Sequestering atmospheric CO₂ inorganically:a solution for Malaysia's CO₂ emission

Malaysia is anticipating an increase of 68.86% in CO2 emission in 2020, compared with the 2000 baseline, reaching 285.73 million tonnes. A major contributor to Malaysia's CO2 emissions is coal-fired electricity power plants, responsible for 43.4% of the overall emissions. Malaysia's forest soil offers organic sequestration of 15 tonnes of CO2 ha(-1) year(-1). Unlike organic CO2 sequestration in soil, inorganic sequestration of CO2 through mineral carbonation, once formed, is considered as a permanent sink. Inorganic CO2 sequestration in Malaysia has not been extensively studied, and the country's potential for using the technique for atmospheric CO2 removal is undefined. In addition, Malaysia produces a significant amount of solid waste annually and, of that, demolition concrete waste, basalt quarry fine, and fly and bottom ashes are calcium-rich materials suitable for inorganic CO2 sequestration. This project introduces a potential solution for sequestering atmospheric CO2 inorganically for Malaysia. If lands associated to future developments in Malaysia are designed for inorganic CO2 sequestration using demolition concrete waste, basalt quarry fine, and fly and bottom ashes, 597,465 tonnes of CO2 can be captured annually adding a potential annual economic benefit of (sic)4,700,000.</p

Effect of moisture damage on gap-graded asphalt mixture incorporating electric arc furnace steel slag and copper mine tailings

Water damage is a vital factor affecting the durability of gap-graded asphalt. There is an urgent need for a pragmatic and reasonable test to evaluate this parameter. Previous research has proposed that tensile strength ratio is a promising test for this application. Therefore, the aim of this paper is to evaluate the effect of moisture damage on gap-graded asphalt mixture incorporating electric arc furnace (EAF) steel slag and copper mine tailings (CMT). Four material mixtures of eight mix designs were investigated. Each mix was conditioned in water for 24-hour and 48-hour before testing. The study adopted retained strength index (RSI), durability index (DI) and tensile strength ratio (TSR) to describe the durability of gap-graded asphalt incorporating EAF steel slag and copper mine tailings. The results reveal that all the mixes fulfill the prescribed criteria. Also, there is a strong correlation between the retained strength index and the durability index with a strong coefficient of determination, R 2 of 0.9543. The results of the study further showed that gap-graded asphalt mixture incorporating EAF steel slag and copper mine tailings did not seem to pose any problem

Volumetric properties and leaching effect of asphalt mixes with electric arc furnace steel slag and copper mine tailings

This study focuses on the potential of electric arc furnace (EAF) steel slag and copper mine tailings as asphalt paving materials with respect to issues of volumetric properties and leaching. In this study, four different asphalt mixes were investigated; each contained EAF steel slag and copper mine tailings of various proportions. Apart from the microstructure analysis of the materials, a toxicity characteristics leaching procedure (TCLP) test was conducted on both the mixes and the aggregates. All the mixes were evaluated by the following parameters: Voids in the mineral aggregates (VMA), voids in total mix (VTM), voids filled with asphalt (VFA), Marshall stability and flow and specific gravity. F-test ANNOVA was used to evaluate the degree of significance of the mixes with each of the evaluated standards. It was observed that the mixes containing either EAF steel slag or copper mine tailings or both gave better results than the control mix. In terms of the TCLP test, none of the detected hazardous elements exceeded the standard limits, which indicates the possibility of using them as construction materials

Recent advances on palm oil mill effluent (POME) pretreatment and anaerobic reactor for sustainable biogas production

Palm oil is one of the leading agricultural crops in the world, as it dominates 34% of the global vegetable oil market, with approximately 64.6*103 million kgs of production in 2017. However, along with its breakthrough, the generation of palm oil mill effluent (POME) as uncontrolled waste has become a serious matter and requires proper management to reduce its negative effects on the environment. Subsequently, the high organic content of POME makes it possible to convert waste into value-added products, such as biogas. A ratio of 0.5 for biological oxygen demand to chemical oxygen demand (BOD/COD) indicates a high possibility for biological treatment. Recently, the utilisation of POME as a cheap source for biogas production has gained an extraordinary amount of attention, and intensive research has been conducted on the upstream to downstream process. Finding the most suitable and efficient pretreatment technique and reactor configuration are vital parameters for the treatment and conversion of POME to biogas. This review describes existing pretreatment processes for POME and recommends recently manufactured high-rate anaerobic reactors as the most suitable and efficient pretreatment technique for maximising the extraction of biogas from POME

Properties of asphaltic concrete containing sasobit®

With increasing interest in the use of hot mix asphalt in the paving industry, more studies in this field for improvement of hot mix asphalt properties seem to be necessary. Hence, the main objective of this study was to investigate the effect of sasobit® content as modified binder in hot mix asphalt. 60/70 penetration grade asphalt was separately modified with sasobit® at different concentrations ranging from 0% to 4.5%. The influence of sasobit® on the hot mix asphalt mixtures properties were detected through conventional tests i.e. penetration and softening point. In addition, the Marshall stability, abrasion loss, and resilient modulus were also examined. Results indicated that the hot mix asphalt containing Sasobit® additive has significant affect in terms of penetration and softening point. Furthermore, the addition of Sasobit® seemed to improve the stability, abrasion loss and modulus of stiffness

Performance of Kaolin Clay on hot-mix asphalt properties

Kaolin clay is a waste product with numerous applications in construction. This study explored the addition effect of kaolin clay on the properties of hot-mix asphalt. Four replacement levels of kaolin clay were considered by weight of binder, i.e., 2%, 4%, 6%, and 8%. The performance of kaolin clay on the hot-mix asphalt was evaluated through a Marshall stability and flow test, including stiffness, density, voids in total mix, and voids in filled with asphalt. Test results showed that kaolin clay can be satisfactorily used as filler replacement material to increase the asphalt mixture properties. Generally, asphaltic concrete with 2% kaolin clay replacement level exhibits excellent performance with good stability and stiffness

An overall review: Modified asphalt binder containing sasobit in warm-mix asphalt technology

Increasing emission of greenhouse gases is an environmental issue, and it is a great concern to curb this problem from further harm to the environment. Warm-mix asphalt (WMA) is one of efforts to curb a reduction in the temperature at which asphalt mixes are produced. WMA can reduce the temperature to 100°C and even lower without compromising the performance of asphalt binder. WMA has various benefits such as, reduction of asphalt binder temperature, reduction in energy consumption and less air pollution. It reduces short-term aging, compacting effort and decreases temperature drop during transportation. Sasobit is one of the organic additives of warm mix asphalt. It is used as a binder modifier to produce rut resistant mixtures. It provides the option of reducing fume emissions, saving energy and reducing production cycles. Therefore, sasobit is the preferred additive for warm-mix asphalt (WMA). In addition, Complex shear modulus will be determined to find the rutting factor and fatigue factor for the asphalt binder (G*/Sind and G*Sind respectively). The overall purposes of this study are to determine the importance of using WMA as a green pavement and introducing sasobit for modifying virgin asphalt binder

A review of the corrosion behavior of metallic heritage structures and artifacts

Awareness about restoring and preserving historically important structures and artifacts is gradually growing in many parts of the world. These artifacts and structures represent the culture, tradition and past of a nation. They are often also a source of national income through tourist activities. Besides masonry and wood work, metallic forms and relics are a vital part of the heritage which needs to be conserved. Certain metals have been used significantly throughout history in the creation of objects and structures. However, metals are prone to decay over time, particularly decay through corrosion. The basic mechanisms of metal corrosion, the various types of corrosion and existing remedial solutions are reviewed in this paper. The most significant factor affecting metal corrosion was found to be the surrounding environment, especially in marine areas. Different remedial measures can be implemented on corroded metals according to their specific properties. Recommendations for further study are offered at the end of the paper

Optimizing the performance of a paper mill effluent treatment

The paper making industry is characterized by high rate of water consumption and hence high rate of wastewater generation. The purpose of this research was to assess and optimize the existing complete mix activate sludge treatment plant that is used to treat the high strength paper mill effluent with the highest possible efficiency at a reasonable cost. The collected paper mill wastewater is equalized in an equalization tank before being pumped to the treatment plant. The treatment plant includes chemical treatment unit, complete mix activated sludge and granular media filtration unit. The results showed that effluent of a chemical treatment unit was found to be relatively similar to the laboratory simulated plain sedimentation unit. It can be concluded that addition of chemical coagulant can be eliminated with an overall saving of chemical addition costs. The complete mixing activated sludge achieved good removal of biochemical oxygen demand (BOD) and chemical oxygen demand (COD). Furthermore, the results showed that the plant is operated under low BOD:P ratio. The treatment efficiency of the plant can be improved by increasing the phosphorous dose to the plant to have BOD:P ratio of 100:0.5 to 100:1. It was found that 50% of the treated effluent is recycled to the manufacturing process, however this percentage can be increased through proper plant optimization and control of nutrient addition to the activated sludge unit

Evaluation of rutting potential and skid resistance of hot mix asphalt incorporating electric arc furnace steel slag and copper mine tailing

In order to promote the use of waste materials in road construction, this paper presents the laboratory results of a study investigating the rutting potential and skid resistance of hot mix asphalt incorporating electric arc furnace (EAF) steel slag and copper mine tailings. To achieve this objective, four different mixes incorporating copper mine tailings and EAF steel slag in different proportions are investigated. The aggregates are blended with the optimum bitumen content of PG(76-22) and 80/100 bitumen binders. The rutting potential of all the mixes is evaluated by the asphalt pavement analyzer (APA), while the skid resistance is measured by the British Pendulum Skid Resistance Tester. The results show that the mix with 20% copper mine tailing and 80% EAF steel slag has the highest skid number, mean texture depth and the least rut depth. It is also observed that the rate of rutting decreased with loading cycles and 70 to 80% of the rut depth is attained at 4000 cycles using the APA