Department of Civil Engineering

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Author: search.filters.author.Singhal, AnupamSubject: search.filters.subject.Civil Engineering

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Now showing 1 - 10 of 21
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    An Assessment of Qualitative and Quantitative Municipal Solid Waste City Compost by Indexing Method
    (Springer, 2023-09) Khare, Srishti; Singhal, Anupam
    Globally, the disposal of municipal solid waste (MSW) is a significant environmental challenge. The production of MSW is continuous in megacities, small cities, and large villages, and if wastes are not managed properly, they can have a detrimental effect on both the environment and human health. Processes such as incineration, anaerobic digestion, and composting are widely adopted. The MSW city compost (MSWCC) generated poses significant challenges due to the presence of a high amount of residual metal toxicity. Therefore, the researcher examined the material's physical and chemical properties, as well as its heavy metal content and spectral characteristics were investigated to assess the applicability of its use for different purposes generated from MSW dump yards. For this purpose, spectral characterization including mineralogical analysis with X-ray diffraction (XRD) was used to determine the presence of heavy metals; topographical imaging and elemental mapping with a scanning electron microscope and energy dispersive X-ray analysis were carried out (FESEM-EDX). Current investigation shows that (i) XRD, SEM–EDX confirms the evidence of HMs in MSWC; (ii) In terms of Zn, Cu, Cd, Pb, and Ni, MSW compost did not meet the quality control guidelines of ‘The Fertilizer (Control) Order 1985.’ (iii) Using the Indexing method, the Fertilizing Index (FI) of compost was found to be 4.4, which means it has a high potential to fertilize. The Clean Index (CI) of compost, on the other hand, was found to be 1.7, which means it has a high potential to pollute with heavy metals; (iv) The compost sample belongs to RU-3 (Restricted Use category 3) class and, hence, has been found unsuitable for any kind of use.
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    Delineation of agricultural fields in arid regions from Worldview-2 datasets based on image textural properties
    (Springer, 2023-04) Singhal, Anupam
    Barren lands are being transformed into agricultural fields with the growing demand for agriculture-based products. Hence, monitoring these regions for better planning and management is crucial. Surveying with high-resolution RS (remote sensing) satellites like Worldview-2 provides a faster and cheaper solution than conventional surveys. In the study, the arid region comprising cropland and barrenlands are efficiently and autonomously delineated using its spectral and textural properties using state-of-the-art random forest (RF) ensemble classifiers. The textural information window size is optimized and at a GLCM (gray-level co-occurrence matrix) window size of 13, a stable trend in classification accuracy was observed. A further rise in window sizes did not improve the classification accuracy; beyond GLCM 19, a decline in accuracy was observed. Comparing GLCM-13 RF with the no-GLCM RF classifier, the GLCM-based classifiers performed better; thus, the textural information assisted in removing isolated crop-classified outputs that are falsely predicted pixel groups. Still, it also obscured information about barren lands present within croplands. Delineation accuracy was 93.8 % for the no-GLCM RF classifier, whereas, for the GLCM-13 RF classifier, an accuracy of 97.3 % was observed. Thus, overall, a 3.5 % improvement in accuracy was observed while using the GLCM RF classifier with window size 13. The textural information with proper calibration over high-spatial resolution datasets improves crop delineation in the present study. Henceforth, a more accurate cropland identification will provide a better estimate of the actual cropland area in such an arid region, which will assist in formulating a better resource management policy.
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    Heavy metal remediation using chelator-enhanced washing of municipal solid waste compost based on spectroscopic characterization
    (Springer, 2023-04) Singhal, Anupam; Srinivas, Rallapalli
    Due to high metal toxicity, mixed municipal solid waste (MSW) compost is difficult to use. This study detected the presence of heavy metals (Cd, Cu, Pb, Ni, and Zn) in MSW compost through mineralogical analysis using X-ray diffraction (XRD) and performed topographical imaging and elemental mapping using a scanning electron microscope and energy dispersive X-ray analysis (SEM–EDX). Ethylenediaminetetraacetic acid (EDTA), a typical chelator, is tested to remove heavy metals from Indian MSW compost (New Delhi and Mumbai). It deals with two novel aspects, viz., (i) investigating the influence of EDTA-washing conditions, molarity, dosage, MSW compost-sample size, speed, and contact time, on their metal removal efficiencies, and (ii) maximizing the percentage removal of heavy metals by determining the optimal process control process parameters. These parameters were optimized in a batch reactor utilizing Taguchi orthogonal (L25) array. The optimization showed that the removal efficiencies were 96.71%, 47.37%, and 49.94% for Cd, Pb, and Zn in Delhi samples, whereas 45.55%, 79.52%, 59.63%, 82.31%, and 88.40% for Cd, Cu, Pb, Ni, and Zn in Mumbai samples. Results indicate that the removal efficiency of heavy metals was greatly influenced by EDTA-molarity. Fourier-transform infrared spectroscopy (FTIR) confirmed the presence of hydroxyl group, which aids heavy metal chelation. The results reveal the possibility of EDTA to reduce the hazardous properties of MSW compost.
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    Effect of urbanization on the urban lake water quality by using water quality index (WQI)
    (Elsevier, 2023-07) Srinivas, Rallapalli; Singhal, Anupam
    Lake water serves an efficient source of drinking, irrigation, agriculture, industry, construction, domestic and recreation use for the urban and rural population of developing countries. The paper focuses on the assessment of water quality on the selected lakes which is affected by the speedy development of the city under the sprawl of urbanization and concretization by applying Water Quality Index (WQI) tool. Four lakes, namely Hebbal, Ulsoor, Allasandra and Mahadevapura are selected in the silicon city, Bengaluru for water quality assessment. A total of 10 parameters were taken into consideration, such as pH, turbidity, total alkalinity, total acidity, total phosphorus, COD, BOD, DO, nitrates and total nitrogen from 2 sampling sites depending upon the source of wastewater or sewage discharges. Water samples were collected and prepared for composite samples. These composite samples were examined for their different chemical and physical properties and the results were compared with standard permissible values. The results of WQI of Hebbal Lake (70.89–72.74), Ulsoor Lake (83.44–83.3), Allasandra Lake (54.47–51.84) and Mahadevapura Lake (159.41–155.81) showed that the lakes fall under poor, very poor and unsuitable categories. The results pointed out the anthropogenic activities and entry of untreated sewage into the lake. This confirms the urgent need for regular monitoring of lakes and setting up of certain policies for lake water management.
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    Bio-chelate assisted leaching for enhanced heavy metal remediation in municipal solid waste compost
    (2024-06) Singhal, Anupam; Srinivas, Rallapalli
    Municipal solid waste compost, the circular economy's closed-loop product often contains excessive amounts of toxic heavy metals, leading to market rejection and disposal as waste material. To address this issue, the study develops a novel approach based on: (i) utilizing plant-based biodegradable chelating agent, l-glutamic acid, N,N-diacetic acid (GLDA) to remediate heavy metals from contaminated MSW compost, (ii) comparative assessment of GLDA removal efficiency at optimal conditions with conventional nonbiodegradable chelator EDTA, and (iii) enhanced pre- and post-leaching to evaluate the mobility, toxicity, and bioavailability of heavy metals. The impact of treatment variables, such as GLDA concentration, pH, and retention time, on the removal of heavy metals was investigated. The process was optimized using response surface methodology to achieve the highest removal effectiveness. The findings indicated that under optimal conditions (GLDA concentration of 150 mM, pH of 2.9, retention time for 120 min), the maximum removal efficiencies were as follows: Cd-90.32%, Cu-81.96%, Pb-91.62%, and Zn-80.34%. This process followed a pseudo-second-order kinetic equation. Following GLDA-assisted leaching, the geochemical fractions were studied and the distribution highlighted Cd, Cu, and Pb's potential remobilization in exchangeable fractions, while Zn displayed integration with the compost matrix. GLDA-assisted leaching and subsequent fractions illustrated transformation and stability. Therefore, this process could be a sustainable alternative for industrial applications (agricultural fertilizers and bioenergy) and social benefits (waste reduction, urban landscaping, and carbon sequestration) as it has controlled environmental footprints. Hence, the proposed remediation strategy, chemically assisted leaching, could be a practical option for extracting heavy metals from MSW compost, thereby boosting circular economy.
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    Innovative lake pollution profiling: unveiling pollutant sources through advanced multivariate clustering techniques
    (Springer, 2024-07) Singhal, Anupam; Srinivas, Rallapalli
    In many developed and developing nations, lakes are the primary source of drinking water. In the current scenario, due to rapid mobilization in anthropogenic activities, lakes are becoming increasingly contaminated. Such practices not only destroy lake ecosystems but also jeopardize human health through water-borne diseases. This study employs advanced hierarchical clustering through multivariate analysis to establish a novel method for concurrently identifying significantly polluted lakes and critical pollutants. A systematic approach has been devised to generate rotating component matrices, dendrograms, monoplots, and biplots by combining R-mode and Q-mode analyses. This enables the identification of contaminant sources and their grouping. A case study analyzing five lakes in Bengaluru, India, has been conducted to demonstrate the effectiveness of the proposed methodology. Additionally, one pristine lake from Jammu & Kashmir, India, has been included to validate the findings from the aforementioned five lakes. The study explored correlations among various physical, chemical, and biological characteristics such as temperature, pH, dissolved oxygen, conductivity, nitrates, biological oxygen demand (BOD), fecal coliform (FC), and total coliform (TC). Critical contaminants forming clusters included conductivity, nitrates, BOD, TC, and FC. Factor analysis identified four primary components that collectively accounted for 85% of the overall variance. Following identification of pollution hotspots, the study recommends source-based pollution control and integrated watershed management, which could significantly reduce lake pollution levels. Continuous monitoring of lake water quality is essential for identifying actual contaminant sources. These findings provide practical recommendations for maximizing restoration efforts, enforcing regulations on pollutant sources, and improving water quality conditions to ensure sustainable development of lakes.
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    Fired clay bricks synergistically valorizing hazardous nickel chrome-plating sludge and fly ash: Performance assessment
    (Elsevier, 2024-04) Singhal, Anupam; Routroy, Srikanta; Bhunia, Dipendu; Lahoti, Mukund
    Nickel Chrome Plating Sludge (NCPS) is a hazardous waste containing 25%-30% nickel and chromium. Previous attempts to immobilize NCPS into fired clay bricks resulted in weakened strength due to porosity and microstructure deterioration. This study introduces co-valorization of NCPS and fly ash in fired clay bricks to address these issues. Factory-scale firing of green bricks, alongside conventional clay bricks, assessed the commercialization potential. The optimal proportion of NCPS, fly ash, and clay was found to be as 12.5:37.5:50.0, respectively. Fly ash addition significantly improved brick properties, causing compressive strength to increase from 3.2 MPa to 11.6 MPa for a NCPS content of 12.5%. Microstructural analysis highlighted fluxing oxides in NCPS, amorphous silica-alumina in fly ash, synergistic ceramic bond formation, enhanced sintering and pore filling during vitrification. The study also demonstrated substantial fuel savings of 40%-50% due to NCPS's high heat of combustion causing internal firing of green bricks. The developed bricks exhibited almost double linear attenuation coefficients, indicating enhanced gamma radiation shielding. Leaching tests confirmed successful heavy metal immobilization. This co-valorization approach not only overcomes previous drawbacks but also offers significant environmental and economic benefits in utilizing NCPS in brick production.
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    Isotopes for Improving Hydrologic Modeling and Simulation of Watershed Processes
    (Springer, 2022) Srinivas, Rallapalli; Singhal, Anupam
    Lake water quality management is an important component of watershed protection and restoration. Hydraulic residence time (HRT) is a guiding parameter for quantifying the extent of exposure of lake ecosystem to chemicals. The impact on the δD and δ18O-year amplitude depends on the lake shape, basin size, connectivity, geology and climate characteristics, perineal fluctuations in lake water mass balance, and hydraulic residence time. HRT in the lake can be dynamic. Usually, HRT is calculated based on the balance between lake’s volume and its input and output parameters, but there is a relatively simple and approximate method that uses stable water isotopes to assess the direction and possible speed of runoff in a lake. This study establishes the importance of stable isotopes in hydrologic modeling.
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    Integrated watershed modeling using interval valued fuzzy computations to enhance watershed restoration and protection at field-scale
    (Springer, 2022-01) Srinivas, Rallapalli; Singhal, Anupam
    Watershed models are scientific tools required not only for replicating the bio-physicochemical processes occurring on the landscape and water bodies, but also for addressing the complex decision-making process. This involves implementation of sustainable, economically feasible best management practices (BMPs) for watershed restoration and protection. Although numerous watershed models working at different spatio-temporal scales are available, it is often challenging for watershed modelers to identify the best ones which can simultaneously address agronomic, hydrologic, socio-economic and ecological objectives at field scale. Some of the popular models are Better Assessment Science Integrating Point and Nonpoint Sources, SWAT (Soil and Water Assessment Tool), Agriculture Conservation Planning Framework (ACPF), Prioritize Target and Measure Application (PTMApp), etc. In this study, we compare nine contemporary models with primary focus on assessing the ability of these models to achieve agronomic, hydrologic, socio-economic and ecological objectives of a watershed through Best Management Practices (BMPs) adopted at field scale. To achieve these fuzzy objectives, ten suitable criteria such as BMP feasibility, Total Maximum Daily Load scenario assessment, uncertainty analysis, climate change incorporation, cost-effectiveness, field-scale implementation, hydrology replication, stakeholder involvement, etc. have been considered. Modified form of traditional fuzzy computations namely interval-valued fuzzy computations has been used to compare various models based on these criteria. Integrated decision support system (DSS) has been developed that takes into account the subjective and uncertain perceptions of watershed modelers and decision-making bodies using fuzzy logic. Study presents two novel aspects viz. (i) Usage of interval-valued fuzzy sets to provide additional freedom or flexibility to stakeholders when making decisions related to watershed management, and (ii) proposing unique integration of three models namely PTMApp, HSPF-SAM and ACPF to achieve watershed planning and management objectives in a cost-effective manner. Although study includes watershed experts from Indian watersheds, the DSS is flexible and replicable to any other watershed across the globe.
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    EFFECT OF SAND REPLACEMENT BY MILL SCALE ON THE PROPERTIES OF CONCRETE
    (International Journal of Engineering Technology Science and Research, 2015-03) Bhunia, Dipendu; Singhal, Anupam
    Concrete is the most widely used construction material in the world. This popularity of concrete carries with it an immense environmental cost. Billions of tons of natural materials are mined and processed each year to be used in concrete, which leaves a substantial mark on the environment. Efforts to use suitable recycled materials as substitutes for concrete aggregate are gaining in importance, such as recycled concrete aggregate, post-consumer glass, tires, etc. But one waste material which has not been extensively tested yet is mill scale. Mill scale is a flaky hazardous solid waste formed on the steel’s surface during the steel manufacturing processes. This work aims to evaluate the use of mill scale in Portland cement concrete, as a replacement for natural fine aggregates. Cement mortars with mix proportioning 1:3 were prepared varying the mill scale content of fine aggregate form 0% to 100%, for determination of compressive and tensile strength. The water/cement ratio used was 0.5 for all mix proportions. The compressive strength at different proportions did not give a general trend and two peaks were obtained at 60% replacement and 100% replacement. Maximum tensile strength was observed at 60% replacement of standard sand. A mix design was also done for M35 grade of concrete by the IS method. OPC of 43 grade was selected and sand replacement was done with mill scale varying from 0% to 80% with a suitable water cement ratio of 0.40. The compressive strength was measured after 28 days of completion of curing. Maximum strength was obtained for 40% sand replacement. Moreover, concrete with mill scale has demanded greater water content to maintain the workability.