Action: Clean waste water before it enters the environment
Key messagesRead our guidance on Key messages before continuing
- One study evaluated the effect, on peatland vegetation, of cleaning waste water before it enters the environment. The study was in a fen.
- Characteristic plants (1 study): One study in a floating fen in the Netherlands found that after input water began to be cleaned (along with other interventions to reduce pollution), cover of mosses characteristic of low nutrient levels increased.
- Vegetation structure (1 study): The same study found that after input water began to be cleaned (along with other interventions to reduce pollution), vascular plant biomass decreased.
Waste water could be cleaned before it is released into peatlands or before it enters the environment in general (ultimately reaching peatlands). Excess nutrients, salts, heavy metals, radioactive materials and organic compounds should be removed. Acidity (pH) should be adjusted. Hot water should be cooled. Waste water could be treated using traditional industrial methods, or in ‘constructed wetlands’ that contain plants and microorganisms to absorb or break down pollutants (Kadlec et al. 2000).
Caution: Peatland vegetation is very sensitive to water chemistry (Rydin & Jeglum 2013). If cleaned waste water is being discharged directly into a peatland, its chemistry should be carefully controlled to match natural input water. Note that bogs receive their water only as rain, so are likely to be harmed by any other water inputs.
Key peatland types for which this action may be appropriate: bogs, fens/fen meadows, tropical peat swamps.
Kadlec R.H., Knight R.L., Vymazal J., Brix H., Cooper P. & Haberl R. (2000) Constructed Wetlands for Pollution Control: Processes, Performance, Design and Operation. IWA Publishing, London.
Rydin H. & Jeglum J.K. (2013) The Biology of Peatlands, Second Edition. Oxford University Press, Oxford.
Supporting evidence from individual studies
A study in 1984–2013 in a floating rich fen in the Netherlands (Kooijman et al. 2016) found that after installing water purification facilities (along with other interventions to reduce pollution), moss cover changed to species characteristic of lower nutrient levels whilst vascular plant biomass decreased. Over 25 years following intervention, four of seven moss species characteristic of low nutrient levels increased in cover (from 1–62% to 11–83%). Meanwhile, six of seven moss species characteristic of high nutrient levels decreased in cover (from 7–78% to 1–32%). Over 28 years, vascular plant biomass decreased from 1,123 g/m2 to 287 g/m2. Since the 1970s, water purification facilities were built to treat the fen water source (no further details reported), the water source was changed from a nutrient-rich river to a nutrient-poor lake, and the water was rerouted to allow more time for nutrient reduction. The study does not distinguish between the effects of these interventions. In addition, there was a general reduction in nutrient input from urban areas. In 1988 and 2013, cover of every moss species was recorded in a 25 x 200 m area. In 1984 and 2012, above-ground vascular plant biomass was collected, dried and weighed.