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Author: search.filters.author.Singhal, AnupamSubject: search.filters.subject.Hazardous waste

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    Synergic valorization of nickel-chrome plating sludge via alkali activation of steel slag and fly ash: performance analysis
    (Springer, 2024-09) Lahoti, Mukund; Singhal, Anupam; Routroy, Srikanta; Bhunia, Dipendu
    Nickel–chromium plating sludge (NCPS) is a hazardous waste due to high concentration (~ 25%–30%) of chromium and nickel. Electric arc furnace slag (EAFS) is a by-product of secondary steel manufacturing through the electric arc furnace route. In this work, we valorized NCPS in an innovative ambiently cured alkali-activated NCPS-Fly ash-EAFS mortar (ANFEM). NCPS substituted the binder from 0 to 25% (by weight) in the step size of 5%. The binder composition had EAFS/fly-ash = 1.0, activator/binder = 0.45, silicate/hydroxide = 2.5. Incorporation of NCPS in ANFEM resulted in several benefits such as successful NCPS immobilization, improving the flash setting and flowability issues of alkali-activated EAFS and minimal degradation in mechanical properties. Microstructural investigation by XRD, FTIR, SEM offered insights on the underlying mechanisms of NCPS valorization and corroborated the observed results of compressive strength, water absorption, bulk density, acid resistance, and surface porosity test. At 10 wt% substitution of NCPS, ANFEM produced optimum results, such as compressive strength of 40 MPa; Wabs enhancement by 4.2%; bulk density reduction by 1.1%; and the least acid-induced deterioration. Extensive leaching tests determined leachate’s heavy metals concentration to be well-within the permissible limits. Factory scale deployment of developed methodology produced paver blocks well-satisfying Indian Standard Code 15,658: 2006.
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    A Study on Utilization of Treated Spent Liquor Sludge with Fly Ash by Making Cement Concrete Hollow Cavity Bricks
    (World Academic Publishing, 2012) Singhal, Anupam
    This solid waste may contaminate surface run-off and surface water. In stainless steel pickling industries, a lot of sludge is generated and disposal of above sludge as per Act of Hazardous Waste (Management & Handling) Rules, 1989 is not easy. In the normal practice, the sludge is being disposed off on both sides of roads and railway tracks to fill low lying areas. This causes a severe problem, because during rains, the entire toxic compound (leachate) goes into ground and pollutes the ground water. Seeing the above problem, a study is taken for utilization of pickling sludge with fly ash to avoid the problem of disposal. Cement concrete hollow cavity bricks can be made and compressive strength of cement concrete hollow cavity brick is found to increase with addition of 7.5% TSLS (treated spent liquor sludge) and 15% fly ash as a partial replacement of cement. Formation of C-S-H gel may be contributing to increase in compressive strength.
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    Trials on sludge of lime treated spent liquor of pickling unit for use in the cement concrete and its leaching characteristics
    (2007) Singhal, Anupam
    Disposal of sludge of lime treated spent liquor pickling unit, as per the Act of Hazardous Waste (Management and Handling) Rules, 1989 is not easy. Its transportation and construction of lined disposal sites pose very severe problem. In the normal practice, sludge is being disposed off on sides of roads and railway tracks to generally fill the low-lying areas. This may cause severe health hazards. An attempt has therefore been made to utilize the treated spent liquor sludge in cement concrete. Design mix M20 has been prepared with varying concentration of sludge in the laboratory. Toxicity characteristics leaching procedure (TCLP) test as per USEPA has been carried out on cement concrete cubes
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    Economical Treatment Method for Waste Pickling Liquor for Micro, Small and Medium Scale Enterprises
    (Tech Journal, 2014) Singhal, Anupam; Gupta, Rajiv; Verma, Sanjay Kumar
    Waste pickling liquor is pertinent to hazardous waste. Various types of recovery and regeneration methods are used to recover and regenerate the acid and metals from waste pickling liquor. But these methods are sumptuous and not amenable for small scale industries. In a developing country like India, where lots of micro, small and medium scale industries exist, only precipitation is a pecuniary treatment method but it generates lots of sludge. There are severe problems in its disposal to lined sites (landfills). This study has been undertaken to minimize the generation of the pickling sludge by different neutralizing agents and their combinations with economic valuation and also sludge characterization has been done. The results show that the treatment of pickling effluent with lime only is the economical solution but the quantity of sludge generation is on a higher side. However, the authors recommend 20% calcium hydroxide and 80% sodium hydroxide for the treatment because sludge reduction is appreciable and lower sludge generation will result in lower cost of sludge handling, i.e., sludge collection, transportation and disposal arrangement. The sludge characterization results show that the sludge generated by the treatment of WPL requires further treatment before using it as a building material.
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    A Study on Utilization of Treated Spent Liquor Sludge with Fly Ash by Making Cement Concrete Hollow Cavity Bricks
    (IJEP, 2012-09) Singhal, Anupam
    This solid waste may contaminate surface run-off and surface water. In stainless steel pickling industries, a lot of sludge is generated and disposal of above sludge as per Act of Hazardous Waste (Management & Handling) Rules, 1989 is not easy. In the normal practice, the sludge is being disposed off on both sides of roads and railway tracks to fill low lying areas. This causes a severe problem, because during rains, the entire toxic compound (leachate) goes into ground and pollutes the ground water. Seeing the above problem, a study is taken for utilization of pickling sludge with fly ash to avoid the problem of disposal. Cement concrete hollow cavity bricks can be made and compressive strength of cement concrete hollow cavity brick is found to increase with addition of 7.5% TSLS (treated spent liquor sludge) and 15% fly ash as a partial replacement of cement. Formation of C-S-H gel may be contributing to increase in compressive strength.
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    Trials on sludge of lime treated spent liquor of pickling unit for use in the cement concrete and its leaching characteristics
    (Elsiever, 2007-01) Singhal, Anupam
    Disposal of sludge of lime treated spent liquor pickling unit, as per the Act of Hazardous Waste (Management and Handling) Rules, 1989 is not easy. Its transportation and construction of lined disposal sites pose very severe problem. In the normal practice, sludge is being disposed off on sides of roads and railway tracks to generally fill the low-lying areas. This may cause severe health hazards. An attempt has therefore been made to utilize the treated spent liquor sludge in cement concrete. Design mix M20 has been prepared with varying concentration of sludge in the laboratory. Toxicity characteristics leaching procedure (TCLP) test as per USEPA has been carried out on cement concrete cubes.
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    A Study on Application of Pickling Sludge in Pavements Tiles
    (RTESE, 2019-06) Verma, Sanjay Kumar; Gupta, Rajiv; Singhal, Anupam; Devi, Anuradha
    Spent pickling liquor disposal is not safe according to US K062 the Environmental Protection Agency (EPA) and Hazardous Waste (Management &Handling) Rule, 1989. In the normal practice pickling sludge is being disposed off on both sides of roads and railway tracks to fill low-lying areas. This may cause a severe problem of ground water contamination. In the present study, an attempt has been made to examine the potential of utilizing Solidification and stabilization (S/S) pickling sludge in pavement tiles as a substitute to cement to avoid disposal problem. The results of this work showed that the compressive strength of pavement tiles increases by replacing cement with pickling sludge up to 10%. As per US EPA TCLP test, heavy metal (Fe, Cr, and Ni) concentrations are below detectable limit in the leachate of pavement tiles at 28 days of curing. Thus, sludge-cement pavement tiles can be safely used on the footpath. Reusing pickling sludge as the raw materials of the pavement will not only solve the disposal problem, but also decrease the producing cost of pavement.