Simulation, drainage

The influent composition was defined so as to simulate drainage wastewater Ifom a metallurgical industry dam. Thus, the eomposition of this synthetic wastewater presented around 80 mg/L zinc, 2 mg/L cadmium, and 800 mg/L sulfate. Table 1 summarizes the main operational eharacteristics of the experimental runs investigated at 25 2 °C. 

A computer prograiiBe was written to simulate drainage of the packing. The Rules for Drainage were ... 

Eor evaluation of flocculants for pressure belt filters, both laboratory-scale filters and filter simulators are available (52,53) in many cases from the manufacturers of the full-scale equipment. The former can be mn either batchwise or continuously the simulators require less substrate and are mn batchwise. The observed parameters include cake moisture, free drainage, release of the cake from the filter cloth, filter blinding, and retention of the flocculated material during appHcation of pressure. 

Vacuum filters are usually simulated with a Buchner funnel test or filter leaf test (54). The measured parameters are cake weight, cake moisture, and filtration rate. Retention aids are usually evaluated using the Britt jar test, also called the Dynamic Drainage Jar, which simulates the shear conditions found on the paper machine and predicts performance (55). 

Furthermore, the implementation of the Gauss-Newton method also incorporated the use of the pseudo-inverse method to avoid instabilities caused by the ill-conditioning of matrix A as discussed in Chapter 8. In reservoir simulation this may occur for example when a parameter zone is outside the drainage radius of a well and is therefore not observable from the well data. Most importantly, in order to realize substantial savings in computation time, the sequential computation of the sensitivity coefficients discussed in detail in Section 10.3.1 was implemented. Finally, the numerical integration procedure that was used was a fully implicit one to ensure stability and convergence over a wide range of parameter estimates. 

Payer80 states that the UNSAT-H model was developed to assess the water dynamics of arid sites and, in particular, estimate recharge fluxes for scenarios pertinent to waste disposal facilities. It addresses soil-water infiltration, redistribution, evaporation, plant transpiration, deep drainage, and soil heat flow as one-dimensional processes. The UNSAT-H model simulates water flow using the Richards equation, water vapor diffusion using Fick s law, and sensible heat flow using the Fourier equation. 

Tests were also run with simulated brackish agricultural drainage water, as illustrated in Table 4. A feedwater composition containing sodium, calcium, chloride, sulfate, and bicarbonate ions was prepared in such a way as to duplicate the water in the Mohawk-Wellton drainage canal at Yuma, Arizona. Salt rejections were relatively poor toward this synthetic feedwater, but when this water was line-softened and acidified to pH 5.5 with sulfuric acid, salt rejection of the 90 10 copolyamide improved markedly. However, the membrane s water flux declined by nearly 50 percent. Salt rejection and flux were found in this and other examples to be markedly dependent on pH. As the pH approached the pKa of... 

Walker, Schreiber and Rimstidt (2006) list the oxidation rate of arsenopyrite in water as io 1014 0 03 mol m-2 s-1 at 25 °C, pH 6.3-6.7, and dissolved 02 concentrations of 0.3-17 mgL-1. Unexpectedly, the dissolved 02 concentrations had essentially no effect on the oxidation rate. However, in laboratory solutions simulating acid mine drainage (pH = 1.8), the oxidation rate of arsenopyrite was found to increase with increasing temperature (15-45 °C) and concentrations of chloride or Fe(III) sulfate (Fe2(S04)3) (Yu, Zhu and Gao, 2004). The oxidation of arsenopyrite primarily released As(III). The oxidation of As(III) to As(V) was slow, but also increased with increasing temperature and chloride or Fe(III) sulfate concentrations (Yu, Zhu and Gao, 2004). 

The aforementioned numerical experiments, namely quasi-static drainage and steady-state flow simulations, are specifically designed to study the influence of microstructure and wetting characteristics on the underlying two-phase behavior and flooding dynamics in the PEFC CL and GDL. 

Figure 10 displays the steady state invading liquid water fronts corresponding to increasing capillary pressures from the primary drainage simulation in the reconstructed CL microstructure... 

Figure 10. Advancing liquid water front with increasing capillary pressure through the initially air-saturated reconstructed CL microstructure from the primary drainage simulation.

Figure 12. 2-D phase distribution maps on several cross-sections along the GDL through-plane direction from the primary drainage simulation.

The primary drainage and steady-state flow simulations, described in the earlier section and typically devised in the petroleum/reservoir engineering applications,53 54 58,60 were deployed to evaluate the capillary pressure and relative permeability relations as functions of liquid water saturation, respectively. 

The capillary pressure response, a direct manifestation of the underlying pore morphology, can be evaluated from the two-phase LB drainage simulation and the corresponding transport relation as function of liquid water saturation can be devised as shown in Fig. 20 for the reconstructed CL micro structure.21 The overall shape of the capillary pressure curve agrees well with those reported in the literature for synthetic porous medium.55 The capillary... 

Similarly, the capillary pressure - saturation relations for the reconstructed GDL structures can be constructed from the two-phase LB drainage simulations. The capillary pressure response for reconstructed non-woven GDL microstructures was also evaluated using a full morphology (FM) approach, detailed in our recent work.33 Briefly, the FM model relies on morphological decomposition of the 3-D digital image of the reconstructed GDL to... 

Czapar, G.F., R.S. Kanwar, and R.S. Fawcett (1994). Herbicide and tracer movement to field drainage tiles under simulated rainfall conditions. Soil Till. Res., 30 19-32. 

The conservation experiments required books uniformly damaged by flood water. A simulated flood, drainage, and book-freezing sequence was developed so that it would be applied to these two groups of books resulting in a minimal variation in damage. The composition of the uncoated and the coated paper was held basically constant in these studies. Future extension of this research effort should consider varying... 

The length of the drainage period after the simulated flood was difficult to determine. The first flood-damaged book was probably frozen 39 hr after the flood waters receded the last books were placed in a freezer 114 hr later. To simulate the exact conditions, the temperature, relative humidity, and movement of the air in contact with the wetted... 

Table I shows the overall variation in the weights when the simulated-flood procedure was applied to similar pairs of identical books over an 8-mo period. The simulated flood was applied to these books as if they were loosely packed on the shelf—i.e., stored with minimum pressure applied to them. The relationship of each book s dry weight with the temperature and relative humidity of the room appears to have been comparable. The variability of the wetting action of both types of books is also similar however, the variances (the standard deviation squared) associated with the weights of the drained books are significantly different (statistical significance reported at the 95% confidence level unless otherwise noted) by use of an F-test (3). Since the handling of book pairs—i.e., one uncoated- and one coated-paper book—was the same in preparing samples for subsequent restoration studies, it might be concluded that drainage water from the books containing uncoated paper could be different from books with coated paper.

Books as a Result of Water After Simulated Flood and during Drainage... 

Simulation of the flood to determine its effect on the quality of paper in books as well as the structure of the book itself is reproducible. The simulation of the drainage conditions is also reproducible for books manufactured with the same materials. There is evidence that the rate of water loss from the books is associated with the type of paper in the text of the book. Evidence exists that comparable amounts of water are... 

There are several methods or approaches for predicting the potential of pyritic material to produce acid drainage (AD). These approaches include (1) determination of potential acidity in pyrite overburden, (2) acid-base accounting, and (3) simulated weathering. A brief discussion of each approach is given below (for details, see Evangelou, 1995b). 

Simulated weathering involves leaching overburden or spoil in laboratory-sc ale experiments with the idea that results are applicable to the field. The effluent is collected and analyzed for pH, acidity, sulfate, iron and so on. The results from these analyses are used to evaluate acid drainage formation potential (Caruccio and Geidel, 1981 ... 

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