Hydrochemistry and energy storage in aquifers - NHV.nu

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exceptional in that after initial removal of carbonate by raising the pH, only minimal further softening is required, which is provided by an ion exchanger system (J. Despois, personnel communication, Oct. 1988). The retrograde solubility of carbonate minerals (Garrels and Christ, 1965) generally results in their rapid precipitation when water that was in equilibrium with a carbonate mineral at some temperature is heated to some appreciably higher temperature. At the St. Paul (USA) site, major portions of the aquifer sediment are dolomitic. Thus, it is not surprising that the groundwaters are in approximate equilibrium with calcite (Holm et al., 1987). Copious amounts (600-800 kg per cycle) of aragonite precipitated (Walton, 1986) after rapidly heating the native groundwater to 87°C in the first short cycle. The partial pressure of CO, may be much above atmospheric levels in confined aquifers. If C02 is allowed to escape from an ATES system, the carbonate equilibria will shift, as illustrated below to produce C02(g) and consume H+, resulting in a pH increase and possible carbonate precipitation: H,CO: < = > H20 + CO, (g) HCOj + H+ < = > H,CO: The degree of oversaturation with pure calcite of a thermally altered water is affected by the formation of solid solutions, the presence of nucleation and crystal growth poisons, and temperature and complexation of Ca by dissolved organic carbon (DOC). The formation of solid solutions between calcite and other metal carbonates that form the same rhombohedral structure can cause large deviations from the equilibrium solubility of pure calcite (E.A. Jenne and R.W. Smith, unpublished data). Nucleation and crystal growth poisons can also cause oversaturation of calcite and its solid-solutions. These factors are thought to account for the observed oversaturation with respect to pure calcite of various ATES waters. At some ATES installations, moderate oversaturation with calcite, even accounting for solid- solution effects, does not result in scaling of the heat exchanger. The rate of calcite
precipitation from solutions at near-neutral pH values without nucleation and crystal growth poisons is such that equilibrium is generally closely approached within several hours (Reddy et al., 1981; Inskeep and Bloom, 1986). One concludes, therefore, that the oversaturation of calcite solid solutions is due to inhibitors that may reduce the rate of precipitation or even prevent the precipitation of CaC03. Known inhibitors include PO;-, M ~ SO:-, ~ Sr, ~ Ba, , Pb, glycerophate, phosphonic acids, organic ligands, and organic acids (Reddy, 1977; Berner et al., 1978; Reynolds, 1978; Reddy and Wang, 1980; Matty and Tomson, 1988). Bricker and Myers (1969) proposed that the adsorption of hydroxyl complexes of metals, such as Fe(II1) and Th(IV), that readily hydrolyze at circumneutral pH values affect crystal growth rates of BaS04. In accord with the inhibition observations for calcite, it has been observed that the poisons noted above are removed in pellet reactors along with the calcium carbonate (Graveland et al., 1983). Indeed, when phosphate and DOC are in excessive concentrations in the pellet reactors (> 1 mg L-I and KMn04 consumption > 50 mg L-I, respectively), both the density of the pellets and carbonate removal efficiency decreases. Organic inhibitors appear to be noticeably more effective at low concentrations than are PO:-, M~~+, or SO;- (Reddy, 1977; Berner et al., 1978; Reynolds, 1978; Reddy and Wang, 1980). The ability of organic compounds to inhibit or prevent carbonate precipitation is used to prevent scale in industrial water processing equipment and in the petroleum industry CWalton, 1967). Inhibitors are effective at concentrations of a few parts per million where the degree of supersaturation is not too great, i.e., considerably less inhibitor is required to inhibit crystal growth than to prevent nucleation from high oversaturations (Matty and Tomson, 1988). The preceding qualitative results require a quantitative framework to be useful in reliable prediction of the likelihood of calcite precipitation and resultant need for water treatment for individual ATES sites and temperatures. Importantly, Ferguson (1984) found that the quantity of inhibitor required to control calcite precipitation in a once-through cooling tower was linearly proportional to the degree of calcite oversaturation, and Matty and Tomson (1988) found that the combined effects of DOC, PO:-, and SO$- on calcium carbonate precipitation were linearly additive. Inskeep and Bloom (1986) determined the effect of several concentrations of DOC on calcite precipitation from oversaturated solutions. It seems likely that the effectiveness of the DOC in a water extract of a soil that is lower than purified fulvic acid in inhibiting calcite precipitation on seed crystals was a result
Page 1 and 2: 4 'Hydrochemistry and energy storag
Page 4 and 5: CONTENTS AUTHORS INTRODUCTION J.W.
Page 6 and 7: 4 Corrosion 5 Some conclusions Refe
Page 8 and 9: AUTHORS 0. Andersson VIAK AB P.O. B
Page 10 and 11: INTRODUCTION J.W. Lyklema This volu
Page 12 and 13: THE INTERNATIONAL ENERGY AGENCY AND
Page 14 and 15: 3 THE IEA The International Energy
Page 16 and 17: In addition to projects in the doma
Page 18 and 19: THE RELATION BETWEEN AQUIFER THERNl
Page 20 and 21: 3 VIABILITY ATES systems contribute
Page 22 and 23: Figure 4 Temperature fluctuations o
Page 24 and 25: 10°C between two cycles. We have t
Page 26: groundwater quality so seriously th
Page 29 and 30: developed within Annex VI (Environm
Page 31 and 32: carbonate phase, the use of a high-
Page 33: generally contain sufficient organi
Page 37 and 38: of the water for storage. These tre
Page 39 and 40: the higher ATES temperatures. There
Page 41 and 42: One of our research objectives is t
Page 43 and 44: COUDRAIN-RIBSTEIN, A. and GOBLET, P
Page 45 and 46: SPOSITO, G, and LeVESQUE, C.S. ; 19
Page 47 and 48: saturation with respect to calcite
Page 49 and 50: system would influence the hydroche
Page 51 and 52: columns were heated from 11°C to 9
Page 53 and 54: (Table 2), clearly shows that the i
Page 55 and 56: Plate 1: CaC03 grain from first cen
Page 57 and 58: decrease in ca2+ activity, to reach
Page 59 and 60: y thermodynamic equilibrium calcula
Page 61 and 62: HOLM, T.R., EISENREICH, S.J., ROSEN
Page 63 and 64: INTRODUCTION The use of aquifers fo
Page 65 and 66: As can be seen "cloggingn has been
Page 67 and 68: specific capacity of the well and c
Page 69 and 70: the water being injected. The reaso
Page 71 and 72: Figure 5 Simplified stability diagr
Page 73 and 74: 3.4 Clogging by organic slime Clogg
Page 75 and 76: 4 CORROSION 4.1 Forms of corrosion
Page 77 and 78: When halogens are known to be prese
Page 79 and 80: available on the market. SOME CONCL
Page 82 and 83: BIOGEOCHEMICAL ASPECTS OF AQUIFER T
Page 84 and 85:
In accordance with Figure 1 mangane
Page 86 and 87:
at a neutral pH is kinetically dete
Page 88 and 89:
of such biocides used against desul
Page 90 and 91:
HYDROGEOCHEMICAL TRANSPORT MODELLIN
Page 92 and 93:
The complexity of the models with a
Page 94 and 95:
The comparison shows that inclusion
Page 96 and 97:
the component O2 (Oxygen) has been
Page 98 and 99:
The results of a recent solubility
Page 100 and 101:
The neutral "exchangeable" complex
Page 102 and 103:
SrC12 elution of Delft sediment, sh
Page 104 and 105:
The saturation ratios can be used i
Page 106 and 107:
Recovered water in the long term te
Page 108 and 109:
Cumulat~ve Flow (103m3) Cumulative
Page 110 and 111:
Dissolution of silicates is in much
Page 112 and 113:
KIRKNER, D.J., and REEVES, H.; 1988
Page 114 and 115:
WATER TREATMENT AND ENVIRONMENTAL E
Page 116 and 117:
Table 1 Ove~iew of chemical treatme
Page 118 and 119:
calculated with a computer model th
Page 120:
Figure 1 Schematic representation o
Page 123 and 124:
addition shows an increase in neces
Page 125 and 126:
Table 4 summarizes the primary envi
Page 127 and 128:
wsts for this overdimensioning may
Page 129 and 130:
_? Primary circuit Figure 7 Reactor
Page 131:
Problems with iron precipitation ca
Page 134 and 135:
RESEARCH ON HYDROCHEMISTRY AND WATE
Page 136 and 137:
ANNEX XI L - -1 I Figure 1 Relation
Page 138 and 139:
stores. F. To test selected water t
Page 140 and 141:
(Fe, Ca, Mg) solid solutions. The p
Page 142 and 143:
corrosion and scaling rates under d
Page 144:
the industry. For this treatment no
Page 149 and 150:
Water nuisance. Proceedings of Tech
Page 151:
No. 36 No. 37 No. 38 Urban storm wa
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