Batch adsorption of organic pollutants from oxidation pond effluents using fly ashes

The batch shaking adsorption study was conducted to determine the potential of fly and volcanic ashes in removing organic pollutants from oxidation pond effluents. Factors affecting organic pollutant removals, such as concentrations and sizes of fly and volcanic ashes, initial pond effluent organic concentrations, washed and unwashed conditions of fly and volcanic ashes, were investigated. The TOC (total organic carbon) removal efficiency varied from 30 to 58 percent. The organic removal efficiency increased with increasing ash concentrations, with decreasing initial pond effluent organic concentrations and with decreasing sizes of ashes.     

Stakeholder impact analysis of infrastructure project management in developing countries: a study of perception of project managers in state‐owned engineering firms in Vietnam

Construction projects can involve a diverse range of stakeholders and the success of the project depends very much on fulfilling their needs and expectations. It is important, therefore, to identify and recognize project stakeholders and develop a rigorous stakeholder management process. However, limited research has investigated the impact of stakeholders on construction projects in developing countries. A stakeholder impact analysis (SIA), based on an approach developed by Olander (2007), was adopted to investigate the stakeholders’ impact on state‐owned civil engineering projects in Vietnam. This involved the analysis of a questionnaire survey of 57 project managers to determine the relative importance of different stakeholders. The results show the client to have the highest level of impact on the projects, followed by project managers and the senior management of state‐owned engineering firms. The SIA also provides suggestions to project managers in developing and evaluating the stakeholder management process.     

Occurrence and formation potential of N-nitrosodimethylamine in ground water and river water in Tokyo

N-nitrosodimethylamine (NDMA), a disinfection byproduct of water and wastewater treatment processes, is a potent carcinogen. We investigated its occurrence and the potential for its formation by chlorination (NDMA-FP_2Cl) and by chloramination (NDMA-FP_2NHCl) in ground water and river water in Tokyo. To characterize NDMA precursors, we revealed their molecular weight distributions in ground water and river water. We collected 23 ground water and 18 river water samples and analyzed NDMA by liquid chromatography-tandem mass spectrometry. NDMA-FP_2Cl was evaluated by chlorinating water samples with free chlorine for 24 h at pH 7.0 while residual free chlorine was kept at 1.0-2.0 mgCl₂/L. NDMA-FP_2NHCl was evaluated by dosing water samples with monochloramine at 140 mgCl₂/L for 10 days at pH 6.8. NDMA precursors and dissolved organic carbon (DOC) were fractionated by filtration through 30-, 3-, and 0.5 kDa membranes. NDMA concentrations were <0.5-5.2 ng/L (median: 0.9 ng/L) in ground water and <0.5-3.4 ng/L (2.2 ng/L) in river water. NDMA concentrations in ground water were slightly lower than or comparable to those in river water. Concentrations of NDMA-FP_2Cl were not much higher than concentrations of NDMA except in samples containing high concentrations of NH₃ and NDMA precursors. The increased NDMA was possibly caused by reactions between NDMA precursors and monochloramine unintentionally formed by the reaction between free chlorine and NH₃ in the samples. NDMA precursors ranged from 4 to 84 ng-NDMA eq./L in ground water and from 11 to 185 ng-NDMA eq./L in river water. Those in ground water were significantly lower than those in river water, suggesting that NDMA precursors were biodegraded, adsorbed, or volatilized during infiltration. The molecular weight of NDMA precursors in river water was dominant in the <0.5 kDa fraction, followed by 0.5-3 kDa. However, their distribution was inconsistent in ground water: one was dominant in the <0.5 kDa fraction, and the other in 0.5-3 kDa. Molecular weight distributions of NDMA precursors were very different from those of DOC. This is the first study to reveal the widespread occurrence and characterization of NDMA precursors in ground water.     

Iron oxide amended biosand filters for virus removal

Laboratory studies were performed to determine if the addition of iron oxides throughout biosand filter (BSF) media would increase virus removal due to adsorption. The proposed mechanism is electrostatic adsorption of negatively charged virion particles to positively charged iron oxides formed during the corrosion of zerovalent iron. Initial tests conducted using continuous flow, small-scale glass columns showed high MS2 bacteriophage removal in an iron-amended sand column (5log₁₀) compared to a sand-only column (0.5log₁₀) over 20 pore volumes. Additionally, two experiments with a column containing iron particles revealed 4log₁₀ and 5log₁₀ removal of rotavirus in the presence of 20 mg/L total organic carbon. Full-scale BSFs with iron particles removed >4log₁₀ MS2 for the duration of the experiment (287 days), while BSF with steel wool removed >4log₁₀ MS2 for the first 160 days. Plug flow for the BSF was shown to depend on uniformity between the iron oxide material and sand media grains. The results suggest that the duration of effective virus removal by iron-amended biosand filtration depends on source water conditions and the quantity and composition of iron material added. Overall, this study provides evidence that iron-amended BSFs may advance the field of point-of-use technologies and bring relief to millions of people suffering from waterborne diseases.     

Polycyclic aromatic hydrocarbons (PAHs) in urban surface dust of Guangzhou, China: Status, sources and human health risk assessment

Ninety-six urban surface dust samples collected from Guangzhou, a typical urban center in South China, were analyzed for 16 PAHs (2-6 rings). ∑ PAHs concentrations in the urban surface dust ranged from 0.84 to 12.3 μg/g with a mean of 4.80 μg/g. High molecular weight compounds (4-6 rings) contributed to 62 to 94% of ∑ PAHs mass in the surface dust samples. Four hotspots with highest ∑ PAHs were identified via kriging prediction mapping, representing the highly-urbanized regions: central downtown, highway and industrial area. Two major origins of PAHs inputs to urban surface dust were identified as vehicle emissions (51.9%) and coal combustion (26.8%). The 95% UCL of Incremental Lifetime Cancer Risk (ILCR) due to human exposure to urban surface dust PAHs in central South China was 3.03 × 10⁻⁶ for children and 2.92 × 10⁻⁶ for adults.     

Zwangbeanspruchung massiver Kraftwerks‐Bodenplatten infolge der Hydratationswärme

Thermal restraint due to hydration heat in thick power plant slabs. Within the enlargement of the lignite‐fired power plant Boxberg by the block R, a measurement program was carried out in order to detect the thermal restraint in the thick slab due to the outflow of hydration heat. With the Finite Element Method thermal and mechanical relations during the hardening process were pointed out. Especially the real occurring restraint during the hardening process was investigated under different conditions. By material models depending on the hydration degree, a good agreement between calculation results and measurement was achieved. The results of this investigation were presented consecutively.     

Study on Installation of Wire Netting with Intumescent Coating at Openings of Buildings to Reduce Fire Spread by Radiation

This study focuses on a new device that can reduce radiation heat at the openings of buildings. Intumescent coating is sprayed on wire netting affixed to the open spaces in the external wall of a building to reduce radiation heat and fire spread. This study uses a 1.2 m × 1.2 m × 1.2 m furnace to conduct fire-resistance tests according to the ISO 834-1 standard (the standard 1 h temperature rise curve and the furnace pressure). The study variables include wire netting with different mesh numbers (mesh widths) and wire netting with different coating thicknesses. The results from six sets of fire tests show that under the same coating thickness, less radiation heat is generated for a larger mesh number (i.e., smaller mesh width). Under the same mesh number for the wire netting, less radiation heat is generated for a larger coating thickness. At distances of 50 cm, 100 cm, and 150 cm from a fire source with a temperature of 945°C, the radiation heat calculated based on the theory is 6.9 W/cm². This study proves that the radiation heat can be dropped to 0.48 W/cm² with the installation of intumescent-coated wire netting, and that this type of netting can effectively prevent fire spreading by radiation.     

Impact of sonication at 20 kHz on Microcystis aeruginosa, Anabaena circinalis and Chlorella sp

Blooms of toxic cyanobacteria such as Microcystis aeruginosa periodically occur within wastewater treatment lagoons in the warmer months, and may consequently cause contamination of downstream water and outages of the supply of recycled wastewater. Lab-scale sonication (20 kHz) was conducted on suspensions of M. aeruginosa isolated from a wastewater treatment lagoon, and two other algal strains, Anabaena circinalis and Chlorella sp., to investigate cell reduction, growth inhibition, release of microcystin and sonication efficiency in controlling the growth of the M. aeruginosa. For M. aeruginosa, for all sonication intensities and exposure times trialled, sonication led to an immediate reduction in the population, the highest reduction rate occurring within the initial 5 min. Sonication for 5 min at 0.32 W/mL, or for a longer exposure time (>10 min) at a lower power intensity (0.043 W/mL), led to an immediate increase in microcystin level in the treated suspensions. However, prolonged exposure (>10 min) to sonication at higher power intensities reduced the microcystin concentration significantly. Under the same sonication conditions, the order of decreasing growth inhibition of the three algal species was: A. circinalis > M. aeruginosa > Chlorella sp., demonstrating sonication has the potential to selectively remove/deactivate harmful cyanobacteria from the algal communities in wastewater treatment lagoons.     

Users as knowledge co-producers in the information system development project

This study investigates the role of users as knowledge co-producers in different stages of the information system development project. Data collected from 269 IS professionals supported our hypotheses that common knowledge has an impact on requirement determination, which, in turn, leads to better project performance. User-IS relationship can substitute the effect of common knowledge on requirement determination in the design stage and user review can ensure that the obtained requirements are actually carried out by developers in the development stage. As a result, higher project performance can be obtained. Discussion of the results and conclusions is also provided.