Water quality, evolution

Figure 2.4.4 shows the evolution of nitrate concentration at the same sampling point (three times) during a period of 12 days. Even if the raw values of the nitrate concentration level measured by PASTEL UV are slightly overestimated in comparison with those obtained by laboratory method, this device can be used to assess trends in water quality evolution and then could help decision making in water management resources. The results obtained for ammonium concentration by Merck test kit lead to more or less to the same conclusions compare to reference method. 

The last application in this chapter deals with the study of water quality evolution in a treatment plant for tap water production. The plant is located close to Montpellier in the... 

Planned tools/methodologies Computer programs to simulate the evolution of the water resources and the water quality and interviews with experts to represent/quantify relationships. 

Oscoz J, Duran C, Pardos M, Gil J, Viamonte A (2008) Historical evolution of the biological water quality in the Ebro Basin (Spain) (1990-2005). Limnetica 27 119-130... 

Berzas J. J., Garcia L. F., Rodrigues R. C., and Martin-Alvarez P. J. (2000) Evolution of the water quality of a managed natural wetland Tables de Daimiel National Park (Spain). Water Res. 34, 3161-3170. 

Among all usual parameters for water quality control, nitrogen is probably the most known and monitored, particularly nitrate. N is present in water in reduced form (organic and ammonium nitrogen) and oxidised form (nitrites and nitrates). The evolution of the N compounds depends on physico-chemical and biological mechanisms occurring in natural water or all along treatment processes (Fig. 2). 

The constant evolution of water quality standards implies the development of faster and cheaper analytical procedures. These are more particularly adapted for online measurement, for the frequent analysis of metallic constituents or for the estimation of... 

The conclusion of this experiment is that, even if the pollution level of the river is low, due to high performances of the wastewater treatment plants, the use of UV spectrophotometry simplifies the field (and laboratory) work by bringing complementary information on the evolution of water quality. 

Another study based on the use of UV spectrophotometry for the evaluation of the impact of treated wastewater discharge in rivers [25] has shown that not only the qualitative and quantitative evolution of river water quality was possible, but also some hydraulic parameters such as the dilution factor of discharge or confluences. 

But even if more adapted methods for spectra exploitation are nowadays used for the estimation of some water quality parameters, the main interest of using UV spectrophotometry for urban wastewater quality monitoring is the significance of UV spectrum shape, the evolution of which gives useful information. 

In addition, there may also be variation of background water quality with time, for example linked to a rising or falling groundwater table, or related to evolution of physicochemical conditions engendered by intensive groundwater pumping. 

The shape of the ageing curves ([Zn] = /(operating time)) was different with TZW nanofiltration concentrate and cannot be described by a simple shape (type 1, 2 or 3). Figure 4.13 shows a comparison between the evolution of zinc concentration (after 8 hours stagnation) and pH of water. Parallel evolution can be seen an increase in pH corresponds to a decrease in zinc. Thus, it appears very likely that variations in zinc concentration is due essentially to changes in water quality (pH, but probably also temperature, oxygen or other parameters) and not (only ) to ageing of the material. 

ISO 9439,1999, Water quality - Evaluation of ultimate aerobic biodegradability of organic compounds in an aqueous medium - Carbon dioxide evolution test International Standard ISO 9439 1999(E), International Oiganization for Standardization (ISO),... 

Downstream from the sources, the geochemical evolution of AMD is usually controlled by (1) oxidation of Fe(ll) to Fe(in), (2) progressive pH increase and dilution of metal concentrations by mixing with pristine waters, (3) hydrolysis and precipitation of different metal cations as pH increases, and (4) sorption of different trace elements (As, Pb, Cr, Cu, Zn, Mn, Cd) onto the solid surfaces of precipitated metal hydroxides/hydroxysulfates [14]. The pH-dependent sequences of precipitation and adsorption are very similar and follow the order Fe(III) > Pb > A1 > Cu > Zn > Fe(II) > Cd [5, 23]. The overall result of these processes represents a mechanism of natural attenuation with environmental benefits for the water quality [12-14, 44]. 

IS09439 1999 Water quality—evaluation of ultimate aerobic biodegradability of organic compounds in aqueous medium—carbon dioxide evolution test... 

ISO 9439 2000(E), Water Quality - Evaluation of Ultimate Aerobic Biodegradability of Organic Compounds in Aqueous Medium - Carbon Dioxide Evolution Test, International Organization for Standardization, Geneve, Switzerland, 2000. 

Phthalide. In a 1 litre bolt-head flask stir 90 g. of a high quality zinc powder to a thick paste with a solution of 0 5 g. of crystallised copper sulphate in 20 ml. of water (this serves to activate the zinc), and then add 165 ml. of 20 per cent, sodium hydroxide solution. Cool the flask in an ice bath to 5°, stir the contents mechanically, and add 73-5 g. of phthalimide in small portions at such a rate that the temperature does not rise above 8° (about 30 minutes are required for the addition). Continue the stirring for half an hour, dilute with 200 ml. of water, warm on a water bath imtil the evolution of ammonia ceases (about 3 hours), and concentrate to a volume of about 200 ml. by distillation vmder reduced pressure (tig. 11,37, 1). Filter, and render the flltrate acid to Congo red paper with concentrated hydrochloric acid (about 75 ml. are required). Much of the phthalide separates as an oil, but, in order to complete the lactonisation of the hydroxymethylbenzoic acid, boil for an hour transfer while hot to a beaker. The oil solidifles on cooling to a hard red-brown cake. Leave overnight in an ice chest or refrigerator, and than filter at the pump. The crude phthalide contains much sodium chloride. RecrystaUise it in 10 g. portions from 750 ml. of water use the mother liquor from the first crop for the recrystaUisation of the subsequent portion. Filter each portion while hot, cool in ice below 5°, filter and wash with small quantities of ice-cold water. Dry in the air upon filter paper. The yield of phthalide (transparent plates), m.p. 72-73°, is 47 g. 

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