Abdelkader T. Ahmed

A lysimeter experimental study and numerical characterisation of the leaching of incinerator bottom ash waste

Incinerator bottom ash (IBA) is a residual produced from incinerating municipal solid waste. In the past, IBA presented a big waste disposal problem; however, various recycling approaches have been adopted in recent years to mitigate this problem, as well as to provide a useful alternative to using primary aggregate resources. The use of IBA as an alternative to conventional aggregates in different civil engineering construction applications helps to conserve premium grade aggregate supplies; however, when IBA is in contact with water in the field, as a consequence of precipitation events or changes in water table, elements, such as salts and heavy metals, may be released to the soil and ground water. In this work, IBA waste was mixed with limestone aggregate to produce a blend with acceptable mechanical properties and minimum environmental risks for use as road foundation. The study focused on evaluating potential environmental impacts of some constituents, including sulphate, chloride, sodium, copper, zinc and lead in IBA blends using a lysimeter as a large scale leaching tool. Moreover, a specific scenario simulating field conditions was adopted in the lysimeter to assess the potential impact of changing conditions, such as IBA content in the blend, liquid to solid ratio (L/S) and pH value, on long-term release of heavy metals and salts. Then, numerical modelling was used to predict the release of the aforementioned constituents from IBA based on initial measurement of intrinsic material properties and the kinetic desorption process concept. Experimental results showed that zinc and lead were released in very low concentrations but sodium and sulphate were in high concentrations. The control limestone only blend also demonstrated low release concentrations of constituents in comparison to IBA blends, where constituent concentrations increased with increase in IBA content. Experimental results were compared with numerical results obtained using a non-equilibrium desorption model. Good agreement was found between the two sets of data.

Effectiveness of novel and traditional treatments on the performance of incinerator bottom ash waste

Management of natural aggregate resources has become one of the most important challenges in construction, especially for high demand applications such as roads. Incinerator bottom ash (IBA), which is produced from burning domestic waste, has been considered a useful solution to the shortage of natural resources. In this research, IBA was mixed with limestone to produce an acceptable blend for use as a road foundation layer. Novel and traditional additives were adopted to improve the mechanical properties of IBA blends. The study focused on the treatment effect of additives on the mechanical characteristics of IBA blends under monotonic and cyclic triaxial stresses. The investigation evaluated fundamental material properties, including resilient modulus, initial Youngs modulus and Poissons ratio. Two nonlinear empirical models were adopted to depict the experimental resilient modulus results of the IBA blends. An approach has been proposed to predict realistic and representative values of resilient modulus for the material. In addition, a new relationship has been established between Youngs modulus, resilient modulus and Poissons ratio. Triaxial test results revealed that additives are more efficient with the control limestone blend than with the IBA blends. Novel additives, such as enzyme I and silica fume, produced a noticeable improvement in IBA properties in comparison to traditional additives.

Deformation Properties of Untreated and Enzyme-Treated Bottom Ash Waste for Use in Foundations

The use of waste and recycled materials in different construction applications is a widespread approach. In this work, incinerator bottom ash (IBA) waste was mixed with limestone at different levels, namely, 0%, 30%, 50%, and 80%, to produce blends for use as pavement foundation layers. The study focused on evaluating the resistance to permanent deformation of IBA–limestone blends, which is vital to prevent or minimize pavement rutting. An experimental program was undertaken to investigate the influence of plant-based enzyme treatment on the behavior of these blends. Cyclic and static triaxial compression tests were adopted to determine the materials’ mechanical characteristics. Emphasis was on examining the effect of various parameters, such as IBA content, enzyme content, moisture content, curing time, stress level, and number of load applications, on the behavior of the investigated blends. The accumulated permanent strain and strain rate were used to describe the blends’ shakedown stress limits. Results showed that IBA blends gave a favorable performance as foundation layers in comparison with the control limestone blend. Enzyme addition improved the permanent deformation resistance for the control limestone blend; however, it did not have any noticeable effect on the IBA blends. According to the shakedown concept analysis, all blends, at a cyclic stress level of more than 21% of the static failure stress, underwent excessive plastic strain.

Chemical and microstructural analyses for heavy metals removal from water media by ceramic membrane filtration

This study aims to investigate the ability of low cost ceramic membrane filtration in removing three common heavy metals namely; Pb2+, Cu2+, and Cd2+ from water media. The work includes manufacturing ceramic membranes with dimensions of 15 by 15 cm and 2 cm thickness. The membranes were made from low cost materials of local clay mixed with different sawdust percentages of 0.5%, 2.0%, and 5.0%. The used clay was characterized by X-ray diffraction (XRD) and X-ray fluorescence analysis. Aqueous solutions of heavy metals were prepared in the laboratory and filtered through the ceramic membranes. The influence of the main parameters such as pH, initial driving pressure head, and concentration of heavy metals on their removal efficiency by ceramic membranes was investigated. Water samples were collected before and after the filtration process and their heavy metal concentrations were determined by chemical analysis. Moreover, a microstructural analysis using scanning electronic microscope (SEM) was performed on ceramic membranes before and after the filtration process. The chemical analysis results showed high removal efficiency up to 99% for the concerned heavy metals. SEM images approved these results by showing adsorbed metal ions on sides of the internal pores of the ceramic membranes.

Backcalculation Models to Evaluate Light Falling Weight Deflectometer Moduli of Road Foundation Layer Made with Bottom Ash Waste

Incinerator bottom ash (IBA) is a residue from burning household waste that once was put into landfills. Nearly two-thirds of this ash is reused, primarily in road construction. In this study, IBA was mixed with limestone to produce a blend with acceptable properties for use as a road foundation layer. In situ simulative testing with a light falling weight deflectometer (LFWD) and subsequent interpretation of the surface deflection data have enabled evaluation of the mechanical properties of the foundation and subgrade layers. An experimental and modeling study of the elastic dynamic response of a foundation layer of IBA waste and limestone that was subjected to LFWD impact loading is presented. Several parameters—such as IBA content, water content, and curing time—were studied. Regression, mathematical, and three-dimensional finite element models were developed to backcalculate the LFWD moduli of the foundation layers. The modeling approach accounted for the static and impact nature of the LFWD load. Results showed that IBA blends underwent less deflection, as a foundation layer, than the control limestone blend. Backcalculated modulus results based on the dynamic effect of the LFWD load produced different values from those calculated by Boussinesqs equation, which is adopted by the LFWD manufacturer.

Experimental and Numerical Evaluation of Stabilization Effect on Pollutant Mobility from Incinerator Bottom Ash Waste

Before incinerator bottom ash waste (IBAW) is used as a construction material, its environmental impacts should be thoroughly investigated. IBAW encompasses ferrous and nonferrous constituents that, in the presence of water, might be released into the groundwater and soil. The aim of this study was to find a treatment technique to improve the quality of IBAW and to reduce, to below regulatory limits, its potential to leach metals and salts. IBAW was mixed with limestone to achieve an environmentally and functionally acceptable blend to be used as a road foundation layer. The research studied the leaching characteristics of some constituents—including sulfate, chloride, sodium, copper, zinc, and lead—in IBAW blends under different conditions, such as initial pH value and the use of novel and traditional treatment agents. The experimental program was designed to recreate a realistic environment; a lysimeter was used as a large-scale leaching tool and a laboratory protocol was developed that simulated road foundation field conditions to evaluate the long-term release of heavy metals and salts from IBAW. In the lysimeter experiments, the concentrations of the leached elements were monitored through a sand substrate underneath the IBAW layer to study the potential element migration and sorption process. Mathematical modeling was then used to simulate the release of the aforementioned constituents from the IBAW on the basis of the initial measurement of intrinsic material properties and the sorption process concept. The experimental results showed that the additive treatment had a varied impact on the IBAW blends’ leaching properties, as element release was reduced by a wide margin, ranging from 5% to 96%.

Impacts of Constructing the Grand Ethiopian Renaissance Dam on the Nile River

The Nile River (NR) is the primary water resource and the life artery for its downstream countries such as Egypt and Sudan. This chapter focuses on the impacts of constructing the Grand Ethiopian Renaissance Dam (GERD) on three main parts of the NR: close to Sudan-Ethiopia border; near Khartoum, Sudan; and the main Nile at the entrance of Lake Nasser, Egypt. The dam is designed to create a storage reservoir that will maintain a holding capacity of about 74 billion cubic meters of water at the full supply level. The impacts are divided into two main categories which are hydrological and environmental impacts. By studying the hydrological impacts, the study delineated the reservoir area to estimate the reservoir volume and its geometrical dimensions for all possible scenarios from starting the dam construction up to reaching the full operation and storage capacity. Results show that the best-accepted scenario for constructing the dam is by filling the dam reservoir with 10 BCM/year or less in 3.8 years. Furthermore, the impacts of the dam breach on Ethiopia and the downstream countries are studied via simulations from HEC-RAS model. In case of dam breach, a severe flood will result in inundation of the Sennar Dam, Sudan, 15 km wide and 200 km long, and the areas in between, until it reaches Khartoum, Sudan. Also, excessive water level with 3 m rise is expected from the dam until it reaches Nasser Lake. By studying the environmental impacts, particularly those of the population displacement, carbon dioxide emissions, agricultural lands, animals, and aquatic life, we will gain a better understanding of potential risks. This chapter discusses successes and many drawbacks of the GERD construction and its hydrological and environmental impacts on the Nile River downstream countries.