruina, Alphaproteobacteria, Flavobacterium, and Sulfuritalea.

Activated petroleum waste sludge biochar for efficient catalytic ozonation of refinery wastewater.

Large quantities of hazardous activated petroleum waste sludge and wastewaters are generated from petroleum refining. The present disposal of the sludge via incineration or landfill may cause secondary pollution as well as additional costs. Treatment of petroleum refinery wastewater (PRW) by catalytic ozonation process (COP) remains a great challenge of developing low-cost and high-efficiency catalysts. Use of waste sludge derived biochar as catalysts in COP of PRW not only solves the solid wastes and wastewaters problems but also improves profitability. The elements of carbon (C), silicon (Si) and metals originally found in activated petroleum waste sludge contribute to the formation of active sites during pyrolysis. The biochar contains functional C groups, SiO structures, and metallic oxides that promote oxidation through the formation of hydroxyl radicals (OHs) mineralizing petroleum contaminants. Catalytic ozonation of PRW using this sludge biochar (SBC) doubles the total organic carbon removal (53.5%) relative to single ozonation (26.9%). Oxygen (Ox)-, nitrogen (NOx)- and sulfur (OxS)-containing contaminants were decreased by 33.4% (989 vs 659), 58.2% (912 vs 384) and 12.5% (384 vs 336). The present study shows the potential of a "wastes-treat-wastes" process for wastewater treatment.

Turf soil enhances treatment efficiency and performance of phenolic wastewater in an up-flow anaerobic sludge blanket reactor.

Phenols are industrially generated intermediate chemicals found in wastewaters that are considered a class of environmental priority pollutants. Up-flow anaerobic sludge blanket (UASB) reactors are used for phenolic wastewater treatment and exhibit high volume loading capability, favorable granule settling, and tolerance to impact loads. Use of support materials can promote biological productivity and accelerate start-up period of UASB. In the present study, turf soil was used as a support material in a mesophilic UASB reactor for the removal of phenols in wastewater. During sludge acclimatization (45-96 days), COD and phenols in the treatments were both reduced by 97%, whereas these contents in the controls were decreased by 81% and 75%, respectively. The phenol load threshold for the turf soil UASB reactor was greater (1200 mg/L, the equivalent of COD 3000 mg/L) in comparison with the control UASB reactor (900 mg/L, the equivalent of COD 2250 mg/L) and the turf soil UASB reactor was also more resistant to shock loading. Improved sludge settling, shear resistance, and higher biological activity occurred with the turf soil UASB reactor due to the formation of large granular sludge (0.6 mm or larger) in higher relative percentages. Granular sludge size was further enhanced by the colonization of filamentous bacteria on the irregular surface of the turf soil.

Efficiencies and mechanisms of ZSM5 zeolites loaded with cerium, iron, or manganese oxides for catalytic ozonation of nitrobenzene in water.

Discharge of industrial wastewater causes water pollution. It is therefore necessary to treat wastewater prior to discharge. Catalytic ozonation processes (COP) using ZSM5 zeolites loaded with metallic (Ce, Fe, or Mn) oxides to remove nitrobenzene from water were investigated. The total organic carbon (TOC) removal by the COP treatment with NaZSM5-38, HZSM5-38, and NaZSM5-100 were increased by 6.7%, 23.1%, and 19.8%, respectively, in comparison with single ozonation efficiency (39.2%). The loadings of Ce, Fe, or Mn oxides increased the catalytic activity relative to ZSM5 zeolites alone. The Ce loaded material (Ce/NaZSM5-38) had the highest TOC removal (86.3%). The different-metallic-oxides loaded zeolites exhibited different chemical processes during the removal of nitrobenzene from water. During COP treatment, NaZSM5-38 zeolites removed nitrobenzene mainly via OH mediated oxidation. HZSM5-38 and NaZSM5-100 zeolites showed powerful adsorption toward nitrobenzene. Both adsorption and direct ozonation contribute the TOC removal in their early uses. The OH mediated oxidation dominates the TOC removal process as the adsorption became saturated after multiple uses. Surface SiO bonds and/or SiO(H)Al structures are the active sites for ZSM5 zeolites. Efficient surface dispersion of the metallic oxides enhances the catalytic activity. This study shows the high potentials of ZSM5 zeolites as catalysts in COP to efficiently treat refractory wastewaters.

Evaluation of an up-flow anaerobic sludge bed (UASB) reactor containing diatomite and maifanite for the improved treatment of petroleum wastewater.

Novel diatomite (R1) and maifanite (R2) were utilized as support materials in an up-flow anaerobic sludge bed (UASB) reactor for the treatment of recalcitrant petroleum wastewater. At high organic loadings (11kg-COD/m3·d), these materials were efficient at reducing COD (92.7% and 93.0%) in comparison with controls (R0) (88.4%). Higher percentages of large granular sludge (0.6mm or larger) were observed for R1 (30.3%) and R2 (24.6%) compared with controls (22.6%). The larger portion of granular sludge provided a favorable habitat that resulted in greater microorganism diversity. Increased filamentous bacterial communities are believed to have promoted granular sludge formation promoting a conductive environment for stimulation methanogenic Archaea. These communities had enhanced pH tolerance and produced more methane. This study illustrates a new potential use of diatomite and maifanite as support materials in UASB reactors for increased efficiency when treating refractory wastewaters.

Potential of wheat bran to promote indigenous microbial enhanced oil recovery.

Microbial enhanced oil recovery (MEOR) is an emerging oil extraction technology that utilizes microorganisms to facilitate recovery of crude oil in depleted petroleum reservoirs. In the present study, effects of wheat bran utilization were investigated on stimulation of indigenous MEOR. Biostimulation conditions were optimized with the response surface methodology. The co-application of wheat bran with KNO3 and NH4H2PO4 significantly promoted indigenous MEOR (IMEOR) and exhibited sequential aerobic (O-), facultative (An-) and anaerobic (A0-) metabolic stages. The surface tension of fermented broth decreased by approximately 35%, and the crude oil was highly emulsified. Microbial community structure varied largely among and in different IMEOR metabolic stages. Pseudomonas sp., Citrobacter sp., and uncultured Burkholderia sp. dominated the O-, An- and early A0-stages. Bacillus sp., Achromobacter sp., Rhizobiales sp., Alcaligenes sp. and Clostridium sp. dominated the later A0-stage. This study illustrated occurrences of microbial community succession driven by wheat bran stimulation and its industrial potential.

Catalytic ozonation of petroleum refinery wastewater utilizing Mn-Fe-Cu/Al2O 3 catalyst.

There is of great interest to develop an economic and high-efficient catalytic ozonation system (COS) for the treatment of biologically refractory wastewaters. Applications of COS require options of commercially feasible catalysts. Experiments in the present study were designed to prepare and investigate a novel manganese-iron-copper oxide-supported alumina-assisted COS (Mn-Fe-Cu/Al2O3-COS) for the pretreatment of petroleum refinery wastewater. The highly dispersed composite metal oxides on the catalyst surface greatly promoted the performance of catalytic ozonation. Hydroxyl radical mediated oxidation is a dominant reaction in Mn-Fe-Cu/Al2O3-COS. Mn-Fe-Cu/Al2O3-COS enhanced COD removal by 32.7% compared with a single ozonation system and by 8-16% compared with Mn-Fe/Al2O3-COS, Mn-Cu/Al2O3-COS, and Fe-Cu/Al2O3-COS. The O/C and H/C ratios of oxygen-containing polar compounds significantly increased after catalytic ozonation, and the biodegradability of petroleum refinery wastewater was significantly improved. This study illustrates potential applications of Mn-Fe-Cu/Al2O3-COS for pretreatment of biologically refractory wastewaters.

A novel "wastes-treat-wastes" technology: role and potential of spent fluid catalytic cracking catalyst assisted ozonation of petrochemical wastewater.

Catalytic ozonation is a promising wastewater treatment technology. However, the high cost of the catalyst hinders its application. A novel "wastes-treat-wastes" technology was developed to reuse spent fluid catalytic cracking catalysts (sFCCc) for the ozonation of petrochemical wastewater in this study. Multivalent vanadium (V(4+) and V(5+)), iron (Fe(2+) and Fe(3+)) and nickel (Ni(2+)) oxides that are distributed on the surface of sFCCc and poisoned FCC catalysts are the catalytic components for ozonation. The sFCCc assisted catalytic ozonation (sFCCc-O) of nitrobenzene indicated that the sFCCc significantly promoted hydroxyl radical mediated oxidation. The degradation rate constant of nitrobenzene in sFCCc-O (0.0794 min(-1) at 298 K) was approximately doubled in comparison with that in single ozonation (0.0362 min(-1) at 298 K). The sFCCc-O of petrochemical wastewater increased chemical oxygen demand removal efficiency by three-fold relative to single ozonation. The number of oxygen-containing (Ox) polar contaminants in the effluent (253) from sFCCc-O treatment decreased to about 70% of the initial wastewater (353). The increased oxygen/carbon atomic ratio and decreased number of Ox polar contaminants indicated a high degree of degradation. The present study showed the role and potential of sFCCc for catalytic ozonation of petrochemical wastewater, particularly in an advantage of the cost-effectiveness through "wastes-treat-wastes".

Increasing Thermal Stability of Gelatin by UV-Induced Cross-Linking with Glucose.

The effects of ultraviolet (254 nm) radiation on a hydrated gelatin-glucose matrix were investigated for the development of a physiologically thermostable substrate for potential use in cell scaffold production. Experiments conducted with a differential scanning calorimeter indicate that ultraviolet irradiation of gelatin-glucose hydrogels dramatically increases thermal stability such that no melting is observed at temperatures of at least 90°C. The addition of glucose significantly increases the yield of cross-linked product, suggesting that glucose has a role in cross-link formation. Comparisons of lyophilized samples using scanning electron microscopy show that irradiated materials have visibly different densities.

Quartet analysis of putative horizontal gene transfer in Crenarchaeota.

Horizontal gene transfers (HGT) between four Crenarchaeota species (Metallosphaera cuprina Ar-4T, Acidianus hospitalis W1T, Vulcanisaeta moutnovskia 768-28T, and Pyrobaculum islandicum DSM 4184T) were investigated with quartet analysis. Strong support was found for individual genes that disagree with the phylogeny of the majority, implying genomic mosaicism. One such gene, a ferredoxin-related gene, was investigated further and incorporated into a larger phylogeny, which provided evidence for HGT of this gene from the Vulcanisaeta lineage to the Acidianus lineage. This is the first application of quartet analysis of HGT for the phylum Crenarchaeota. The results have shown that quartet analysis is a powerful technique to screen homologous sequences for putative HGTs and is useful in visually describing genomic mosaicism and HGT within four taxa.

The analysis of macroalgae biomass found around Hawaii for bioethanol production.

Macroalgae commonly found in the ocean around Hawaii were collected from near shore locations and their potential as biomass feedstock for fermentative ethanol was investigated. A green alga, Ulva reticulata, was selected for further analysis. This species forms large complex structures that grow quickly and has high dry biomass percentage (20%), soluble carbohydrates (18%); and high total carbohydrates along with low quantities of lignin (13%). During acid saccharification, it was determined that 49% of the total mass was observed as sugars in the hydrolysate; however, fermentation was problematic. Enzymatic saccharification using cellulase from Trichoderma reesei was attempted which recovered a measured maximum of 20% glucose based on the initial dry mass. Fermentation successfully converted all the glucose to ethanol. The measured ethanol yield corresponded to approximately 90 L per tonne of dried macroalgae.