Glossary / A

The ability of paper to absorb fluids such as water or printing ink.

Decrease in the pH of soil and water due to precipitation containing dissolved ammonium compounds, sulphur and nitrogen oxides; an indirect cause of forest damage.

Activated sludge treatment
A biological method of cleaning up waste waters in three stages. Stage I involves (anaerobic) equilibration. In stage II activated sludge containing micro–organisms is led into an aeration basin to speed up oxidation of organic matter and ammonia. In stage III the sludge is allowed to settle and the treated waste water is run off. Some sludge is removed and a portion is returned to the aeration basin.

Adhesive paper
Paper that has an adhesive substance applied to one side, which when dampened adheres to the surface it is pressed against.

Aerated lagoon
A biological waste water treatment method in which air (oxygen) fed into an aeration basin reduces the effluent load.

Air drying
Method of drying the paper web on the paper machine by blowing air along the direction of the web.

Air mail paper
Light weight, thin and mainly woodfree writing papers for air mail. Anaerobic treatment Process employing micro–organisms to reduce organic matter in waste water in the absence of oxygen.

AOX (Absorbable Organohalogens)
Absorbable organic halogens. AOX is a sum parameter measuring total concentration of chlorine bound to organic compounds in waste water. AOX measures all chlorine compounds both harmful and harmless (a sum parameter).

Art paper
High quality and rather heavy two–side coated printing paper with smooth surface. The reproduction of fine screen single–and multicolour pictures ("art on paper") requires a paper that has an even, well closed surface and a uniform ink absorption.

Artificial parchment
Woodfree paper that is produced by fine and extended grinding of certain chemical pulps and/or the admixture of special additives. As a result of the "smeary" grinding, the fibre structure closes homogeneously. It is used e.g. for wrapping meat and sausages or as corrugating medium for biscuit packaging.

Auxiliary chemical
A chemical added to a stage of paper–making aimed at improving the efficiency of a part of the process.