Ash is a highly available industrial and agricultural waste by-product. Giving insights into the huge generation of ash and environmental concern of disposal issue, aesthetic attention has been drawn ...on the sustainable utilization of ash as a renewable supporting material in the synthesis of photocatalytic nanocomposites. Coal fly ash, rice husk ash and volcanic ash are currently being investigated for their potential to be applied as an effective precursor material for photocatalyst preparation, owing to their advantages of high adsorption capability, high ion-exchange capacity, significant specific surface area and high reusability. The novelty of these studies is that prepared ash based photocatalysts could provide a synergistic effect of the adsorption capacity of ash and the photocatalytic activity of photocatalysts to enhance the overall degradation efficiency of dye. Exploring the possible usage of these abundant by-products not only solving the environmental problem but also highlighting its further economic value of utilization with the concept of “waste to wealth”. This paper presents a fundamental information pertaining to the basic principles of photocatalysis and semiconductor based photocatalysts. A brief overview of the role of ash based nanocomposites in terms of the preparation methods and conditions, morphologies, physiochemical properties and their photocatalytic performances on the degradation of dye pollutants is highlighted. The optimization, mechanism and stability study are also reviewed. The finding showed that the porous structure and the presence of aluminosilicate in the ash greatly enhance the adsorption capacity of the total composite in the dye degradation process. The photocatalytic performance was dependent on the calcination temperature, catalyst loading, solution pH, initial dye concentration and light source. However, reusability test indicated the high stability of the prepared ash based composites, with most of the dye degradation efficiency greater than 80% even after a few successive regeneration cycles.
•A brief historical study of photocatalysis.•State the basic principles of photocatalysis.•An overview of ash based composites with different preparation methods.•Discuss the application in degradation of dye pollutants.•Indicate the high stability of ash based composites.
A well-designed engineered soil for bioretention is important as it ensures that pollutant removal requirements are met. This laboratory study investigated the nutrient removal efficiency of ...bioretention media enhanced with 10% (by volume) additives from various waste materials (cockle shell, newspaper, printed paper, coconut husk and tyre crumb) and planted with Red Hot Chinese Hibiscus (Hibiscus rosa-sinensis), a common landscape shrub in tropical countries. The results showed that media enhanced with shredded newspaper demonstrated a significant improvement in total nitrogen (TN) removal (80.4%), compared to standard bioretention media (57.5%) without compromising total suspended solids (TSS) and total phosphorus (TP) removal, when dosed with actual runoff. The thick root system and rapid growth rate of the plant was proven to contribute to TN removal. This study concluded that shredded newspaper can be a potential addition to enhance bioretention media performance in treating stormwater, especially nutrient rich runoff from mixed development areas.
Genetic programming (GP) has nowadays attracted the attention of researchers in the prediction of hydraulic data. This study presents linear genetic programming (LGP), which is an extension to GP, as ...an alternative tool in the prediction of scour depth around a circular pile due to waves in medium dense silt and sand bed. Field measurements were used to develop LGP models. The proposed LGP models were compared with adaptive neuro-fuzzy inference system (ANFIS) model results. The predictions of LGP models were observed to be in good agreement with measured data, and quite better than ANFIS and regression-based equation of scour depth at circular piles. The results were tabulated in terms of statistical error measures and illustrated via scatter plots.
Over the years, the emergence of pesticides practice has prevailed to be the most intricate environmental turmoil amongst the scientific community. Specifically, pesticides constitute an ...accumulative, persistent and detrimental impact towards the survival of flora, fauna and environmental matrix. This has inspired a developing research with a variety of treatment technologies. Adsorption is recognized as the most efficient and promising approach, due to the ease of operation, simplicity of design, insensitivity to the toxic substances and superior capability for removing a broad range of pollutants. Its diverse applications, however, are retarded by the high cost of adsorbents and difficulties associated with regeneration. Montmorillonite and its derivatives, a unique group of under-utilized clay-based minerals has been proposed to be a suitable candidate for the treatment of contaminated wastewater. It plays a key role as the natural scavenger of pesticides, due to the abundantly availability, large specific surface area and high adsorptive and ion exchange properties. This paper describes the origin, physical, chemical and physicochemical properties of natural montmorillonite. The preparation procedure, reusability, commercial product and economical evaluation are highlighted. The specific classification, environmental and health implication of organo-pesticide are discussed. The revolution of montmorillonite-assisted adsorption process for the remediation of organo-pesticide was summarized. Additionally, the characterizations, surface chemistry and mechanism investigation are outlined.
Constructed wetlands (CW) are built to improve water quality while serving as an alternative sustainable habitat for aquatic life. In Malaysia, CWs are designed according to the guideline for Urban ...Stormwater Management Manual for Malaysia (MSMA 2nd Edition) 2012. This study shall evaluate the performance of constructed wetland design as stipulated by MSMA through assessment of water quality and phytoplankton growth, which acts as a biodiversity indicator. A 5-month sampling period with phytoplankton abundance in a constructed wetland was correlated with the selected water quality index (WQI) parameters comprising dissolved oxygen (DO), ammoniacal oxygen (AN), chemical oxygen demand (COD), biological oxygen demand (BOD), total suspended solid (TSS), and pH. The constructed wetland consists of three main zones, namely the forebay, macrophytes and micropool zones. The highest WQI value was obtained from the micropool zone with a range of 78.98-85.45 (82.71±3.35) while the lowest WQI value was collected from the macrophytes zone with a range of 68.13-77.96 (73.25±3.42). A total of 15 phytoplankton species from 5 different algal phyla were identified in the constructed wetland. Phytoplankton distribution was high in the macrophytes zone (521 cell m-3) during dry season due to high nutrient concentration as opposed to the other zones. The phytoplankton distribution was found to be closely associated with DO, AN, TSS and total phosphorus. At the same time, the macrophyte zone design also affects the distribution of phytoplankton.
Understanding of the fate of pollutants, disposed of in streams, is a matter of concern in recent years for the effective control of pollution. Transverse mixing of the pollutants in open channels is ...arguably more important than the longitudinal mixing and near-field mixing. Several attempts have been made to establish the relationship between the transverse mixing coefficient and bulk channel and flow parameters such as width, depth, shear velocity, friction factor, curvature and sinuosity. This paper presents adaptive neuro fuzzy inference system (ANFIS) approach to predict the transverse mixing coefficient in open channel flows. Available laboratory and field data for the transverse mixing coefficients covering wide range of channel and flow conditions are used for the development and testing of the proposed method. The proposed ANFIS approach produces satisfactory results (R(2)=0.945) compared to the artificial neural network (ANN) model and existing predictors for mixing coefficient.
Non-radiative wireless power transfer (WPT) system using magnetic resonance coupling (MRC) technique has recently been a topic of discussion among researchers. This technique discussed more scenarios ...in mid-range field of wireless power transmission reflected to the distance and efficiency. The WPT system efficiency varies when the coupling distance between two coils involved changes. This could lead to a decisive issue of high efficient power transfer. This paper presents case studies on the relationship of operating range with the efficiency of the MRC technique. Demonstrative WPT system operates at two different frequencies are projected in order to verify performance. The resonance frequencies used are less than 100MHz within range of 10cm to 20cm.
This paper evaluates the performance of three soft computing techniques, namely Gene-Expression Programming (GEP) (Zakaria
et al
2010), Feed Forward Neural Networks (FFNN) (Ab Ghani
et al
2011), and ...Adaptive Neuro-Fuzzy Inference System (ANFIS) in the prediction of total bed material load for three Malaysian rivers namely Kurau, Langat and Muda. The results of present study are very promising: FFNN (
R
2
= 0.958, RMSE = 0.0698), ANFIS (
R
2
= 0.648, RMSE = 6.654), and GEP (
R
2
= 0.97, RMSE = 0.057), which support the use of these intelligent techniques in the prediction of sediment loads in tropical rivers.
A new total bed material load equation that is applicable for rivers in Malaysia was developed using multiple linear regression analyses. A total of 346 hydraulic and sediment data were collected ...from nine natural and channelized rivers having diverse catchment characteristics in Malaysia. The governing parameters were carefully selected based on literature survey and field experiments, examined and grouped into five categories namely mobility, transport, sediment, shape, and flow resistance parameters. The most influential parameters from each group were selected by using all possible regression model method. The suitable model selection criteria namely the
R
-square, adjusted
R
-square, mean square error, and Mallow’s
Cp
statistics were employed. The accuracy of the derived model is determined using the discrepancy ratio, which is a ratio of the calculated values to the measured values. The best performing models that give the highest percentage of prediction from the validation data were chosen. In general, the newly derived model is best suited for rivers with uniform sediment size distribution with a
d50
value within the range of 0.37–4.0 mm and performs better than the commonly used Graf, Yang, and Ackers–White total bed material load equations.
Celotno besedilo
Dostopno za:
DOBA, FGGLJ, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Researchers in the past had noticed that application of Artificial Neural Networks (ANN) in place of conventional statistics on the basis of data mining techniques predicts more accurate results in ...hydraulic predictions. Mostly these works pertained to applications of ANN. Recently, another tool of soft computing, namely, Genetic Programming (GP) has caught the attention of researchers in civil engineering computing. This article examines the usefulness of the GP based approach to predict the relative scour depth downstream of a common type of ski-jump bucket spillway. Actual field measurements were used to develop the GP model. The GP based estimations were found to be equally and more accurate than the ANN based ones, especially, when the underlying cause-effect relationship became more uncertain to model.
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