The Times - UK (2021-12-21)

the times | Tuesday December 21 2021 2GMS1 27

News

Wildlife flourishes

after waterways

healed naturally

When the swans set up home it was an
early indication that the first wetland
created to remove phosphorus from
our waterways might have benefits that
go beyond filtering out pollution.
“They used to charge at you but they
are becoming more amenable,” Ruth
Barden, director of environmental
solutions at Wessex Water, said.
The two swans arrived a few months
after the 12 wetland pools were created
last year next to Cromhall sewage
works, a site in rural south Gloucester-
shire serving 2,000 people. This year
the pair had five cygnets. The birds also
act as security guards. “They scare off
the Canada geese, who could decimate
the plants we need to make this whole
thing work,” Barden said.
The wetland, with its careful balance
of plants and microbes, has been
constructed as a test case to prove that
nature can be used as a sustainable

such as ferric chloride, and energy-

intensive filtration systems to remove

phosphorus, which Barden admits is

economically and environmentally un-

sustainable. The plants and microbes at

Cromhall wetland absorb the phospho-

rus naturally. Barden said that to meet

new standards for phosphorus levels

they would probably have to double the

dose of ferric chloride, creating more

slurry as a byproduct, and install addi-

tional filtration processes. “Hopefully

we can do the same job without the

carbon and by actually sequestering

carbon [from the air], because that is

what wetlands do,” she said.

The wetland was commissioned in

April last year and has five years in

which to show it can produce water re-

leased into the nearby Tortworth

Brook with phosphorus levels of 2mg

per litre. After 18 months the average

levels are about 0.5 to 1mg per litre.

The number and range of birds, bats

and insects has flourished as well.

“Wetlands are like beacons from the air

and birds just know when a new one is

created,” Roberts said. When ecologists

carried out a survey in September they

spotted skylarks and linnets, both on

the red list after big declines in breeding

populations, as well as six species of bat

feasting on the insect life supported by

the pools. Smooth and palmate newts

have also made the site their home.

With help from Times readers, the

WWT aims to restore 100,000 more

hectares of wetland. Donations will be

doubled up to £115,000 through an

anonymous gift of £90,000 and

£25,000 from Moto in the Community.

Will Humphries
Southwest Correspondent

christmas
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method of removing excess phosphorus

from wastewater. Too much phospho-

rus in rivers, largely from treated do-

mestic sewage, as well as agriculture

and industrial run-off, can lead to

excessive algae growth and

reduced oxygen levels,

upsetting the balance of life

in waterways.

Wessex Water received

permission from the Envir-

onment Agency to test the

new approach after teaming

up with the Wildfowl & Wet-

lands Trust (WWT) charity,

which is supported by The Times

and Sunday Times Christmas Ap-

peal. “The Environment Agency hasn’t

really until now accepted wetlands as a

water treatment solution,” Barden said.

Dan Roberts, the WWT’s project

manager for nature-based solutions,

said wetlands were complicated sys-

tems but the charity had decades of

experience in maximising their

benefits.

About 90 per cent of this country’s

natural wetlands have been lost, often

covered in Tarmac or drained for farm-

land, with serious consequences. In

75 years the WWT has restored and

protected thousands of hectares of

wetland around

Britain. They soak up

floodwaters to protect

homes and businesses and can

absorb huge quantities of carbon

dioxide from the air. They also provide

vital habitat for rare birds and tranquil

spaces to boost our mental wellbeing.

Their ability to extract pollutants

from water — trapping heavy metals in

their silt or soaking up phosphorus via

their vegetation and microbial life — is

growing clearer at a time when the

pollution of our waterways has

prompted a nationwide investigation

by environment watchdogs.

At present water companies use a

combination of iron-based chemicals,

Ruth Barden at Cromhall, where skylarks have been spotted

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