The experience of measuring aluminium ion in water

Summary

Practical use of the measuring techniques (specified in ПНД Ф 14.1:2:4.166-2000 and State Standard ГОСТ 18165-89) revealed a number of defaults in the process of determining low concentrations of aluminium in water. The technique of measurement is using the effect of aluminium-aluminon complex coloration with different chemical dosing methods. The experimental investigations showed that replacing successive addition of low concentrations of chemicals with reaction mixture improves the reproducibility of the results. However, the estimate accuracy of measurements (below 0.1 mg/l concentration) carried out with the certified aluminium determination techniques were not reached. Thus, the metrological performance of ПНД Ф 14.1:2:4.166-2000 and State Standard ГОСТ 18165-89 technique have to be revised the more especially that they have been widely used.

Key words

potable water , concentration , aluminium , aluminon solution , sample , absorbency

Establishment of Periodicity of Water Quality Monitoring with Due Regard for Measurement Inaccuracy

Summary

The periodical monitoring of quality of water with changeable characteristics is connected with sampling errors. Methods of accounting of these errors together with characteristics of measurement inaccuracy of polluting substances concentration for assessment of the risk of false conclusions about water compliance (or non-compliance) with specified requirements are offered. It is reasonable to establish the periodicity of measurements from the calculation of proportionality of sampling errors and meteorological inaccuracy specified by the certified measuring technique. The table of optimal periodicity of measurements depending on maximum permissible concentration of a polluting substance and changeability of its concentration in a water body as well as the scheme of prediction of water quality with a specified confidence level are offered for practical application.

Key words

water supply , reliability , pollution , water disposal , standard , quality control , periodicity , selection , samples , measurement inaccuracy , concentration