Monitoring Leachate Migration in Compacted Soil Using Digital Image Technique

As leachate has been a source of groundwater contamination worldwide, this paper examines the phenomenon of leachate migration on different gradations of compacted laterite soil used as sanitary landfill liners. Three different soil gradations (30%, 40% and 50% with respect to fines content) used in this study were compacted in circular acrylic columns to provide a clear visualization of leachate migration into the soils. Digital image technique was used in capturing photos at successive time intervals to monitor the leachate migration. The captured digital images were fed into Matlab and converted into hue-saturation-intensity (HSI) format. Surfer software then read the HSI and generated 2D contour plots. The results of the experiments showed that the leachate moves downward faster in the soil gradation with the least fines content. Hydraulic conductivity values decrease with increase in time duration and equally with increase in fines content. The hydraulic conductivities of the leachate for 30%, 40% and 50% fines were 3.64×10-9m/s, 2.40×10-9m/s, and 1.24×10-9m/s respectively. This reveals that for tropical laterite soils, gradation containing 50% fines content provides better hydraulic conductivity. The use of noninvasive digital image technique can enable designers/engineers to monitor and visualize the leachate migration in compacted soils in waste containment application systems

Monitoring Leachate Migration in Compacted Soil Using Digital Image Technique

As leachate has been a source of groundwater contamination worldwide, this paper examines the phenomenon of leachate migration on different gradations of compacted laterite soil used as sanitary landfill liners. Three different soil gradations (30%, 40% and 50% with respect to fines content) used in this study were compacted in circular acrylic columns to provide a clear visualization of leachate migration into the soils. Digital image technique was used in capturing photos at successive time intervals to monitor the leachate migration. The captured digital images were fed into Matlab and converted into hue-saturation-intensity (HSI) format. Surfer software then read the HSI and generated 2D contour plots. The results of the experiments showed that the leachate moves downward faster in the soil gradation with the least fines content. Hydraulic conductivity values decrease with increase in time duration and equally with increase in fines content. The hydraulic conductivities of the leachate for 30%, 40% and 50% fines were 3.64×10-9m/s, 2.40×10-9m/s, and 1.24×10-9m/s respectively. This reveals that for tropical laterite soils, gradation containing 50% fines content provides better hydraulic conductivity. The use of noninvasive digital image technique can enable designers/engineers to monitor and visualize the leachate migration in compacted soils in waste containment application systems

Load-deformation analysis on a slope at Gunung Pulai water treatment plant, Sultan Ibrahim reservoir

The Sultan Ibrahim Reservoir located at Gunung Pulai catchment area was previously managed by the Singapore's Public Utilities Board before the Board handed over the reservoir to Johor State Government under current management of the Syarikat Air Johor. At the present time, the Syarikat Air Johor is operating a Gunung Pulai Water Treatment Plant consisted of two main plants, i.e. Water Sedimentation Plant and Water Filtration Plant for treating raw water from the reservoir before supplying to the consumers. However, the integrity of water treatment plant's structure should be checked due to several cracks were observed, and moreover the structure was built over more than 90 years. The formation of the cracks in the Gunung Pulai Water Treatment Plant may be induced by movement of the sloping area to the south-east of Water Sedimentation Plant. The calculated Factor of Safety (FOS) via sensitivity analysis for cross sections of original slope indicates any decrease in friction angle and/or cohesion strength or increase in horizontal seismic load will further cause instability on slope. Also, the results of Load-Deformation analysis on cross sections of original slope show significant vertical displacement and horizontal displacement on the bottom and both sides of sedimentation tanks, respectively. The results indicate applied structural and water loads significantly affect deformation at both vertical and horizontal directions which could have contributed to FOS < 1 in slope stability analysis

Effect of dope extrusion rate on morphology and performance of hollow fibers membrane for ultrafiltration

The objective of this study is to determine the effects of dope extrusion rate (DER) on polyethersulfone hollow fiber ultrafiltration membrane performance and morphology. The hollow fiber ultrafiltration membranes were produced by using a simple dry/wet spinning process with forced convection in the dry air gap. A newly developed dope solution consists of 20.6 wt.% polyethersulfone (PES), 63.6 wt.% 1- methyl-2-pyrrolidone (NMP), 9.3 wt.% polyethylene glycol (PEG) and a mixture of potassium acetate and water (20/80 wt.%) was used as a bore fluid in this study. This newly developed dope solution was designed to be very close to its cloud point (binodal line) in order to speed up the coagulation process so that the relaxation effect on molecular orientation can be reduced. The dope extrusion rate was varied from 2.0 to 4.0 cm3/min with 0.5 cm3/min increments in order to study the effect of DER on fiber performance and morphology. The experimental results showed that the flux of the hollow fiber ultrafiltration membranes decreases while the separation performance for particular solute increases with an increase in dope extrusion rate. This suggests that the outer skin layer of the membranes becomes apparently thicker and denser with increasing dope extrusion rate. Once the separation performance reaches maximum (critical point), the rejection decreases with increasing dope extrusion rate, observed possibly due to formation of less tighten outer skin structure at high dope extrusion rate. Plane-polarized Fourier transform infrared spectroscopy revealed that membrane spun at dope extrusion rate of 3.5 cm3/min showed largest spectrum difference suggesting that higher molecular orientation is responsible for an enhanced separation performance. This study also indicated that ultrafiltration hollow fiber membrane produced has a high potential to be used for cyclodextrin separation

Bio-composite materials potential in enhancing sustainable construction

According to the sustainability principles, building should have zero-embodied energy in order to minimize the amount of carbon. In previous practices, construction materials have been composed with non-recyclable materials and after demolition of buildings the debris were put on different landfills. Nowadays, most of the material manufacturers have shifted their concerns to produce materials by using renewable resources, and also gained opportunity in utilizing wasted streams. The proposed biomaterials have been produced using natural fibers which reinforce biodegradable polymeric, in which naturally occurring aliphatic thermoplastic polyesters are produced by microbes via bacterial fermentation in carbon-rich environments. The composite material produced exhibits comparable properties to structural grade wood and is rapidly biodegradable in specific anaerobic conditions, at the end of its useful life. Using anaerobic digester sludge from local wastewater treatment plants as the biodegradation medium, the material decomposes into biogas that consists mostly of inert gases and, of particular interest, methane, which can be captured and used either as a biofuel or as a closed-loop carbon source. This paper documents bio-based composite material development, durability issues, anaerobic biodegradation, and potential industrial applications

Daylight factor for energy saving in retrofitting institutional building

In Malaysia, lighting is the second electric power consumption after air conditioning and it is increasing every year. Most of the lighting design standard for building in Malaysia is based on MS1525, and this being taken without further measure on daylight consideration. Movement from inefficient and unsustainable energy practice to more energy efficient initiatives is vital for building. Universiti Teknologi Malaysia as one of the major institutional building is consuming 9 to 16 million kWh per year. Thus, about 20% of energy consumed was from artificial lighting. This paper aim to highlights the cost benefit study of lighting retrofit, which integrates the utilization of daylight into existing building. Data for this study was obtained through illumination in-situ measurement on two types of artificial lighting with the inclusive of day lighting before and after lighting retrofit. The measurement was conducted in a typical building in Block C09 of Universiti Teknologi Malaysia (UTM). Annual saving and payback period were analysed from the collected data. It is estimated that total energy consumption decreasing around 47.7% over a year from 84,232kWh to 44,014kWh by retrofitted the fluorescent T8, 36W with fluorescent T5, 25W. The estimated total annual electricity bill saving is at RM11,073 (USD3500.00). The return in retrofitting cost is at 2.5 years payback period. The payback analysis portray that lighting design is best integrated with daylight. The significant amount of saving in energy consumption and the cost of retrofit is obtained by integrating daylight as a source of lighting for interior space

Building energy intensity measurement for potential retrofitting of zero energy building in higher learning institution

Energy is currently world debate and being a prominent issue especially in industrial, transportation, residential and service sector. Service sector that includes all commercial and public buildings are also being the major contributor of global energy consumption. Higher Learning Institution (HLI) are among public buildings that the energy demand has become a critical issue, in which HLI need to spend a considerable high amount of money annually for electricity consumption. This energy issue somehow can be improved by implementing the retrofit to existing building which employed energy efficient technology, where it involves modifications using sustainable building criteria. This paper highlighted various options for building retrofitting which from lean steps, green technology and clean energy. M50 building in Faculty of Civil Engineering Universiti Teknologi Malaysia (UTM) was chosen as a case study and in situ energy audit of Building Energy Intensity (BEI) was conducted by identifying the types of equipment and machinery used in the building together with its period of operations and their power usage under typical operation. The outcome of the study proposed the retrofit strategies that are suitable to be implemented towards zero energy building. It is a cornerstone of reducing the energy usage with sustainability efforts together with economic stimulus packages

Soil water characteristic curves for laterite soil at different water contents and methods as lining system

Preventing groundwater contamination from the most common method of solid waste disposal technique i.e. landfilling is by proving hydraulic barriers. Accordingly, water movement in unsaturated soil is important in the analysis of leachate migration in soil material used as hydraulic barrier in waste containment systems. A full-scale experiment would be prohibitively costly and time consuming. The only feasible recourse therefore is to construct a model, which reasonably portray the behaviour of the full-scale system and simulate the relevant physical parameters and describes the overall significant characteristics of the transport phenomena. This paper presents the trends and patterns of soil water characteristic curves (SWCC) in terms of volumetric water content versus soil suction developed for compacted laterite soil specimens using data from pressure plate tests. Specimens were prepared at three different water contents corresponding to dry of optimum, optimum, and wet of optimum conditions. Models suggested by Brooks and Corey (BC), van Genuchten (VG), and Fredlund and Xing (FX) were used to obtain curve fitting parameters using the program "SWRC Fit" which performed nonlinear fitting of soil water retention curves. The SWRC Fit can simultaneously calculate the fitting parameters of these models with Root Mean Square Error values and draw the fitting curves. By comparing the results of the models using SWRC Fit, the model that best fits the laterite soil investigated will be chosen to be used for further analysis. The results show that the BC model represents the soil water retention curves better than the VG and FX models when the soil has distinct air entry suction. On the other hand, the VG and FX models can fit most soil water retention curves very well when discussion on the pore-size distribution is desired

Application of Digital Image Processing Technique in Monitoring LNAPL Migration in Double Porosity Soil Column

This paper investigates the phenomenon of light non-aqueous phase liquid (LNAPL) migration in double porosity soil. Investigation on the migration of LNAPL in double porosity soil was performed on aggregated kaolin using the digital image analysis. The photographic technique was used to capture the migration of LNAPL in aggregated soil samples. The captured digital images were fed through an image processing code to convert them to the hue-saturation-intensity (HSI) format which were subsequently used to plot the 2D LNAPL migration behaviour. The results of Experiment 1 and 2 show that the LNAPL moved downward faster when the moisture content increased. Another observation was that the kaolin granules started to disintegrate at a water content of 35%. In conclusion, using image analysis technique has enabled the researchers to monitor and visualize the LNAPL migration in the double porosity soil columns based on HSI values. The contour plots of HSI intensity value has provide detailed and useful information for future research