Surface Of Tank Research Articles

Nitrogen and carbon dynamics beneath on-site wastewater treatment systems in Pitt County, North Carolina

On-site wastewater treatment systems (OWS) are a potentially significant non-point source of nutrients to groundwater and surface waters, and are extensively used in coastal North Carolina. The goal of this study was to determine the treatment efficiency of four OWS in reducing total dissolved nitrogen (TDN) and dissolved organic carbon (DOC) concentrations before discharge to groundwater and/or adjacent surface water. Piezometers were installed for groundwater sample collection and nutrient analysis at four separate residences that use OWS. Septic tank effluent, groundwater, and surface water samples (from an adjacent stream) were collected four times during 2012 for TDN and DOC analysis and pH, temperature, electrical conductivity, and dissolved oxygen measurements. Treatment efficiencies from the tank to the groundwater beneath the drainfields ranged from 33 to 95% for TDN and 45 to 82% for DOC, although dilution accounted for most of the concentration reductions. There was a significant positive correlation between nitrate concentration and separation distance from trench bottom to water table and a significant negative correlation between DOC concentration and separation distance. The TDN and DOC transport (>15 m) from two OWS with groundwater saturated drainfield trenches was significant.

Spatial and short-term temporal distribution of fugitive methane and nitrous oxide emission from a decentralised sewage mining plant: a pilot study

The decentralisation of wastewater treatment operations exposes several environmental consequences. This includes the fugitive emission of two greenhouse gases, nitrous oxide (N2O) and methane (CH4). The magnitude of these emissions is presently unclear. Therefore, it is necessary to measure the extent of the release of N2O and CH4 gas from decentralised wastewater treatment plants (WWTPs) in order to quantify the impact these emissions will have on the environment and to determine strategies to reduce them. Specifically, this pilot study employed an online non-dispersive infrared (NDIR) gas analyser and flux hood to evaluate the spatial and short-term temporal distribution of N2O and CH4 flux over half a day, from an aeration tank system within a decentralised sewage mining plant. The aeration tank system was able to emit N2O fluxes of up to 11.6 g N2O m−2 day−1 and CH4 fluxes of up to 1.1 g CH4 m−2 day−1. The N2O and CH4 fluxes varied rapidly over short time intervals in the same position (as high as 45% for N2O and 36% for CH4) and could almost triple in magnitude between two different positions across the surface of the aeration tank (within a distance no greater than 1.5 to 2 m).

An experimental study of an LPG tank at low filling level heated by a remote wall fire

This paper describes an experimental study of 2300 L pressure vessels exposed to remote fire heating by a natural gas fuelled wall fire simulator. The tanks were filled to 15% capacity with commercial liquid propane. The flame intensity and distance were varied to study the effect of different heating levels on the tank and its lading.The fire simulator is first characterized with tests including fire thermocouples, radiative flux meters and thermal imaging. With the appropriate positioning of a target tank it is possible to get very realistic fire heat fluxes at the tank surface.Three tests were conducted with the 2300 L tanks filled to 15% capacity with propane. The tanks were positioned at three different distances from the wall fire resulting in measured average peak heat flux at the tank surfaces ranging between 24 and 43 kW m−2. The data shows rapid rise in vapour space wall temperatures, significant temperature stratification in the vapour space, and moderate rate of pressure rise. These results provide excellent data for the validation of computer models used to predict the response of pressure vessels exposed to moderate heating from a remote fire.

Selecting Sensor for On Load Tap Changer Contacts Degree of Wear Diagnostics

Results of scienti c research works considering selection of measuring transducer applied for registration of acoustic emission signals generated by on load tap changers are presented in the paper. During the coupling process acoustic emission signals are generated by: the mechanical setup of tap changer, contacts operation, and other phenomena. For most on load tap changers types, the working medium is insulation oil in which the acoustic wave being formed propagates to the steal tank. There exists a possibility to register acoustic emission signals with a piezoelectric transducer attached to the outer tank surface or with a hydrophone immersed in the oil. Acoustic emission signal obtained in such manner contains information which describes operation of the power tap changer and the selector. A comparative analysis of acoustic emission signals generated by on load tap changers working under laboratory conditions, with applied measuring transducers with di erent transmittances, is presented in the paper. The comparative analysis was performed in order to determine their suitability for on load tap changers technical condition diagnosis. Based on the results achieved, one transducer which allows the registration of acoustic events generated during on load tap changers operation was selected.

In vitro model study for biofilm formation by Bacillus cereus in dairy chilling tanks and optimization of clean-in-place (CIP) regimes using response surface methodology

An in vitro model study was carried out to check biofilm formation by a selected strain of Bacillus cereus isolated from a chilling tank where pasteurized milk was stored. The strain was able to form biofilm even at 4 °C. From the study of different simulated conditions it was found that B. cereus cell count reached up to 106 cfu/cm2 of the surface of stainless steel tank if inadequately cleaned tanker is left to stand empty at room temperature. Prevalence of biofilm in dairy environment is a matter of concern as it can be an important reservoir for food spoilage and can lead to foodborne outbreaks. In the present study response surface methodology (RSM) was used to optimize parameters influencing biofilm cell removal. The RSM results were used to design an optimized clean-in-place (CIP) regime which consisted of 1.5% NaOH at 65 °C for 30 min – water rinse – 1% HNO3 at 65 °C for 10 min – water rinse. Effectiveness of reference CIP (1% NaOH at 65 °C for 10 min – water rinse – 1% HNO3 at 65 °C for 10 min – water rinse) and optimized CIP was assessed against 24 h-old biofilm. While the reference CIP caused 3.29 log reduction/cm2 in B. cereus biofilm cells, the optimized CIP achieved 4.77 log reduction/cm2 in biofilm cell count. Thus, the optimized CIP regime designed in the present study was found to be significantly (p < 0.05) more effective in biofilm cell removal as compared to the reference CIP.

Optimization and evaluation of a bottom substrate denitrification tank for nitrate removal from a recirculating aquaculture system

A bottom substrate denitrification tank for a recirculating aquaculture system was developed. The laboratory scale denitrification tank was an 8 L tank (0.04 m2 tank surface area), packed to a depth of 5 cm with a bottom substrate for natural denitrifying bacteria. An aquarium pump was used for gentle water mixing in the tank; the dissolved oxygen in the water was maintained in aerobic conditions (e.g. > 2 mg/L) while anoxic conditions predominated only at the bottom substrate layer. The results showed that, among the four substrates tested (soil, sand, pumice stone and vermiculite), pumice was the most preferable material. Comparing carbon supplementation using methanol and molasses, methanol was chosen as the carbon source because it provided a higher denitrification rate than molasses. When methanol was applied at the optimal COD:N ratio of 5:1, a nitrate removal rate of 4591 ± 133 mg-N/m2 tank bottom area/day was achieved. Finally, nitrate removal using an 80 L denitrification tank was evaluated with a 610 L recirculating tilapia culture system. Nitrate treatment was performed by batch transferring high nitrate water from the nitrification tank into the denitrification tank and mixing with methanol at a COD:N ratio of 5:1. The results from five batches of nitrate treatment revealed that nitrate was successfully removed from water without the accumulation of nitrite and ammonia. The average nitrate removal efficiency was 85.17% and the average denitrification rate of the denitrification tank was 6311 ± 945 mg-N/m2 tank bottom area/day or 126 ± 18 mg-N/L of pumice packing volume/day.

2D and 3D soil moisture imaging using a sensor-based platform moving inside a subsurface network of pipes

Summary In this study a prototype sensor-based platform moving inside a subsurface network of pipes with the task of monitoring the soil moisture content is presented. It comprises of a mobile platform, a modified commercial soil moisture sensor (Diviner 2000), a network of subsurface polyvinylchloride (PVC) access pipes, driving hardware and image processing software. The software allows the composition of two-dimensional (2D) or three-dimensional (3D) images with high accuracy and at a large scale. The 3D soil moisture images are created by using 2D slices for better illustration of the soil moisture variability. Three case studies of varying soil moisture content using an experimental soil tank were examined. In the first case study, the irrigation water was applied uniformly on the entire tank surface. In second and third case studies, the irrigation water was applied uniformly only on the surface of the intermediate and last part of the soil tank respectively. The processed images give a detailed description of the soil moisture distribution of a layer at 15 cm depth under the soil surface in the tank. In all case studies that have been investigated, the distribution of soil moisture was characterized by a significant variability (difference between poorly and well-drained regions) of the soil tank. A very poorly-drained region was located in the middle of the soil tank, while well-drained soil areas were located southwest and northeast. The knowledge of the spatial and temporal distribution of soil moisture is a valuable tool for proper management of crop irrigation.

Flow Field Study of Sodium Aluminate Solution Slurry in an Unagitated Precipitation Tank by CFD Simulation

In order to explore the feasibility of remove agitation in gibbsite precipitation process, computational fluid dynamics method was carried out to study the flow field of sodium aluminate solution slurry in an unagitated precipitation tank. The solid content distribution is investigated by volume fraction of solid phase. The simulation results showed that little difference of solid content is found in the range between the tank bottom and the height position of 25 meters, which is the most zone of the tank, and there is a somewhat large difference in the top 5 meters zone, where the stratification occurs. With the inlet velocity increases, the zone of stratification shrinks to near the tank surface, which makes the solid content distribution in the whole tank seem uniform much more. Therefore, without agitation, the solid content would not concentrate to tank bottom completely in the normal work flow.

Retention and distribution of Cu, Pb, Cr, and Zn in a full-scale hybrid constructed wetland receiving municipal sewage

This study was conducted to investigate the retention and distribution of Cu, Pb, Cr, and Zn in a hybrid constructed wetland (CW) that consists of both vertical baffled flow wetlands (VBFWs) and horizontal subsurface flow wetlands (HSSFs) with unique flow regimes and oxygen distribution. The heavy metal concentrations in water, sediments, and plant tissues in the hybrid CW were analysed. The removal of heavy metals from the water stream in the monitoring period was not statistically significant. Metal concentrations in the sediments generally decreased along the wastewater treatment process. The reductive anaerobic condition in the VBFW may promote the sulphate reduction and form highly insoluble Cu, Pb, and Zn sulphides, resulting in the higher concentration of the bivalent cations in the VBFW sediments than the corresponding values in the HSSF; however, the aerobic and anoxic environments in the HSSF enhanced the removal of Cr with the co-precipitation of iron and manganese oxides, and their hydroxides. Metal concentrations in plant tissues were not significantly influenced by the concentrations in sediments, while roots contained statistically higher metal concentrations than stems and leaves. The sediments stored 94.01, 86.31, 95.85, and 89.51% of the total Cu, Pb, Cr, and Zn retained in the hybrid CW system, respectively, while only small fractions (<10%) were accumulated in the harvestable macrophyte tissues. It is important to clean not only the accessible sediments in free water surface tank and ponds but also the embedded sediments in vegetated beds for the sustainable removal of heavy metals.

Effects of tank wall pattern on survival, bone injury rate, and stress response of juvenile Pacific bluefin tuna, Thunnus orientalis

Juvenile Pacific bluefin tuna (PBT), Thunnus orientalis, aged 30 or more days post hatching (≥5cm total length) are at high risk of mortality through contact or collision with tank walls. In this study, survival rates of PBT reared under three tank wall treatments (polka dot pattern, lattice pattern, and dark-green single color (control) were investigated. White tape was attached to the tank's surface to form either a polka dot or a lattice pattern. Fish were then reared in the tanks for 9 days. Fish survival rates in the lattice patterned and polka-dot patterned tanks were higher than that in the control tank. Bone and parasphenoid injury rates in the control group were significantly higher than those in the polka dot and lattice patterned treatment groups. The plasma cortisol content of juvenile PBT reared in the control group was higher than for fish reared in patterned tanks. These results suggest that juvenile PBT mortality from contact or collision with tank walls was reduced when wall visibility was improved by creating patterns on the tank walls.

EPIDEMIOLOGIA MOLECULAR APLICADA AO MONITORAMENTO DE ESTIRPES DE Staphylococcus aureus NA PRODUÇÃO DE QUEIJO MINAS FRESCAL

We studied the molecular epidemiology of Staphylococcus aureus strains potentially toxigenic, isolated from the production process of Minas frescal cheese in a small dairy plant in the state of Sao Paulo. For this, samples were taken during the period from June 2008 to July 2009. Samples were collected from the surface of the receiving and storage tanks of raw milk, the surface of the balance tank of pasteurized milk, the water supply system, the pipes and equipments, the hands of the handler and from the packaged cheese, totaling 140 samples. The colonies isolated on Baird-Parker Agar confirmed as Gram positive and positive for catalase, coagulase and acetoin production, were submitted to extraction of bacterial DNA using the Invitek - Uniscience® kit. Confirmation of the isolated species and enterotoxins SEA, SEB, SEC, SED and TSST-1 toxin was carried out through the amplification of specific fragments of chromosomal DNA. Among the 74 strains of isolated coagulase-positive staphylococci, only 41 (55.4%) strains were confirmed as Staphylococcus aureus , of which 25 (61.0%) were positive to the presence of staphylococcal toxins. The most frequently identified enterotoxin was SEA. The toxigenic strains of Staphylococcus aureus were more frequently isolated from hands of the handler (16.0%), raw milk receiving tank (12.0%), pasteurized milk for cheese making (12.0%) and fresh white cheese ready for consumption (12.0%). KEYWORDS: food safety; fresh white cheese; PCR; Staphylococcus aureus ; staphylococcal toxins.

Experimental and numerical investigation of localized fire test for high-pressure hydrogen storage tanks

Vehicle fires may cause localized fires on on-board high-pressure hydrogen storage tanks. To verify the safety performance of such tanks under localized fire exposure, a localized fire test was proposed in the Global Technical Regulation for Hydrogen Fuel Cell Vehicles. However, practicality and validity of the proposed test still require further verification. In this paper, this new fire test was experimentally investigated using the type 3 tanks. Influences of hydrogen and air as the filling media were studied. A three-dimensional computational fluid dynamics model was developed to analyze the effects of filling pressure and localized fire exposure time on the activation of thermally-activated pressure relief device (TPRD). The experimental results showed that temperature distribution on the tank surface was uneven around the circumference. The rising temperature of internal hydrogen or air contributed little to TPRD activation. The simulation results indicated that TPRD activation time was slightly affected by the variations of the filling pressures, but it increased when the localized fire exposure time was extended.

Methane emissions from a swine manure tank in western Canada

Flesch, T. K., Verge, X. P. C., Desjardins, R. L. and Worth, D. 2013. Methane emissions from a swine manure tank in western Canada. Can. J. Anim. Sci. 93: 159-169. The emission rate of methane (CH4) to the atmosphere was measured from a concrete manure tank at a farrow-to-finish swine facility in western Canada. Measurements were made during four seasonal campaigns using a bLS inverse-dispersion technique. Emission rates were highest in summer and lowest in winter, with intermediate rates in spring and fall. Annual emissions were estimated at 7600 kg CH4, or 6.3 kg CH4 m-2 of tank surface area. Site-specific factors used for estimating CH4 emissions were calculated from our measurements. A simple methane conversion factor, used by the Intergovernmental Panel on Climate Change to relate emissions to the volatile solids content of the manure, was calculated as 0.23. This value may be unrepresentatively high due to the long duration (15 mo) that manure was stored in the tank. A more sophisticated calculation...

Methane emissions from a swine manure tank in western Canada

Flesch, T. K., Vergé, X. P. C., Desjardins, R. L. and Worth, D. 2013. Methane emissions from a swine manure tank in western Canada. Can. J. Anim. Sci. 93: 159–169. The emission rate of methane (CH4) to the atmosphere was measured from a concrete manure tank at a farrow-to-finish swine facility in western Canada. Measurements were made during four seasonal campaigns using a bLS inverse-dispersion technique. Emission rates were highest in summer and lowest in winter, with intermediate rates in spring and fall. Annual emissions were estimated at 7600 kg CH4, or 6.3 kg CH4 m−2 of tank surface area. Site-specific factors used for estimating CH4 emissions were calculated from our measurements. A simple methane conversion factor, used by the Intergovernmental Panel on Climate Change to relate emissions to the volatile solids content of the manure, was calculated as 0.23. This value may be unrepresentatively high due to the long duration (15 mo) that manure was stored in the tank. A more sophisticated calculation methodology considers the influence of manure storage duration and temperature, and includes a critical management design practices (MDP) factor. The MDP factor was calculated as 0.31 for our tank. This MDP value implies that emissions from our manure tank were lower than expected given the results from other studies.

Cardiac Ablation Catheter Guidance by Means of a Single Equivalent Moving Dipole Inverse Algorithm

We developed and evaluated a novel system for guiding radiofrequency catheter ablation therapy of ventricular tachycardia. This guidance system employs an inverse solution guidance algorithm (ISGA) using a single equivalent moving dipole (SEMD) localization method. The method and system were evaluated in both a saline tank phantom model and in vivo animal (swine) experiments. A catheter with two platinum electrodes spaced 3 mm apart was used as the dipole source in the phantom study. A 40-Hz sinusoidal signal was applied to the electrode pair. In the animal study, four to eight electrodes were sutured onto the right ventricle. These electrodes were connected to a stimulus generator delivering 1-ms duration pacing pulses. Signals were recorded from 64 electrodes, located either on the inner surface of the saline tank or on the body surface of the pig, and then processed by the ISGA to localize the physical or bioelectrical SEMD. In the phantom studies, the guidance algorithm was used to advance a catheter tip to the location of the source dipole. The distance from the final position of the catheter tip to the position of the target dipole was 2.22 ± 0.78 mm in real space and 1.38 ± 0.78 mm in image space (computational space). The ISGA successfully tracked the locations of electrodes sutured on the ventricular myocardium and the movement of an endocardial catheter placed in the animal's right ventricle. In conclusion, we successfully demonstrated the feasibility of using an SEMD inverse algorithm to guide a cardiac ablation catheter.

An Integrated Collector Storage Solar Water Heater and Study of its Temperature Stratification

In this paper we describe an integrated collector storage solar water heater for the North Western region of India for use as domestic water heater during the winter season and present the experimental results of temperature stratification. The system consists of a steel water storage tank with azimuthal orientation such that its walls face south east, south west, north east and North West directions. The sunlit walls (south east and south west) and the top cover surface of the storage tank are covered with transparent insulation material (TIM) and the off-sunlit sides with opaque insulation. Experimental results show that the top layer is at the highest temperature. The top layer is drained using a new design of the outlet. The system can be used in rural areas or as a pre heater in more affluent households. The system can return the cost of conversion of the storage tank into a Solar Water Heater in one winter season by saving the cost of electrical energy required for heating water during winter months.

Fluid-Structure-Soil Interaction Effects on Seismic Behaviour of Elevated Water Tanks

Abstract The multiple base motion effect on hydrodynamic pressure, acceleration of tank and fluid surface elevation problem in Elevated water tank is understood as a Fluid-Structure-Soil Interaction problem. Where, Soil-Structure interaction causes rocking motion and Fluid Structure interaction causes the hydrodynamic behaviour of water tank. According to the available literature, substantial amount of study has been done on behaviour of elevated steel water tank under pure rocking, but no study is done on water tanks with horizontal and vertical earthquake excitation, along with rocking motion. An experimental investigation for a 1:4 scale model of cylindrical steel elevated water tank has been carried out on shake table facility at CSIR-SERC, Chennai. Test program on elevated steel water tank consisted of combined horizontal, vertical and rocking motions, for a synthetic earthquake excitation for 0.1 g and 0.2 g accelerations, with increasing angle of rocking motion. The impulsive base shear and impulsive base moment values increase with increase in earthquake acceleration. Whereas, the convective base shear and base moment values increase for increase in earthquake acceleration, but decrease with increasing angular motion. Hence, there is no considerable effect of rocking motion on sloshing of water. The non-linearity in structure is observed, when the impulsive pressure of tank decreases with increase in tank acceleration. The pressure variation along tank height due to vertical excitation increased with increasing acceleration, and increased furthermore with added rocking. Using various codes available on water tanks, the recorded experimental results were used to calculate and compare the base shear, base moment, pressure variation in the tank.

Electric field computation inside a rectangular petrol tank

Abstract In the paper was developed a hybrid method (analytic–numeric) for the electric field computation inside a rectangular petrol tank. For this problem it will be assumed a static state and all the computations will be developed in a Cartesian coordinate system. Two regions will be delimitated: first one is the free space and second one is the liquid electro-statically charged (petrol) inside the tank. For solving the Laplace equation in the first region, variable separation method will be applied and the electric potential will be determined. In the second region the Poisson equation will be solved, assuming a particular solution and then the electric potential will be obtained. To determine the constants from the potential expressions the zero potential condition at the tank surface and the continuity conditions at the separation surface was considered. Using mathematical manipulations (series development, numerical approximations etc.) an ill conditioned matrix system (23 × 23) resulted. This system will be numerically solved/discussed using a developed MathCad algorithm. The condition number of the coefficients matrix is being computed and the regularization methods applied to the system will be discussed.

Comparison of biofilm formation and water quality when water from different sources was stored in large commercial water storage tanks

Rain-, ground- and municipal potable water were stored in low density polyethylene storage tanks for a period of 90 days to determine the effects of long-term storage on the deterioration in the microbial quality of the water. Total viable bacteria present in the stored water and the resultant biofilms were enumerated using heterotrophic plate counts. Polymerase chain reaction (PCR) and Colilert-18(®) tests were performed to determine if the faecal indicator bacteria Escherichia coli was present in the water and in the biofilm samples collected throughout the study. The municipal potable water at the start of the study was the only water source that conformed to the South African Water Quality Guidelines for Domestic Use. After 15 days of storage, this water source had deteriorated microbiologically to levels considered unfit for human consumption. E. coli was detected in the ground- and potable water and ground- and potable biofilms periodically, whereas it was detected in the rainwater and associated biofilms at every sampling point. Imperfections in the UV resistant inner lining of the tanks were shown to be ecological niches for microbial colonisation and biofilm development. The results from the current study confirmed that long-term storage can influence water quality and increase the number of microbial cells associated with biofilms on the interior surfaces of water storage tanks.

Analytically approximate natural sloshing modes for a spherical tank shape

AbstractThe multimodal method requires analytical (exact or approximate) natural sloshing modes that exactly satisfy the Laplace equation and boundary condition on the wetted tank surface. When dealing with the nonlinear sloshing problem, the modes should also allow for an analytical continuation throughout the mean free surface. Appropriate analytically approximate modes were constructed by Faltinsen &amp; Timokha (J. Fluid Mech., vol. 695, 2012, pp. 467–477) for the two-dimensional circular tank. The present paper extends this result to the three-dimensional, spherical tank shape and, based on that, establishes specific properties of the linear liquid sloshing.