Reedbeds and Mine Water Treatment

Reedbeds are the most ecologically friendly way of treating what is a serious problem - Minewater. The reedbeds provide a visually attractive solution to the minewater problem brought about by years of coal mining and more recently the cessation of dewatering of such mines which has allowed many watercourses in Britain to become polluted with Iron Ochre, lowering their ecological diversity drastically and in some cases completely.

The constructed wetlands form a concentrated habitat for insects and birds which can also be used as a public amenity with some of the Authority's minewater treatment schemes incorporating picnic areas, paths, benches and viewing points.

However, there is a scientific side to reedbeds. Reedbeds serve two main purposes in minewater treatment these are:

1. Filtration - Filtration occurs both within the soil and subsoil of the reedbed and through the roots of the reeds themselves. As the water makes the journey through the reedbed, the particles of Ferric Hydroxide become caught and remain within the natural filter whilst the rest of the mixture progresses. A successful treatment scheme is one where the reedbeds are of a sufficient size that all of the particles are removed before the water re-enters the watercourse.
   
2. Settlement - Settlement occurs once filtration has taken place. Most of the Authority's reedbeds have a design life (storage capacity) of in excess of 15 years. Settlement is the process by which the particles formed during filtration collect together and fall to the base of the reedbed.

At present we allow approximately 10mg/l to enter the reedbeds at all our schemes with less than 1mg/l entering the watercourses at the end of the reedbed process.