How are mills’ emissions monitored and supervised?
The most significant emissions are air emissions from pulp mills and power plants, and wastewater emissions from pulp, paper and board mills. The basic requirements of emission monitoring and reporting are usually stated in the mill’s environmental permits. Nowadays the detailed monitoring programs often have to be separately approved by the authorities. Air emissions are monitored daily usually by on-line meters that measure the content of flue gases. In addition, these on-line measurements may be supplemented by regular emissions measurements, where flue gas samples are analyzed with external analysis equipment. Typical substances measured in flue gases are particles, sulphur dioxide (SO2), nitrogen oxides (Nox), and carbon monoxide (CO). For wastewater monitoring, regular samples are taken from the wastewater flow. Several samples are usually combined to form a daily or weekly sample, which is then analyzed in a laboratory. The sampling interval varies from mill to mill depending on
