Saiful Azhar Ahmad Tajudin

The monitoring and cementation behavior of electrokinetic stabilisation technique on batu pahat marine clay

This paper outlines the monitoring and soil fabric results from an experimental study of electrokinetic stabilisation (EKS) technique. The monitoring results were important in assessing the efficiency of the technique towards Batu Pahat marine clay. Two reactors were set up; 1.0 M of calcium chloride (CaCl2) and sodium silicate (Na2SiO3) as the electrolyte and stainless steel plates as the electrodes. EKS technique was continued for 21 days with a constant voltage gradient (50 V/m). This technique was performed in two phases where the alteration of EKS was the combination of stabilizers used. The combinations of stabilizers in phase 1 and 2 were CaCl2 - distilled water (DW) and CaCl2 - Na2SiO3, respectively. The technique was monitored using electric current, total inflow and outflow of electrolytes and pH of electrolytes. It showed fluctuated profiles of electric current for both phases, attributed by the introduction of calcium ions from the anode compartment. The inflow and outflow of electrolytes results showed that electromigration and electroosmosis occurred during EKS and it indicated the movement of anion and cation to the opposite direction. The pH of electrolytes kept constant value and balanced by electrolysis process at the cathode. Image of soil fabric for untreated and treated clay were presented where most images shows a flaky particles. The observation of those images indirectly explained the effect of cementation behavior of treated clay.

The potential of biodiesel production from Botryococcus sp. biomass after phycoremediation of domestic and industrial wastewater

The aim of the present work is to investigate the capability of microalgae, known as Botryococcus sp. for wastewater phycoremediation and potential biodiesel production. The vertical closed photobioreactors (PBR) were employed and supplemented with domestic wastewater (DW) and food industry wastewater (FW) at different batch of study. The cultivation was conducted under natural outdoor condition for 12 days. The results revealed that the removal of pollutant and nutrients presence in both wastewaters with constantly decrease proportionate to the increase in cultivation time. The chemical oxygen demand (COD), total phosphorus (TP) and total organic carbon (TOC) were successfully removed up to 84.9%, 69.3% and 93.3%, respectively in DW while 96.1%, 35.5% and 87.2%, respectively in FW. The result on FT-IR analysis of microalgae oil was shown comparable with conventional palm oil based biodiesel in term of IR spectra. This study suggests that Botryococcus sp. has tremendous potential in pollutants removal and biodiesel production for renewable energy development.

Groundwater Seepage Mapping using Electrical Resistivity Imaging

In recent years, electrical resistivity method (ERM) has widely being applied as an alternative tool in engineering, environmental and archeological studies. A global image of groundwater seepage problem was difficult to obtained using conventional geotechnical method due to the efficiency of cost, time and result coverage. This study was conducted using electrical resistivity survey in order to investigate the potential of the problematic zone due to the groundwater seepage problem. ABEM SAS 4000 equipment set was used in during the resistivity data acquisition stage. Six (6) resistivity spread lines (SP) were performed across the slopes area using 2-D electrical resistivity imaging. The raw data was processed using RES2DINV and SURFER software for 2-D and 3-D subsurface image. Interpretation of electrical resistivity results was verified using the existing borehole and geochemistry results. Geochemistry results analyses were used Atomic Absorption Spectrometer (AAS) for determining cation and Ion Chromatography (IC) is for anions. Anion elements were studied consists of chloride, bicarbonate, nitrate and sulfate while cation elements consists of sodium, potassium, calcium and magnesium. All the elements were analyzed by using Piper Diagram to determine geochemistry facies in the groundwater. It was found that low resistivity value (ERV) which associated to groundwater (10 ~ 100 Ωm) can be found starts from the ground surface (0 m) to a greater (> 10 m) depth of the subsurface profile. The finding of the study water seepage can be categorized as Ca-HCO that indicator a typical of shallow fresh groundwater. The finding of the study is important to determine source process of water seepage on that area. This study has successfully demonstrates that the application of ERM with supporting borehole and geochemistry data was able to provide a comprehensive results due to the groundwater leakage detection.

Leaching Behavior of Lead Contaminated Soil Sample by Using Sugarcane Bagasse in Stabilization/Solidification Method

Recently, Stabilization/Solidification (S/S) method has been focusing on the usage of agricultural waste as an alternative towards environmental friendly and low cost material to substitute cement. The aim of this study is to determine the leachability of lead contaminated soil by using sugarcane bagasse as partial replacement of cement in S/S method. In this study, different percentages (2.5%, 5% and 7.5%) of treated and untreated sugarcane bagasse have been utilized as a partial replacement to cement. Toxicity Characteristic Leaching Procedure (TCLP) and Synthetic Precipitation Leaching Procedure (SPLP) have been conducted to determine the leachability of lead contaminated soil. The results indicate that with 7.5% of treated sugarcane bagasse replacement in cement resulted significant reduction of lead contaminant in soil up to 99 % after 28 days. As a conclusion, treated sugarcane bagasse could be an alternative low cost material in the S/S method as it can significantly reduce the remediation cost normally incurred by the usage of cement.

Leachate Characteristics of Contaminated Soil Containing Lead by Stabilisation/Solidification Technique.

Contaminated soil is often a problem and typical concern in the developing countries due to the lack of clean soil for development, such as in Malaysia. The objective of this study is to investigate the performance of the available techniques for soil remediation contaminated with lead (Pb) through Stabilisation/Solidification (S/S) technique. In this study, cockle shell powders at different percentages (2.5%, 5% and 7.5%) were added as a partial replacement of cement. Toxicity Characteristics Leaching Procedure (TCLP) was conducted to determine the effectiveness of the S/S technique to treat the contaminated soil. The results showed a 99% reduction of Pb concentration after the contaminated clay soil was treated with S/S technique. The combination of cement and cockle shell powders is very effectively used in the remediation of lead contaminated soil and reducing the amount of cement usage for sustainability approaches.

The Soil-Water Characteristic Curve of Unsaturated Tropical Residual Soil

This study was conducted to determine the SWCC of unsaturated tropical residual soil in Kuala Lumpur, Malaysia. Undisturbed soil samples at five locations of high-risk slopes area were taken at a depth of 0.5 m using block sampler. In the determination of the SWCC, the pressure plate extractor with the capacity of 1500 kN/m2 has been used. The index properties of the soil such as natural moisture content, Atterberg limits, specific gravity, and soil classification are performed according to BS 1377: Part 2: 1990. The results of index properties show that the natural moisture content of the soil is between 36% to 46%, the plasticity index is between 10% - 26%, the specific gravity is between 2.51 - 2.61 and the soils is classified as silty organic clay of low plasticity. The SWCC data from the pressure plate extractor have been fitted with the Fredlund and Xing equation. The results show that the air entry value and residual matric suction for residual soils are in the range of 17 kN/m2 to 24 kN/m2 and 145 kN/m2 to 225 kN/m2 respectively. From the fitting curve, it is found that the average value of the Fredlund and Xing parameters such as a, n and m are in the range of 0.24-0.299, 1.7-4.8 and 0.142-0.440 respectively.

Barren Acidic Soil Assessment using Seismic Refraction Survey

Seismic refraction method is one of the geophysics subsurface exploration techniques used to determine subsurface profile characteristics. From past experience, seismic refraction method is commonly used to detect soil layers, overburden, bedrock, etc. However, the application of this method on barren geomaterials remains limited due to several reasons. Hence, this study was performed to evaluate the subsurface profile characteristics of barren acidic soil located in Ayer Hitam, Batu Pahat, Johor using seismic refraction survey. The seismic refraction survey was conducted using ABEM Terraloc MK 8 (seismograph), a sledge hammer weighing 7 kg (source) and 24 units of 10 Hz geophones (receiver). Seismic data processing was performed using OPTIM software which consists of SeisOpt@picker (picking the first arrival and seismic configureuration data input) and SeisOpt@2D (generating 2D image of barren acidic soil based on seismic velocity (primary velocity, Vp) distribution). It was found that the barren acidic soil profile consists of three layers representing residual soil (Vp= 200-400 m/s) at 0-2 m, highly to completely weathered soil (Vp= 500-1800 m/s) at 3-8 m and shale (Vp= 2100-6200 m/s) at 9-20 m depth. Furthermore, result verification was successfully done through the correlation of seismic refraction data based on physical mapping and the geological map of the study area. Finally, it was found that the seismic refraction survey was applicable for subsurface profiling of barren acidic soil as it was very efficient in terms of time, cost, large data coverage and sustainable.

Simulation of Sub-Drains Performance Using Visual MODFLOW for Slope Water Seepage Problem

Numerical simulation technique was used for investigating water seepage problem at the Botanic Park Kuala Lumpur. A proposed sub-drains installation in problematic site location was simulated using Modular Three-Dimensional Finite Difference Groundwater Flow (MODFLOW) software. The results of simulation heads during transient condition showed that heads in between 43 m (water seepage occurred at level 2) until 45 m (water seepage occurred at level 4) which heads measurement are referred to mean sea level. However, elevations measurements for level 2 showed the values between 41 to 42 m from mean sea level and elevations for level 4 between 42 to 45 m from mean sea level. These results indicated an increase in heads for level 2 and level 4 between 1 to 2 m when compared to elevations slope at the level 2 and level 4. The head increases surpass the elevation level of the slope area that causing water seepage at level 2 and level 4. In order to overcome this problems, the heads level need to be decrease to 1 until 2 m by using two options of sub-drain dimension size. Sub-drain with the dimension of 0.0750 m (diameter), 0.10 m (length) and using 4.90 m spacing was the best method to use as it was able to decrease the heads to the required levels of 1 to 2 m.

Monitoring of Electric Current During Electrokinetic Stabilisation Test for Soft Clay using EKG Electrode

Electrokinetic Stabilisation (EKS) method has the potential to overcome problems on highly compressible clay. This study presents the monitoring results from an experimental study of EKS on soft clay soil. Inactive kaolinite clay, inert electrode and distilled water (DW) were used as a pure system mechanism before any chemical stabilisers are utilised for stabilisation. Therefore, this monitoring data will provide a baseline study to improve efficiency of the EKS approach for ground improvement application. An inert electrode of Electrokinetic Geosythentic (EKG) developed at the Newcastle University was utilised to apply a constant voltage gradient of 50 V/m across a soil sample of 400 mm length. The distilled waters were used at the pore electrolyte fluid compartments and supplied under zero hydraulic gradient conditions for periods of 3, 7 and 14 days. Throughout, monitoring data of electric current for all treatments were measured. Results showed that the electric current trend in this pure system was attributed to the electrochemical effects in the clay-water electrolyte system.

Preliminary Investigation on the Behavior of Pore Air Pressure During Rainfall Infiltration

This paper focused on the preliminary investigation of pore air pressure behaviour during rainfall infiltration in order to substantiate the mechanism of rainfall induced slope failure. The actual behaviour or pore air pressure during infiltration is yet to be clearly understood as it is regularly assumed as atmospheric. Numerical modelling of one dimensional (1D) soil column was utilized in this study to provide a preliminary insight of this highlighted uncertainty. Parametric study was performed by using rainfall intensities of 1.85 x 10-3m/s and 1.16 x 10-4m/s applied on glass beads to simulate intense and modest rainfall conditions. Analysis results show that the high rainfall intensity causes more development of pore air pressure compared to low rainfall intensity. This is because at high rainfall intensity, the rainwater cannot replace the pore air smoothly thus confining the pore air. Therefore, the effect of pore air pressure has to be taken into consideration particularly during heavy rainfall.