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Author: search.filters.author.Bhargava, D.S.

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Now showing 1 - 9 of 9
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    BOD contribution by benthalsludge deposits-Part II: Effect of stream characteristics
    (Kalpana Corporation, 2008) Bhargava, D.S.; Shrihari, S.
    Organic matter that settles to the river bottoms is the benthalsludge deposits. Decomposition of benthalsludge deposits in streams affect the overlying waters by removal of the dissolved oxygen (DO) from the overlying waters as well as by the benthos and periphytons in the aerobic top layers of the overlying waters and by the immediate oxygen demand of the reduced substances emanating from the deeper anaerobic layers. Secondly, the benthalsludge deposits can also release organic substances and various nutrients into the overlying waters. The oxygen utilisation rate by the benthalsludge deposits may also depend on the stream characteristics as well as the sludge characteristics. In this second part of the paper, the variations of the total oxygen uptake rate in any one days duration and the rate of BOD contribution in respect of different stream characteristic parameters have been correlated and discussed. The flow rate of overlying waters influenced the BOD contribution rate significantly, both at the top and bottom most layers of overlying waters. The rate of BOD contribution manifested optimum values affected by h/d ratios, at the top layers of overlying waters. Predictive models involving all the sludge and stream characteristic parameters have been developed. © 2008 - Kalpana Corporation.
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    BOD contribution by benthalsludge deposits Part-1: Effect of sludge characteristics
    (Kalpana Corporation, 2008) Bhargava, D.S.; Shrihari, S.
    Organic matter that settles to their river bottoms is the benthalsludge deposits. Decomposition of benthalsludge deposits in streams affect the overlying waters by removal of the dissolved oxygen (DO) from the overlying waters as well as by the benthos and periphytons in the aerobic top layers of the overlying waters and by the immediate oxygen demand of the reduced substances emanating from the deeper anaerobic layers. Secondly, the benthalsludge deposits can also release organic substances and various nutrients into the overlying waters. The oxygen utilisation rate by the benthalsludge deposits may also depend on the sludge characteristics as well as the stream characteristics. In this first part of the paper, the variations of the total oxygen uptake rate in any one days duration and the rate of BOD contribution by benthalsludge in respect of different sludge characteristic parameters have been correlated and discussed. At the top layers of overlying waters, the rate of BOD contribution manifested an optimum high value at benthalsludge depth of 0.1m, and an optimum low value of initial BOD of benthalsludge top layers of around 475 mg/L. The cumulative oxygen consumption till a particular day, was lower or almost same at greater depths of benthalsludges, and manifested a low value at Kd-b value of 0.035. However, the influence of S b-o seemed to be less. The percent BOD contribution indicating the sludge age, manifested an optimum low at benthalsludge depths of 0.2m, both at the top and bottom most layers of overlying waters. The COC values at the interface showed similar trends as in the top layers of overlying waters. The rate of BOD contributions as well as percent contributions, at the interface showed an increasing trend with the Kd-b values. The rate of BOD contributions at the interface also increased with increasing Sb-o values, but the percent BOD contributions manifested an optimum low value. © 2008 - Kalpana Corporation.
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    Modelling for organics and nutrients release during Benthal sludge stabilisation : Part I -organics
    (2008) Bhargava, D.S.; Shrihari, S.
    Settleable solids in the untreated and partially treated domestic and industrial effluents discharged into a river system undergoes settling and decomposition in the form of benthal sludge deposits, Early models of biochemical oxygen demand (BOD) assimilation in rivers do not account for the BOD contribution by these benthal sludge deposits. In this paper, a model for computations of the BOD contribution by benthos (both from the top aerobic layers and the leached portion of BOD from the bottom anaerobic layers) was presented. Observations from three sets of experiments at the chosen overlying water flow rates (500 ml/min, 1000ml/ min and 1500 ml/min) show a higher BOD contribution by benthos at higher overlying water flow rates. The ratio of the BOD contributions by benthos to the volatile solids in the top aerobic layers was lower when compared to the similar ratio in respect of the bottom layer volatile solids showing that a higher contribution was made by the top layers.
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    Modelling for organics and nutrients release during benthal sludge stabilisation part il - Nutrients
    (2009) Bhargava, D.S.; Shrihari, S.
    Settleable solids from untreated or partially treated domestic and industrial effluents undergoing stabilisation in stream beds contain significant amount or nutrients such as ammonia and phosphates apart from carbonaceous organic material. An experimental investigation was carried out to study the contribution of biochemical oxygen demand (BOD) and nutrients by this benthal-sludge undergoing stabillisation in steam beds. Sludge was collected from a sewage channel and placed at the bottom of an experimental reactor, and a continuous flow of clean tap water was maintained, in such a manner that the sludge was not disturbed. The first part of this work contained a discussion on degreadation of carbonaceous matter. The degradation of the nutrients, such as ammonia and phosphates being released from the sediments into the overlying waters at different flow rates of over laying waters is evaluated. It was noticed that the ammonia and phosphates released from the sediments into the overlying waters become more or less uniform after some days. The ammonia release and phosphate release were found to be affected by changes in the flowrates of overlying waters. The ammonia and phosphates remaining in the top and bottom layers of the sediments also showed similar trends. Predictive models have been presented for the variation of ammonia and phophate release into the overlying water, ammonia and phosphates remaining in the sediment layers at different times and different flow rates.
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    Nutrient contributions by benthal sludge deposits
    (2009) Bhargava, D.S.; Shrihari, S.
    Settled solids from effluents discharged into a river system, undergoing decomposition at the river bottom, form an appreciable internal nutrient source for the biological activities in the river system. During the stabilization of benthal deposits, a variety of nutrients are released into the overlying waters. The exchange between sediment and overlying waters is a major component of the nitrogen and phosphorous cycles in the natural waters. The releases of such nutrients is a surface phenomenon, regulated by the conditions of benthal sludge layers, flow rate of overlying waters, etc. The rate of ammonia nitrogen release manifested an optimum low value when benthal sludge depth was 0.2 m, but was not influenced by the flow rate of overlying water and h/d ratios. The rate of phosphate release from benthal sludge was independent of depth of benthal sludge, flow rate and h/d ratios. The nutrients in the benthal sludge layers were increasing with time, and were concentrated at a layer 10 cm below the top surface. The nutrients release (percent of nutrient remaining in top benthal sludge layers) decreased with time and became almost constant after about 40 days. The nutrients release under continuously accumulating conditions of benthal sludge and me effects of frequency of addition have been discussed in this paper. The nutrients release was less when the frequency of addition was less.
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    Benthalsludge stabilization in the river Ganga at Kanpur - Part 2
    (Kalpana Corporation, 2011) Bhargava, D.S.; Shrihari, S.
    Field observations conducted at Kanpur, to analyze the ration of biochemical oxygen demand (BOD) contributions by benthalsludge to the overlying waters of the river Ganga were presented in Part 1 of this paper. This data was later correlated to the data obtained under different conditions of operating and process variables in the laboratory. Observations were made at 3 sections along the river downstream of an outfall discharging partially treated wastewater. The rate of BOD contribution by benthalsludge to the overlying waters was estimated by utilizing the observed values of dissolved oxygen (DO) and BOD. The rate of BOD contribution was higher at section A during summer and at section B during winter, throughout the depth of overlying waters. This is because of the higher stabilization of the settled organic matter during summer. In winter, the BOD released gets carried away to the downstream sections. The rate of BOD contributions (expressed as a percentage of the BOD remaining in the top benthalsludge layers) was insignificant during winter. The rate of BOD contribution (expressed as a percentage of the BOD added continuously) was higher at sections closer to the out fall during summer, but higher at section B in winter. Predictive models were developed for the rate of BOD contribution by benthalsludge. The observations in the laboratory were done on a significantly smaller model and the field data differed by an order of magnitude. Models were developed to predict the overall scale factor (OSF) for different field conditions by benthalsludge by using the laboratory models. © 2011 - Kalpana Corporation.
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    Benthal sludge stabilization in the river Ganga at Kanpur: Part I - Field observations
    (Kalpana Corporation, 2011) Bhargava, D.S.; Shrihari, S.
    Field observations were conducted at Kanpur to analyze the ration of biochemical oxygen demand (BOD) contributions by benthalsludge to the overlying waters of the river Ganga. This data was later correlated to the data obtained under different conditions of operating and process variables in the laboratory. Observations were made at 3 sections along the river downstream of an outfall discharging partially treated wastewater. The rate of BOD contribution by benthalsludge to the overlying waters was estimated by utilizing the observed values of dissolved oxygen (DO) and BOD and is presented in Part 2 of this paper. The rate of BOD contribution was higher at section A during summer and at section B during winter, throughout the depth of overlying waters. This is because of the higher stabilization of the settled organic matter during summer. In winter, the BOD released gets carried away to the downstream sections. The rate of BOD contributions (expressed as a percentage of the BOD remaining in the top benthalsludge layers) was insignificant during winter. The rate of BOD contribution (expressed as a percentage of the BOD added continuously) was higher at sections closer to the outfall during summer, but higher at section B in winter. Predictive models were developed for the rate of BOD contribution by benthalsludge. The observations in the laboratory were done on a significantly smaller model and the field data differed by an order of magnitude. Models were developed to predict the overall scale factor (OSF) for different field conditions by benthalsludge by using the laboratory models. © 2011 - Kalpana Corporation.