In recent years, the checking for heavy metals discharged from industrial sewage treatment plants and in surface water used for the preparation of drinking water has increasingly become the focus of official monitoring in many countries. Examples of this are the detection of chromium (VI) and total chromium in the leather and dyeing industry, the detection of copper and nickel in wastewater from galvanising businesses, and the detection of iron, lead and manganese in the conditioning of drinking water. The operating companies are obliged to submit measurements to the responsible environmental authority as the controlling body on a continuous basis. It is therefore an advantage to determine this information online.

When choosing the appropriate measuring technology, it must be noted that Volta metric determination, as a conventional laboratory method, is not suitable for online measurement in process plants. It is sometimes necessary to spend considerable sums on this measuring equipment in order to ensure consistently reliable measuring results in quasi-continuous operation without the intervention of laboratory personnel.

A cost-effective alternative is provided by photometric detection methods, which enable heavy metals to be measured right down to trace level. With the PowerMon range of units, Bran+Luebbe online analysers from SPX provide an ideal platform for these measurements. Applications are available for the above-mentioned examples, among others, thanks to the flexible equipment options. Depending on the application, the verification limits lie in the range from 0.3 µg/l to 3 µg/l, which also makes the units outstandingly suitable for monitoring limits in drinking water.

It is also possible to incorporate sample extracts in order to measure different oxidation stages and complex-bound percentages. The choice of suitable reagents allows interference to be suppressed and the selectivity of the respective measurements to be increased. Furthermore, the list of available applications is continuously being expanded and adapted to suit the latest legislation. Automatic calibration, self-monitoring and support for all common data transmission interfaces enable fully automatic operation without human intervention.