Advanced Materials Research Vols. 864-867

Abstract: A new kind of high strength cementitious material is made from phosphogypsum (PG), active carbon and fly-ash. Through the orthogonal research, it was showed that the calcination temperature, retention time, dosage of active carbon and fly ash on the compressive strength of cementitious binder are the most important. The result also showed that, in the conditions of temperature 1200°C, time retention 30 min, dosage of active carbon 10%, dosage of fly ash 5%, the compressive strength of the cementitious material for 3d and 28d could reach to 46.35MPa and 92.70MPa, the content of sulfur trioxide was 11.60% accordingly. A lot of active mineral materials, such as dicalcium silicate, tricalcium silicate, tricalcium aluminate were formed in the calcination. The C-S-H gel, calcium hydroxide and ettringite were found in 3d and 28d hydrates. It is found that the lime saturation ratio and silica modulus need to be control between 0.40~0.65 and 4~8 in order to produce high strength cementitious material.

Abstract: TG analysis was used to investigate the thermal decomposition of waste printed circuit board (WPCBs) under pyrolysis (in N₂), gasification (in CO₂) and combustion (in Air) conditions. The experiments were performed at different heating rates (10, 20 and 30 K/min) up to 1233 K. Kissinger method was applied to obtain the kinetic parameters from the experimental data. The results show that the heating rate affects the TG and DTG curves due to the heat transfer limitation. The DTG curve of pyrolysis has only a single peak while that of both gasification and combustion process has two peaks. The activation energy of the first gasification stage is near to that of the pyrolysis process, while the activation energy of the first combustion stage is lower than that of pyrolysis or gasification process. And the activation energy for the second stage of gasification and combustion is much higher than that of the first stage.

Abstract: Antibiotic bacterial dregs with the characteristics of large amount, difficult disposal, potential impacts for the environment, need to be treated or disposed by safe methods. In the present paper, the resource utilization of antibiotic bacterial residues and their treatment and disposal methods have been summarized and reviewed. Based on the analytic hierarchy process (AHP), the reasonable and safe ways to treat antibiotic bacterial dregs have been chosen and compared. The results indicated that the first considered way to treat antibiotic bacterial residues was the compost technology and its weight was 0.2517. Additionally, followed by the anaerobic denitrification, the weight was 0.2215. The result of the study can be used as references for future planning or selection of antibiotic bacterial dregs treatments.

Abstract: In the present work, spent LiCoO₂ was processed to remove impurities by ultrasound with the aim to renovate its electrochemical characteristics. The composition and amount of organic materials remained in the LiCoO₂ particle surface were characterized by GC-MS, FT-IR and TGA, respectively. The morphology and particle sizes of PVDF (Polyvinylidene fluoride) was analyzed by SEM. Experimental results show that ultrasonic cavitation could be effectively used to remove organic substance stuck on LiCoO₂ surface. At room temperature, the spent LiCoO₂ was successfully remove impurities, including EC (Ethylene carbonate) and PVDF, with ultrasound applied for 12 h. It can be considered that most of the PVDF (82.0 wt.%) has decomposed under ultrasonic irradiation. Furthermore, the EC has completely decomposed under such ultrasonic irradiation.

Abstract: In this study, co-metabolism reduction of p-nitrophenol (PNP) under anaerobic condition was investigated in an upflow anaerobic sludge blanket (UASB) reactor. p-Aminophenol (PAP) was identified as the dominant product of PNP reduction in UASB, and no further degradation of PAP was observed under anaerobic condition in UASB. The performance of three cosubstrates, namely sodium acetate, glucose and methanol, was compared, demonstrating that sodium acetate had the best performance as the external cosubstrate. Both PNP removal and PAP formation increased with the increase of acetate concentrations and the increase of hydraulic retention times (HRTs). Both PNP removal and PAP formation was significantly influenced by initial PNP concentration, exhibiting the inhibitory nature of PNP.

Abstract: This paper presents a fraction of the ongoing research at the Faculty of Civil Engineering Brno University of Technology which is devoted to the verification of the possibility to use solidification products prepared from selected types of hazardous waste in building industry. Presented paper deals with the verification of possibility of its use as a material used in the construction of road embankment. Two types of hazardous waste were chosen - the first of these is an inorganic waste sludge from the wire drawing process (indicated as A) and the second is waste pressed sludge from the neutralization station from tooling (indicated as B).Solidification formulas for these wastes were proposed, then sample specimens were prepared and laboratory tested in accordance to their future use were provided.

Abstract: The influence of Na₂CO₃ on RF4-type waste printed circuit board (PCB) pyrolysis in carbon dioxide was studied with thermogravimetric analysis, and the reaction kinetics was calculated based on the Coats - Redfern method. It is shown that the weight loss process of waste PCB in carbon dioxide includes two stages. The first stage of weight loss is between 280 °C and 450 °C, at which the decomposition of epoxide resin leads to volatile materials release. The second stage of weight loss is the reaction between carbon residue and carbon dioxide between 600°C~960 °C, and carbon monoxide is formed. Addition of Na₂CO₃ decreases the initial temperature of the second weight loss stage of waste PCB and increases the weight loss rate, which indicates the enhancement effect on gasification reaction between carbon residue and carbon dioxide. From the different mechanism function, the optimal mechanism function is f(a)=5(1-a)/4[-ln(1-a)]⁴ and the range of activation energy is 75～135 kJ/mol.

Abstract: The reuse of iron and steel scrap has high economic value as well as ecological benefits. By analyzing existing process of iron and steel scrap recycling, this paper studied the internal and external conflicts that blocked the smooth going of iron and steel scrap recycling process from the perspective of supply chain. To coordinate these conflicts, a push-pull iron and steel scrap supply chain was built to recover iron and steel scrap resources as more as possible in purpose of environmental protection by push strategy and match market demand by pull strategy. The results indicate that push-pull supply chain is an effective mode that well fit into economic demand as well as environmental demand in iron and steel scrap recycling process.

Abstract: the carbide can be used as of Calcium carbide residue is a kind of industrial waste produced in the preparation of acetylene gas from hydrated calcium carbide, and the main component of the calcium carbide residue is calcium hydroxide. In this paper, the production of calcium carbonate by calcium carbide residue was studied, and carbide slag and ammonium bicarbonate was the main materials. The impurity in the carbide slag was removed through the leaching reaction, and the calcium carbonate was prepared by liquid-liquid reaction. The different reaction conditions which had an influence on the grain diameter of the product in the process of leaching and carbonation reaction were also investigated. The characteristics of materials and products in the experiment were tested by XRD, SEM and laser particle size instrument. The results showed that the calcium carbide residue after appropriately treated can be used as the raw materials to prepare calcium carbonate in different particle size.

Abstract: This paper assesses the current management of municipal solid waste in Kano metropolis, Nigeria. Data was collected through a desk study of the operations of the state agency responsible for waste management, - Refuse management and sanitation board (REMASAB); interview with key officials of the agency; participation in the day to day activities of the agency; direct measurement and segregation of the waste; laboratory analysis of some bacterial isolate in the waste and interview with residents of the city between 2006 - 2013. The results of the study indicates that 79.25% of the residents do not use official dump site , 68% consider the service as very poor, 55% believe frequency of collection is unsatisfactory and 92.4% believe coverage is very poor. Presence of some bacterial isolate in the waste such as escherichia coli 86.7%, staphylococus aureus 76.7%, shigella 43.3% samonella Sp 46.7%, klebsiela Sp 43.3%, protues Sp 33.3%, indicates presence of faecal matter and may be the source of the high prevalence of cholera, diarrhea and typhoid in Kano metropolis. The high organic content 61%, ash and dirt 20 %, use of unsanitary landfill portends great potential for methane generation which is dangerous to the global environment. The paper recommends a decentralised system to local authorities where local businesses can be created to utilise the large pool of unemployed as well as to explore the opportunities of the waste management chain in recycling, composting, re-use and equipments manufacture. The paper highlighted some of the constraints that must be addressed to ensure the success of the proposal, which includes, lack of data collection on waste stream, lack training and need to create awareness among the public. Key Words: Sustainable development, municipal waste management; recycling; composting; reuse