Coupling surfactants with ISCO for remediating of NAPLs: Recent progress and application challenges.

Non-aqueous phase liquids (NAPLs) pose a serious risk to the soil-groundwater environment. Coupling surfactants with in situ chemical oxidation (ISCO) technology is a promising strategy, which is attributed to the enhanced desorption and solubilization efficiency of NAPL contaminants. However, the complex interactions among surfactants, oxidation systems, and NAPL contaminants have not been fully revealed. This review provides a comprehensive overview on the development of surfactant-coupled ISCO technology focusing on the effects of surfactants on oxidation systems and NAPLs degradation behavior. Specifically, we discussed the compatibility between surfactants and oxidation systems, including the non-productive consumption of oxidants by surfactants, the role of surfactants in catalytic oxidation systems, and the loss of surfactants solubilization capacity during oxidation process. The effect of surfactants on the degradation behavior of NAPL contaminants is then thoroughly summarized in terms of degradation kinetics, byproducts and degradation mechanisms. This review demonstrates that it is crucial to minimize the negative effects of surfactants on NAPL contaminants oxidation process by fully understanding the interaction between surfactants and oxidation systems, which would promote the successful implementation of surfactant-coupled ISCO technology in remediation of NAPLs-contaminated sites.

Self-Assembled Photonic Microsensors with Strong Aggregation-Induced Emission for Ultra-Trace Quantitative Detection.

Ultratrace quantitative detection based on fluorescence is highly desirable for many important applications such as environmental monitoring or disease diagnosis, which however has remained a great challenge because of limited and irregular fluorescence responses to analytes at ultralow concentrations. Herein the problem is circumvented via local enrichment and detection of analytes within a microsensor, that is, photonic porous microspheres grafted with aggregation-induced emission gens (AIEgens). The obtained microspheres exhibit dual structural and molecular functions, namely, bright structural colors and strong fluorescence. Large fluorescence quenching induced by nitrophenol compounds in an aqueous environment is observed at ultralow concentrations (10-12-10-8 mol/L), enabling quantitative detection at a ppb level (ng/L). This is achieved within a porous structure with good connectivity between the nanopores to improve analyte diffusion, an internal layer of poly(ethylene oxide) (PEO) for analyte enrichment via hydrogen bonding, and homogeneous distribution of AIEgens within the PEO layer for enhanced fluorescence quenching. The fluorescent porous microspheres can be readily obtained in a single step templated by well-ordered water-in-oil-in-water double emulsion droplets with AIE amphiphilic bottlebrush block copolymers as the effective stabilizer.

Comparative energy and carbon footprint analysis of biosolids management strategies in water resource recovery facilities.

Biosolids or sludge management has become an environmental and economic challenge for water resource recovery facilities (WRRFs) and municipalities around the world. The electric energy and operational costs linked to the solid processing stage can account for 20% and 53% of the overall treatment respectively, and as such they are primary factors among utilities which must be considered while working toward more efficient strategies with less energy use. As part of the growing awareness of greenhouse gas (GHG) emissions, municipal wastewater treatment plants have begun reporting their GHG emission inventories. However, there is not yet a standardized or fully comprehensive CFP analysis for the biosolids management. In this paper, two major metropolitan WRRFs in China and the USA with two different biosolids management approaches were compared in terms of energy and carbon footprint (CFP). Site-specific equipment inventories coupled with state-of-the-art methodologies were used for the carbon and energy intensity assessment. Tailored biosolids management strategies and scenarios were included in the analysis to provide a venue for the reduction of their environmental impact. Co-digestion with food waste (FW) and the economic feasibility of its implementation were proposed as a GHGs mitigation strategy to highlight the energy recovery potential. Although both plants had similar energy intensity, Plant A (Shanghai) exhibited three times larger CFP primarily due to site-specific limitations on their biosolids management. The study showed the potential to improve CFP by 28.8% by selecting convenient strategies (i.e., incineration with AD). Energy recovery with its concurrent environmental benefits can be further enhanced by implementing FW co-digestion. This study shows the economic and environmental relevance of selecting adequate biosolids processing strategies and energy recovery practices in WRRFs.

Four complete mitochondrial genomes of living wild-type chinese giant salamander Andrias davidianus (Amphibia: Cryptobranchidae).

The Chinese giant salamander (CGS), Andrias davidianus (Amphibian, Caudata, Cryptobranchidae), is endemic to China. After overhunting in the 1990's, it is very difficult to find the CGS in the wild. Due to mating disorder, the captive breeding population is genetically confounded. The genetic backgrounds of all wild-release individuals in China are not explicit. Herein, we reported four living wild-type complete mitochondrial genomes of this species. The gene order and contents are identical to those found in typical vertebrates. Thirteen protein-coding genes (PCGs) of 7 A. davidianus (4 from this study, 3 retrieved from GenBank) and 11 other closely species retrieved from GenBank were used to reconstruct phylogenetic tree. The Maximum likelihood (ML) topology shown that the clade of CGS has two subclades with a high support (100%). This study provides partial fundamental information for further exploring the true genetic background of whole population of A. davidianus.

The effect of lime-dried sewage sludge on the heat-resistance of eco-cement.

The treatment and disposal of sewage sludge is a growing problem for sewage treatment plants. One method of disposal is to use sewage sludge as partial replacement for raw material in cement manufacture. Although this process has been well researched, little attention has been given to the thermal properties of cement that has had sewage sludge incorporated in the manufacturing process. This study investigated the fire endurance of eco-cement to which lime-dried sludge (LDS) had been added. LDS was added in proportions of 0%, 3%, 6%, 9%, and 12% (by weight) to the raw material. The eco-cement was exposed to 200, 400, or 600 °C for 3 h. The residual strength and the microstructural properties of eco-cement were then studied. Results showed that the eco-cement samples suffered less damage than conventional cement at 600 °C. The microstructural studies showed that LDS incorporation could reduce Ca(OH)(2) content. It was concluded that LDS has the potential to improve the heat resistance of eco-cement products.

Complete mitochondrial genome of a living wild-type Chinese giant salamander Andrias davidianus (Amphibia: Cryptobranchidae) in Huangshan.

The Chinese giant salamander, Andrias davidianus, is the biggest extant amphibian in the world. The population from Huangshan is distinct from other populations. The complete mitochondrial genome of a living wild-type Chinese giant salamander from Huangshan was sequenced. The total length is 16,565 bp, containing 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and a D-loop. The phylogenetic tree of A. davidianus and 12 other closely species belonging to the order Caudata was reconstructed.

Turbiscan Lab ® Expert analysis of the biological demulsification of a water-in-oil emulsion by two biodemulsifiers.

The long-term destabilization process of a water-in-oil emulsion was investigated with two different biodemulsifiers produced under different culture conditions by Alcaligenes sp. S-XJ-1. Biodemulsifier I was obtained by using paraffin as substrate at initial culture pH of 10 and biodemulsifier II was produced with waste frying oils at pH of 7. The former exhibited higher demulsifying ability and interfacial activity than the latter. Bottle test, microscopy and Turbiscan Lab(®) Expert were used to investigate the biological demulsification process. It was found that biodemulsifiers' ability to decrease the interfacial tension played a more important role in demulsification than their ability to decrease the surface tension. Owing to their amphiphilic nature, demulsification process began with the adsorption of the biodemulsifiers onto the water-oil interface. Then the biodemulsifiers reacted with the emulsifiers because of their interfacial activity. As a result, thin liquid film was removed from the surface of dispersed droplets and coalescence occurred. This led to the settling of the dispersed droplets and the clarification of the continuous phase. Turbiscan Lab(®) Expert can be used to evaluate the demulsification efficiency and to analyze the destabilization process of different biodemulsifiers. It is a rapid and accurate method to screen high-efficiency demulsifiers from other bioproducts.

Optimization of biodemulsifier production from Alcaligenes sp. S-XJ-1 and its application in breaking crude oil emulsion.

A biodemulsifier-producing strain of Alcaligenes sp. S-XJ-1, isolated from petroleum-contaminated soil of the Karamay Oilfield, exhibited excellent demulsifying ability. The application of this biodemulsifier significantly improved the quality of separated water compared with the chemical demulsifier, polyether, which clearly indicates that it has potential applications in the crude oil extraction industry. To optimize its biosynthesis, the impacts of carbon sources, nitrogen sources and pH were studied in detail. Paraffin, a hydrophobic carbon source, favored the synthesis of this cell wall associated biodemulsifier. The nitrogen source ammonium citrate stimulated the production and demulsifying performance of the biodemulsifier. An alkaline environment (pH 9.5) of the initial culture medium favored the strain's growth and improved its demulsifying ability. The results showed paraffin, ammonium citrate and pH had significant effects on the production of the biodemulsifier. These three variables were further investigated using a response surface methodology based on a central composite design to optimize the biodemulsifier yield. The optimal yield conditions were found at a paraffin concentration of 4.01%, an ammonium citrate concentration of 8.08 g/L and a pH of 9.35. Under optimal conditions, the biodemulsifier yield from Alcaligenes sp. S-XJ-1 was increased to 3.42 g/L.

Characterization and phylogenetic analysis of biodemulsifier-producing bacteria.

Based on demulsification performance, twenty biodemulsifier-producing strains were isolated from various environmental sources. Five of them achieved nearly or over 90% of emulsion breaking ratio within 24 h. With the aid of biochemical and physiological tests and 16S rDNA analysis, these isolates were classified into eleven genera, in which six genera (Brevibacillus sp., Dietzia sp., Ochrobactrum sp., Pusillimonas sp., Sphingopyxis sp. and Achromobacter sp.) were firstly reported as demulsifying strains. Moreover, with data in this study and other literatures, a phylogenic tree was constructed, showing a rich diversity of demulsifying bacteria. Half of these bacteria belong to Actinobacterale order, which is famous for hydrocarbon degradation and biosurfactant biosynthesis. However, some strains in the same genera differed remarkably in demulsifying capability, surface properties and biochemical and physiological characteristics. This implied the biosynthesis and composition of biodemulsifier were more complicated than expected.

Comparison between waste frying oil and paraffin as carbon source in the production of biodemulsifier by Dietzia sp. S-JS-1.

In order to lower the production cost, waste frying oils were used in the biosynthesis of demulsifier by Dietzia sp. S-JS-1, which was isolated from petroleum contaminated soil. After 7 days of cultivation, the biomass concentration of the most suitable waste frying oil (WFO II) culture reached 3.78 g/L, which was 2.4 times the concentration of paraffin culture. The biodemulsifier produced with WFO II culture broke the emulsions more efficiently than that produced with paraffin culture, given the same volume ratio of carbon source in the culture medium and the same cultivation conditions. It achieved 88.3% of oil separation ratio in W/O emulsion and 76.4% of water separation ratio in O/W emulsion within 5 h. With the aid of thin layer chromatography (TLC) and Fourier transform infrared (FTIR) spectrometry, biodemulsifiers produced from both paraffin and WFO II were identified as a mixture of lipopeptide homologues. The subtle variation in the distribution of these homologues and high biomass concentration of WFO II cultures may account for the afore-mentioned good demulsification performance.

Iron and manganese removal by using manganese ore constructed wetlands in the reclamation of steel wastewater.

To reclaim treated steel wastewater as cooling water, manganese ore constructed wetland was proposed in this study for the removal of iron and manganese. In lab-scale wetlands, the performance of manganese ore wetland was found to be more stable and excellent than that of conventional gravel constructed wetland. The iron and manganese concentration in the former was below 0.05 mg/L at hydraulic retention time of 2-5 days when their influent concentrations were in the range of 0.16-2.24 mg/L and 0.11-2.23 mg/L, respectively. Moreover, its removals for COD, turbidity, ammonia nitrogen and total phosphorus were 55%, 90%, 67% and 93%, respectively, superior to the corresponding removals in the gravel wetland (31%, 86%, 58% and 78%, respectively). The good performance of manganese ore was ascribed to the enhanced biological manganese removal with the aid of manganese oxide surface and the smaller size of the medium. The presence of biological manganese oxidation was proven by the facts of good manganese removal in wetlands at chemical unfavorable conditions (such as ORP and pH) and the isolation of manganese oxidizing strains from the wetlands. Similar iron and manganese removal was later observed in a pilot-scale gravel-manganese-ore constructed wetland, even though the manganese ore portion in total volume was reduced from 100% (in the lab-scale) to only 4% (in the pilot-scale) for the sake of cost-saving. The quality of the polished wastewater not only satisfied the requirement for cooling water but also suitable as make-up water for other purposes.

Evaluation of screening methods for demulsifying bacteria and characterization of lipopeptide bio-demulsifier produced by Alcaligenes sp.

In this paper, surface tension measurement, oil-spreading test and blood-plate hemolysis test were attempted in the screening of demulsifying bacteria. After the comparison to the screening results obtained in demulsification test, 50 mN/m of surface tension of culture was proposed as a preliminary screening standard for potential demulsifying bacteria. For the identification of efficient demulsifying strains, surface tension level was set at 40 mN/m. The detected strains were further verified in demulsification test. Compared to using demulsification test alone as screening method, the proposed screening protocol would be more efficient. From the screening, a highly efficient demulsifying stain, S-XJ-1, was isolated from petroleum-contaminated soil and identified as Alcaligenes sp. by 16S rRNA gene and physiological test. It achieved 96.5% and 49.8% of emulsion breaking ratio in W/O and O/W kerosene emulsion within 24h, respectively, and also showed 95% of water separation ratio in oilfield petroleum emulsion within 2h. The bio-demulsifier was found to be cell-wall combined. After soxhlet extraction and purification through silicon-gel column, the bio-demulsifier was then identified as lipopeptide biosurfactant by TLC and FT-IR.