case study - industry - an abbattoir
Ref: W02c

Wetland - Culm grassland R. Lew catchment

An abattoir, where meat from farms is handled, was situated near the river. The floors were routinely washed and the dirty water ran into the surface drains. Nobody gave much thought to where the drains led - in this case the drains went straight into the nearby river.

The dirty water, as you can imagine, contained a lot of blood. Blood absorbs oxygen and so it took oxygen that was in the river. But the oxygen in rivers is needed to support animal life like fish and water dwelling mini-beasts. These creatures fill important roles in food chains that involve many other animals (see B06d).

In the section of river that was polluted by the abattoir it was noticed that the quantity of mini-beasts was few, and that only mini-beasts that didn’t need very much oxygen could survive. The red chironomid midge larvae is an example of a mini-beast that can survive with low oxygen levels, but other mini-beasts like the dragonfly nymph are not quite so lucky.

Footslope wetland, Inny catchment

To prevent pollution occurring in the future the water that is used to wash down the abattoir now goes through a separate waste system instead of a surface drain that empties into the river. Chemicals are used to treat the water in the waste system until it is at a standard that the Environment Agency will allow to go into the river.

Reed beds are also used to improve the quality of the water before it goes into the river. Reed beds act as a natural buffer (a stopper), cleaning the water of pollutants. Wetlands which offer a home to reeds, grasses, sedge and many other important species of plants (and animals) are often recommended as the best way to breakdown pollutants before they reach a river (refer to L06j wetlands & L06f buffer zones).