**6. Conclusions**

on aluminum oxide (Tb(acac)<sup>3</sup>

322 Desalination and Water Treatment

0 to 40.7 ppm [90].

**Scheme 3** [12]:

**5. Other applications**

**Scheme** 3. Bioluminescent reaction catalyzed by firefly luciferase.

well as some porphyrin complexes of Pt and Pd [86], is worth mentioning.

**4. Fluorescent total ATP count in wastewaters**

The emitted blue light (~ 475 nm) of a photogenerator excites the fluorescence of a specially selected chemical complex, placed at the end of a fiber-optic oxygen sensor (sol–gel matrix). The exited complex generates fluorescence with a wavelength which is around 600 nm. This fluorescence gets suppressed by the oxygen present in a sample [87–89]. This provides an effective oxygen concentration measurement in water within the range from

The total bacterial count in wastewater is based on bioluminescence. Normally it is used for the industrial and wastewater quality assessment, while for the drinking water it is not so common. The method is known since 1947, when McElroy has demonstrated that bioluminescence of a glowworm is closely associated with adenosine triphosphate (ATP) content [91]. Thus, the measurement of ATP provides an efficient indication of bacterial pollution of water according to

Analysis involves the firefly luciferase-luciferin system. Its contact with ATP molecules generates the "cold" light, counted by a luminometer within 15–20 s. The sensitivity of analysis is very high. It provides detection of 10–17 ATP moles per liter. Recently, there have been some standard solutions for luminometers present at the market: EnSURE™, SystemSURE Plus™ Clean Trace™, NovaLum™, Firefly 2™, Accupoint™, russian-made LYUM-1, Lumitester PD-20™ etc. [92].

Some water treatment facilities require the oil component control in wastewater [9, 93]. Organic pollutants can occur in the cooling water, in the technical-use water, in a boiler-feeding water, and due to the leaks of oils into the steam condensate. For online pollutants' monitoring, the fluorescent sensors are broadly used. The method is highly sensitive. Depending on the type of oil, the detection limits may vary from 1 to 100 ppm. Most of the oils contain some polycyclic aromatic hydrocarbons (PAHs) [94], capable of generating blue or violet fluorescence being exposed to UV irradiation. Usually the excitation light wavelength corresponds

to 254 nm, while the detection operates in a 360 nm spectrum range.

phen), where acac-acetylacetone [85], as shown in **Figure 11**, as

The fluorescent markers added to the circulating water or wastewaters find a broad spectrum of analytical applications for online quality monitoring. The most promising and a fastdeveloping field is a scale inhibitor concentration detection via antiscalant-tagged reagents. At the same time the visualization of scale inhibition mechanisms by the fluorescent-tagged antiscalants is a very promising tool of the scale inhibition theory development. Besides, these reagents can provide some unique opportunities for reverse osmosis membrane mapping, scale inhibition traceability, and a scale inhibitor localization in a circulation water facility.
