Faculty Publications

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    Assessment of ferrous slag with relevance to physico-chemical properties
    (Springer, 2020) Anjali, M.S.; Poorani, M.; Shrihari, S.; Sunil, B.M.
    Blast furnace slag is generated as a by-product in the production of iron. Large quantities of slag are visible in the industrial premises that can have adverse effects on the environment. To mitigate such problems, proper environmental management of slag is of great concern. In this regard, a qualitative and quantitative evaluation of ferrous slags such as crystallinity, surface morphology, and elemental composition were done using X-Ray Diffraction and Field Emission Scanning Electron Microscope with EDS (Energy Dispersive X-Ray Spectrometer), respectively. It is also characterized to determine heavy metals and functional groups using Atomic Absorption Spectroscopy and Fourier Transform Infrared Spectroscopy techniques for various geo-environmental applications. The nonplastic slag material showed 85–92% sand-size particles and 8–15% silt-size particles. The SiO2 and CaO values were found to be high followed by Al2O3, MgO, and other compounds. Since slag performed similarly to sand, it could be used as an alternative source of sand. © Springer Nature Singapore Pte Ltd. 2020.
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    Effect of wastewaters on the geo-technical properties of laterite
    (2005) Sunil, B.M.; Shrihari, S.
    Soil contamination arises from variety of sources, which include acid rain, hazardous liquid and solid waste from industries, animal waste, salt-water intrusion, etc. Literature relevant to the soil-pollutant interaction reveals that soil properties and behaviour is influenced and altered due to contamination by pollutant. The soil pollutant interaction depends on various factors such as nature and chemical composition of soil, dielectric constant of pore fluid, organic matter etc. Sulphur dioxide and oxides of nitrogen are the two most important parameters responsible for acid rain. Atmospheric pollution has resulted in the precipitation having pH less than 5.6 disturbing the nature's delicate balance and also contamination of soil. The soil and ground water contamination will result in Socio-economic and environmental impact. Several studies by various researchers have highlighted the influence of physico-chemical factors on the engineering properties of soil. The alteration of characteristic properties of the soil in the vicinity of industrial plants occurs mainly as a result of their pollution. Literature review on the effect of acid rain on soils indicated that the pH value of soils generally decreased with continuous infiltration. The major soil chemical parameters affecting the contaminant partitioning are hydrogen ion concentration in the soil, which influences all chemical reactions and biological activities. Laterites and lateritic soil have a very important place in Civil Engineering activities in India, especially in the South and Central parts. They form a good foundation material and are composed essentially of hydrated aluminium and iron oxides. In this paper, the results of an investigation on the effect of pH on the characteristic properties of laterite soil procured from the quarry near Mangalore, located on the western coast of south India, has been discussed. The effect of pH on the characteristic properties of laterite was studied under different pH conditions (i.e. pH =5.0, pH=7.0, pH=8.0). The pH of water in which the laterite blocks were soaked (up to ninety days) was maintained using buffers. The important properties considered for the study are: compressive strength of laterite blocks, Atterbeig limits, shear strength properties and chemical characteristics of laterite soil (pH, conductivity, alkalinity, hardness, chloride, sulphate and ammonia nitrogen). From the investigation it is observed that the engineering properties and chemical characteristics of laterite soil are altered in all the three pH conditions (pH=5.0, pH=7.0, pH=8.0). The compressive strength of laterite blocks reduced under all the pH conditio is and considerable reduction in strength was observed when the pH of water was maintained as 5.0. The pH of adjoining water body has remarkable influence on the pH of soil. Accordingly when the pH of water was low (p -1=5.0), the corresponding pH of soil decreased from its initial value. Similarly soil pH increased when the pH of water was maintained as 8.0 for soaking up to ninety days. The various other effects on the engineering behaxiour and chemical characteristics of laterite are noted and discussed in the present work.
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    Soil-leachate interaction and their effects on hydraulic conductivity and compaction characteristics
    (2008) Sunil, B.M.; Shrihari, S.; Nayak, S.
    Leachate is the most dangerous component of the solid waste management process. In a small landfill, the amount of leachate generated may not create a serious problem. As the size of landfill and variety of solid wastes disposed increases, large amounts of leachate will be generated and create environmental problems such as leaching of nutrients and heavy metals into the soil which leads to soil and ground water contamination. The problem of change in behaviour of soils on one hand and the contamination of ground water on the other is a cause of concern for geotechnical and environmental engineers. In this paper, results of a laboratory study to determine the effects of leachate contamination on the hydraulic conductivity and compaction characteristics of shedi soil (also known as lithomargic clay) have been presented. The study has indicated that leachate can modify the soil properties and significantly alter the behaviour of soil. There is a general deterioration in soil properties which is attributed to the chemistry of leachate and of soil. The interaction of leachate with soil is responsible for the modified behaviour of the soil.
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    Modeling of the transport of leachate contaminant in a landfill site: A case study in mangaluru
    (CRC Press/Balkema, 2018) Divya, A.; Shrihari, S.; Ramesh, H.
    Ground water flow and the solute transport model MODFLOW and MT3DMS were established to determine the spread of contamination from a landfill maintained by Mangaluru City Corporation at Vamanjoor, located nearly 8.5 km from the center of the city. As Vamanjoor is home for many educational institutes and also a residential area, the spread of the contamination has to be analyzed. For this study, the aquifer considered is a subbasin of the Gurupur basin. This study has focused on handling the data available in the most efficient way to develop a consistent simulation model. The model was calibrated successfully with RMSE value of observed versus simulated head as 0.32 m. The evaluation of model was also done by comparing with the measured water head and chloride level from the field on a seasonal basis. After validating successfully, the model was run to determine the extent of contamination and also to forecast a scenario for maximum rainfall. The results show that the contamination has spread to a distance of 1 km from the landfill and with maximum rainfall the spread will be around 1.8 km from the landfill. © 2018 Taylor & Francis Group, London.
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    Spatial Variability of Organic Carbon and Soil pH by Geostatistical Approach in Deccan Plateau of India
    (Springer Science and Business Media Deutschland GmbH, 2023) Vinod, N.T.; Shetty, A.; Shrihari, S.
    Proper soil nutrient management is necessary to meet India’s rising population without degrading the environment. However, the state of soil organic carbon (SOC) and soil pH is a concern, especially in Indian vertisols that are productive when well managed. Due to a lack of scientific knowledge and poor soil management among the small-scale farmers (most Indian farmers hold less than 2 ha), the crop yield has declined. The current study examines the correlation between soil pH and SOM and their spatial variability in vertisols (Black-Cotton soil). Geostatistics and conventional statistics are used to produce the spatial distribution maps, with the R software and the SpaceStat. Sixty-eight soil samples at the root zone level (0–15 cm depth) are collected from Gulbarga Taluk, Karnataka, India. The random sampling method is adopted according to the agriculture fields distribution, and each sample consists of five subsamples. The soil pH was estimated by pH meter and SOC by Walkley and black method. The violin plots indicate that most soil pH samples range from 8.5 to 7.5 and SOM 0.20–0.50%. The Pearson correlation indicated a negative correlation between the two parameters (r = −0.21). In semivariogram analysis, the spherical and exponential models were best fitted for soil pH and SOM, respectively. The ordinary kriging accomplished by a traditional estimator is adapted for generating spatial distribution maps. In line with the negative correlation of soil pH and SOC, the predictable maps are the mirror images. The spatial variability maps give an overview of how extrinsic and intrinsic factors affect the availability of soil pH and SOC. In this region, the parent materials, fertilizers application, and agricultural practices are affecting the soil variability. Small scale farmers should assess these spatial variability maps before applying the fertilizers. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
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    Seasonal and Lockdown Effects on Air Quality in Metro Cities in India
    (Springer Science and Business Media Deutschland GmbH, 2023) Krishna Raj, K.; Shrihari, S.
    Air pollution is one of the worst avoidable threats in developing nations across the world. India has undergone a substantial number of infrastructure changes during recent years due to the ever-increasing population. This and the consequent industrialization, the air quality of Indian cities became worsened. The changes in climatic conditions across various cities in India also contribute to air pollution. To control the air pollution within the acceptable limit several control measures have been imposed in India, despite these efforts the air pollution level has not decreased considerably. In India, the first COVID-19 case has reported on 30th January 2020 in the state of Kerala. To control the quick spread of COVID-19 in India, the central government executed a three-week nationwide lockdown from 24th March 2020, and further, it has extended into several phases. It was the first time in India a long-term shutting down of all the sectors happening and which resulted in positively on the environment. This study is dealing with the lockdown effect on air quality in metro cities in India and is compared with the pre-existing conditions. Also, the seasonal variations in air quality in the course of the past two years are compared. The data of pollutants PM10, PM2.5, SO2, NO2, O3, CO, and NH3 from metro cities were collected and by adopting the National Air Quality Index to depict the variations in overall air quality. During the lockdown period, most of the cities experience a considerable improvement in overall air quality and PM10, NO2, PM2.5, and CO concentrations. Whereas, the Ozone shows some increasing trend in a few cities might be due to the increment in the temperature caused by the exposure of sun during the summer season. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
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    Green Synthesis of Zinc Oxide Nanoparticles and Study of Its Adsorptive Property in Azo Dye Removal
    (Springer Science and Business Media Deutschland GmbH, 2023) Anupama, C.; Shrihari, S.
    Dyes are important colouring chemical compounds widely used in textile, paper, food, cosmetics and pharmaceutical industries. Most of the dyes are highly toxic and potentially carcinogenic. Exposure to high doses of these compounds can have severe effects in the human body. When untreated dye effluents are directly discharged into water bodies it leads to water contamination. Adsorption is an efficient method for the dye removal. It is also an economical technique. Green synthesis helps in the production of cost-effective and ecofriendly adsorbent. In this paper, green-synthesized zinc oxide nanoparticles were widely used for the removal of azo dye; methyl orange. Zinc oxide nanoparticles (ZnO NPs) were synthesized using Plectranthus Amboinicus leaf extract. The structure of nanoparticles was visualized using Field Emission Scanning Electron Microscope (FESEM). Nanoparticles due to their small size and thus large specific area are strong adsorbents. The effect of various parameters like dye dosage, zinc oxide nanoparticle loading, pH and contact time was evaluated. In batch adsorption study, maximum removal efficiency of 85.41% was obtained with zinc oxide nanoparticle dosage of 3 g initial dye concentration of 10 mg/l, pH 6 and contact time of 3 h. Adsorption parameters fitted well in the Langmuir isotherm model with a correlation coefficient (R2) of 0.975. Adsorption kinetic studies revealed that adsorption strongly followed pseudo-second order. This paper suggests a safe, economical and environment-friendly technique for the removal of azo dyes. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
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    A comprehensive analysis of water quality of open wells at Alevuru and Badagabettu-76 village of Udupi Taluk, Karnataka, India
    (Institute of Physics, 2024) Sharma, H.S.; Rakesh, R.; Shrihari, S.
    The availability of pure water is one of the most essential requirements for all living organisms. In rural areas of Udupi, Karnataka, India, well water serves as the primary source of water for residents. Hence the objectives of the study were to find the physical and chemical characteristics of the well water sources in Udupi taluk; and to assess the suitability of the well water sources in Udupi taluk for drinking purposes by determining water quality index (WQI). Water samples (n=24) were collected from open wells from Alevuru and Badagabettu-76 villages of Udupi taluk during October 2023. Water quality parameters analyzed were pH, total dissolved solids, electrical conductivity, turbidity, total alkalinity, total hardness, dissolved oxygen, nitrate, chloride, sulphate, chemical oxygen demand and iron. The WQI revealed that the well water in majority of the sites was fit for drinking. All parameters were within the permissible limits in majority of the wells except for iron and pH. © Published under licence by IOP Publishing Ltd.
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