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Journal ArticleDOI

Empirical models for change in pH and temperature within gravity-based reactor columns

TL;DR: In this paper, column-reactor models of volume size 3,000 and 1,500 cm3 were made using organic materials such as sawdust and immature (drumstick) Moringa oleifera and other natural materials, such as gravels and ball clay available locally at Jodhpur, India.
Abstract: Column reactor models of volume size 3,000 and 1,500 cm3 are made using organic materials such as sawdust and immature (drumstick) Moringa oleifera and other natural materials such as gravels (6 mm size) and ball clay available locally at Jodhpur, India. Water is passed through these porous reactors under gravity at once. The experiments were aimed at finding low-cost solutions for wastewater or sewage disposal at point of use. The change in pH during water filtration experiments is measured and modelled as functions of X1 (column height), X2 (flow rate), X3 (cumulative percolation time) and X4 (change in electrical conductivity). The parameters X1, X2, X3 and X4 are found to be highly correlated to each other irrespective of materials used for making the bioreactors. There is a hyperbolic relationship between temperature gradient within the porous material column bed through which water is percolating and time taken during that process. The temperature distribution in the gravel or sawdust media...
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Journal ArticleDOI
TL;DR: The comparison demonstrates that using an integrated bioreactor with stacked configuration in treating high strength industrial wastewaters is advantageous due to minimal space requirements, low capital cost and excellent COD removal efficiencies.

959 citations

Journal ArticleDOI
TL;DR: A survey of the available literature on energy intensity for water use in the municipal and agricultural sectors and separating the process into several stages is presented in this article, where water supply, water treatment, residential end use, wastewater treatment, and agriculture end use are considered.
Abstract: Energy is consumed at every stage of the cycle of water supply, treatment, use and disposal. The intensity of energy consumption (kW h/m 3 ) depends upon the specific technologies applied at each stage of the water cycle. For some technologies, the intensity may be relatively low, whereas the intensity of other technologies is substantially greater. This report surveys the available literature on energy intensity for water use in the municipal and agricultural sectors and separates the process into several stages. Water supply, water treatment, residential end use, wastewater treatment, and agriculture end use are considered. Representative values of the energy consumed per unit water are given for a broad range of processes. Water extraction and pumping from ground and surface sources is considered. The energy intensity of treatment required for different types of water source is found to vary widely between the extremes of relatively fresh surface waters, which use energy mainly in pumping, and seawater, which requires desalination. Energy usage for different methods of irrigation including pressurized as well as surface irrigation is studied. The energy intensity of residential end use is very high relative to other parts of the water supply cycle. Processes such as heating water, washing clothes and dishes, and cooking are briefly studied within the water end-use stage. Hot water usage is responsible for making end use the most energy intensive stage of the water cycle. Hot water use in different buildings is briefly reviewed. Wastewater treated with various processes is considered, and the energy intensity is found to be highest when advanced wastewater treatment methods are applied. Energy consumption in the agricultural sector, which is principally related to irrigation pumping, is generally of lower energy intensity than for the municipal treatment or end use.

490 citations

Journal ArticleDOI
TL;DR: Bacterial survival in soil is affected by moisture content, temperature, organic matter, and antagonism by soil microflora as discussed by the authors In most instances the survival of bacterial pathogens in the soil is less than 2-3 months Removal of bacteria from sewage during percolation through soil is accomplished largely at the soil surface by straining, sedimentation, and adsorption.
Abstract: Bacterial survival in soil is affected by moisture content, temperature, organic matter, and antagonism by soil microflora In most instances the survival of bacterial pathogens in the soil is less than 2-3 months Removal of bacteria from sewage during percolation through the soil is accomplished largely at the soil surface by straining, sedimentation, and adsorption While relatively large numbers of bacteria and viruses appear to be removed through a few feet of soil under normal conditions, once they have gained entrance into the underground aquifer distances of travel as far as several hundred feet have been observed Removal of viruses by soil occurs largely by adsorption Salt concentration, pH, soil composition, organic matter, and the electronegativity of the virus and the soil may influence the degree of retention of viruses by the soil Viruses attached to soil particles can become deadsorbed with changes in water quality, resulting in greater subsurface travel Viruses survive at least as long as pathogenic bacteria in the soil

286 citations

Journal ArticleDOI
TL;DR: Large reductions (99.99% or more) of virus would be expected after passage of secondary sewage effluent through 250 cm of the calcareous sand similar to that used in the authors' laboratory columns unless heavy rains fell within 1 day after the application of sewage stopped.
Abstract: Secondary sewage effluent containing about 3 X 10(4) plaque-forming units of polio virus type 1 (LSc) per ml was passed through columns 250 cm in length packed with calcareous sand from an area in the Salt River bed used for ground-water recharge of secondary sewage effluent. Viruses were not detected in 1-ml samples extracted from the columns below the 160-cm level. However, viruses were detected in 5 of 43 100-ml samples of the column drainage water. Most of the viruses were adsorbed in the top 5 cm of soil. Virus removal was not affected by the infiltration rate, which varied between 15 and 55 cm/day. Flooding a column continuosly for 27 days with the sewage water virus mixture did not saturate the top few centimeters of soil with viruses and did not seem to affect virus movement. Flooding with deionized water caused virus desorption from the soil and increased their movement through the columns. Adding CaCl2 to the deionized water prevented most of the virus desorption. Adding a pulse of deionized water followed by sewage water started a virus front moving through the columns, but the viruses were readsorbed and none was detected in outflow samples. Drying the soil for 1 day between applying the virus and flooding with deionized water greatly reduced desorption, and drying for 5 days prevented desorption. Large reductions (99.99% or more) of virus would be expected after passage of secondary sewage effluent through 250 cm of the calcareous sand similar to that used in our laboratory columns unless heavy rains fell within 1 day after the application of sewage stopped. Such virus movement could be minimized by the proper management of flooding and drying cycles.

109 citations

Journal ArticleDOI
TL;DR: High recirculation and low C/NO-N ratio in the anaerobic FFB feed favoured the denitrification to the detriment of the methanogenic process, and the stability of the nitrification process was the controlling factor of the nitrogen removal.

91 citations