Issue 4, November 2010
BIOREACTOR LANDFILL LYSIMETERS STUDIES FOR LEACHATE CHARACTERIZATION AND WASTE STABILIZATION IN INDIAN CONDITIONS
Reader, Department of Civil Engineering,
Ujjain Engineering College, Ujjain, M.P.–456010
Professor, Department of Civil Engineering and Applied Mechanics
SGSITS, Indore M.P.–452003
Land-filling of solid waste has been considered to be one of the best options of Municipal solid waste disposal. Bioreactor landfills have proved its worth in faster stabilization of wastes as well as treatment of the re-circulated leachate. In Indian context the organic content of the solid waste is more due to consumption of unprocessed food items. The bioreactor land fills are most suited landfills that are efficient and economical. However, no much work is reported in this direction in India. The experimental modeling of landfills relies heavily on lysimeter studies that have been in practice since long. The present study is an attempt to perform lysimeter experiments for organic solid waste for bioreactor feasibility in Indian context. Two lysimeters under different operational conditions have been experimented for leachate characterization and waste stabilization. The results indicate that the leachate characteristics indicate faster decay of pollutants. The trend of decay of pollutant level in 24 weeks indicates encouraging results related to the quality of leachate. The lysimeter studies can be extended to prototype studies of bioreactors.
Keywords: Bioreactor landfill, Neutralized leachate, Leachate recirculation, Organic waste, Acidogenic phase and Methanogenic phase etc.
SEASONAL VARITATION AND MUNICIPAL SOLID WASTE COMPOSITION—ISSUES FOR DEVELOPMENT OF NEW WASTE MANAGEMENT STRATEGIES IN ABUJA, NIGERIA
Clive L. Roberts, Glynne D. Watkin and Chukwunonye Ezeah*
Research Centre in Applied Sciences, School of Applied Sciences
University of Wolverhampton, City Campus-South, Wulfruna Street, Wolverhampton, WV11LY
Paul S. Phillips
SITA Centre, University of Northampton,Northampton, NN2 7AL
Solid Waste Management Department, Abuja Environmental Protection Board, Abuja
The state of solid waste management in cities of developing countries like Nigeria is a major social/environmental challenge. While research to understand the nature of the barriers to sustainable management methods have been carried out, the impact of seasonal changes in waste composition and practice is still in its infancy in developing countries. This paper investigates seasonal variation in municipal solid waste composition in Abuja, Nigeria, a classic tropical urban environment. Weekly waste collections from eighty randomly selected dwellings in Garki District of Abuja Municipality were sampled and analyzed at two peaks of the main tropical seasons: January-February (dry season) and August-September (wet season) in 2008. Results of compositional analysis and physical characterization were statistically analyzed and indicate that waste stream has approximately 11% and 60% recyclable and biodegradable components respectively. This investigation finds no significant difference in the proportion of biodegradable components of the waste stream from both seasons. Findings from this investigation helped develop strategies designed to improve current management practices.
Keywords: Nigeria, MACROBUTTON MACROBUTTON municipal solid waste composition, seasonal variation, strategy
ENVIRONMENTAL ASSESSMENT OF BITUMINOUS MIXES CONTAINING IMPERIAL SMELTING FURNACE (ISF) SLAG
Dr. A.K. Vyas**
Dr. A.B. Gupta**
*Research Scholar, **Professor, Department of Civil Engineering
Malaviya National Institute of Technology, Jaipur – 302 017
Imperial smelting furnace (ISF) slag is a byproduct from pyrometullurgical process of Zinc production. Its chemical composition shows presence of heavy metals. Particle size distribution of the slag is very close to that of fine aggregate used for bituminous road construction. Possibility of its use in bituminous mixes has been explored. Bituminous mixes such as Bituminous Concrete (BC) and Dense Bituminous Macadam (DBM) were designed replacing fine aggregate by ISF slag in the range of 0% to 25%. Binder content was also varied from 4 to 5.5% for BC mixes and 4 to 4.5% for DBM mixes. The Engineering properties of these mixes were evaluated by Marshall method and the environmental acceptability of such mixes was determined by Toxicity characteristics leaching procedure (TCLP) test recommended by USEPA. This paper presents the detailed results of TCLP, which indicate that the concentrations of heavy metals leached were within limits recommended by USEPA up to 20% and 25% replacement of fine aggregate by slag in BC and DBM mixes, respectively. The leaching of metals was found to be reduced with higher binder content in mixes. However based on engineering properties a replacement of fine aggregate by ISFslag is recommended only up to 20% by weight.
Keywords: Stability, Leaching, Environmental, Slag, Toxicity
HYDROLYSIS OF UNSORTED MUNICIPAL SOLID WASTE USING A PERCOLATING REACTOR MECHANISM
Department of Environmental Science, Faculty of Biosciences
Kwame Nkrumah University of Science & Technology, Kumasi
Chair of Waste Management
Faculty of Environmental Sciences and Process Engineering
Brandenburg University of Technology, Siemens-Halske-Ring 8, 03046, Cottbus
The results of a percolating reactor during hydrolysis of unsorted municipal solid waste (UMSW), where various dilution rates were applied is presented. Water flow rates in the hydrolytic reactor were varied in order to evaluate the effect of these factors. The various water flow rate regimes on leaching/degradation of unsorted municipal solid waste resulted in leaching rate yields in the range of 42.8�2.6% – 60.8�2.5%. Degradation rate was in the range of 23% – 63%. Lower leaching and degradation rates were observed for both at extremely high and low water flow rates. Organic acid production was observed to be the main component of the COD concentration, contributing about 74% of the COD while VOS predicts 60%.
Salt concentration measured as conductivity did not pose any observable problem as it was always far less than the threshold for inhibition. The natural buffer system was good to offset any observable threat from low pH.
Keywords: Municipal Solid waste, Hydrolysis, Dilution, Leaching, Degradation
STUDIES ON THERMALLY STABLE SILANE TREATED CENOSPHERE FILLED PP COMPOSITES FOR THE STRUCTURAL APPLICATIONS
Advanced Materials and Processes Research Institute (AMPRI)
Hoshangabad Road, Bhopal- 462026
Among polymers, polypropylene is one of the most widely used because of its thermal stability, when filled with low-cost fillers. In this project, cenosphere, a low-cost filler was used to develop PP composites. Cenosphere filled polypropylene (PP) composites were developed by melt mixing and their mechanical performance (e.g. tensile strength and elongation capacity) were evaluated. Mechanical properties of silane-treated and untreated cenosphere filled PP composites were compared .It was found that increase of cenosphere content decreases the tensile strength of composites. However, addition of 10wt.% silane coupling agent treated cenospheres to PP increased the tensile strength from 6.48 MPa to 8.15 MPa, and increased the elongation capacity from 76% to 81.5 %. Thermal properties of cenosphere filled PP composites were determined by DSC. The onset temperature was found to be shifted to higher values for silane treated composites. An increase of heating rate from 10 to 30�C /min shifted the peak temperature from 124.2 to 127.8�C for untreated cenosphere – PP composites. Upon treatment of cenospheres with silane coupling agent, the peak temperature of cenosphere – PP composites (10/90) decreased, whereas increasing the heating rate led to a rise in the peak temperature. Increase of silane treated cenosphere content in the composite from 10 to 20% decreased the onset and peak temperature. The activation energy of silane treated 10wt% cenosphere –filled PP composites was found to be 340.5 KJ/mol as compared to 379.3 KJ/mol for untreated cenosphere (10/90) composite.
Keywords: Cenosphere, PP, thermal, DSC, tensile strength, elongation
DETECTING CONTAMINANTS IN GROUNDWATER: STRATEGIES FOR INCORPORATING CUTOFF WALLS
Paul F. Hudak
Department of Geography and Environmental Science Program
University of North Texas
P.O. Box 305279
Denton, TX 76203-5279
Traditionally used for remediating contaminated groundwater or dewatering construction sites, slurry cutoff walls may also have utility for detecting contaminant releases from waste storage facilities. The objective this study was to design and evaluate alternative networks of monitoring wells, some incorporating a 40-m long slurry cutoff wall, to detect contaminant releases from a hypothetical solid waste landfill. The rectangular landfill was oriented oblique to regional groundwater flow in an unconfined, unconsolidated aquifer. Computer models calculated flow fields, concentration distributions, and detection capability for various aquifer conditions and monitoring strategies. The most effective wall-augmented network incorporated a slurry cutoff segment along the landfill’s downgradient boundary segment most perpendicular to regional groundwater flow. This wall accompanied by six wells detected contaminant releases from all potential source nodes in a homogenous hydraulic conductivity field. A conventional ten-well network, not incorporating a cutoff wall, detected all releases under the same aquifer conditions. Both conventional and wall-augmented networks performed well under uncertain, heterogeneous conditions, detecting 99.3 and 98.6 percent of releases, respectively. While construction costs may be higher, in some cases wall-augmented networks may be less expensive over time, due to savings in sampling costs associated with fewer wells.
Keywords: Slurry cutoff wall; landfill; groundwater monitoring
SELECTION OF LANDFILL LEACHATE MANAGEMENT STRATEGY USING DECISION SUPPORT SYSTEM
H.A. Abu Qdais
Civil Engineering Department
Jordan University of Science and Technology
P.O. Box 3030, Irbid
Tel: +962 2 7201000
This paper describes the criteria affecting the management strategy of landfill leachate and proposes an analytical hierarchy process (AHP) to aid decision makers to prioritize and select leachate management options. Commercially available Expert Choice Software was used in the development of the AHP model. A four level AHP model, with three criteria, nine sub criteria and five management alternatives was constructed using information from literature and data solicited from experts’ opinions. Management alternatives were evaluated against criteria that included potential environmental and health risks, technical, and socio-economic aspects.
AHP analysis revealed that onsite treatment option ranked most favorably. The discharge without treatment and evaporation alternatives were least preferred due to potential higher health and environmental risks. When eliminating the environmental and public health risks criteria, the disposal without treatment option is preferred as it is the least expensive and does not need sophisticated technology.
Dynamic sensitivity analysis based on what- if scenarios, revealed that decreasing the weight of environmental and public health risk criteria by 0.28 did not change the rankings of alternatives. However the weights of alternatives were changed. The most sensitive alternative was found to be the disposal without treatment, while the least sensitive is the recirculation option.
The benefits of the relative importance scale to indicate the relative strengths of the evaluation criteria were demonstrated in this study. The study showed the suitability of AHP model to landfill leachate management decision making.
Keywords: Landfill leachate, Management, Strategy, Decision support system, Analytical hierarchy process
Issue 3, August 2010
PERFORMANCE OF HIGH RECYCLED ASPHALT PAVEMENT (RAP) CONTENT AS BASE LAYER IN FLEXIBLE PAVEMENT
Magdy Abdelrahman, Ph.D. 1
Assistant Professor, Department of Civil Engineering
North Dakota State University
Phone: (701)231-7249, Fax: (701)231-6185, Email: firstname.lastname@example.org
Tahsina Binte Alam
Graduate Research Assistant, Department of Civil Engineering
North Dakota State University
Office of Materials
Minnesota Department of Transportation
Between 80 and 90 percent of the asphalt pavement construction projects are the rehabilitation of asphalt pavements that have reached the end of their service lives. These rehabilitation projects produce about 100 million tons of Recycled Asphalt Pavement (RAP) per year from millings, presenting a major solid waste concern. RAP has an ever-growing value to practitioners in pavement construction. However, limited research exists to quantify the performances of the pavement layers especially for high RAP contents. This paper investigates the performance of the pavement base layer having high RAP content using resilient modulus (MR) as the primary indicator for base layer characterization. Testing results of RAP blends was collected from the Minnesota Department of Transportation. Conclusions indicate that RAP has a potential to be used in high percentages in pavement base layer applications. Testing indicates that MR increases with RAP content, with asphalt content and with aggregate dry density. Moisture content has less significant effect on the resilient modulus as compared to aggregate sources.
Keywords: RAP, Pavement, Base layer, Resilient modulus
HIGH-RECYCLED-CONTENT CONCRETE FOR ENERGY-EFFICIENT BUILDING CONSTRUCTION
Parviz Soroushian1, Roz-Ud-Din Nassar2
1Professor of Civil and Environmental Engineering
Michigan State University
Email: email@example.com, Telephone: +1 517 355 2216
2Ph.D. Candidate, Civil and Environmental Engineering Department
Michigan State University
Concrete materials incorporating different recycled aggregates were evaluated based on thermal, mechanical and durability characteristics. Recycled mixed plastics, wood, tire, steel and concrete were examined as concrete aggregates. The thermal properties investigated were thermal conductivity and specific heat. Durability under wet-dry and temperature cycles, heat resistance, compressive and flexural strengths, and impact resistance were also evaluated. Two buildings, one with normal concrete and the other with concrete with high recycled plastic content were designed, constructed and monitored for energy-efficiency. The results showed that the refined thermal properties of recycled plastic concrete lower the cooling and heating loads of buildings.
Keywords: concrete; recycled aggregate; thermal properties; energy-efficient; buildings; mechanical performance; durability
MANAGING HAZARDOUS COMPONENTS IN HOUSEHOLD WASTE IN DEVELOPING COUNTRIES—LESSONS LEARNT FROM COMMUNITY COMPOSTING IN CAMEROON
Lawrence O. Mbeng*, Paul S. Phillips and Roy Fairweather
School of Applied Sciences
University of Northampton
Northampton NN2 7AL
Composting is increasingly being adopted as a practicable, valuable and environmentally sound option for the sustainable management of biodegradable household waste. However, despite the community enthusiasm for compost production in Cameroon, compost producers are constrained by the increasing presence of the hazardous components in the household waste e.g. batteries, used paints and solvents, waste electrical and electronic equipments (WEEE). Based on this, semi-structured interviews, participant observation and participatory appraisal methods were used at targeted community composting sites to study socio-economic issues of community composting and their contribution to quality assurance for compost. The study showed that composters were aware of the importance to pre-sort and remove the hazardous components but were constrained by the fact that it was manual and labour intensive. The results of the study also shows that despite constraints, many communities were prepared to undertake composting as there was a significant increase in the demand for compost for use in Agriculture, Horticulture and Landscaping in Cameroon. On this basis, the paper proposes new strategy component for managing household hazardous waste (HHW) during compost production in Cameroon as well as the prospect of organizing waste pickers and training them in the pre-sorting, removal and marketing of recyclables from the composting sites.
Keywords: Household hazardous waste; community composting; quality assurance
RECYCLING OF BAGASSE ASH IN CEMENT MORTAR AND CONCRETE AND ITS IMPACT ON CHLORIDE RECEPTIVITY
Department of Chemistry
Abdul Wali Khan University Mardan (AWKUM)
In this investigation bagasse ash has been utilized in the high strength Portland cement concrete which not only improves the early strength but also increases the compactness of the concrete. It has been found that bagasse ash blended in concrete resists the chloride permeation in concrete. Corrosion performance was evaluated using rapid chloride ion permeation test. Results indicate that Bagasse ash is an effective mineral admixture and pozzolan with the optimal replacement ratio of 20% cement, which enhanced the high early strength and resistance to chloride diffusion and the water permeability.
EFFECT OF VERMICOMPOST OF DIFFERENT ORGANIC WASTES ON THE GERMINATION, GROWTH AND PRODUCTIVITY OF CERTAIN CROPS
The aim of the present study was to investigate the potential of vermicompost of different combinations of animal, agriculture and kitchen wastes and its effect on the germination, growth, flowering and productivity of crops (wheat, gram, pea and mustard). The vermicomposts obtained from different combinations of animal, agriculture and kitchen wastes with the help of earthworm Eisenia foetida have significantly increased in total kjedhal nitrogen (TKN), total potassium (TK), total phosphorus (TP), total calcium (TCa) and significantly decreased in total organic carbon (TOC), C:N ratio, pH and Electrical conductivity (EC) in final vermicomposts compared to the initial feed mixture. These final vermicompost have a significant effect on the germination, growth and productivity of crops. The combination of buffalo dung+ gram bran has a significant positive effect on the germination, growth, flowering and productivity of crops among all the vermicomposts.
Keywords: Organic wastes, Eisenia foetida, vermicomposts, chemical
BIOMASS ASSESSMENT FOR POTENTIAL BIO-FUELS PRODUCTION: SIMPLE METHODOLOGY AND CASE STUDY
U. Zaher1, H. Khachatryan2, T. Ewing1, R. Johnson1, S. Chen1, and C.O. Stockle1
1Department of Biological Systems Engineering
Washington State University, P.O. Box 646120, Pullman, WA 99164-6120
2 School of Economic Sciences
Washington State University, P.O. Box 646210, Pullman, WA 99164-6210
United States is experiencing increasing interests in fermentation and anaerobic digestion processes for the production of biofuels. A simple methodology of spatial biomass assessment is presented in this paper to evaluate biofuel production and support the first decisions about the conversion technology applications. The methodology was applied to evaluate the potential biogas and ethanol production from biomass in California and Washington states. Solid waste databases were filtered to a short list of digestible and fermentable wastes in both states. Maximum methane and ethanol production rates were estimated from biochemical and ultimate analysis of each waste and projected on a GIS database. Accordingly, the optimal locations for methane and ethanol production plants were approximately determined.
The available net power for transportation and electricity generation was evaluated considering three process efficiency factors in the waste to power life cycle. The net power from methane and ethanol would ultimately cover ~ 6 – 8% of the transportation needs for motor gasoline or cover ~ 3 – 4% of the electrical power consumption in each state.
Keywords: Anaerobic digestion, biomass, bio-energy, fermentation, GIS database
Issue 2, May 2010
A COMPARATIVE STUDY OF RECOVERING FINE SCHEELITE IN TAILINGS BY FLOTATION CELL AND FLOTATION COLUMN
Guangyao Huang*, Qiming Feng, Leming Ou
Xiqing Wu, Yiping Lu, Guofan Zhang
School of Minerals Processing and Bioengineering
Central South University, Changsha, 410083
There are nearly 2000 tons of cleaner circuit tailings containing about 0.32~0.78% WO3 at the tailings dam in Xiang’an Tungsten mine, China, which results in a great resource loss. In order to recover fine scheelite from the tailings, conventional mechanical cell and modified flotation column were investigated. With a flotation cell, different kinds of collectors and depressants as well as their dosages were tested. The results show that flotation cell did not recover fine scheelite because of a very low enrichment ratio. The first flotation column with the height of 2,800 mm and diameter of 140 mm was designed and manufactured for pilot scale test. The important operating parameters such as the superficial velocity of the feed and air, the addition of wash water were studied. The optimum operation parameters were: the superficial velocity of the feed 0.27 cm/s, the superficial velocity of air 1.57 cm/s. The second flotation column with the height of 7,000 mm and diameter of 600 mm was designed and manufactured for full scale column flotation experiments, which were carried out in the flotation plant of Xiang’an Tungsten mine. The average recovery of WO�3 reached 43.41% with an average grade of 24.52%, resulting in an enrichment ratio of 35.03. The recoveries of the particles between +5~-10�m and +10 ~-19�m were 67.23% and 70.81%, respectively. The results indicate that it is feasible to use modified flotation column to recover fine scheelite from the flotation tailings. Application of such flotation column will make full use of the resource and bring great economic profits to the enterprise.
Keywords: Recycling; Fine particles; Column flotation; Scheelite; Flotation tailings; Flotation froth
USE OF RAW CHAT IN HMA SURFACE—ENVIRONMENTAL AND ENGINEERING CHARACTERIZATION
Nazimuddin M. Wasiuddin
Assistant Professor, College of Engg. and Science, Louisiana Tech University
600 West Arizona Ave., Room 245, Ruston, LA 71270, USA
Tel: 318-257-2392; Fax: 318-257-2306; Email: firstname.lastname@example.org
Wamiq B. Hamid
Project Manager, ECS Limited and Former Graduate Student, University of Oklahoma
6909 International Drive, Suite 103, Greensboro, NC 27409, USA
Tel: 405-325-7993; Fax: 405-325-4217; Email: email@example.com
Musharraf M. Zaman
David Ross Boyd Professor and Aaron Alexander Professor, Associate Dean for Research
College of Engg., University of Oklahoma, Room 107, 202 West Boyd Street, Norman, OK, 73019, USA
Tel: 405-325-2626; Fax: 405-325-7508; Email: firstname.lastname@example.org
Robert W. Nairn
School of Civil Engg. and Environmental Science, University of Oklahoma, Room 334
202 West Boyd Street, Norman, OK, 73019, USA
Tel: 405-325-3354; Fax: 405-325-4217; Email: email@example.com
Over 35 million cubic meters of chat, a waste material from abandoned lead and zinc mining operations, are presently stockpiled in large piles on the surface of the Tar Creek Superfund Site. Currently, Oklahoma Department of Transportation (ODOT) uses a rather small percentage (about 20%) of washed (not raw) chat. There is a pressing need to significantly increase the use of raw chat in hot mix asphalt (HMA) by the DOTs in the region. Recently, researchers at the University of Oklahoma reported that as much as 50% raw chat can be used safely in an S3-type Superpave base mix. In the present study it has been revealed that as much as 80% raw chat can be used in an S5-type Superpave surface mix. A relatively small percentage (40%) of raw chat produces high VMA (15% or more), and it increases with an increase in chat percent. Chat-asphalt mixes also did well in performance tests, namely moisture susceptibility, APA rut, and permeability. A suite of environmental tests were performed to examine the leaching potential of heavy metals (lead, zinc, and cadmium) in chat due to dry and wet rut tests, and simulated milling. Tests indicate that chat-asphalt can be used safely as a roadway surface.
Keywords: Raw Chat, Tar Creek Superfund Site, Asphalt Pavement, Superpave Mix Design, Hot Mix Asphalt (HMA), Heavy Metals
INVESTIGATION OF INDUSTRIAL WASTE IN HOT MIX ASPHALT FOR MOISTURE DAMAGE RESISTANCE
Kunnawee Kanitpongand Kitsumate Pummarin
Transportation Engineering Program
School of Engineering and Technology, Asian Institute of Technology
P.O. Box 4, Klong Luang, Pathumthani, 12120
Moisture damage is one of the main problems in asphalt pavement which is found especially in areas with high a amount of rainfall. One effective solution is to apply anti-stripping additives in asphalt mixtures to reduce the stripping of asphalt binder from the aggregate surface due to moisture. Another solution is to select an aggregate type that provides better affinity with asphalt binder rather than water and hence provides better adhesion. In this study, fly ash and cement kiln dust (CKD) were selected as the anti-stripping additives, while steel slag and reclaimed concrete were selected as the aggregates in asphalt mixtures. The resilient modulus test and the indirect tensile strength test were conducted to evaluate the performance of asphalt mixtures. It was found that the use of CKD as additive increased the stiffness of asphalt mixtures at intermediate and high temperatures, while the application of fly ash and reclaimed concrete reduced the stiffness of the asphalt mix. Results also indicated that asphalt mixtures with fly ash and CKD additives and those with slag and reclaimed concrete aggregates could resist moisture damage.
Keywords: Industrial waste, fly ash, cement kiln dust, slag, reclaimed concrete, Superpave
THERMODYNAMIC MODELLING OF ZINC OXIDE AND ZINC FERRITE FORMATION IN ELECTRIC ARC FURNACE DUST
Department of Mining Engineering
Kingston, Ontario K7L 3N6
The remelting of automobile scrap in an electric arc furnace (EAF) results in the generation of electric arc furnace dust, which can contain a commercially significant amount of zinc. Typically, the majority of the zinc exists as zinc oxide (ZnO) and zinc ferrite (ZnFe2O4). The development of processes to recover the zinc has been hindered by several factors, including the presence of zinc ferrite in the dust. There is a paucity of information on the modeling of the behaviour of zinc during the dust formation process, particularly under actual furnace gas compositions. In the present research, the Gibbs solver of Outokumpu HSC Chemistry �5.1 was utilized to determine the equilibrium amounts of the zinc-containing species in the dust from a typical EAF operation. The effects of the following parameters on the dust composition were determined: the off-gas composition and temperature, the amount of zinc and oxygen in the off-gas and the presence of other species such as calcium oxide. In order to account for kinetic factors, selected species that were not expected to form were deleted from the model. In general, these modified model calculations were in good agreement with the behaviour of zinc in actual EAF dusts. Additionally, some potential methods for minimizing zinc ferrite formation were discussed.
Keywords: Electric arc furnace, dust, hazardous waste, modeling, zinc oxide, zinc ferrite
ANALYSIS AND ASSESSMENT OF COMPRESSIVE STRENGTH IN FaL-G COMPOSITES
Department of Civil Engineering, R V College of Engineering,
Bangalore- 560 059
Tel: +919886127398, Fax: +918028600337
FaL-G, a composite prepared using Fly ash (Fa), Lime (L) and Gypsum (G) in a definite proportion, was used as a binder. FaL-G compressed mortar blocks were prepared considering various parameters like fineness of fly ash, aggregate-to-binder ratio, degree of saturation, age, and water-to-FaL-G ratio. FaL-G concrete cubes were prepared using different parameters like water-to-FaL-G ratio, binder content, and age. The blocks and cubes were tested for unconfined compression to determine the compressive strength. The strength was analysed separately for the mortar blocks and concrete cubes. It was interesting to find that strength development followed a definite pattern in both mortar and concrete irrespective of the parameters. In both the cases, the strength data was generalised for a reference value of water-to-FaL-G ratio. A phenomenological model was developed in both the cases to account for synergy between the materials used. Its robustness was verified with an independent set of experimental data. The predicted strength values are in close agreement with the experimental strength. This reinforces the possibility of using the model in the field to re-proportion the FaL-G mix of any consistency.
Keywords: FaL-G, fly ash, lime, gypsum, compressive strength, water-to-FaL-G ratio, phenomenological model
Issue 1, February 2010
THE PHYSICO-CHEMICAL CHARACTERISTICS AND MICROBIAL
INFLUENCE ON TAPIOCA SOLID WASTEVERMICOMPOSTING
Ramalingam Malathi, Anitha Subash*
Department of Biochemistry, Biotechnology & Bioinformatics
Avinashilingam University for Women, Coimbatore- 641 043, Tamil Nadu
Phone: 091(422)2440241, Fax: 091(422)2438786
Vermicomposting is the most economical and sustainable option for organic waste management. Tapioca solid waste (TSW) is one of the major biodegradable wastes containing high amounts of organic matter. Utilization of earthworms to breakdown organic wastes is gaining importance in solid waste management in different parts of the world. Trichoderma viridae, a cellulase producing fungi and Bacillus polymyxa a free living nitrogen fixing bacteria enrich the nutrient content of final compost. The present study has investigated the suitable ratio of tapioca solid waste (TSW) and cow dung (CD) to obtain high quality vermicompost and also to assess the combined effects of poly culture worms and microbes on tapioca solid waste vermicomposting by analyzing the physico-chemical properties of the final compost on the 75th day. The increased levels of nutrients suggest that the suitable ratio of TSW and CD treatment mixture was 1:1, 2:1 and 3:1.The per cent increase in N, P, K, Ca, Mg, Fe and other trace elements were significantly high in the 3:1 ratio sample, which proved to be the most effective treatment mixture. Similarly, there was an increase in the macro and micronutrients (N, P, K, Ca, Mg, Fe, Zn, and Mo) and decrease in Na, Cu and S contents in media treated with a combination of earthworms with microorganisms. Thus, our study showed that the combined use of T. viridae and B. polymyxa with polyculture worms was the best method for tapioca solid waste composting.
Keywords: Biodegradation, Organic matter, Polyculture worms, Trichoderma viridae, Bacillus polymyxa
THE EFFECT OF AIR FLOW RATE AND MIXING PERIOD
ON COMPOSTING OF FOOD RESIDUES
Department of Technology Transfer
Agricultural Engineering Research Institute (AEnRI)
Tel: 202-3375853; Fax: 202-3356867
food waste and sawdust were used to produce compost using a composting bioreactor system. The moisture content and C:N ratio of the initial mixture were adjusted at 60% and 30:1, respectively. Three aeration rates and two mixing periods were used in this experiment. The moisture content, dry matter, pH, total Kjeldahl nitrogen, total carbon, bulk density, total phosphate and total potassium were measured on the initial mixture and at the end of composting process. The temperature changes and CO2 rates were monitored and recorded in all the bioreactors. The results indicated that the maximum temperature ranged from 48 to 52 oC depending on the aeration rate and mixing speed. The maximum temperature that was higher than 50 oC was found only in bioreactors C1 and C2 and was maintained for three days. In all reactors the CO2 emission increased and was proportional to the temperature and aeration rates. The relation between the temperatures, the emissions of carbon dioxide, the aeration rates and the mixing period in this study was found to be (T = 20 + 6.5 CO2 + 24 A – 0.01M); T: the compost temperature (oC), A: the aeration rate (m3/h), M: mixing period (h), CO2: emission of carbon dioxide (%). An aeration rate of 0.15 m3/h and mixing period of 12 h produced good quality compost in 18 days and saved 50% of the power consumed in the mixing operation.
Keywords: Aeration rates, bioreactor, compost, food residues, mixing, waste recycle, CO2, temperature
A STUDY ON THE MANUFACTURING SI-AL-BA-FE ALLOY DIRECTLY FROM COAL FLY-ASH
BY ELECTRO-THERMAL METHOD
Wenqiang Xiong1, Min Xiong2
1College of Resource & Environmental Science, Chongqing University
2College of Software Engineering, Chongqing University
An experiment of manufacturing Si-Al–Ba-Fe Alloy from Coal Fly-Ash by Electro-thermal Method was introduced. The raw material is powder coal ash. The average components of the final obtained product in this experiment are: Si 34.93%、Al 23.90%、Ba 7.18%、Fe 27.08%、Ca 1.7%、C 0.7%、P 0.066、S 0.029%. This kind of Si-Al-Ba-Fe alloy can be used as a deoxidizer in order to reduce the metal aluminum consumption in steel-making industry. This is a viable method to make full and integrated use of powder coal ash. This method has economy benefit, environmental benefit and social effectiveness. It is worth being studied and applied further.
Keywords: Powder coal ash, Electro-thermal Method, Si -Al –Ba Alloy
FLYASH FILLING FOR IMPROVED WEAR RESISTANCE OF
GLASS-POLYESTER COMPOSITES—AN EXPERIMENTAL STUDY
Amar Patnaik1, S.S. Mahapatra2, R.R. Dash3
1Mechanical Engineering Department, National Institute of Technology
2Mechanical Engineering Department, National Institute of Technology
3Mechanical Engineering Department, Gandhi Institute of Engineering and Technology
Flyash is a solid waste generated in huge quantities from coal fired thermal power stations during the combustion of coal. In India, less than half of this is used as a raw material for concrete manufacturing and construction; the remaining is directly dumped on land side as land fill or simply piled up. Only a small fraction of it is used in development of high valued product. Due to environmental regulations, new ways of utilizing flyash are being explored in order to safeguard the environment and provide useful ways for its utilization and disposal. With its richness in various metal oxides, it has tremendous potential to be utilized as a filler material in polymer composites. These days glass reinforced polyester composites find widespread application in erosive environment due to several advantages like high wear resistance, strength-to-weight ratio, and low cost. The cost of the composites can be further brought down using cheaper filler materials. To this end, this work uses flyash in composite making and thereby suggests a new way of better utility of this industrial waste. It includes the processing, characterization and study of the erosion behavior of a class of such flyash filled polyester-glass fiber composites. It further outlines a methodology based on Taguchi’s experimental design approach to characterize this erosion behavior. This technique eliminates the need for repeated experiments, thus saves time and material. The systematic experimentation leads to determination of significant process parameters and material variables that predominantly influence the erosion rate.
Keywords: Flyash, Waste utilization, Composites, Erosion, Taguchi method, Genetic algorithm
EXPERIMENTAL STUDY OF LEACHING YELLOW PHOSPHORUS SLAG BY PHOSPHORIC ACID
Yi Su,* Guobing Li, Jupei Xia
Institute of Chemical Engineering, Kunming University of Science and Technology
PEOPLE’S REPUBLIC OF CHINA
This paper describes the technology of producing precipitated silica, in which yellow phosphorus slag is leached by phosphoric acid and calcium is separated in form of calcium phosphate monobasic. The experimental results show that optimal technical conditions are: phosphoric acid concentration 31%, reaction time 0.5 hour, stirring speed 400rpm, liquid-solid ratio 5:1 and natural temperature.
Keywords: Yellow phosphorus slag，phosphoric acid，leaching, precipitated silica
AN ALTERNATIVE PROCEDURE TO RECYCLING PLASTIC WASTE FOR BASEMENT UNDERGROUND THERMAL INSULATION IN COLD CLIMATE BUILDINGS
Ahmed Ch�rif Megri, Ph.D.
Department of Civil and Architectural Engineering
University of Wyoming, Dept. 3295
1000 E. University Avenue, Laramie, WY 82071
Email: firstname.lastname@example.org, Phone: (307) 766-3299
Recycled plastic waste materials can be used as an alternative to traditional insulation materials. Experimental and numerical studies were carried out to quantify the heat loss of 13 different basement configurations using this new insulation approach. The objective of this study was to make use of the specific products found in the typical plastic waste discarded by public and private centers, such as hospitals, industry, and residential households. Emphasis has been placed on polyethylene waste used for packing material. Two transient methods were used to measure thermal characteristics such as conductivity, diffusivity and volumetric heat capacity of the new material composed from the plastic waste (now intended to be used as a basement thermal insulator). The thermal properties were used as input data for a comprehensive computational analysis program to determine a building’s heat loss through its basement. For all 13 case studies, the quantitative values of the heat loss through the basement demonstrate that this new plastic material can be considered as a potential building insulation material.
Keywords: Insulation, Energy Conservation and Heat Loss, Recycling, Waste, Basement, Thermal Comfort