An air pollution control (APC) system is used at these plants to reduce such emissions. First, solid particle separation occurs via an electrostatic precipitator. Following this, the flue gas undergoes scrubbing, starting with a cooling process achieved by water spraying which simultaneously removes chlorides and heavy metals (Figure 2). Then, desulfurization occurs (this is also known as the alkaline phase), which is achieved by introducing caustic soda into the scrubbing water.

The cleaned waste gas is released into the environment, while the purified ash and APC residue are discarded appropriately. Since these impurities are dissolved in the scrubbing water, the water must undergo treatment and subsequent examination in the wastewater treatment plant (WWTP).

The plant's wastewater must comply with the local regulatory limit values. Traditionally, monthly in-house inspections use atomic absorption spectroscopy and photometry in the laboratory.

However, the contaminant levels in the purified wastewater vary due to its original composition and the charge status of the ion exchanger which requires periodic regeneration. As a result, samples collected during inspections only provide a brief overview. This makes it challenging for operators and authorities to ensure that set limits are consistently met.

Hence, online process analyzers become important for compliance. The 2060 VA Process Analyzer, for instance, provides hourly measurements of the concentration of zinc, cadmium, lead, or other metals in the process wastewater.

Employing voltammetric determination, the 2060 VA Process Analyzer (Figure 3) operates fully automatically. It also features an alarm system that notifies plant personnel when any of the monitored heavy metals approach the limit values. This timely alert enables the introduction of ion exchanger regeneration or other strategies for mitigation, effectively preventing limit value breaches.