Selective removal of phosphorus from wastewater combined with its recovery as a solid-phase fertilizer

Influx of Phosphorus (P) into freshwater ecosystems is the primary cause of eutrophication which has many undesirable effects. Therefore, P discharge limits for effluents from WWTPs is becoming increasingly common, and may be as low as 10 μg/L as P. While precipitation, filtration, membrane processes, Enhanced Biological Phosphorus Removal (EBPR) and Physico-chemical (adsorption based) methods have been successfully used to effect P removal, only adsorption has the potential to recover the P as a usable fertilizer. This benefit will gain importance with time since P is a non-renewable resource and is mined from P-rich rocks. This article provides details of a process where a polymeric anion exchanger is impregnated with iron oxide nanoparticles to effectuate selective P removal from wastewater and its recovery as a solid-phase fertilizer. Three such hybrid materials were studied: HAIX, DOW-HFO, & DOW-HFO-Cu. Each of these materials combines the durability, robustness, and ease-of-use of a polymeric ion-exchanger resin with the high sorption affinity of Hydrated Ferric Oxide (HFO) toward phosphate. Laboratory experiments demonstrate that each of the three materials studies can selectively remove phosphate from the background of competing anions and phosphorus can be recovered as a solid-phase fertilizer upon efficient regeneration of the exchanger and addition of a calcium or magnesium salt in equimolar (Ca/P or Mg/P) ratio. Also, there is no leaching of Fe or Cu from any of these hybrid exchangers.     

A study of vishnukundin coins

Three types of Vishnukundin coins belonging to Andhra region were subjected to chemical and microstructural studies. The source of the ores used, the nature of the alloy and the techniques employed have been inferred from the data obtained. Trace elemental data have shown that the coins were made of unrefined metal which was also confirmed by electron microprobe results.     

Development of systemic immunologic responses against hepatic metastases during gene therapy for peritoneal carcinomatosis with retroviral HS-tk and ganciclovir

Gene therapy with retroviral mediated gene transfer of the herpes simplex thymidine kinase (HS-tk) gene into a tumor mass confers sensitivity of the tumor cells to ganciclovir (GCV). Tumor-specific immunologic responses may develop following treatment of the primary tumor with retroviral HS-tk and GCV. In the present study we assessed whether GCV treatment of HS-tk transduced colon cancer (TK+) implanted in the peritoneal cavity induced a systemic antitumor response that would inhibit growth of a second wild-type (TK-) tumor implanted in the liver. DHDK12 rat colon cancer cells were transduced in vitro with the retroviral HS-tk vector and established as a permanent cell line (TK+ cells). TK+ or TK- DHDK12 cells (6x10(6) cells) were injected intraperitoneally on day 0 into BD-IX rats. On day 10, TK- cells (3x10(6) cells) were injected into the liver in all the groups. The animals were then treated with GCV (150 mg/kg) for 13 days. TK+ peritoneal tumors underwent significant regression during therapy with GCV (0.05+/-0.004 g; n=7) compared to wild-type (TK-) tumors (2.2+/-0.7g; n=6) (P<0.05). The volume of TK- tumors in the liver was significantly lower in GCV-treated rats with TK+ peritoneal tumors (12.5+/-8.3 mm3) compared to rats with TK- peritoneal tumors (96.7+/-18.1 mm3) (P<0.05). Histology of the liver tumors in the TK+ groups showed a dense monocytic infiltrate with fibrosis and only occasional viable tumor cells. Gene therapy with retroviral HS-tk vectors may provide a novel approach to treatment of gastrointestinal cancer by both direct cytotoxicity and an indirect mechanism that may include enhanced immuno logic responses against disseminated disease.     

Mixing in mechanically agitated gas-liquid contactors,bubble columns and modified bubble columns

Mixing time measurements were made in 300 and 1000 mm i.d. mechanically agitated contactors with different types of impellers, located at different heights from the bottom of the vessel. Mixing time measurements were also made in 150, 200, 385 and 1000 mm i.d. bubble columns with varying liquid heights. Transient pH measurement and conductivity measurement were used to measure the mixing times. Impeller speed was varied in the range of 3.33–20 r/sec in the case of mechanically agitated contactors and gas superficial velocity was varied in the range of 10–250 mm/sec in bubble columns. Effect of physical properties of the fluid (surface tension, ionic strength, liquid viscosity) and that of the non-Newtonian behavior on mixing time was studied. Mixing time in the presence of drag reducing agents was also investigated.In the range of variables covered in this work mixing time in mechanically agitated contactors and bubble columns was found to be in the range of 4–6Mixing time predictions based on the longest loop length and circulation velocity are made in the presence and absence of a gas for mechanically agitatA procedure is given for the prediction of the critical impeller speed for gas phase dispersion in mechanically agitated contactors.     

Sono-chemical leaching of uranium

A fundamental study on the mechanism of uranium leaching in nitric acid and sulphuric acid media has been carried out to understand the effect of the ultrasound on leaching. The use of ultrasound clearly improves the leaching rate within the studied leach acid media. The enhancement in the leaching rate in the presence of ultrasound is higher with low leach acid concentration of nitric acid (HNO₃), and it is high at high leach acid concentration in the case of sulphuric acid (H₂SO₄) being used as a leachant, when compared to conventional mechanical agitation. The basic reason behind this observed variation is explained on the basis of the reaction mechanism involving the oxidative conversion of acid insoluble tetravalent uranium form to the soluble hexavalent form of uranium in the presence of ultrasound at a faster rate.     

Design and analysis of a novel mechanical loading machine for dynamic in vivo axial loading

This paper describes the construction of a loading machine for performing in vivo, dynamic mechanical loading of the rodent forearm. The loading machine utilizes a unique type of electromagnetic actuator with no mechanically resistive components (servotube), allowing highly accurate loads to be created. A regression analysis of the force created by the actuator with respect to the input voltage demonstrates high linear correlation (R(2) = 1). When the linear correlation is used to create dynamic loading waveforms in the frequency (0.5-10 Hz) and load (1-50 N) range used for in vivo loading, less than 1% normalized root mean square error (NRMSE) is computed. Larger NRMSE is found at increased frequencies, with 5%-8% occurring at 40 Hz, and reasons are discussed. Amplifiers (strain gauge, linear voltage displacement transducer (LVDT), and load cell) are constructed, calibrated, and integrated, to allow well-resolved dynamic measurements to be recorded at each program cycle. Each of the amplifiers uses an active filter with cutoff frequency at the maximum in vivo loading frequencies (50 Hz) so that electronic noise generated by the servo drive and actuator are reduced. The LVDT and load cell amplifiers allow evaluation of stress-strain relationships to determine if in vivo bone damage is occurring. The strain gauge amplifier allows dynamic force to strain calibrations to occur for animals of different sex, age, and strain. Unique features are integrated into the loading system, including a weightless mode, which allows the limbs of anesthetized animals to be quickly positioned and removed. Although the device is constructed for in vivo axial bone loading, it can be used within constraints, as a general measurement instrument in a laboratory setting.     

Petroleum Residue Upgrading Via Delayed Coking: A Review

World petroleum residue processing capacity has reached about 725 million metric tons per annum (MMTPA). The high demand for transportation fuels and the ever-rising heavy nature of crude oil have resulted in a renewed interest in the bottom-of-the-barrel processing using various conversion processes. Delayed coking, known for processing virtually any refinery stream (which not only poses a serious threat to environment, but also involves a disposal cost) has garnered tremendous importance in the current refining scenario. Needle coke obtained from delayed coking process is a highly sought-after product, which is used in electric arc furnaces (in the form of graphite electrodes) in steel making applications. In the present communication, the published literature has been extensively analyzed and a state-of-the-art review has been written that includes: (1) importance and place of delayed coking as a residue upgrading process in the current refining scenario; (2) coking mechanism and kinetics; (3) design aspects; (4) feedstocks suitable for the production of needle coke; (5) characteristics of needle coke; (6) factors affecting needle coke quality and quantity; and (7) future market for needle coke. An attempt has been made to get the above-mentioned aspects together in a coherent theme so that the information is available at a glance and could be of significant use for researchers and practising refiners.     

Finite Deflection of Slender Cantilever with Predefined Load Application Locus using an Incremental Formulation

In this paper, a class of problems involving space constrained loading on thin beams with large deflections is considered. The loading is such that, the locus of the force application point moves along an arbitrarily predefined path, fixed in space. Both linear elastic as well as elastic-perfectly plastic materials are considered. A simplification is realized using the moment-curvature relationship directly. The governing equation obtained is highly non-linear owing to inclusion of both material and geometric non-linearity. A general algorithm is described to solve the governing equation using an incremental formulation coupled with Runge Kutta 4^th order initial value explicit solver. Additionally, the presented method is capable of handling unloading and reverse loading conditions. An example problem where the load application point locus is an inclined straight line is solved to demonstrate the performance of the method. It is found that, the force response due to the inclined locus is stiffer than the vertical locus. This response is akin to dry friction condition on a vertical locus case.     

Incorporating air density into a Gaussian process wind turbine power curve model for improving fitting accuracy

A power curve conventionally represents the relationship between hub height wind speed and wind turbine power output. Power curves facilitate the prediction of power production at a site and are also useful in identifying the significant changes in turbine performance which can be vital for condition monitoring. However, their accuracy is significantly influenced by changes in air density, mainly when the turbine is operating below rated power. A Gaussian process (GP) is a nonparametric machine learning approach useful for power curve fitting. Critical analysis of temperature correction is essential for improving the accuracy of wind turbine power curves. The conventional approach is to correct the data for air density before it is binned to provide a power curve, as described in the IEC standard. In this paper, four different possible approaches of air density correction and its effect on GP power curve fitting model accuracy are explored to identify whether the traditional IEC approach used for air density correction is most effective when estimating power curves using a GP. Finding the most accurate air density compensation approach is necessary to minimize GP model uncertainty.