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In this study, an artificial wetland filler matrix capable of effectively fixing phosphorus was prepared using a non-combustion process to save energy. To evaluate the adsorption performance of this filler, adsorption experiments were performed and the phosphorus adsorption mechanism characterization was studied. An alkaline environment was found to be conducive to the increase of adsorption capacity, but excessive alkalinity was not conducive to adsorption. Static adsorption experiments showed that the phosphorus removal rate could reach 95% in the simulated phosphorus-containing wastewater after adsorption completion. The adsorption process is closely simulated by the pseudo-second-kinetic adsorption model. The isothermal adsorption experiment data were consistent with the Langmuir and the Freundlich adsorption isotherms. The characterization results showed a large number of micropores and adsorption binding sites inside and on the surface of the filler. Speciation analysis on the adsorbed phosphorus revealed that chemisorption by calcium in this filler was the dominant adsorption mechanism. The research results of this study provide the basis and reference for the development of high-efficiency phosphorus removal filler in constructed wetlands. [ABSTRACT FROM AUTHOR]

A novel process for sewage sludge bioleaching by mixed Thiobacilli (Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans) using a 12-stage, 180 L working volume continuous plug-flow bioreactor, is presented. The objective of the present study was to assess the impact of some parameters on the sludge dewaterability and to improve the sludge dewaterability by optimization of these parameters. The parameters examined were sludge moisture content, nutrients dosage, aeration rate, and the number of reactors. The order of the influence of these factors on sludge dewaterability was found to be sludge moisture content>nutrients dosage> aeration rate> number of reactors. The optimized conditions were: sludge moisture content, 98.0%, nutrients dosage, 9 g/L, aeration rate, 8 m³/h, and 10 reactors. Confirmation experiments conducted under optimum conditions demonstrate the sludge dewaterability to be remarkably improved. After 2 days of bioleaching, the moisture of bioleached sludge cake was reduced to below 60%. [ABSTRACT FROM AUTHOR]

Aquatic plants easily wither and go into dormancy in winter when temperature is extremely low. Little is known about nitrogen and phosphorus uptake by plants and its role in removing nutrient in constructed wetlands (CWs). Investigating the performance of CWs planted with overwintering plants and selecting out which plants will support an effective CW over the winter period are important. In this study, microcosmic subsurface vertical flow constructed wetlands (MVFCWs) were planted with Iris sibirica for treating simulated polluted river water and evaluated for nutrient removal, plant growth characteristics and plant nutrient uptake under different nutrient concentrations. Treatment performances indicated that the highest average total nitrogen (TN), ammonia nitrogen (NH4+-N), total phosphorus (TP), soluble reactive phosphorus (SRP), and chemical oxygen demand (COD) removal efficiencies were obtained in MVFCW units with medium nutrient (10-16 mg/L TN, 7-10 mg/L NH4+-N, 1.8-2.5 mg/L TP, and 80-120 mg/L COD); the removal efficiencies were 45.8 ± 15.4%, 62.1 ± 8.8%, 57.7 ± 8.3%, 59.1 ± 10.1%, and 39.3 ± 12.1%, respectively. MVFCW units with low nutrient (5-8 mg/L TN, 3.5-5 mg/L NH4+-N, 0.9-1.25 mg/L TP, and 40-60 mg/L COD) exhibited the worst treatment effects. Plant nutrient uptake in the different MVFCW units ranged from 19.86% to 50.19% of N removal and from 13.19% to 22.32% of P removal at the end of experiment. The N and P accumulation ability of the below-ground part of plants was better than that of the above-ground part. The I. sibirica plants demonstrated high nutrient uptake in winter, and MVFCWs facilitated a certain degree of nutrient removal. Thus, I. sibirica can be considered an effective overwintering plant selection in CWs for restoring polluted river water and potentially be suitable for generalizing elsewhere, especially over the winter period. [ABSTRACT FROM AUTHOR]

Considering the characteristics of rural domestic sewage in central China, an unpowered complex eco-technology composed of anaerobic baffled reactor (ABR), composite soil filling (CSF) system, and free water surface (FWS) constructed wetland was developed to treat rural sewage. The Guogang Village sewage treatment demonstration project at Xinmi City showed that the complex ecosystem had remarkable pollutant removal efficiency. The removal rate was over 90% for chemical oxygen demand and total phosphorus, and over 70% and 80% for TN and NH4+-N, respectively. The effluent concentration met the integrated wastewater discharge standard of China (GB18918-2002) level 1B. The complex eco-technology could effectively purify water quality, and it was cheaper and had simpler operation. Thus, it could be considered as an effective method for treating rural domestic sewage. [ABSTRACT FROM AUTHOR]

Here, a three-dimensional (3D) carbohydrate microarray-based plasmon resonance light scattering (RLS) assay has been established for studying carbohydrate–lectin binding with high selectivity. The 3D carbohydrate microarray is fabricated by immobilizing amino-modified carbohydrates on the home-made fourth-generation (G4) NH2-terminated poly(amidoamine) dendrimers (PAMAM)-modified substrate. After marking the carbohydrate–lectin binding events by 13 nm peptide-stabilized gold nanoparticles through the biotin–avidin reaction, the 3D microarray can be directly detected by the RLS scanner without the conventional silver enhancement step. The well defined recognition systems: three monosaccharides (Man-α, Glc-α and Gal-β) with two lectins (Con A and RCA 120), have been chosen here to establish the RLS assay, respectively. Quantitative determination of the surface dissociation constants (KD,surf) for surface carbohydrates and lectins has been achieved. In addition, inhibition values (i.e.the inhibition constants (Ki) and the concentrations of inhibitors required to produce 50% inhibition (IC50)) for inhibitors in solution are also demonstrated by the saccharide competing assays. [ABSTRACT FROM AUTHOR]

To develop a novel high-throughput tool for monitoring specific affinity of microbes with lectins, a kind of lectin microarray has been fabricated by immobilizing lectins on epoxide-derivatized glass slides and used to capture microbes. The capturing events are marked by attachment of lectin-conjugated gold nanoparticles followed by silver deposition to enhance the resonance light scattering (RLS) of the particles. The interactions of 16 lectins with four bacteria and one fungus were proffled by this approach. We demonstrated that the gold-nanoparticle-labeled array was suitable for identifying the binding affinity of lectin with bacterium, as well as determining the bacterium with high sensitivity. More importantly, we found that the growth of microbial strains in different culture media resulted in significant changes in their binding affinities with lectins, which might be important to the pathogenesis of the organisms. [ABSTRACT FROM AUTHOR]

In order to develop a novel high-throughput tool for monitoring carbohydrate-protein interactions, we prepared carbohydrate or glycoprotein microarrays by immobilizing amino modified carbohydrates on aldehyde- derivatized glass slides or glycoprotein on epoxide-derivatized glass slides and carried out lectin binding experiments by using these microarrays, respectively. The interaction events are marked by attachment of gold nanoparticles followed by silver deposition for signal enhancement. The attachment of the gold nanoparticles is achieved by standard avidin-biotin chemistry. The detection principle is resonance light scattering (RLS). The well-defined recognition systems, namely, three monosaccharides (Man-α, Glc-β and Gal-β) or three glycoproteins (Asf, RNase A and RNase B) with two lectins (ConA and RCA120), were chosen here to establish the RLS assay, respectively. Highly selective recognition of carbohydrate-protein down to 25.6 pg/mL for RCA120 in solution and 8 μM for Gal-β and 32 ng/mL for Asf on the microarray spots is demonstrated. [ABSTRACT FROM AUTHOR]

Bioleaching has been demonstrated to be an effective technology for the removal of heavy metals and sludge dewaterability. Since bacteria gain nutrients by diffusion of soluble compounds, the insolubility of elemental sulfur may slow the growth of bacteria. Thus, it is very important to find an energy substance quickly become available to Acidithiobacillus thiooxidans. This paper studies the improvement of sludge dewaterability and heavy metal removal with sodium thiosulfate as the source of energy for Acidithiobacillus thiooxidans. Through orthogonal experiments with specific resistance to filtration (SRF) as the target index, four factors (FeSO4 dosage, Na2S2O3 dosage, sludge reflux ratio and sludge moisture content) were identified to be the important influencing parameters. The optimal conditions were: FeSO4 dosage, 8 g/L; Na2S2O3 dosage, 1.5 g/L; sludge reflux ratio, 30%; sludge moisture content, 97%. Results indicated that the SRF of the sludge decreased from 9.89 x 1012 to 1.03 x 1011 m/kg. The removal efficiencies of heavy metals Cu, Zn, Pb and Cr could reach 83%, 78%, 31% and 38% within 3 days, respectively. These results confirm the potential of sodium thiosulfate as an alternative energy substance in bioleaching to improve sludge dewaterability as well as removal of metals. [ABSTRACT FROM AUTHOR]

Bioleaching is a promising technology for removal of metals from sludge and improvement of its dewaterability. Most of the previous studies of bioleaching were focused on removal of metals; bioleaching in cold environments has not been studied extensively. In this study, Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans were acclimated at 15 °C and co-inoculated to explore the optimal conditions for improvement of sludge dewaterability and removal of metals by the sequencing batch reactors. The data show after 6 days of bioleaching at 15 °C, 89.6% of Zn, 72.8% of Cu and 39.4% of Pb were removed and the specific resistance to filtration (SRF) was reduced to ~12%. In addition, the best conditions for bioleaching are an initial pH of 6, a 15% (v/v) inoculum concentration, and A. thiooxidans and A. ferrooxidans mixed in a ratio of 4:1. We found that bioleaching of heavy metals is closely related to final pH, while the sludge SRF is dominated by other factors. Bioleaching can be completed in 6 days, and the sludge dewaterability and removal of metals at 15 °C meet the requirements of most sewage treatment plants. [ABSTRACT FROM AUTHOR]