Pond Ash Research Articles

Fly Ash Management and Condition Monitoring of Ash Pond

A thermal power plant is the most conventional source of electric power. In the thermal power plants, the coal is used as a fuel which is burnt through combustion process in boilers, and hence, ash is generated as a waste product. Ash is a major pollutant for environment and, thus, is detrimental to the animal and plant life. Also disposal of huge quantity of ash is a burning problem due to non-availability of land. Therefore, an ash pond is essential for the disposal of ash generated in a thermal power station. The ash pond consists of a large pond with ring embankment all around, internal and external drainage system, and toe protection at downstream side. The operation in ash pond takes place by filling with ash slurry, allowing the water to drain and evaporate from the pond over time. The industries are constructing ash ponds of various sizes and shapes depending upon the size and layout of available land and approval from the statutory authorities. The capacities of ponds/lagoons are being increased by raising the dyke height. For the improvement of the reliability and stability of ash ponds, it is necessary to take appropriate measures in every stages, such as designing, construction, operation, maintenance, supervision, and monitoring. Besides the constructional improvement, condition monitoring of ash pond is essential to keep it in normal operating state. This paper focuses on different condition monitoring tools and techniques to enhance the reliability of ash ponds.

Mechanical strength characteristics of fiber-reinforced pond ash for pavement application

The pavement construction sector throughout the world is facing a major challenge of non-availability of suitable construction materials. On the other side, many waste/sub-products are being generated from manufacturing/production units causing environmental pollution. One of such waste materials is pond ash produced from thermal electric power plants, which can be utilized as an alternative construction material in place of traditional materials. In this context, an attempt was made on fiber-reinforced pond ash as subbase layer of flexible pavements to understand its engineering behavior by conducting static (California bearing ratio, CBR) and dynamic (repeated load triaxial, RLT) tests. Randomly distributed polypropylene fibers of various proportions were used in pond ash as reinforcement inclusions. The test results were analyzed to address the influence of fiber on conventional parameters of pond ash such as CBR, resilient modulus (MR), and permanent strain (ϵp). Also, the influence of confining (σc) and deviatoric stress (σd) levels on MR as well as ϵp with load cycles have been investigated for both unreinforced and reinforced pond ash. The results obtained have shown that the inclusion of fiber improves the CBR, MR and ϵp characteristics of the pond ash. With an increase in stress levels (σc and σd), the MR of reinforced pond ash increased compared to non-reinforced ash. Irrespective of the fiber content in pond ash, permanent strain values were increased with an increase in the number of loading cycles and cyclic deviatoric stresses. However, with the introduction of fiber, the rate of strain development in pond ash was reduced significantly. Furthermore, the experimentally obtained MR and ϵp values were validated against existing models established by previous researchers. From the above findings, it can be concluded that fiber-reinforced pond ash can be used effectively in pavement layer applications.

Experimental Investigation on Dynamic Characterization of Equi-Proportionate Silt–Sand Range Pond Ash at High Strain

In the present study, it was attempted to investigate the cyclic resistance of equi-proportionate silt–sand range pond ash (with 50% fines) at relatively high shear strains using the strain-controlled cyclic triaxial test. The cyclic triaxial tests have been performed considering the effect of relative compaction (97–99%), cyclic shear strain (0.6–1.35%), frequency of loading (0.3–1 Hz) and effective confining pressure (50–100 kPa) on cyclic resistance of pond ash. Dynamic characteristics such as dynamic shear modulus and damping ratio of equi-proportionate silt–sand range pond ash was evaluated for all the parameters considered at high shear strain. The maximum value of the dynamic shear modulus and damping ratio of pond ash observed in this study was 6534.8 kPa and 23.64%, respectively. The dynamic shear modulus and damping ratio of pond ash was decreased from 6534.8 to 5023.87 kPa and 23.64 to 14.17% with the increase in shear strain amplitude from 0.6 to 1.35%. Besides, few relationships were established between the amount of energy dissipated until liquefaction and parameters influencing liquefaction using an energy concept.

Predicting the characteristics of pond ash concrete using artificial neural networks

To improve the Engineering perspectives towards the eco-friendly environment, many efforts and researches made in the field of concrete. Adding many supplements to the concrete mix mostly results in durable concrete. Thermal power plants produce a large number of wastes like flyash, pond ash, and bottom ash. Flyash is already being used in cement industries to produce Portland Pozzolana Cement. Some researchers concluded that pond ash could also replace river sand in the concrete mix. Anticipating the compressive strength of pond ash concrete has consistently been trouble since the concrete is sensitive to its blend segments, techniques for blending, compaction, curing condition, and so forth. Scientists have given various strategies for foreseeing the properties of concrete. However, some others were not appropriate enough to predict the compressive strength of pond ash concrete. The point of this investigation is to assess the ability of the Artificial Neural Network Model (ANN) in predicting the compressive strength of pond ash concrete after 28 days of curing. Accordingly, considering specific Concrete characteristics as input factors by considering various rates 0% to 25% in steps of 1% increment of Pond Ash replaced in place of sand in Traditional Concrete of M30 Mix, Artificial Neural Network Model is built, and the properties of concrete predicted. Results demonstrated that ANN could be an alternative approach for anticipating the compressive strength properties of pond ash concrete.

Characterization of pond ash-bentonite mixes as landfill liner material.

Characterization of pond ash-bentonite mixes is made to assess their suitability as liner material for waste disposal facilities by examining the relevant index and engineering properties. Further, a comparative assessment is made between sand-bentonite and pond ash-bentonite mixes for the range of bentonite content varying from 0 to 30% by weight at an interval of 5% to ensure an effective substitution of sand with pond ash. Addition of bentonite to sand or pond ash significantly influences the plasticity, strength and permeability properties. Besides, the shape parameters of the coarser fraction and morphology of compacted mixes also influence the engineering properties. A multiple linear regression equation is suggested to predict the hydraulic conductivity of these mixes by considering the basic material properties such as liquid limit, plasticity index and void ratio as an input variable with a correlation coefficient of 0.92 between the measured and predicted hydraulic conductivity values. At comparable conditions, compacted pond ash-bentonite mixes exhibit higher strength but also higher permeability than sand-bentonite mixes. Pond ash-bentonite and sand-bentonite mixes met the liner requirements when compacted with modified Proctor compaction effort at a minimum bentonite content of 20% and 15%, respectively.

A review on fly ash from coal-fired power plants: chemical composition, regulations, and health evidence.

Throughout the world, coal is responsible for generating approximately 38% of power. Coal ash, a waste product, generated from the combustion of coal, consists of fly ash, bottom ash, boiler slag, and flue gas desulfurization material. Fly ash, which is the main component of coal ash, is composed of spherical particulate matter with diameters that range from 0.1 μm to >100 μm. Fly ash is predominately composed of silica, aluminum, iron, calcium, and oxygen, but the particles may also contain heavy metals such as arsenic and lead at trace levels. Most nations throughout the world do not consider fly ash a hazardous waste and therefore regulations on its disposal and storage are lacking. Fly ash that is not beneficially reused in products such as concrete is stored in landfills and surface impoundments. Fugitive dust emissions and leaching of metals into groundwater from landfills and surface impoundments may put people at risk for exposure. There are limited epidemiological studies regarding the health effects of fly ash exposure. In this article, the authors provide an overview of fly ash, its chemical composition, the regulations from nations generating the greatest amount of fly ash, and epidemiological evidence regarding the health impacts associated with exposure to fly ash.

Antioxidant responses against aluminum metal stress in Geitlerinema amphibium

In the current scenario, aluminum is one of the major metals that cause environmental pollution and has ill impact on organism health. As around 40% of bauxite deposits of India are available in Odisha, aluminum toxicity in the soil has impacted as an intimidating problem of Odisha. This aluminum metal pollution is regarded as a primary factor for limiting crop productivity in acidic soils of tropic and subtropic countries. The presence of a high degree of aluminum metal in the soil leads to loss of beneficial microflora, i.e., nitrogen-fixing cyanobacteria that play a key role in soil fertility. Hence, this investigation was performed on a filamentous non-heterocystous cyanobacterium Geitlerinema amphibium isolated from the aluminum-polluted sites, i.e., NALCO, Ash pond, Angul to uncover the defense mechanism of the strain exhibited under such stress. The strain was treated with different doses of AlCl3 (0–100 µM), and we observed redox imbalance leading to oxidative stress. Post-treatment of AlCl3, a remarkable decline in growth was evident with possible modifications in pigments associated with the phenomena. Further to combat against the stress under the redox environment, the organism activated antioxidant enzymes CAT, APX, GR, GPX, and SOD which were measured to identify the key responses involved in it. All the stress responsive enzymes were analyzed to demonstrate the interlink between the induction of stress and their detoxification through cellular response. The outcome of the work explored the multifaceted role of oxidative upset caused by AlCl3 pollutants and the cellular antioxidative strategies deployed by G. amphibium to nullify them.

Non-invasive biomonitoring of mercury in birds near thermal power plants: lessons from Maharashtra, India.

Thermal power plants (TPPs) have emerged as a major source of air, water, and soil pollution because of the presence of many toxic metals. The presence of mercury (Hg) in fly ash has proven to be toxic in nature because of its tendency to get bioaccumulated and biomagnified in the food chain. The aim of the present study was to understand the presence of toxic Hg in the feathers of wetland birds undertaking the study around a TPP located in Nagpur, India. Local wetland birds especially cattle egrets, heron, and Moorhen were commonly observed dwelling close to fly ash ponds for various purposes (roosting, breeding, feeding, etc.). Samples of fly ash, soil, water, plants, and bird feather were collected, cleaned, and processed for Hg analysis. A mercury analyzer was used to assess the concentration of toxic levels of Hg in samples. Our results reflect leaching of Hg in soil and uptake by plant samples, whereas in water, ash, and bird feather samples concentrations of Hg were fairly below the prescribed limits (World Health Organization). A non-invasive method for understanding the mercury concentration in wetland birds has been established as a potential important monitoring tool to track the fate of toxic metal Hg in the food chain. In summary, our results indicate fairly low Hg levels in feather samples projecting non-invasive biomonitoring as a promising strategy. The study also suggests that a comprehensive monitoring action plan in place for Hg and other toxic metals in the food chain that comes from TPP will be efficient to avoid any pitfalls. Graphical abstract.

Mercury, arsenic, lead and cadmium in waters of the Singrauli coal mining and power plants industrial zone, Central East India.

The present investigation is an attempt to assess the contamination of heavy metals in the ground and surface water of the Singrauli industrial belt area. Pollution indices like heavy metal index (HPI), contamination index (CD) and heavy metal evaluation index (HEI) are used for the evaluation of heavy metal pollution (arsenic As, mercury Hg, cadmium Cd, and lead Pb). Contour maps are constructed to interpret metal spatial distribution. Further, the land-use/land-cover (LULC) maps for the year 2000, 2010 and 2016 are prepared using Landsat satellite data. A total of 48 water samples (Groundwater (27), Surface water (21)) are analysed for heavy metal concentration. Eighty-eight percent of groundwater and 90% of surface water samples are contaminated with Hg. Similarly, high concentrations of Pb and Cd were found in the samples. Surprisingly, all the water samples have As concentration above the WHO permissible limit of 10ppb. Further, 95% of the samples have an HPI value greater than 100 indicating high heavy metal contamination. CD value denotes contamination of 89% of the samples with heavy metals (As, Hg, Cd, Pb). Through spatial distribution, it can be interpreted that most of the contaminated samples lie near thermal power plants, ash ponds, and coal mines. LULC (land use/land cover) study shows a significant decrease in water bodies by (108km2), agricultural land by (54km2) and bare/fallow land by (51km2) from 2000 to 2016. During these 16years, there has been a fourfold increase in the overburden, a threefold increase in dumping yards, a 2.5 times increase in urban areas, and a twofold increase in mining areas. Both the environment and the water quality are deteriorating at an alarming rate. Such scientific investigations are relevant for risk management studies of potable water. The knowledge acquired from such assessment shall be considered with utmost priority by concerned authority considering degrading water quality in the study area. Hence, this study is applicable for designing action plans and control measures to reduce water resource pollution.

A Proposed Mix Design of Concrete with Supplementary Cementitious Materials by Packing Density Method

Various mix design methods have been proposed by different researchers for determining the quantities of concrete ingredients, using local materials and to achieve required strength and durability. It is always desirable to compose the aggregates as dense as possible when selecting a concrete mix design. Hence packing density is one of the most important parameters which minimize the necessary amount of binder, result in less shrinkage and creep. In this research, a mix design method is proposed by using the principle of dense particle packing arrangement to sustainable concrete by partial replacement of cement and sand with fly ash and pond ash, respectively. Various mixes were prepared with combinations of replacement material, and a best combination is selected according to maximum compressive strength of 28-day curing. That optimized combination is further designed by packing density method and compared the mix proportions with Indian Standard Code method. It is concluded that packing density method reduces the material consumption as well as cost of construction with keeping the environment clean and green without compromising the strength and durability.

Evaluation of a 3.5-MW Floating Photovoltaic Power Generation System on a Thermal Power Plant Ash Pond

This study evaluated the design and performance of an improved 3.5 MW floating photovoltaic (PV) power generation system consisting of fiber-reinforced polymer (FRP) members and its installation in the ash pond of a thermal power plant. The FRP design code of the American Society of Civil Engineers was used to design the structure. The safety of the structure was then confirmed using a finite element analysis indicating that the induced stresses were less than the allowable stresses dictated by the Korean Highway Bridge Design Code. An examination of the energy performance of the floating PV energy generation system after installation determined that the measured electricity production was as high as approximately 94% of the installed 3.5-MW capacity. The energy production of the floating PV structure with the improved design and module angles was found to increase by 7.65 times.

T Ikatan Baja Tulangan Pada Beton Pond Ash Sebagai Pengganti Sebagian Pasir

Pond ash concrete bond is expected to increase bond strength, because in previous studies pond ash concrete resulted in increased mechanical properties of concrete. Bond strength is the bonding mechanism between steel reinforcement and concrete in reinforced concrete construction as the main tool to transfer internal strength between reinforcement and concrete. In this study, a total of thirty-six cylinder concrete with a diameter of 15 cm and a height of 30 cm. Variations of the test parameters are three reinforcement diameters of 12 mm, 16 mm and 25 mm and two types of reinforcement namely plain reinforcement and deform reinforcement for normal concrete and pond ash concrete, using a 25 MPa normal concrete mix design and water cement ratio of 0.52. The results showed that the increase in bond strength on the plain reinforcement from 84.49 kg/cm2 to 91.33 kg/cm2 an increase of 8.09%, while for deform reinforcement there was in increase from 119.70 kg/cm2 in concrete normal to 131.32 kg/cm2 an increase of 9.71% in pond ash concrete. Split collapse occurs in deform reinforcement, whereas in plain reinforcement, slip collapse occurs.

Modeling of UCS value of stabilized pond ashes using adaptive neuro-fuzzy inference system and artificial neural network

This paper investigates the capability of adaptive neuro-fuzzy inference system (ANFIS) and artificial neural network (ANN) modeling approach to predict the unconfined compressive strength (UCS) of stabilized pond ashes with lime alone and in combination with lime sludge. Out of 170 data set, a total of 119 data were randomly selected for training, whereas remaining 51 were used for testing the model. Four membership’s functions (MFs) such as Gaussian, generalized bell-shaped, triangular, and trapezoidal were used with ANFIS model. Statistical parameters were used to compare the performance of four MF-based ANFIS and ANN models. A comparison of results suggests that Triangular MF-based ANFIS model exhibit better predictive performance with higher CC = 0.980 and lower MSE = 3028.515 and RMSE = 55.032 than other MF-based ANFIS and ANN model. The results of single-factor analysis of variance indicate that there is an insignificant difference between measured and predicted values of UCS using different models. Further, results of sensitivity analysis depict that the curing period, lime sludge, and lime are the most important parameters which affect the performance of Triangular MF-based ANFIS in predicting the UCS of stabilized pond ashes. Thus, the Triangular MF-based ANFIS model could be a useful tool in predicting the UCS value of stabilized pond ashes because of its adequacy in handling uncertainties in the test results with accuracy.

Environmental impact assessment of inland purification and desalination plants: case study of Al Asyah plant, Qassim region, Central Saudi Arabia

The impact of reject brine chemical composition and disposal from Al Asyah inland desalination on soil and groundwater was evaluated. The reject brine is disposed directly into a surface impoundment in a permeable soil with low clay content. Samples were collected from four evaporation ponds and chemically analyzed. The total dissolved salts (TDS) and the concentration of radioactive constituents were quantified. The results indicate high concentrations of TDS in the evaporation ponds where it ranges from 9650 to 15,460 mg/l. The majority of TDS include sodium chlorides produced throughout the isolation process of fresh water from brine. Moreover, the radioactive isotopes of radium-226 and radium-228 have been identified with total concentrations of 78.89 and 198.77 (pCi/l), respectively. These concentrations may be increased over time due to increasing of radon accumulation in the filtration sands. These results indicate that these constituents are above the standards set by the Gulf Cooperation Council and the Saudi National standards for drinking water and effluents discharged into the desert. Hence, reducing of the environmental impact resulting from both the radioactive materials and the ratio of salinity in water is of utmost importance for Al Asyah plant. Furthermore, the continuous monitoring of the effects of radioisotopes on the validity of the adjacent groundwater is highly recommended.

Design of Foundation Footings on Fly Ash Under Axial Loading

Nearly 65,000 acres (27) of valuable land is occupied by ash ponds. The pond ash deposits are characterized by its very low bearing capacity and high compressibility, rendering them unsuitable for any civil engineering structures constructed over it. Any construction activity over abandoned ash ponds needs a proper understanding of the physical and mechanical properties of these deposits and also the suitability of any ground improvement techniques that can be adopted. Even though adequate substitute full scale field tests are not available. Tests at laboratory scale provide a means to closely control many of the variable encountered in practice. The trends and behaviour pattern observed in the laboratory tests can be used in understanding the performance of the structures in the field and may be used in formulating mathematical relationship to predict the behaviour of field structures. Keeping this in mind laboratory investigations were carried out to determine the physical and mechanical properties of pond ash. In addition, axial load tests were carried out to determine the settlement behaviour of footing specimens. The article outlines experimental work undertaken, the methodology adopted and the salient test results.

Estimating the feasibility of using industrial solid wastes as raw material for polyurethane composites with low fire hazards

Solid wastes including phosphate tailings (PT) and fly ash (FA) are by-products with large quantities and deposited in surface impoundment without treatment, which can easily trigger environment issues. The comprehensive utilization of industrial solid wastes has received intensive attention. In present work, the recycling of industrial solid wastes was studied to explore the probability of utilizing PT and FA as fillers for fabrication of polymer materials with low fire hazards. The micro-sized PT and FA powders were firstly treated with silane coupling agents and then introduced into thermoplastic polyurethane (TPU) through solvent blending method. The influences of solid wastes on the thermal degradation behavior, as well as the fire hazards of TPU were explored. The thermogravimetric analysis results illustrated that due to the introduction of PT and FA, the thermal degradation rate was reduced while the thermal degradation temperature and char yields were increased, in contrast to pristine TPU. The cone calorimetry test results demonstrated the introduction of PT and FA obviously reduced the heat release rate (HRR), total heat release (THR), smoke production rate (SPR), total smoke release (TSR), carbon monoxide (CO) and carbon dioxide (CO2) emission rate of TPU composites. Therefore, the PT and FA might be promising fillers for fabrication of polymeric materials with controllable properties and provide a novel solution for effective recycling of industrial solid wastes.

Compaction and strength characteristics of an expansive clay stabilised with lime sludge and cement

The chemical stabilization of expansive soils has been found to be quite successful in controlling detrimental volume changes due to swell-shrink behaviour. Lime, cement, CaCl2, fly ash, pond ash and other chemical reagents have been effective in stabilizing expansive soils and improving their characteristics. The influence of lime sludge, a by-product of the paper industry, on the index properties of expansive clays was investigated. Their LL, PI and FSI, and the engineering characteristics of these clays were measured after being treated, including their compaction characteristics, stress-strain behaviours at different curing periods and CBRs. The index and engineering properties of the clay-lime sludge blends were studied for different lime sludge contents. As the compacted density did not show a satisfactory improvement upon addition of lime sludge, 10% cement was added to all the lime sludge-clay blends to study its influence on the above properties of lime sludge–treated expansive clay. The addition of 10% cement resulted in lower LL, PI and FSI and higher densities, strengths and CBRs.

Suitability Of Geocomposite Layer For Fly Ash Ponds

At present main source of energy in India are thermal power plants that run on coal for energy production. An estimated total fly-ash produced as by-product from these electric plants yearly accounts to 100 million tons. Fly ash utilisation has picked up by cement factories and others but still percentage is unsatisfactory. This fly-ash is pumped into the ash pond which with time escapes into the environment at the bottom level or from surface. Thus the hazardous waste is a critical challenge to the environment and water bodies, therefore, must be managed at the earliest. Recent GCL or HDPE bottom lining layers are a suggestive solution for preventing toxic materials from seepage into the surrounding areas.

Enhancing the Bearing Capacity of Pond Ash Soil by Inducing Stone Columns

As all of us know that ash pond deposits consist of large compressiblity,less bearing power,that is why large amount of these weak land sections gets abandoned or squandered.These slumy areas have less tangential shear force. As we know our country population is growing day by day.In future ,it will become very difficult to acquire any piece of land for construction of buildings and any other engineering structures.Nowadays many improvement methods for these low quality soils are implementedwhich makes them fit for use for common practices which can be carried out by these soils.As ,this is great area of concern for many highly standard people and other common organisations .On one side growing population with rapid increase and other side lot of sections of land gets trapped up under these ash deposits.A lot of studies and observations have been evaluated about inducing stone columns at plastic Cohesive soils.But yet no such works or observations have been implemented on these weak deposits.So in current study our main efforts relies upon testing these weak deposits of soil individually and after getting upon results from them,we try to observe these weak soils on treating them with some segments of fresh stones and then observe the variations and differences between first and second stages of these testing programmes.

Design of Eco-Friendly Geo-Composite Liner for Fly ash Ponds

This paper aims to design of geocomposite liner for fly ash ponds. Our country has many thermal plants, which generates huge amount of flyash as a waste and their disposal require some of the crucial treatment and engineered flyash pond. The problems from coal based thermal plants is disposal of such flyash. In the present research, Clayey soils, Sodium bentonite and black cotton soils used as a liner for fly ash pond, instead of HDPE sheet to reduce the heavy metal contaminants leachate. Recent GCL, HDPE or Geocomposite liners as bottom lining layers are a suggestive solution for preventing toxic materials from seepage into the surrounding areas. The obtained results of this research indicate that the more percentage of concentration of heavy metals like Arsenic, lead, cadmium and chromium are retained in sodium bentonite layer than the black cotton soil. Hence it is, recommended that among the different liners, sodium bentonite is the most appropriate geocomposite liner, as it’s self-healing and swelling properties provides more retention capacity of toxic heavy metals. The present invention relates to a geocomposite liner system for fly ash pond to reduce the leaching of toxic metals in ground water. The geocomposite liner system comprises of at least one fibrous layer having a layer of sodium bentonite material; a non-fibrous layer mechanically and non-adhesively affixed between fibrous layers. A suitable thickness of bentonite clay is encapsulated between the fibrous and non-fibrous layers, it can retain the Arsenic, Cadmium, Chromium and Lead metals in it. This Geo composite liner is most suitable, economical and easy to install over CCLs and GCLs.