Techno Talk
Mixed menu
Mark Nelson
This month, we have two tales that are as different as chalk and cheese, but they both mix biology
and electronics. Let’s tuck in…
T
he name London Underground
probably suggests bustling tube
trains running deep below the
city’s streets – but, of the network’s 250
miles of track, a mere 21% are below
ground in tunnels. The remaining 79%
of the system is in open air at surface
level, with – for most of the way – verdant greenery and all manner of wildlife
on each side of the track. Much of this
is highly desirable, but something very
unwelcome has also colonised the green
corridors: Japanese Knotweed. Fastgrowing, highly invasive and almost
impossible to eliminate, its vast root
systems damage physical structures
by undermining their foundations and
drainage arrangements. Over time, it can
even make them structurally unsound.
Boiling it alive
The highly regarded www.ianvisits.
co.uk website reports that dealing with
Japanese Knotweed is a serious issue
for the Underground, simply because
the common method of dealing with it
– injecting glyphosate weedkiller into
the plants – is labour-intensive and timeconsuming. Often, it takes several years
of repeated applications to fully kill the
plants right down to the roots. Now the
organisation is trialling an electrical
method of successfully killing off these
infestations instead of injecting them with
chemicals. The Warwickshire company
RootWave is the originator of this method, in which operatives use handheld
‘electric wands’ and a compact mobile
generator to give the knotweed the kiss
of death. The web report explains that
waving the wand over plants applies a
high-current shock that causes the water
in them to boil, damaging the plant’s cellular structure. This works both below
and above ground level, with the damage done below ground that is critical
in stopping the plant from regrowing.
Project manager Craig Ward reports:
‘The plant dies instantly when we use
RootWave Pro, halving the number of
treatments we would expect to make
with conventional methods.’ He adds
that using electric wands, two operatives can cover the same area as twelve
8
people injecting glyphosate into the
plants using the old method. The latter
system also requires expensive specialist
removal of the dead plants to a contaminated waste depot, whereas with
RootWave the team leaves the plants to
die on site and rot down naturally. You
can watch a YouTube video of the process at: https://youtu.be/6fvdB96i470
Feeding hungry bacteria
Even tech-savvy readers of this article
may be surprised to learn that as many
as 40 different metals can be found within the complex structure of a printed
circuit board; gold, copper as well as
numerous rare earth materials, many of
which are used in technology such as
mobile phones. Some of these minerals are now in short supply, especially
when they are mined in conflict zones.
Recycling unwanted mobile phones and
other tech is a no-brainer, but PCBs may
need to travel thousands of miles to refineries for burning, with much of this
valuable material lost and not recovered.
But could these metals be recovered here
in our own country, time after time and
selectively by type? You bet they can!
Eat, don’t heat
Geographical (the official magazine of
the Royal Geographical Society) explains
that the current techniques for recycling
e-waste and electric vehicle batteries are
known as pyrometallurgy and hydrometallurgy. Both processes involve searing
temperatures with a high energy demand
and deep carbon footprint, as well as toxic chemicals, all of which are harmful to
the environment; consequently, the hunt
is on for smarter solutions.
One that looks promising and is starting
to enter commercial use is ‘bioleaching’,
also known as ‘bio-mining’. This involves
covering an object in microbes to extract
metals from e-waste using living organisms. Simply put, the bacteria munch on
cast-off PCBs and other e-scrap. Several
species of fungi can also be used for bioleaching. Bioleaching does not need
high temperatures, but it does produce
toxic substances, including sulphuric
acid, that can damage the environment.
Commercial exploitation
N2S, based in the Suffolk cathedral town
of Bury St Edmunds, is the firm leading
the way with this exciting biotechnology.
The company has been advocating and
providing circular solutions for extending the life of technology for many years,
but most recently it has collaborated with
Coventry University to develop a way of
harnessing the power of nature, using
biotechnology to extract the valuable material within PCBs in an environmentally
friendly way. The firm has also built a
biotech laboratory where this new refining process will be developed.
The initial project, completed last
autumn, has exceeded everyone’s expectations. It has proved not only that
the science can scale up to recover many
more metals than originally planned, but
N2S has also transformed into a biotechnology company, with new laboratories
and staff trained to develop the technology further. For Coventry University it
has also been hugely successful, leading
to academic papers, new funding and
PhDs as just some of the benefits. The
university project leader has started a new
career heading up the new bioleaching
facility at N2S, after gaining technical and
project management training, as well as
graduating from the Knowledge Transfer
Partnership’s Innovation Strategy course.
Sebastien Farnaud, Professor in
Enterprise and Innovation in Healthcare
and Technologies at Coventry University
summed up: ‘We have developed an innovative, efficient and green solution
targeting closed-loop systems, based on bioleaching technology to recover precious
metals from e-waste. This technology has
been embedded at N2S Ltd’s premises,
and has transformed their commercial
capacities of IT waste management and
revolutionised UK industry within the
‘circular economy’, while tackling environmental issues, and tightening security
surrounding e-waste disposal.
He continued, ‘This is a unique
collaboration between a life science
laboratory and a recycling company,
which developed successfully a unique,
novel approach to recovering metals
from e-waste.’
Practical Electronics | July | 2022
