Surface World January 2019 Surface World January 2019 | Page 18
INDUSTRY NEWS
Does lime hold future
for waste treatment?
By Xavier Mear, Product Manager for Neutralac at Lhoist
Add in to the mix the uncertainties
surrounding Brexit and, while Lhoist sees
continued success for its liquid lime
technology, we are being asked questions
about the security of its supply chain and
how it can contribute to users’ own security
of manufactured goods. The good news is
that, as Lhoist owns a large lime quarry just
south of Buxton, whatever geopolitical
uncertainties continue to dog the UK, there’s
going to be no issue when it comes to lime
dosing supplies!
For the water utilities,
lime dosing is a proven
technology that works,
helping them to ensure
that they achieve the
required consent limits
imposed on them by the
environmental regulator.
As these consent levels
show no sign of easing off
– indeed, if anything, they
are likely to become stricter
over time – the water
companies are constantly
on the look-out for new
technologies, hardware,
machinery – anything which
will help them to reduce
contamination levels,
ideally, at the same time as
reducing chemical use.
On a different note, the recycling or reusing
of waste streams is becoming very topical.
Individual customers, who might have trace
elements of heavy metals in their waste, are
beginning to understand that it could be
economically viable to recycle their sludge
and organic waste streams, and
subsequently, to modify it. The volume of
material now being processed means that
there is pressure on to modify and recycle the
sludge.
Suitable for anaerobic
digestion and biogas
Agriculture produces slurry and sludge, food
manufacturers create quantities of waste
from washing and processing vegetables, for
example, and abattoirs create an acidic,
sludge-based waste. Some of these are
suitable for anaerobic digestion and biogas.
Long term, there is real potential, and, as gas
and electricity prices continue to rise, so ways
of using waste to generate energy are going
to become more attractive – and are
certainly a better option than landfill.
For Lhoist, there is potential in this waste-to-
energy, biogas market. Taking the food
industry as an example, some of the waste is
‘fairly consistent’ and requires no pre-
conditioning, while plenty of waste does
require pre-conditioning before entering the
AD waste stream system. To ensure efficiency,
bacteria needs to work in optimal
environments, ensuring that gas production is
as high as possible, and Lhoist products are
applicable here.
We have carried out AD research that shows
there is a biogas increase when using our
products and after the AD process, the
sludge fraction goes to agricultural use with
treated water going down the drain.
Focus on sludge
nutrient recovery
There has been increasing focus on sludge
nutrient recovery – phosphate in particular,
which is a key nutrient in fertilisers. Right
now, these levels are very high and the water
utilities are looking at both phosphate
reduction and recovery ideas. The phosphate
consent standard is incredibly tight, and is
perhaps going to go beyond what standard,
known practices can achieve.
When it comes to sludge chemistry, there are
several start-up companies and various
research and development projects that are
looking to provide solutions. It is unlikely that
one solution will provide the answer for
everyone, but a combination of different
approaches will, hopefully, provide an overall
solution.
Lime is an important reagent that has been
used for centuries and there are many
day-to-day applications of using that
chemistry. Amongst other projects, we are
working on removal efficiencies and dealing
with the implications of both storing and
dosing applications.
Blockages and dust emissions are two
potential issues, but the industry has moved
forward in terms of addressing these.
In any case, Lhoist encourages potential
customers or existing customers with new
applications to test the lime dosing solution
first. We know that customers want to test
materials in real life to check that there will
be no negative impact on their plant. So, we
set up parallel trials to run alongside the
existing sludge and chemical dosing process.
This means that the customer can select what
they are happy with, and there’s always the
option to switch back.
Once the trial is set up it stays on without
interruption, and the customer can assess
such parameters as the cleanliness of the
water, the contamination removal and how
easy it is to deal with the sludge. We source
CONTINUED ON PAGE 20
16
JANUARY 2019
twitter: @surfaceworldmag