Effluent particle removal by microirrigation system filters

The aim of this work was to determine whether the filters used in microirrigation systems can remove potentially emitter-clogging particles. The particle size and volume distributions of different effluents and their filtrates were established, and the efficiency of the removal of these particles and total suspended solids by screen, disc and sand filters determined. In most of the effluents and filtrates, the number of particles with a diameter > 20 μm was minimal. By analysing the particle volume distribution it was found that particles larger than the disc and screen filter pores appeared in the filtrates. However, the sand filter was able to retain particles larger than the pore size. The filtration efficiency depended more on the type of effluent than on the filter. It was also found that the particle size distribution followed a potential law. Analysis of the β exponents showed that the filters did not significantly modify the particle size distribution of the effluents

CO2, CH4 and N2O fluxes in an Ultisol treated with sewage sludge and cultivated with castor bean

Organic residue application into soil alter the emission of gases to atmosphere and CO2, CH4, N2O may contribute to increase the greenhouse effect. This experiment was carried out in a restoration area on a dystrophic Ultisol (PVAd) to quantify greenhouse gas (GHG) emissions from soil under castor bean cultivation, treated with sewage sludge (SS) or mineral fertilizer. The following treatments were tested: control without N; FertMin = mineral fertilizer; SS5 = 5 t ha-1 SS (37.5 kg ha-1 N); SS10 = 10 t ha-1 SS (75 kg ha-1 N); and SS20 = 20 t ha-1 SS (150 kg ha-1 N). The amount of sludge was based on the recommended rate of N for castor bean (75 kg ha-1), the N level of SS and the mineralization fraction of N from SS. Soil gas emission was measured for 21 days. Sewage sludge and mineral fertilizers altered the CO2, CH4 and N2O fluxes. Soil moisture had no effect on GHG emissions and the gas fluxes was statistically equivalent after the application of FertMin and of 5 t ha-1 SS. The application of the entire crop N requirement in the form of SS practically doubled the Global Warming Potential (GWP) and the C equivalent emissions in comparison with FertMin treatments.

DNA extraction using the QIAsymphony: Evaluation of PCR inhibitor removal

The goal of this study was to compare the quantity and purity of DNA extracted from biological tracesusing the QIAsymphony robot with that of the manual QIAamp DNA mini kit currently in use in ourlaboratory. We found that the DNA yield of robot was 1.6-3.5 times lower than that of the manualprotocol. This resulted in a loss of 8% and 29% of the alleles correctly scored when analyzing 1/400 and 1/800 diluted saliva samples, respectively. Specific tests showed that the QIAsymphony was at least 2-16times more efficient at removing PCR inhibitors. The higher purity of the DNA may therefore partlycompensate for the lower DNA yield obtained. No case of cross-contamination was observed amongsamples. After purification with the robot, DNA extracts can be automatically transferred in 96-wellsplates, which is an ideal format for subsequent RT-qPCR quantification and DNA amplification. Lesshands-on time and reduced risk of operational errors represent additional advantages of the robotic platform.

Performance of a chromatographic procedure used in the certification of reference material for polycyclic aromatic hydrocarbons in sewage sludge

Semi-automatic capillary gas chromatographic method with classical flame ionization detection, which satisfies the conditions for required performance and gave acceptable results within the framework of an interlaboratory certification programme for PAHs in sewage sludge, is described. The interesting feature of the procedure is that it incorporates automatic operations such as sample fractionation by semi-preparative HPLC, fraction collection at signal level recognition and evaporation under nitrogen flow. Multiple injections in the GC capillary column are performed in the on-column mode via an autosampler with temperature-programmable injector. Automatic data acquisition and chromatogram treatment are made via computer software. This partially automatic procedure releases personnel from tedious and time-consuming tasks and its robust character was validated through the certification of reference material for PAHs in sewage sludge, demonstrating its reliable performance.

Leaching of nitrogen, potassium, calcium and magnesium in a sandy soil cultivated with sugarcane

A lysimeter experiment was carried out with sugarcane aiming to evaluate the leaching of nitrogen derived from either urea (15N) or the soil/sugarcane crop residues. The leaching of K+, Ca2+, and Mg2+ was also evaluated. The experiment was a factorial 2x4. The influencing factors were: firstly, the differential addition of two kinds of sugarcane remains to the soil, simulating conditions of cane- plantation renewal after the cane crop harvest, with and without previous straw removal by burning; secondly, four doses of N: 0, 30, 60, and 90 kg ha-1. During the experimental period the total volume of water received by the sugarcane-soil system was 2,015 mm, with 1,255 mm as precipitation and 760 mm as irrigation. The loss of N by leaching from the fertilizer (15N) was not detected. In the first three weeks the largest losses of N by leaching occurred, originating from the soil/sugarcane remains-N. The mean of leached N during the experimental period of 11 months was of 4.5 kg ha-1. The mean losses of K+, Ca2+, and Mg2+ were of 13, 320 and 80 kg ha-1, respectively.

Efficiency of five biosolids to supply nitrogen and phosphorus to ryegrass

Biosolids have been considered satisfactory to supply crops and plant nutrients. The ideal biosolids application rate should result in high crop yields and nutrient uptake, and leave low concentrations of nutrients in soils to avoid environmental problems. The objective of this study was to estimate the capacity of five biosolids to supply N and P to ryegrass (Lolium perenne) after a single application of either fertilizers or biosolids to a Spodosol and an Oxisol. Results showed that 6% - 36% of N and 3% - 7% of P applied as biosolids were recovered in plants grown on the Spodosol, while the range on the Oxisol was 26%-75% for N and 1.2%-3.7% for phosphorus. Biosolids' efficiency on supplying N and P to plants was similar to fertilizer on the Spodosol, but on the Oxisol it refrained to 65%-67% fertilizer's efficiency. After a single application of biosolids followed by six consecutive harvests, 25%-94% of the N and 93%-99% of the P were not used by plants and remain in the soils.

The problem of nitrogen disposal in the obese

Amino-N is preserved because of the scarcity and nutritional importance of protein. Excretion requires its conversion to ammonia, later incorporated into urea. Under conditions of excess dietary energy, the body cannot easily dispose of the excess amino-N against the evolutively adapted schemes that prevent its wastage; thus ammonia and glutamine formation (and urea excretion) are decreased. High lipid (and energy) availability limits the utilisation of glucose, and high glucose spares the production of ammonium from amino acids, limiting the synthesis of glutamine and its utilisation by the intestine and kidney. The amino acid composition of the diet affects the production of ammonium depending on its composition and the individual amino acid catabolic pathways. Surplus amino acids enhance protein synthesis and growth, and the synthesis of non-protein-N-containing compounds. But these outlets are not enough; consequently, less-conventional mechanisms are activated, such as increased synthesis of NO∙ followed by higher nitrite (and nitrate) excretion and changes in the microbiota. There is also a significant production of N(2) gas, through unknown mechanisms. Health consequences of amino-N surplus are difficult to fathom because of the sparse data available, but it can be speculated that the effects may be negative, largely because the fundamental N homeostasis is stretched out of normalcy, forcing the N removal through pathways unprepared for that task. The unreliable results of hyperproteic diets, and part of the dysregulation found in the metabolic syndrome may be an unwanted consequence of this N disposal conflict.

Purification and fractionation by nanotiltration in dairy and sugar and sweetener industry applications

Nanotiltration is a membrane separation method known for its special characteristic of rejecting multivalent ions and passing monovalent ions. Thus, it is commonly applied with dilute aqueous solutions in partial salt removal, like in drinking water production. The possibilities of nanofiltration have been studied and the technique applied in a wide branch of industries, e.g. the pulp and paper, the textile and the chemical processing industry. However, most present applications and most of the potential applications studied involve dilute solutions, the permeating stream being generally water containing monovalent salts. In this study nanotiltration is investigated more as a fractionation method. A well-known application in the dairy industry is concentration and partial salt removal from whey. Concentration and partial demineralization is beneficial for futher processing of whey as whey concentrates are used e.g. in baby foods. In the experiments of this study nanotiltration effectively reduced the monovalent salts in the whey concentrate. The main concern in this application is lactose leakage into the permeate. With the nanofiltration membranes used the lactose retentions were practically ? 99%. Another dairy application studied was the purification and reuse of cleaning solutions. This is an environmentally driven application. An 80% COD reduction by nanofiltration was observed for alkaline cleaning-in-place solution. Nanofiltration is not as commonly applied in the sugar and sweeteners industry as in the dairy industry. In this study one potential application was investigated, namely xylose purification from hemicellulose hydrolyzate. Xylose is raw material for xylitol production. Xylose separation from glucose was initially studied with xylose-glucose model solutions. The ability of nanofiltration to partially separate xylose into the permeate from rather concentrated xylose-glucose solutions (10 w-% and 30 w-%) became evident. The difference in size between xylose and glucose molecules according to any size measure is small, e.g. the Stokes diameter of glucose is 0.73 nm compared to 0.65 nm for xylose. In further experiments, xylose was purified into nanoliltration permeate from a hemicellulose hydrolyzate solution. The xylose content in the total solids was increased by 1.4—1.7 fold depending on temperature, pressure and feed composition.

Dry matter accumulation and mineral nutrition of arracacha in response to nitrogen fertilization

Abstract:The objective of this work was to evaluate the effect of nitrogen fertilization on the growth and yield of arracacha (Arracacia xanthorrhiza), as well as on the plant's nutrient uptake, distribution, and removal. The experiment was carried out in a typical Oxisol, with sandy texture. A randomized complete block design was used, with four replicates. The treatments consisted of five N rates: 0, 50, 100, 200, and 400 kg ha-1. The plots were composed of three 8-m-length rows, spaced at 0.60 m between rows and 0.40 m between plants. The plants were harvested after an 8-month cycle. Nitrogen fertilization significantly increased the proportion of N and S accumulated in stems, and of Ca, Mg, Fe, and Mn in leaves. N supply increased Zn distribution to stems and leaves, whereas high N rates increased Cu allocation to stems more than to the rootstock. High N rates increase plant dry matter (DM) production and nutrient uptake and removal, but do not result in the greatest yield due to the greater development of leaves and stems, and to the lower allocation of DM in storage roots.

Selective catalytic reduction of nitrogen oxides with ammonia in forced unsteady state reactors - Case based reasoning and mathematical model simulation reasoning

The application of forced unsteady-state reactors in case of selective catalytic reduction of nitrogen oxides (NOx) with ammonia (NH3) is sustained by the fact that favorable temperature and composition distributions which cannot be achieved in any steady-state regime can be obtained by means of unsteady-state operations. In a normal way of operation the low exothermicity of the selective catalytic reduction (SCR) reaction (usually carried out in the range of 280-350°C) is not enough to maintain by itself the chemical reaction. A normal mode of operation usually requires supply of supplementary heat increasing in this way the overall process operation cost. Through forced unsteady-state operation, the main advantage that can be obtained when exothermic reactions take place is the possibility of trapping, beside the ammonia, the moving heat wave inside the catalytic bed. The unsteady state-operation enables the exploitation of the thermal storage capacity of the catalyticbed. The catalytic bed acts as a regenerative heat exchanger allowing auto-thermal behaviour when the adiabatic temperature rise is low. Finding the optimum reactor configuration, employing the most suitable operation model and identifying the reactor behavior are highly important steps in order to configure a proper device for industrial applications. The Reverse Flow Reactor (RFR) - a forced unsteady state reactor - corresponds to the above mentioned characteristics and may be employed as an efficient device for the treatment of dilute pollutant mixtures. As a main disadvantage, beside its advantages, the RFR presents the 'wash out' phenomena. This phenomenon represents emissions of unconverted reactants at every switch of the flow direction. As a consequence our attention was focused on finding an alternative reactor configuration for RFR which is not affected by the incontrollable emissions of unconverted reactants. In this respect the Reactor Network (RN) was investigated. Its configuration consists of several reactors connected in a closed sequence, simulating a moving bed by changing the reactants feeding position. In the RN the flow direction is maintained in the same way ensuring uniformcatalyst exploitation and in the same time the 'wash out' phenomena is annulated. The simulated moving bed (SMB) can operate in transient mode giving practically constant exit concentration and high conversion levels. The main advantage of the reactor network operation is emphasizedby the possibility to obtain auto-thermal behavior with nearly uniformcatalyst utilization. However, the reactor network presents only a small range of switching times which allow to reach and to maintain an ignited state. Even so a proper study of the complex behavior of the RN may give the necessary information to overcome all the difficulties that can appear in the RN operation. The unsteady-state reactors complexity arises from the fact that these reactor types are characterized by short contact times and complex interaction between heat and mass transportphenomena. Such complex interactions can give rise to a remarkable complex dynamic behavior characterized by a set of spatial-temporal patterns, chaotic changes in concentration and traveling waves of heat or chemical reactivity. The main efforts of the current research studies concern the improvement of contact modalities between reactants, the possibility of thermal wave storage inside the reactor and the improvement of the kinetic activity of the catalyst used. Paying attention to the above mentioned aspects is important when higher activity even at low feeding temperatures and low emissions of unconverted reactants are the main operation concerns. Also, the prediction of the reactor pseudo or steady-state performance (regarding the conversion, selectivity and thermal behavior) and the dynamicreactor response during exploitation are important aspects in finding the optimal control strategy for the forced unsteady state catalytic tubular reactors. The design of an adapted reactor requires knowledge about the influence of its operating conditions on the overall process performance and a precise evaluation of the operating parameters rage for which a sustained dynamic behavior is obtained. An apriori estimation of the system parameters result in diminution of the computational efforts. Usually the convergence of unsteady state reactor systems requires integration over hundreds of cycles depending on the initial guess of the parameter values. The investigation of various operation models and thermal transfer strategies give reliable means to obtain recuperative and regenerative devices which are capable to maintain an auto-thermal behavior in case of low exothermic reactions. In the present research work a gradual analysis of the SCR of NOx with ammonia process in forced unsteady-state reactors was realized. The investigation covers the presentationof the general problematic related to the effect of noxious emissions in the environment, the analysis of the suitable catalysts types for the process, the mathematical analysis approach for modeling and finding the system solutions and the experimental investigation of the device found to be more suitable for the present process. In order to gain information about the forced unsteady state reactor design, operation, important system parameters and their values, mathematical description, mathematicalmethod for solving systems of partial differential equations and other specific aspects, in a fast and easy way, and a case based reasoning (CBR) approach has been used. This approach, using the experience of past similarproblems and their adapted solutions, may provide a method for gaining informations and solutions for new problems related to the forced unsteady state reactors technology. As a consequence a CBR system was implemented and a corresponding tool was developed. Further on, grooving up the hypothesis of isothermal operation, the investigation by means of numerical simulation of the feasibility of the SCR of NOx with ammonia in the RFRand in the RN with variable feeding position was realized. The hypothesis of non-isothermal operation was taken into account because in our opinion ifa commercial catalyst is considered, is not possible to modify the chemical activity and its adsorptive capacity to improve the operation butis possible to change the operation regime. In order to identify the most suitable device for the unsteady state reduction of NOx with ammonia, considering the perspective of recuperative and regenerative devices, a comparative analysis of the above mentioned two devices performance was realized. The assumption of isothermal conditions in the beginningof the forced unsteadystate investigation allowed the simplification of the analysis enabling to focus on the impact of the conditions and mode of operation on the dynamic features caused by the trapping of one reactant in the reactor, without considering the impact of thermal effect on overall reactor performance. The non-isothermal system approach has been investigated in order to point out the important influence of the thermal effect on overall reactor performance, studying the possibility of RFR and RN utilization as recuperative and regenerative devices and the possibility of achieving a sustained auto-thermal behavior in case of lowexothermic reaction of SCR of NOx with ammonia and low temperature gasfeeding. Beside the influence of the thermal effect, the influence of the principal operating parameters, as switching time, inlet flow rate and initial catalyst temperature have been stressed. This analysis is important not only because it allows a comparison between the two devices and optimisation of the operation, but also the switching time is the main operating parameter. An appropriate choice of this parameter enables the fulfilment of the process constraints. The level of the conversions achieved, the more uniform temperature profiles, the uniformity ofcatalyst exploitation and the much simpler mode of operation imposed the RN as a much more suitable device for SCR of NOx with ammonia, in usual operation and also in the perspective of control strategy implementation. Theoretical simplified models have also been proposed in order to describe the forced unsteady state reactors performance and to estimate their internal temperature and concentration profiles. The general idea was to extend the study of catalytic reactor dynamics taking into account the perspectives that haven't been analyzed yet. The experimental investigation ofRN revealed a good agreement between the data obtained by model simulation and the ones obtained experimentally.

Response of wheat to additional nitrogen fertilizer application after pig slurry on over-fertilized soils

Pig slurry is a valuable nutrient resource but constitutes a waste disposal problem in areas of high animal density. In the semiarid area of Pla d’Urgell, in the Ebro Valley, North-East Spain, irrigated crops receive large amounts of nutrients in the form of manure and mineral fertilizers. We studied the effect of pig slurry and additional side-dress mineral fertilizers on irrigated wheat, Triticum aestivum L., on a coarse loam soil, with high soil P and K levels. Yields increased by 62.3% when using pig slurry. The application of ammonium sulfate nitrate sidedress did not significantly increase wheat production. The average apparent recoveries were higher for potassium (88.7%) than for nitrogen (51.3%) and phosphorus (36.3%). Greater amounts of soil NO3-N were measured over the four growing seasons, which was consistent with the amount of N applied. Macronutrient and micronutrient uptake was significant higher for pig slurry treatments, but only small differences were found between the pig slurry and pig slurry plus ammonium sulfate nitrate treatments. The unfertilized treatment showed significantly lower soil P, K, Cu and Zn content than pig slurry treatments; 34%, 21%, 34%, and 26% respectively. These findings could be used to develop a nutrient management plan based on knowledge of soil test results and crop nutrient removal. This could help to improve the use of pig slurry and mineral fertilizers on limited available land areas and prevent the accumulation of potentially toxic elements in soils and the export of nutrients through agricultural drainage.

Influence of EfOM on the oxidation of micropollutants by Ozone and UV/H2O2 in secondary effluents

The aim of this work was to study the influence of effluent organic matter (EfOM) on micropollutants removal by ozone and UV/H2O2. To perform the experiments, deionized water and municipal secondary effluents (SE) were artificially contaminated with atrazine (ATZ) and treated by the two proposed methods. ATZ concentration, COD and TOC were recorded along the reaction time and used to evaluate EfOM effect on the system efficiency. Results demonstrate that the presence of EfOM can significantly reduce the micropollutant removal rate due to competition of EfOM components to react with radicals and/or molecular ozone. The hydroxyl radical scavenging caused by EfOM was quantified as well as the contribution of molecular ozone and �OH radicals during the ozonation of SE. EfOM components promoted higher inhibition of ATZ oxidation by hydroxyl radicals than by molecular ozone.

Chelating Adsorbents in Purification of Hydrometallurgical Solutions

In this thesis, equilibrium and dynamic sorption properties of weakly basic chelating adsorbents were studied to explain removal of copper, nickel from a concentrated zinc sulfate solution in a hydrometallurgical process. Silica-supported chelating composites containing either branched poly(ethyleneimine) (BPEI) or 2-(aminomethyl)pyridine (AMP) as a functional group were used. The adsorbents are commercially available from Purity Systems Inc, USA as WP-1® and CuWRAM®, respectively. The fundamental interactions between the adsorbents, sulfuric acid and metal sulfates were studied in detail and the results were used to find the best conditions for removal of copper and nickel from an authentic ZnSO4 process solution. In particular, the effect of acid concentration and temperature on the separation efficiency was considered. Both experimental and modeling aspectswere covered in all cases. Metal sorption is considerably affected by the chemical properties of the studied adsorbents and by the separation conditions. In the case of WP-1, acid affinity is so high that column separation of copper, nickel and zinc has to be done using the adsorbent in base-form. On the other hand, the basicity of CuWRAM is significantly lower and protonated adsorbent can be used. Increasing temperature decreases the basicity and the metals affinity of both adsorbents, but the uptake capacities remain practically unchanged. Moreover, increasing temperature substantially enhances intra-particle mass transport and decreases viscosities thus allowing significantly higher feed flow rates in the fixed-bed separation. The copper selectivity of both adsorbents is very high even in the presence of a 250-fold excess of zinc. However, because of the basicity of WP-1, metal precipitation is a serious problem and therefore only CuWRAM is suitable for the practical industrial application. The optimum temperature for copper removal appears to be around 60 oC and an alternative solution purification method is proposed. The Ni/Zn selectivity of both WP-1 and CuWRAM is insufficient for removal of the very small amounts of nickel present in the concentrated ZnSO4 solution.

Uses of natural zeolite in the removal of Pb2+ from contaminated water

In this paper, we carry out a study on the process of sorption of lead in polluted waters usingnatural zeolites, with the objective of analyzing their behavior in the purification of water.Experiments are carried out under static and dynamic conditions to determine the influence of other metal ions, such as: Ca (II), Mg (II), K (I) and Na (I), on this process. We demonstrate that the affinity of Pb (II) with regard to zeolite is higher than that of the ions mentioned above. It allows us to use this material in the capture of lead in residual waters. A lineal model of regression was obtained using a computer program called Eureka which relates the capacity of interchange of zeolite with respect to the concentration of the metal ions present in waters. We also studied the selectivity of zeolite in the process of sorption of Pb (II) compared with other heavy metals like Zn (II) and Cd (II).The results achieved in both cases increase the expectancy about the usage of zeolite as a low cost material for purifing waters.