Coal Ash - The Grey Resource

Research and Development of Coal Ash in Israel

Supreme objectives

  • To ensure the continuous removal of coal ash from power stations courtyards.
  • To extract technical, economical and environmental benefits potentially stem from coal ash utilization.
  • To position coal ash as a non strategic factor in national decision about coal based electricity generation system.
  • To be ready for the increase in the amount of coal ash generated by the establishment of new coal-fired electricity production units.
  • To extract technical, economical and environmental benefits potentially stem from coal ash utilization.

Contributory objectives

  • To create of knowledge infrastructure that supports the application of technologies for the efficient use of coal ash.
  • To determine reasonable environmental conditions to enable and encourage the use of coal ash.
  • To determine engineering standardization to enable and encourage the applications of coal ash uses.
  • To position the uses of coal ash as green applications that contribute to the improvement of the local and global environment through sustainable development.
  • To create a supportive public atmosphere that grants social legitimacy to the uses of coal ash.
  • To develop a competitive sellers' market (surplus demand) for a variety of uses.
  • To develop continuous and stable uses in controlled industrial processes.
  • To be ready for prolonged crisis situations (surplus supply) by developing high volume default applications and defining reasonable environmental restrictions for accumulating sites.

List of projects that serve the R&D objectives

Basic research
Environment
 
 
 
Occupational hygiene
Construction
 
 
Infrastructures  
 
 
 
 
 
Agriculture
 
 
 
 
Industry
 
 
 

Mineralogy of the amorphous matter in coal ash - probe study

Problem
Lack of in-depth mineralogical knowledge on the amorphous matter in coal ash limits the possibility of optimal exploitation of the features of coal ash and prevention of environmental hazards in its uses.
Objective
To understand the factors that affect the significant processes in the environmental aspects and the principle applications: solubility of pollutants, chemical reactions, physical characteristics in order to formulate physical-chemical models for the optimization of coal ash in its uses.
Research hypothesis
Understanding the mineralogy of the amorphous matter, which represents 40%-80% of the fly ash, will make it possible to provide a more precise definition of the conditions for optimal technological and environmental exploitation of its features.
Interim findings
An in-depth survey of the literature did not uncover any publications relating to the study of the amorphous matter in coal ash. A chemical analysis was carried out on nine coal ashes, representative of different sources of coal in Israel.
Chief researcher
Dr. Yaakov Nathan of the Geological Institute y.nathan@gsi.gov.il

Environmental characterization of coal ash using method based on the European CEN/TC 292

Problem
It is doubtful whether the environmental restrictions (flushing of pollutants) for coal ash applications determined in Israel reflect the dangers in the typical local reality.
Background data
The main development areas in Israel are located above the aquifers that represent the country's main water sources.
The list of maximum permitted values for pollutants in "usable coal ash" is based on the TCLP examination process of the EPA. However, the extent to which it indeed reflects the process that actually occur is debatable.
Objective
To explore the adoption of the European environmental characterization method principles, based on a pH Dependence Test, analyzed using the Leach XS model as a reflection of the true dangers that actually occur, and the determination of appropriate maximum values for pollutants in usable coal ash.
Research hypothesis
Characterization of the coal ash using tools that provide a better representation of what actually occurs will make it possible to relax some of the environmental restrictions of its utilizations.
Chief researchers
Dr. Yaakov Nathan of the Geological Institute y.nathan@gsi.gov.il
Dr. Hans A. van der Sloot, ECN The Netherlands vandersloot@ecn.nl

Behavior of fly ash in an aqueous environment

Problem
The leaching of oxyanions from coal ash exposed to an aqueous environment restricts the potential use of sites for interim storage of coal ash in open piles.
Background data
The capacity for interim storage of coal ash is limited in coastal power stations.
The accumulation of large surpluses of coal ash occur during economical recession or when new coal-driven power plans are operating.
Potential sites for interim storage are located above the main aquifers.
Objective
To define the operational conditions in large amassments of coal ash for interim storage to prevent pollution of the aquifers, which take into account the processes that occur when the coal ash is exposed to the environment over time.
Research hypothesis
Understanding the behavior of wet coal ash exposed to atmosphere as a function of time will give us the tools to define the treatment conditions of the piles in order to minimize the processes that could cause the pollutants to leach into the aquifers.
Interim findings
Considerable differences in the chemical processes was observed when fresh coal ash was compared with wet coal ash that exposed to the atmosphere for various time periods, when leached with distilled water. The main differences are (1) the rate of change in pH of the leachate solution, (2) the electrical conductivity of the leachate, and (3) the solubility rate of certain pollutants.
Chief researcher
Prof. Rami Keren, Soil, Water and Environmental Sciences Institute, Agricultural Research Organization, Volcani Center, rkeren@agri.gov.il

Sealing of fly ash in road embankments to water over time

Problem
Restricting the use of coal ash in infrastructures construction in areas of medium to high sensitivity of aquifers
Background data
The new development of infrastructures sites in Israel are located above the aquifers that serve as its main water sources.
A water permeability test carried out on a fly ash road embankment site during three years since it was established showed various coefficients of conductivity, up to absolute sealing, dependant on the processing of the coal ash at the time of paving.
Objective
To define the rate of hydraulic conductivity reduction of the fly ash layer exposed to the atmosphere that used as structural filling in road paving.
Research hypothesis
The carbonization processes and precipitation of limestone in the compacted fly ash layer pores exposed to the atmosphere resulting an impermeable layer for water and rules out the dangers of pollution to the groundwater.
Interim findings
The infiltration rate of the fly ash layer in the embankment a year after construction was reduced by 50% of its initial value obtained immediately after the construction was completed.
Chief researcher
Prof. Rami Keren, Soil, Water and Environmental Sciences Institute, Agricultural Research Organization, Volcani Center rkeren@agri.gov.il

Survey of radiation from advanced concretes

Problem
The severe restrictions contained in Israel Standard 5098 "Radioactive elements content in building materials" places in doubt the possibility of adding coal ash to common concretes.
Background data
The policy of the Ministry of Environmental Protection is focused on maintaining the relative local advantage, which results from a relatively low level of background radiation, compared to the common background radiation levels in the world.
The concentration of radioactive elements in raw materials used for construction in Israel has risen in recent years as a result of the following developments:
  • Adoption of advanced concrete standards involves changes in the composition of raw materials used in the production of concrete and in the transition from a limestone aggregate weak in radioactive elements to a dolomite aggregate rich in these elements.
  • The exhaustion of dune-sand reserves requires a transition to the use of fossil sand quarried in internal land areas near uranium-rich phosphate deposits.
  • Advanced technologies for the manufacture of clinkers for cement (dry process) enable more effective utilization of limestone deposits including deposits that in the past were considered useless, which contain higher concentrations of radioactive elements.
  • The addition of coal ash to cement and concrete at significant levels as a result of the policy that encourages the recycling of waste in effective uses and the cancellation of the permit given for a limited time to dump coal ash surpluses into the sea.

The use of coal ash as a supplement to concrete is the most general application from a comprehensive economic standpoint. An economic analysis points to the socio-economic justification of the use of coal ash against the increase involved in the exposure to radiation, up to an addition of mSv 0.5 per person per year above the natural background radiation, whereas the standard is seemingly based on the restriction of a permitted addition to only mSv 0.3 per person per year, and the contribution of coal ash in regular mixes should not exceed mSv 0.1 per person per year.
The application of the standard has been postponed until early 2008 in order to enable the concrete industry and the National Coal Ash Board to test it in practical terms.
Objective
To examine the indices of the standard and its demands in order to determine them on a level that will enable a production of concrete mixtures according to the advanced standards and that are made of the main available domestic raw materials, including coal ash as a component of concrete on a level justified in overall socio-economic terms.
Research hypothesis
The limitations of the standard, which make the use of common concrete mixes containing coal ash borderline or disqualify them for normal use in residential and business buildings, need to be revised in order to enable the use of coal ash as a major component in concrete, as is the accepted practice throughout the world.
Companion expert
Dr. Victor Steiner, Director Ionizing Radiation, Ministry of Environmental Protection victors@sviva.gov.il

Free crystalline silica in respirable fly ash dust

Problem
Fly ash is defined in Israel as hazardous and pneumoconiotic dust due to the presence of free crystalline silica (quartz). This definition holds for any percent weight of quartz (even less than 0.1%) in the fly ash. One of the implication of this definition is that fly ash dust should be regarded as silicotic regardless its crystalline silica content and even below an accepted epidemiologic non-carcinogenic NOAEL (No Observed Adverse Effect Level).
Background data
The occupational hygiene standards in Israel define fly ash as hazardous dust that requires medical monitoring, including lung x-rays for employees exposed over the long term to coal ash dust.
Objective
To have coal ash dust defined as nuisance dust, the accepted practice in European countries, or in accordance with the hazardous category defined by the ACGIH in the United States for Particulates (insoluble or poorly soluble) Not Otherwise Specified (PNOS) (ACGIH values are legally adopted in Israel), or in accordance with another category somewhere between hazardous dust and nuisance dust, if a justification for it emerges.
Investigation hypothesis
Based on studies carried out throughout the world, most of the silica in coal ash is related to aluminosilicates, the free crystalline silica is embedded in the coal ash particles to a large extent, the percentage of quartz in the respirable fraction (under aerodynamic diameter of 7 microns) of fly ash is lower than 0.1%-0.2%. Accordingly, fly ash can be defined as nuisance dust or as dust lacking a status silicotic and lung tissue fibrosis agent.
Future plans
To monitor general and respirable dust in the area of the fly ash reservoir in the power station and conduct a physico-chemical analysis of it in an expert laboratory.
Chief researchers
Dr. Asher Pardo, Occupational Safety and Hygiene Institute, A_Pardo@netvision.net.il
Dr. Yaakov Nathan, Geological Institute, y.nathan@gsi.gov.il

The effect of fly ash quality on the durability of concrete in Israel

Problem
Strict restriction on the level of cement replacement with coal ash in the constructive concrete mix reduces the cost-effectiveness of the use of coal ash in this application
Background data
The revised Israeli Standard 118 - "Concrete for structural uses: Production control and compressive strength" will enable to replace cement with coal ash with an efficiency coefficient of k=0.4-0.5, conditional upon the environmental exposure conditions (dryness and chlorides) in areas with a temperate environment.
Israeli Standard 1209 "Fly ash as an additive to concrete" distinguishes between two types of fly ash in accordance with the LOI concentrations: Type A 0%-3%; Type B 0%-7%.
Objective
To explore the possibility of using higher efficiency coefficient k (effectiveness of coal ash as a replacement for cement) for cement replacement by coal ash, and define it in all zones in Israel, as a function of the type of coal ash.
Research hypothesis
The use of coal ash with an LOI lower than 3% makes it possible to reduce the minimum cement content (clinker) to maintain the concrete durability in more severe areas of exposure.
Interim findings
The findings regarding concrete durability under conditions of accelerated carbonation pointed to the relative inferiority of mixes containing coal ash as a replacement for cement, but which meet the demands of the standard in reducing the minimum cement content to 200 kg. per cubic meter, with a replacement coefficient of k = 0.5. Under exposure to the natural environment, no essential differences could be seen between the mixes even after two years.
Chief researchers
Prof. Arnon Bentur, National Building Research Institute, Technion Research and Development Foundation, bentur@tx.technion.ac.il
Dr. Hadasa Baum, National Building Research Institute, Technion Research and Development Foundation, baum@technion.ac.il

High volume fly ash concrete - a probe study

Problem
Forecast for the generation of large surpluses of coal ash as a result of the growth rate of coal ash, which will exceed the rate of growth of concrete production.
Background data
An increase of over 50% in coal ash can be expected with the establishment of new coal-driven power stations in the coming decade, compared to the expected increase of only about 30% in the concrete industry.
An expected bottleneck in the construction industry in Israel will be the availability of local cement, due to difficulties, mainly environmental ones, involved in the establishment of an additional cement factory. Consequently, the price of cement will necessarily rise in the future and will increase the cost-effectiveness of coal ash as a replacement for cement.
The environmental emphasis in the developmental trend in the world to reduce the emissions of CO2 is already causing prices of €10-30 per ton of reduced CO2. These prices will create business interest in the use of coal ash as a replacement for cement in amounts larger than are accepted today.
The radiation standard for construction products could restrict the applications of concrete rich in coal ash in buildings intended for prolonged human residence.
Objective
To define the types of structural concrete to enable using coal ash in proportions greater than 10% weight, dependent on the composition of the coal ash and its quality.
Research hypothesis
The application of coal-ash rich concrete requires coal ash of a defined and unvarying quality, both chemically (ratio between the silica, calcium and alkaline) and granulometrically (remainder on a 45-micron sieve).
Preliminary findings
The use of coal ash from a South African source, rich in calcium and sulfates in relation to the silicates makes it possible to manufacture structural concrete in amounts higher than 350 kg. per cubic meter.
Initial plan
To conduct a feasibility study, including a survey of the professional literature and to carry out preliminary tests.
Chief researchers
Prof. Arnon Bentur, National Building Research Institute, Technion Research and Development Foundation, bentur@tx.technion.ac.il
Prof. Kosta Kovler, National Building Research Institute, Technion Research and Development Foundation, cvrkost@tx.technion.ac.il
Dr. Rina Wassermn, National Building Research Institute, Technion Research and Development Foundation, wassermn@tx.technion.ac.il

Fine bottom ash as an alternative to natural sand in dry concrete products

The problem
The aggregates Standard and concrete products Standards do not allow the use of bottom ash as a raw material in concrete products.
Background data
The fraction of particles smaller than 4 mm. represents more than 75% of the bottom ash and is obtained after sieving the coarse particles intended for agricultural use.
The depletion of dune sand reserves increases the cost-effectiveness of the development of alternatives, including fine bottom ash.
Israeli Standard, SI 3, "Mineral Aggregates from Natural Sources" allows the use of aggregates only from natural sources.
The trend in the development of construction blocks is focusing on reduction in weight and the use of alternative fine aggregates.
Objective
To develop complementary uses for the fine bottom ash remaining after sieving the coarse particles intended for agricultural uses.
To adopt the new European standardization from 2002 (BS EN 12620) that allows the use of artificial aggregates from industrial sources, including recycled aggregates, in construction products.
Development hypothesis
The replacement of natural sand with fine bottom ash will improve the features of dry concrete products (construction blocks, paving bricks, concrete pipes, etc.)
Preliminary findings
The main problems in the use of bottom ash in the production of construction blocks arise from the particles larger than 8.0 millimeters and from the pyrites (coal mill waste).
The relative low weight of the coal ash and its high thermal resistance represent a significant advantage in the manufacture of construction blocks.
Future plans
To introduce bottom ash into the Israeli standard for aggregates and dry concrete products.
To conduct industrial experiments among the large manufactures of construction blocks, paving bricks and infrastructure products.
Chief developer
Prof. Dan Ravina, National Building Research Institute, Technion Research and Development Foundation cvravina@tx.technion.ac.il

Ash-based Hydraulic Road Binder (HRB) mixes to strengthen road pavements

Problem
The skepticism of the professional community in the field of paving and infrastructures to recognize the benefits of new technologies based on the unique properties of fly ash bound mixtures (FABM) to enhance the engineering and economic aspects of road paving.
Background data
A laboratory study carried out in the Technion based on European knowledge (especially French and British), which was presented previously at a study day on this subject, proved the efficacy of FABM mixtures combining selected active supplements (gypsum, lime, etc.)
Objectives
To introduce the use of fly ash in FABM mixes in road construction specifications of the principal paving and infrastructures companies, as a feasible alternative to reduce the dependence on the seasonal fluctuations in the concrete and aggregates market over the medium and long term ranges.
Future plans
Develop a work-plan with the state and local road authorities to carry out well planned and documented field experimental sections.
Chief developers
Dr. Mario Hoffman, Yona - Engineering Consulting and Management Ltd. marioh@yonaltd.com
Prof. Ilan Ishai, Technion Institute for Traffic Research (?), Technion Research and Development Foundation iishai@tx.technion.ac.il

Fly ash as a filler in basalt asphalt mixtures

Problem
Proof of contribution of fly ash as a filler to provide legitimacy for the use of basalt sand in asphalt mixtures.
Background data
According to the Ma'atz - National Roads Corporation, basalt asphalt mixtures are required for upper stratification in interurban roads system mainly due to its resistance to motorcar wheels skidding.
Basalt sand may not be used in asphalt mixtures in Ma'atz roads because of its low affinity to bitumen, which leads to the stripping of bitumen from the aggregates and the crumbling of the asphalt stratification layer.
Quarry lime or dolomite sand, which takes the place of basalt sand in the mixtures, contains surplus filler requiring removal at high costs and involving operational and environmental problems.
Objective
To develop an application of unique value to coal ash that is beneficial to the basalt deposits, lower costs for the basalt asphalt factories.
To develop alternatives involving the use of fly ash to reduce the dependence on the cyclical fluctuations in the concrete industry, over the long term.
Research hypothesis
Quality of asphalt mixture made of basalt aggregates (coarse, as well as fine) and fly ash as a filler, is not less than conventional mixture made of basalt aggregate and lime or dolomite sand and filler.
Interim findings
A lab study and field experiments confirm that the basalt mixture meets the demands of the Ma'atz specifications.
Future plans
To gradually introduce, in a controlled manner, of the use of asphalt mixture on interurban roads system.
Chief developers
Engineer Nathan Livnat nlivnatiishai@tx.technion.ac.il

Fine Bottom Ash as an alternative to sand fractions in asphalt mixtures

Background and problem
The asphalt mixing plants are usually located inside or near quarries and utilize the available and inexpensive raw materials (mineral aggregates) at minimal conveyance costs. On the other hand, certain asphalt mixing plants are not located in active quarries and can utilize other suitable resource materials, among them fine bottom ash, under engineering cost-effective conditions.
Lime sand contains surplus filler, which is removed as waste, involving high costs and operational and environmental problems.
Objective
To introduce fine bottom ash as a partial permanent alternative to quarry sand in asphalt mixing plants located near the power stations and remote from quarries.
Interim findings
The replacement of lime quarry sand with fine bottom ash in asphalt mixes involves several trends: It increases the use of bitumen content and reduces the cost-effectiveness of the alternative use of coal ash. However, whereas according to the criterion of the maximum air voids, the increase in the optimum bitumen content is significant, based on the criterion of maximum stability, the rise in bitumen content is very moderate.
In durability testing of asphaltic mixtures, under prolonged hot immersion, considerably strengthening occurred in mixes containing coal ash. The conclusion is that fine bottom ash contributes to the adhesion between the bitumen and the aggregates in the mix, and to the resistance of to water damage that causes the stripping of the bitumen from the aggregates.
Although the values obtained in the various tests of the mixes containing coal ash were slightly inferior to the values obtained in the conventional mixes, the replacement of about a third to a half of the quarry sand in the mix with coal ash maintains the characteristics of the asphalt at a high level that is in keeping with the requirements of the standards.
Future plans
To implement asphalt courses on an experimental section using a mixes containing fine bottom ash, in comparison to a section with a conventional mix, by means of potential asphalt mixing plants for the use of coal ash. Investigation of additional factors related to mixture type and under variable loading conditions.
Chief Developer
Prof. Ilan Iishai, Transportation Research Institute, Technion - Israel Institute of Technology. iishai@tx.technion.ac.il

Bottom ash as an aggregate to stabilize dirt trails

Problem
To introduce new technology in a developing area - the stabilization of dirt trails for tourism and recreational sports in nature reserves.
To implement the use of bottom ash, which is exposed to the environment and to wear and tear, without dust hazards.
Background data
A recommendation to give priority to the use of bottom ash as an aggregate structure on dirt trails following a comparative field study of various natural and recycled minerals.
The permission to use bottom ash from the Water Commission in infrastructures in small amounts for unlimited field units.
Objective
To develop a bottom ash application that utilizes the coal ash at its rate of production and prevents the accumulation of coal ash piles in the power stations.
Interim findings
Field experiments confirm the preference for bottom ash for geotechnical (stability), environmental (lower wear and tear preventing dust) and aesthetic (color blends into natural surroundings).
Future plans
Gradual and controlled introduction of the method to stabilized dirt trails.
Long-term monitoring of the stability of the roads under extended wear and tear by light transport, and of pedestrian trails and their maintenance methods.
Chief developers
Architect Erez Lotan, Lotan Architecture and Landscaping elotan@013.net
Dr. Rafi Yaron, Aram Engineers RafiY@aram-engineers.com

Fine bottom ash as an alternative to sand in covering for underground pipes

Problem
Lack of knowledge and a conservative approach are preventing designers and potential castomers of underground pipes from the use of fine bottom ash as backfill material.
Background
The fine particle fraction smaller than 4 millimeters includes more than 75% of the bottom ash and is obtained from what is left over from the sifting of the coarse particles intended for agricultural use.
The depletion of high-quality dune sand reserves increases the cost-effectiveness of the development of alternatives, including fine bottom ash.
Objective
To develop complementary uses for left over fine bottom ash remaining after sifting/sieving/removal of the coarse particles intended for agricultural use.
To develop a continuous and stabile application that utilizes coal ash at the rate of its production, to prevent the accumulation of piles in the power stations.
To prepare specifications for laying conditions of pipes to be adapted as standards by major/main/nation-wide potential users (water carriers, oil and gas pipeline companies).
Interim findings
Bottom ash is a lightweight, stable and free draining material, suitable and convenient to use as filling material for pipes installation at the appropriate compaction level, and provides structural support to the buried pipe as required by the engineering standards;
As a well-defined combustion by-product, bottom ash can serve as bedding layer that prevents stress concentration at the pipe bottom, a side support to prevent excessive pipe deflection, and a protective layer of the pipe and its coating against stones, clods and foreign bodies that may be found in natural soil backfill used to complete the pipe covering.
Because it has broad particle distribution (SM with fines), the bottom ash can meet the criteria to prevent the migration of fines from the natural soil to the pipe zone, making unnecessary the use of geotechnical fabric that is required when using coarser backfil materials.
Future plans
A field study and specifications for bottom ash laying conditions, with the participation of the Mekorot Water Co. Ltd., the national water carrier.
Authorization from the Israel Electric Company and the national gas company for the use of fine bottom ash in the covering of natural gas pipes.
Chief researcher
Prof. Naftali Galili, Faculty of Civil and Environmental Engineering, Technion - Israel Institute of Technology galilin@012.net.il

Sealing (fuel spill bunds and landfills) with clay and fly ash mixture

Problem
The phenomenon of cracking in clay used to seal sites that require low water conductivity of the infrastructure or facing.
Background data
The Ministry of Environmental Protection requires conductivity lower than 10-7 centimeters per second for the infrastructure layer in fuel spill containments and garbage landfills.
Mixing fly ash, especially from South African coal ash, which is rich in calcium cancels, by means of a cation exchange process, the effect of the swelling and shrinkage of the sodium on the clay montmorillonite soil in its exposure to wet and dry cycles.
Objective
To propose an inexpensive and effective alternative to the existing sealing methods (HDPE).
To develop an alternative use for fly ash, to reduce dependence on the concrete industry, especially in recession periods.
Research hypothesis
Mixing fly ash, especially South African coal ash rich in calcium, offsets, by means of the cation exchange process, the effect of the swelling and shrinkage of the sodium on the clay and montmorillonite soil in its exposure to wet and dry cycles.
Interim findings
In laboratory tests of the clay mix at various degrees of plasticity with ashes from various sources, hydraulic conductivity coefficients lower than 10-7 centimeters per second in a compound containing 30%-40% coal ash and the primary and repetitive property of swelling was offset in the clay and in compounds containing coal ash at a proportion of 15% and above.
In a field study on a commercial level, low hydraulic conductivity values as low as 10-8 centimeters per second were obtained in a test carried out two years after the placement in the field. These values were obtained despite the performance difficulties that restricted the quality of the mixture of the materials.
Future plans
Controlled penetration of the method in fuel spill containments and domestic waste landfills.
Chief Developer
Engineer Shmuel Geffen, Soil and stabilization engineering
sgeffen@zahav.net.il

Fly ash for structural and chemical improvement of agricultural soil

Problem
Low fertility of sandy soil due to the poor water-retention qualities; problems of erosion, water runoff and crusting of loessial soil, cracking in high-sodium soils during
dry periods.
Background data
Soils in extensively cultivated areas in Israel, especially in the northern Negev, suffer from problems that limit crop yield and adversely affect crop quality.
A comprehensive survey of the literature and certain preliminary attempts point to the potential for structural improvement of the soil by using fly ash.
Objective
To propose inexpensive and simple solutions to the cultivation of problematic agricultural soil.
Research Hypothesis
The chemical properties of fly ash, the size of its grains and their spherical shape bring about chemical and physical changes in the soil to which the ash is added that have the potential of improving the soil's fertility.
Interim findings
The addition of fly ash to loess soil increased the structural stability of the soil and hindered the creation of a crust on the soil's surface, thereby improving
water penetration.
The addition of coal ash to sandy soil led to a decrease of up to 90 percent in the rate of water penetration compared to identical soil without coal ash while substantially increasing the water retention. Similarly, the strength of the aggregates in the soil increases, as a result of the pozzolanic features of the ash.
Chrome is the only element whose content in corn ears is significantly affected by the addition of coal ash to the soil. However, despite the high levels of coal ash added to the soil (800 T/hectare), the concentration of chrome (which is a essential element) in the corn ears grown in the plots enriched with coal ash did not reach a level that poses a health hazard.
Future plans
Field experiments to be carried out in various types of soil
Chief researcher
Uri Mingelgrin, Soil, Water and Environmental Sciences Institute, Agricultural Research Organization, Volcani Research Center uriming@agri.gov.il
Dr. Pinhas Fine, Soil, Water and Environmental Sciences Institute, Agricultural Research Organization, Volcani Research Center finep@volcani.agri.gov.il

Fly ash-stabilized urban sewage sludge as a supplement to agricultural soil

Problem
The Israeli regulations require that only enhanced treated sludge ("Class A") be applied on land. Hence sewage treatment plants adopt technologies to pasteurize sludge that is used in agriculture, forestry, etc.
Background data
The Dan Region Sewage Treatment Cities Association (Shafdan) which treats approximately one half of the country's sewage water is required to stop sludge dumping at sea.
The Israeli franchise owners of the N-Viro process, a sludge liming technology which also uses fly ash as active filler, have been selected to build a pilot plant at the Shafdan to lime-stabilize 15-30% of the sludge.
Objective
To propose an inexpensive and high-quality alternative for a filler to stabilize the sewage sludge using the N-Viro method.
To develop alternative uses for fly ash to decrease the long-term dependence on the cyclical fluctuations in the concrete industry.
Research hypothesis
There is no danger to the plant, soil, food chain or the environment in the use of sewage sludge stabilized with lime and coal ash, and no significant change in the biological or nutritional characteristics of the soil will ensue from their use.
Interim findings
Lab tests confirm that the sludge stabilized with alkaline supplements and coal ash filler meet health requirements for Type A sludge both regarding the pathogen count and concentrations of heavy metals.
Greenhouse experiments confirmed that the effect of alkaline stabilized sludge on pH of mixtures with sand was transient and that P nutrition status of the mixtures and of corn test plants was not positively affected.
Future plans
Multi-year field experiments in rain-fed and irrigated crops.
Chief researchers
Dr. Pinchas Fine, Soil, Water and Environmental Sciences Institute, Volcani Research Center, Agricultural Research Organization, Ministry of Agriculture, finep@volcani.agri.gov.il
Uri Mingelgrin, Soil, Water and Environmental Sciences Institute, Volcani Research Center, Agricultural Research Organization, Ministry of Agriculture, uriming@agri.gov.il

Coarse bottom ash as a growth medium in agriculture and gardening

The problem
Low economic value for raw bottom ash in common civil engineering applications.
Global environmental restrictions on the use of methyl-bromide as a disinfectant against diseases in agricultural soils require a transition to container media (substrate growth media).
Authorization has to be obtained from the national food service in the Ministry of Health to grow edible crops on a growth medium containing coarse bottom ash.
Background data
High tech crop production can be better achieved when plants are grown in greenhouses on detached media rather than on local soils.
In some regions of the country the availability of local soils is limited. Substitution is greatly desired.
Raising crops on a detached media facilitates the employment of disinfection methods without the utilization of methyl-bromide.
Authorization has been requested from the National Food Service for the production of annual crops (vegetables, leafy plants, herbs and spices). This authorization request was based on a risk assessment and a comprehensive comparative study of the uptake to plants of heavy metals and radionuclides in edible crops grown on bottom ash medium compared to tuff medium (volcanic ash, widely used in Europe).
Objective
To enhance the economic value of coal ash by separating the particles into size fractions suitable for unique applications having a high added value.
Interim findings
Crop yields on a bottom ash medium with an addition of 20%-30% compost are better compared to natural soil and similar to the results obtained with the commonly used tuff-based medium.
The concentrations of heavy metals in the one-year plant crops grown on coal ash and tuff media are similar to and significantly lower than the maximum permitted values for food.
Coal ash in a mix with compost maintains its high quality as a medium for the continues use for the growth of tomatoes, for as long as eight years after first being utilized in the growth containers.
Future plans
Testing of crops on a medium containing coal ash in detached media, in nutrition throughs obtained over a number of years.
Completion of the permit from the National Food Service for the use of bottom ash as a medium for the growth of perennial plants.
Chief Developer
Professor Yona Chen, Faculty of Agricultural, Food and Environmental Quality Sciences, Hebrew University, Jerusalem yonachen@agri.huji.ac.il

Fine bottom ash as poultry litter

Problem
The development of the use of the leftover fines obtained from sifting of bottom ash.
Background data
The fraction of particles smaller than 4 millimeters represents more than 75% of the bottom ash and is obtained after the filtering of the coarse particles intended for agricultural use.
Poultry growers use wood sawdust as litter to absorb the droppings that accumulates in the henhouses, to prevent disease caused by damp litter and to decrease ammonia concentrations in the air. Sawdust is expensive and quality is not uniform.
Each broiler's grower, which has a six-week growth period, requires the preparation of new litter.
The consumption of litter materials is five times greater than the amount of fine bottom ash needed.
Objective
To define the conditions and identify the types of poultry suitable for the use of fine bottom ash as litter that can absorb liquid dung.
Interim findings
The findings in the area of poultry breeding are not unequivocal, both for the suitability of coal ash for the varying needs of the pullets throughout the growth period, as well as for the final weight of the pullets at the end.
Because of the coal ash's water-adsorption and the volatilization capacities, compared to that of sawdust, it may apparently be possible to scatter litter in henhouses for layers half as frequently.
The large quantitative potential in the raising of a variety of different types of poultry, at the current litter costs, justifies continued research and development.
Chief Developer
Dr. Yisrael Yoselewitz, Agricultural Extension Service (SHAHAM), Ministry of Agriculture isyos@shaham.moag.gov.il

Bottom Ash as absorbent infrastructure in henhouses

Problem
The danger of soil and groundwater pollution with nitrates and chlorides created in large amounts in the dung of layers and which filter down into the ground water.
Background data
Layer henhouses are scattered all over the country, especially in the mountainous area above the principal aquifers, endangering the groundwater. The older family-owned henhouses do not have a cost-effective solution to the problem.
Objective
To propose an inexpensive solution to protect the soil and groundwater in henhouses for layers and meat.
Interim findings
Bottom ash appears to have general water-adsorption capabilities, and in particular the adsorption of nitrates and chlorides, which significantly decreases the percolation of pollutants into the soil. Extracting maximum potential is conditional on the definition of the optimum interface (amount and frequency) for scattering the coal ash.
Future plans
Experiments in batteries in layer henhouses for table-eggs to define the optimum interface for scattering the coal ash.
Chief Developer
Dr. Yisrael Yoselewitz, Agricultural Extension Service (SHAHAM), Ministry of Agriculture isyos@shaham.moag.gov.il

Coal ash as raw material in ceramic glass products

Stage of development
A technological upgrade of a semi-industrial facility for an industrial plant.
Background data
Proven industrial ability to manufacture a wide range of decorative products for the construction and sanitation industries; industrial instruments; protection/armoring products; setting hazardous waste and filtering of liquids.
American licensing for the manufacture of roof shingles for hurricane-sensitive areas in the context of an initiative by investors to build a plant.
Bullet-proof vests manufactured from ceramic glass based on coal ash meet the NATO shooting tests Level III NIJ0101.03.
The products met the maximum-level engineering and environmental testing demands.
Objective
To obtain a higher added value for coal ash.
To develop stable and promising alternative applications for the continued removal of coal ash from power stations and the reduction of dependence on the cement and concrete industry.
Principle quality factors
Ash-based ceramic glass products excel in various properties that can be determined by a processing regime appropriate to the desired product and to attain the best required values: toughness; resistance to blows, bending and pressure; resistance to wear and tear; resistance to extreme changes in temperature; resistance to aggressive chemical environments; positive permeability to liquids, gases and radioactive radiation; different shades and textures.
Dedicated production specifications must be prepared for each coal ash source in order to guarantee products of high quality.
The quality of each product is dependent on a unique temperature profile during the processing.
The remaining unincinerated carbon must be removed before the coal ash is melted in the glass-manufacturing process, to prevent a reducing environment at the heating stage, which triggers the formation of iron alloys.
Future plans
To organize the establishment of a shingle factory.
To continue the development of products with a high added value and the search for markets and investors to establish plants.
Chief Developer
Dr. Alex Raichel, GlassCeraX CeraX@netvision.net.il

Fly ash as filler for plastic products

Development Stages
Experiments in an industrial facility
Background data
The success of the production of gray-colored products containing fly ash filler.
Objective
To obtain a higher added value for coal ash.
To develop a stable industrial application alternative that can assure the continued removal of coal ash from power stations and lower the dependence on the cement and concrete industry.
Chief quality factors
A preliminary study points to the contribution of fly ash to improve the resistance of polypropylene-based plastic products to UV radiation exposure, and attain equality in most other features to those products that contain lime filler.
Future plans
An experiment involving the direct feed of fly ash to through feed mix to the extruder.
Tests to examine the metal and radionuclide content required by the European (French) standard as a condition for the marketing of products geared to children.
Chief Developer
Prof. Shmuel Kenig, Israel Plastics & Rubber Center - IPRC, Shenkar College

Coal ash as filler in emulsion in the production of thermal-acoustic isolation sheets

Development stage
Run on an industrial scope
Background data
Proof of the applicability of the process in the context of a technological incubator funded by the chief scientist of the Ministry of Industry.
Objectives
To obtain a higher added value for coal ash.
To develop a stable industrial application alternative that can assure the continued removal of coal ash from power stations and lower the dependence on the cement and concrete industry.
Chief quality factors
The addition of fly ash increases the density of the sheet and improves the acoustic and thermal capabilities.
The coal-ash based emulsion improves the resistance of the sheet to fire.
Future plans
Completion of the production array.
Chief developers
Prof. Samuel Prestnov, Alexander Prestnov
David Saadon, CEO Isoltherm davidsaadon@nana.co.il

Coal ash as a filler in emulsion for bituminous sheets

Development stage
Integration in existing industrial process
Background data
A successful experiment in replacing lime filler with a bituminous emulsion in the manufacture of isolation sheets designated for the prevention of the passage of water.
Objective
To obtain a higher added value for coal ash.
To develop a stable industrial application alternative that can assure the continued removal of coal ash from power stations and lower the dependence on the cement and concrete industry.
Future plans
To monitor dust during the manufacture of sheets with fly ash to enable completion of the environmental permit process.
Integration of coal ash in the routine manufacture process
Chief Developer
Pazkar factory