Browsing by Author "Rashmi, H.R."

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    Dewatering performance of sludge using coconut shell biochar modified with ferric chloride (Sludge dewatering using bio-waste)
    (Springer Science and Business Media Deutschland GmbH, 2022) Rashmi, H.R.; Devatha, C.P.
    Coconut shell is a bio-waste, and its availability is high to waste in the coastal region of Karnataka, India. The present study focused on using coconut shell biochar modified with ferric chloride to enhance the sludge dewaterability, and it is evaluated experimentally (Capillary suction time, moisture content, settleability, zeta potential, heavy metals, and phosphate). Further, scanning electron microscopy, Fourier transformation infrared spectroscopy, and X-ray diffraction characterization were carried out to identify the structure's change. A significant reduction in capillary suction time (56 s) and the moisture content (96.5%) of the dewatered sludge cake was obtained. Sludge dewatering using coconut shell biochar modified with ferric chloride was optimized by a Box Behnken method with three main factors including dosage, rapid mixing time, and slow mixing time. Optimum capillary suction time (55.6 s) was achieved at coconut shell biochar modified with ferric chloride dosage (41% dry solids), rapid mixing time (10 min), and slow mixing time (19 min). The significant structural change in sludge particles was confirmed through characterization studies. During the dewatering process, the removal of heavy metal (cadmium, chromium, lead, and nickel) and phosphate (50.6%) was evident. Hence attempt of coconut shell biochar modified with ferric chloride as a skeleton material is an economical and promising option for sludge dewatering. © 2021, Islamic Azad University (IAU).
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    Phosphorus recovery as induced struvite from deep dewatered liquors using magnesium chloride as a magnesium source
    (2019) Rashmi, H.R.; Devatha, C.P.
    The phosphorus recoveries in municipal wastewater treatment plants (WWTPs) are in much demand as the price of phosphate rock are increased from the last decade. Due to the increase in pollution levels of the sewage sludge, it is difficult to use sewage sludge directly as fertilizers in agricultural fields. The present study aimed to work on the recovery of phosphorus from the deep dewatered liquors in a laboratory, batch test mode. Experiments were conducted to identify the initial characteristics of sludge and for recovery analysis, by varying the phosphorus and Magnesium (Mg:P) molar ratio. Characterization studies were performed by SEM and FTIR for confirmation of struvite formation. Results obtained revealed that recovery is 94% of the incoming phosphorus. � 2019 IOP Publishing Ltd. All rights reserved.
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    Phosphorus recovery as induced struvite from deep dewatered liquors using magnesium chloride as a magnesium source
    (Institute of Physics Publishing helen.craven@iop.org, 2019) Rashmi, H.R.; Devatha, C.P.
    The phosphorus recoveries in municipal wastewater treatment plants (WWTPs) are in much demand as the price of phosphate rock are increased from the last decade. Due to the increase in pollution levels of the sewage sludge, it is difficult to use sewage sludge directly as fertilizers in agricultural fields. The present study aimed to work on the recovery of phosphorus from the deep dewatered liquors in a laboratory, batch test mode. Experiments were conducted to identify the initial characteristics of sludge and for recovery analysis, by varying the phosphorus and Magnesium (Mg:P) molar ratio. Characterization studies were performed by SEM and FTIR for confirmation of struvite formation. Results obtained revealed that recovery is 94% of the incoming phosphorus. © 2019 IOP Publishing Ltd. All rights reserved.
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    Recovery of phosphorus as struvite from the dewatered liquor through crystallization using seawater as magnesium source
    (Elsevier, 2023) Devatha, C.P.; Rashmi, H.R.
    Because of the finite and nonrenewable nature of the phosphate resource, recycling and reuse of nutrients is an environmental and economic motivation that finally leads to water reuse. In recent times, phosphorus recovery has been attempted using waste materials. Hence in this paper, the recovery of phosphorus was studied from the dewatered liquor using seawater as a magnesium source, using the struvite crystallization technology, which is one of the most widely recommended technologies for the recovery of phosphorus. The sludge dewaterability was achieved with varying dosages of granulated blast furnace slag as skeleton material. Initial characteristics of dewatered liquor and seawater were investigated. Batch studies were conducted with varying pH (7–11) and a molar ratio of Mg/P (0.6–1.4) to determine the optimum condition for the maximum recovery of phosphorus. Characterization studies were carried out to study morphology by scanning electron microscope, the composition of solids by Fourier transform infrared, and phase identification by X-ray powder diffraction for the confirmation of struvite formation; 94% of the phosphorus was recovered as struvite, demonstrating good phosphorus recovery capability. The goal of the study is to develop an innovative and economical method for crystallizing struvite in order to extract phosphorus from the dewatered liquid. It can be concluded that seawater can also be considered as a source of magnesium for the production of struvite. © 2023 Elsevier Inc. All rights reserved.