Sustainable green technology on wastewater treatment: The evaluation of enhanced single chambered up-flow membrane-less microbial fuel cell

This study demonstrated the potential of single chamber up-flow membrane-less microbial fuel cell(UFML-MFC) in wastewater treatment and power generation. The purpose of this study was to evaluate and enhance the performance under different operational conditions which affect the chemical oxygen demand(COD) reduction and power generation,including the increase of KCl concentration(MFC1) and COD concentration(MFC2). The results showed that the increase of KCl concentration is an important factor in up-flow membrane-less MFC to enhance the ease of electron transfer from anode to cathode. The increase of COD concentration in MFC2 could led to the drop of voltage output due to the prompt of biofilm growth in MFC2 cathode which could increase the internal resistance. It also showed that the COD concentration is a vital issue in up-flow membrane-less MFC.Despite the COD reduction was up to 96%, the power output remained constrained.     

Popular Cognition of National Monuments in Singapore

Monumental features or landmarks in the urban built environment are distinguished by clear form, prominent location, a high degree of visibility and in Lefebvres (1991:143) words, "impose a clearly intelligible message". In Singapore, the gazetting and preservation of national monuments come under the ambit of the Preservation of Monuments Board. From the states perspective, national monuments embody historical value: as enduring landmarks of the city which link the present to the past, they give "lithic memory to the life of a nation" and are integral to the process of building national solidarity, identity and pride. This paper examines popular cognition of Singapores national monuments, that is, the extent to which the general public are able to identify gazetted monuments in visual and nomenclatural terms. A questionnaire survey of 284 respondents selected from a public housing estate as well as in-depth interviews with a smaller sample yielded information on Singaporeans visual recognition, nomenclatural accuracy and historical knowledge with respect to national monuments. The results showed that while visual identification of monuments was strong and the public could clearly identify the main attributes and general forms which national monuments take, the specific names of these monuments were often overlooked and historical knowledge of them rather shallow. In the conclusion, it is argued that if monuments are to serve their purpose as the countrys "psyche" annd "memory", deeper knowledge of the history and meaning behind these monuments must be inculcated in the Singaporean consciousness.     

Application of fluidized bed combustion to industrial waste treatment

Landfill and sea-dumping appear to be on their way out as acceptable methods for the disposal of untreated industrial wastes in Taiwan. Recently, there has been interest in the application of fluidized bed technology to waste incineration for efficient energy utilization and environmental protection. A pilot fluidized bed combustion system was used to investigate the incineration performance and parametric test for the waste from an industrial park. According to the experimental results, the appropriate operating conditions, including temperatures of 800-840 degrees C, aeration rates of U(0)/Um(f)-2.0 or so, and on-bed feeding, were recommended to treat such waste. The emissions of SO(x), NO(x) and CO in flue gas meet the ROC-EPA regulation.     

Chemical composition of fine particles from incense burning in a large environmental chamber

 This study is aimed to characterize the major chemical compositions of PM_2.5 from incense burning in a large environmental chamber. Chemical analyses, including X-ray fluorescence for elemental species, ion chromatography for water soluble inorganic species (chloride, nitrate, sulfate, sodium, potassium, ammonium) and thermal/optical reflectance analysis for carbon species were carried out for combustion of three incense categories (traditional, aromatic and church incense). The average concentrations from incense burning ranged from 139.8 to 4414.7 μg m⁻³ for organic carbon (OC), and from 22.8 to 74.0 μg m⁻³ for elemental carbon (EC), respectively. The average OC and EC concentrations in PM_2.5 of three incense categories were in the order of church incense>traditional incense>aromatic incense. OC/EC ratios ranged from 7.0 to 39.1 for the traditional incense, with an average of 21.7; from 3.2 to 11.9 for the aromatic incense, with an average of 7.7. The concentrations of Cl⁻, SO₄²⁻, Na⁺ and K⁺ were highly variable. On average, the inorganic ion concentration sequence was traditional incense>church incense>aromatic incense. The profiles for elements were dominated by Na, Cl and K. In general, the major components in PM_2.5 fraction from incense burning are OC (especially OC2, OC3 and OC4), EC and K.     

DECISION SUPPORT FOR ALLOCATION OF WATERSHED POLLUTION LOAD USING GREY FUZZY MULTIOBJECTIVE PROGRAMMING1

ABSTRACT: This paper uses the grey fuzzy multiobjective programming to aid in decision making for the allocation of waste load in a river system under versatile uncertainties and risks. It differs from previous studies by considering a multicriteria objective function with combined grey and fuzzy messages under a cost benefit analysis framework. Such analysis technically integrates the prior information of water quality models, water quality standards, wastewater treatment costs, and potential benefits gained via in‐stream water quality improvement. While fuzzy sets are characterized based on semantic and cognitive vagueness in decision making, grey numbers can delineate measurement errors in data collection. By employing three distinct set theoretic fuzzy operators, the synergy of grey and fuzzy implications may smoothly characterize the prescribed management complexity. With the aid of genetic algorithm in the solution procedure, the modeling outputs contribute to the development of an effective waste load allocation and reduction scheme for tributaries in this subwatershed located in the lower Tseng‐Wen River Basin, South Taiwan. Research findings indicate that the inclusion of three fuzzy set theoretic operators in decision analysis may delineate different tradeoffs in decision making due to varying changes, transformations, and movements of waste load in association with land use pattern within the watershed.     

Sensitivity analysis of ground-level ozone concentration to emission changes in two urban regions of southeast Texas

Air pollutant emission is one of the predominant factors affecting urban air quality such as ground-level ozone formation. This paper assesses the impact of changing emission inventory scenarios, based on combinations of point, mobile, area/non-road and biogenic sources, on the tropospheric ozone concentration in two southeast Texas urban areas, i.e. Houston-Galveston and Beaumont-Port Arthur, during the rapid ozone formation event (ROFE) on August 25, 2000. The EPA's Community Multiscale Air Quality (CMAQ) modeling system with 1999 national emission inventory (NEI99) estimates and updated SAPRC99 chemical mechanism are used in the sensitivity analysis for twelve different emission scenarios. Based on model results, it is found that the point source emission of NOx and VOC contributes the greatest ozone peak in the ROFE. Removing Texas point sources of VOC and NOx emission from the inventory results in a reduction in peak O3 concentration by 128 and 70 ppbv in Houston urban area, respectively. Similar but less drastic impact from point source is also observed in the Beaumont-Port Arthur area. The effect on peak ozone concentration due to mobile, area and non-road sources emissions are less significant compared to that of point source emission. Reducing VOC emission appears to be more effective than reducing NOx emission in lowering peak O3 concentration in the studied region. Although biogenic emission can contribute up to 37 ppbv of peak ozone level over a large area, the affected area is away from the urban region of concern, and should not be the main cause for O3 non-attainment in the two urban areas. Removing CO emission from mobile sources does not lead to significant reduction (< 1 ppbv) in ozone concentrations. The modeled data also show that the transport of O3 precursors from adjacent states can cause a significant ozone plume near Beaumont due to its proximity to the state border based on the conditions during the August 25, 2000 O3 episode.     

Importance and uncertainty analysis of flue gas scrubber systems with extreme reliability parameter values

Although reliability analyses have been used to improve the reliability of industrial systems, generic reliability data from publications, such as component failure intensities and repair times, are used to calculate reliability measures instead of the real reliability data collected from the plant. One reason is that the repair history of the components is not well managed in the plant. In this work, the effect of extreme reliability parameter values on system reliability and unavailability is studied. To do this, importance and uncertainty analysis of the components of flue gas scrubber systems is carried out, and results calculated with the extreme reliability parameter values are compared with those with the mean reliability values of the systems. The different reliability parameter values can give us totally different ranks of the components critical to the reliability of the representative scrubber system. Consequently, the effort to establish a reliable database is emphasized to perform accurate reliability analysis of the system.     

Dietary separation between two blennies and the Pacific gregory in northern Taiwan: evidence from stomach content and stable isotope analyses

Two blennies, Ecsenius lineatus Klausewitz and Ecsenius namiyei (Jordan and Evermann), and a cohabiting territorial damselfish, the Pacific gregory, Stegastes fasciolatus (Ogilby), were collected from shallow reefs in northern Taiwan between September and November 2004, and in October 2005 for stomach content and δ ¹³C and δ ¹⁵N analyses in an effort to study how extensively their food sources overlapped and to delineate the pattern of cohabiting interactions. These analyses showed differences in food use between the Ecsenius blennies and S. fasciolatus. However, there were inconsistencies. Epiphytic algae were their major food items of E. namiyei and E. lineatus. Macroalgae were rarely taken. Nevertheless, δ ¹³C and δ ¹⁵N signatures suggested that E. namiyei and E. lineatus might have assimilated mainly macroalgae-derived detritus instead of epiphytic algae. In contrast, macroalgae were the major food items of S. fasciolatus, followed by epiphytic algae. Differences in both δ ¹³C and ¹⁵N values indicated that for S. fasciolatus, algae (both macroalgae and epiphytic algae) might not be as important as the stomach contents showed. Instead, polychaetes were possibly its major food source. Differences between stomach contents and evidence from the separation of stable isotope signatures between blennies and the Pacific gregory indicate that some of the interspecific interactions derived from exploitative competition may have been alleviated. Moreover, their widespread territory overlap is possibly a sign of mutualism: S. fasciolatus allows territory sharing, while Ecsenius blennies, in return, clean up the algal mat by removing sand and detritus.     

Development of an empirical equation for the transverse dispersion coefficient in natural streams

In this study, a new empirical equation for the transverse dispersion coefficient has been developed based on the hydraulic and geometric parameters in natural streams using a regression technique. First, a total of 32 data sets in 16 streams were collected. Among those sets, 16 sets were used for deriving the new equation, and the other 16 sets were used for verifying the equation. Then, through dimensional analysis, it was found that the normalized transverse dispersion coefficient is associated with several parameters such as sinuosity, aspect ratio, and a friction term. The robust least square method was applied to estimate regression coefficients. The newly proposed equation was proven to be superior in explaining the dispersion characteristics of natural streams more precisely compared to the existing equations.