Chlor-alkali plant

Fig. 2. Operating chlor—alkali plants in the United States and Canada (5). Courtesy of the Chlorine Institute, Inc. (500 miles = 800 km.)...

The unit cost of the d-c supply decreases with increasing voltage and amperage (see Fig. 4). A chlor—alkali plant is therefore most economical when as many high amperage cells as possible are connected in series. 

D. L. Peet and J. H. Austin, Nafion Pefluorinated Membranes, Operation in Chlor—Alkali Plants, Chlorine Institute Plant Managers Seminar, Tampa, The Chlorine Institute, Feb. 1986. 

D. L. Peet, Membrane Durability in Chlor—Alkali Plants, Electrochemical Society Meeting, Honolulu, Hawaii, Oct. 1987 Proceedings of the Symposium on Electrochemical Engineering in the Chlor—Alkali and Chlorine Industries, PV. 88-2, 1988, pp. 329—336. 

Markholm mm and Bennett JP (1998) Mercury accumulation in transplanted llypogymniaphy-sodes lichens downwind of Wisconsin chlor-alkali plant. Water, Air Soil Poll 102 427-436. 

According to the different sentinel species analyzed, THg levels in specimens collected downstream from the impacted areas are 10-20 times greater than upstream levels. It clearly points out the relevance of chlor-alkali plants in terms of mercury river pollution. 

Keywords Aquatic organisms, Chlor-alkali plants, Crayfish, Fish, Mercury, Methylmercury, Zebra mussel... 

In Europe, Spain is the third country - after Germany (18) and France (10) -as regards the number of chlor-alkali plants, with a total of nine. Nevertheless, Spain is ahead along with Germany, in respect to the number of plants (8) which are still using Hg-electrolysis technology. The membrane technology represents... 

Finally, it should be mentioned that three out of the eight Spanish chlor-alkali plants operating with the mercury process are located in the Ebro River basin in the cities of Sabinanigo and Monzon - along the tributaries Gallego and Cinca Rivers, respectively - and Flix along the Ebro River (Fig. 1). Indeed, mercury emissions from the Hix and Monzon have already been reported [28]. Therefore, the mid-low Ebro River watershed might be considered as a hot spot of aquatic pollution of mercury in Spain. 

On the other hand, the industrial activity of the other two mercury cell chlor-alkali plants have caused important Hg pollution in Sabinanigo (capacity of 25 x 103 Mg chlorine/year) and Monzon (31 x 103 Mg chlorine/year) (see Fig. 1), two small and industrial cities located in the middle course of the Gallego and Cinca Rivers, respectively, two tributaries of the Ebro River [31]. 

Fig. 2 Location of the lower Ebro River catchment, zebra mussel, crayfish, and fish species sampling sites in the Flix dam area. Samples were taken at several stations in the four areas (RF = control site upstream WR = wildlife reserve HS = hot spot or chlor-alkali plant, and MD = meander). Positions of dams (black bars) and overflow dams (grey bars) are indicated to illustrate the mutual isolation of aquatic organisms sampled...

Another well-documented case of feral fish chronically exposed to mercury through the effluent of the chlor-alkali plant is the case of the Cinca tributary [64, 65]. Barbel and bleak were collected upstream (SI) and downstream (S2) a chlor-alkali plant located at Monzon (Fig. 3). It is important to point out that there is no physical barrier between SI and S2 to prevent fish upstream migration of suspicious contaminated fishes from S2. 

Fig. 3 Map with the sampling sites in the Cinca River, upstream (SI) and downstream (S2) of the chlor-alkali plant of Monzon showing THg levels. Adapted from [65]...

In this regard, high liver/muscle ratios of mercury concentration were reported in fish exposed to the effluents from a chlor-alkali plant in a contaminated area [68, 69]. Then, liver of fish downstream from the plant also had very high inorganic mercury to THg ratios [69]. 

Hence, the low THg levels reported in both barbel and bleak specimens sampled upstream the chlor-alkali plant in Monzon, suggest that neither of these fish species migrate upstream the factory, and therefore the fishing area upstream from Monzon does not carry a very high risk to public health, at least for these two fish species studied. 

The case study of Flix is another well-documented concern about fish that are chronically impacted by Hg throughout a chlor-alkali plant. Here, we review all the data available about the reported levels of Hg. A description of the biological effects is not the aim of this chapter and will not be covered, but we will mention whether or not these effects exist. 

The determination of THg levels in liver, kidney, and muscle of common carp from the Flix area and sampling points of interest located downstream has been extensively reported [33, 34]. In this regard, the specimens were collected in five stations, namely Ribaroja reservoir (located 10 Km upstream from Flix) the Flix reservoir (chlor-alkali plant and a waste dumping site) Asco, Xerta, and the irrigation channels of the Ebro Delta Natural Park, three sites situated 5.6 Km, 37 Km, and 70 Km downstream from Flix, respectively (Fig. 2). 

Delta irrigation channels (Faria, personal communication) indicate a saline water intrusion in the irrigation channels of the Delta. This saline intrusion may cause a dilution of mercury pollution originated at the chlor-alkali plant, hence resulting in lower average THg concentrations in Delta specimens. 

Biester H, Muller G, Scholer HF (2002) Estimating distribution and retention of mercury in three different soils contaminated by emissions from chlor-alkali plants part I. Sci Total Environ 284 177-189... 

Landis MS, Keeler GJ, Al-Wali KI, Stevens RK (2004) Divalent inorganic reactive gaseous mercury emissions from a mercury cell chlor-alkali plant and its impact on near-field atmospheric dry deposition. Atmos Environ 38 613-622... 

Montuori P, Jover E, Diez S, Ribas-Fito N, Sunyer J, Triassi M, Bayona JM (2006) Mercury speciation in the hair of pre-school children living near a chlor-alkali plant. Sci Total Environ 369 51-58... 

OSPAR (2008) Implementation of PARCOM Decision 90/3 on reducing atmospheric emissions from existing chlor-alkali plants. ISBN 978-1-905859-88-7... 

A substance of main environmental and health concern is mercury. Tons of mercury are released annually form Flix and Monzon mercury cell chlor-alkali plants, and there is evidence that it reaches sediments and animals downstream these plants. In fact, a substantial fraction of fish from the low Ebro River (arriving as far downstream as Xerta) contains too much Hg in their bodies to be considered apt for human consumption [8, 9]. 

This section of the Ebro River is under the direct impact of the Flix chlor-alkali plant and of its residue sediments. Contamination of Hg and OCs is maximal in these sediments, and there is evidence that it leaks downstream as far as at least to Xerta, 37 km away Flix ([8, 9], Fig. 4a, d). Fish populations in Flix show poorer condition and fecundity than their counterparts sampled in Riba-roja or the Delta [38]. In addition, HSI and CF in carps showed good correlation (positive and negative, respectively) with OC burden (Fig. 4c). These data indicate that the pollution by Flix residues and, specifically, by OCs, affects the growth and health status of fish from the low Ebro River. 

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