Anna Riikka Nickull has been following developments in the field for 25 years. She believes environmental
efficiency is becoming increasingly important.
The mill conducts numerous analyses of wastewater and the treatment plant to monitor use and load.
produced in the digester was released untreated straight into the waterway below. When waterway impacts began to be surveyed along the Ääne- koski–Vaajakoski route in 1975, the waters were found to be in a disastrous condition. “Quite frankly, the rapids were like sewers back then,” says Leppänen. The stink from the waterway was such that people crossing Kuusaa bridge used to roll up their car windows. The fish pop- ulation also suffered. From the mid-1950s, trout caught in the Kuusaankoski rapids tasted of the pulp mill’s wastewater, and sports fishing in the rapids had to be discontinued. Rising environmental awareness in the 1980s Wood trucks carry a steady stream of logs to the Äänekoski mill area, covering nearly 200 hectares. At the centre of the industrial ecosystem rises Metsä Fibre’s bioproduct mill, with an annual capacity of 1.3 million tonnes of softwood and birch pulp. The mill is also producing many other bioproducts, such as biochemicals and bioenergy. Although the scale of industrial operations has multiplied since the 1930s, the times when you had to hold your nose crossing Kuusaa bridge are long gone. Nowadays, Kuusaankoski rapids are a popular recreational spot and one of the few breeding sites for the endangered brown trout. Anna Riikka Nickull , Metsä Group’s Environmental Manager, says the turn for the better happened in the early 1980s, when Metsä-Botnia, now known as Metsä Fibre, decided to build a new and larger pulp mill in Äänekoski.
“The Supreme Administrative Court set unprecedentedly tight emissions limits for the pulp mill. An activated sludge plant was built for the mill, and it contributed to rapidly cleaning the waste- water.” In the 40 years since, technology has progressed by leaps and bounds. The current bioproduct mill operates within the same wastewater permit limits, despite production volumes that are nearly three times greater. The wastewater is sent to a multistage biological wastewater treatment plant with an aeration basin, where microbes break down its oxygen-consuming matter into carbon dioxide and water. If required, a final chemical treatment can be included in the tertiary phase. The biosludge is pressed into biopellets suita- ble for use as fuel, for example for industrial heating boilers. The sludge is also made into biogas for vehicle fuel. “The mill conducts numerous analyses of the wastewater and the treatment plant to monitor their use and load. Some of the samples are analysed by an outside laboratory.” Metsä Fibre reports the results to the environmental author- ities. When the bioproduct mill was started up, monitoring of the downstream waterway was increased. Separate surveys are conducted to determine the impacts on the thickness of ice and movement of migratory fish. Thousands of waterway analyses annually Metsä Fibre’s Joutseno pulp mill is in Lappeenranta on the shores of Lake Saimaa. The mill has an annual capacity of 690,000 tonnes of softwood pulp, used as raw material for various paper and paperboard grades.
Antti Leppänen A fish biologist, who works at KVVY Tutkimus Oy, a provider of laboratory, research, design and expert services. He carries out fishery observations along the Äänekoski–Vaajakoski waterway.
Anna Riikka Nickull Environmental Manager, Metsä Group’s technology department, environmental team. Responsible for official procedures at Metsä Fibre’s production units and support for environmental management.
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