Online wastewater analysis for the determination of mercury, arsenic and selenium at trace concentrations, using atomic fluorescence spectrometry.

Mercury, arsenic and selenium are considered environmental priority pollutants and the determination of these metals in wastewater from industrial sources is a challenging application. In recent years wastewater treatment plants have been installing technologies to capture and remove the metals. The efficiency of these treatment processes needs to be monitored using accurate analytical systems.

Many industrial processes require wastewater monitoring for these elements including thermal coal power generation (FGD wastewater), oil and gas refineries (produced/desalter water), smelting plants, semiconductor fabrication, incineration wastewater and chor-alkali plants. The targeted sample matrices are often quite difficult to manage so any online approach must be capable of handling a variety of complex waste waters.

It is widely accepted that online analysers offer some major operational and cost benefits compared to traditional laboratory analysis. Not only does the online solution offer improved efficiency, accuracy, and consistency of data but also lower operating costs and labour saving and safety through automation. Unlike laboratory methods, online analysers have no data gaps – as they offer 24/7 analysis and real time results with pre-set alarms to enable a rapid reaction when a problem is detected.

PS Analytical’s latest models represent the third iteration of their online offerings for aqueous liquid streams. Both of PSA’s systems have some standard features such as a touch screen PC, multiple sample streams including grab samples, self-cleaning sample filtration, very low reagent and utility consumption, online digestion and sample preparation and customisable alarm output options. Atomic fluorescence spectroscopy is simple to operate, inexpensive to run and enables ultra-trace limits of detection, wide analytical linear ranges and no chemical interference.