Best Available Techniques: Guidelines for UK Landfill Leachate Treatment - Help Us write them

My company, Enviros Consulting based in the UK, has recently been
awarded the contract by the UK Environment Agency to consult and
prepare the above BAT guidance.

A detailed press release on the project has been also published in the
UK Waste Management Press, and thus can be seen by visiting our
website www.leachate.co.uk and clicking on the "News" button on the
left menu.

We are keen to obtain as much comment as possible during the
consultation stage from all those involved in leachate management - so
please do feel free to respond to this thread or contact us direct.

The UK approach to leachate treatment is to adopt the Best Available
Technique solution. This will be specific to the site, and the
potential impact of the leachate at the discharge point. The UK
environmental legislation also incorporates the principle of BATNEEC
(Best Available Technology Not Exceeding Excessive Cost) , and this
philosophy will be inherent in the guidance ultimately derived for BAT
in the UK.

We consider that in leachate treatment as in all good engineering,
good practice lies in applying appropriate solutions, not in
unecessary spending at many sites to achieve a blanket "one solution
fits all solution" which would only appropriately apply to a few worst
case sites (eg Reverse Osmosis). "High tech" solutions such as reverse
osmosis are very costly when compared to alternatives, and may not
provide any real tangible benefits when compared with biological only
treatment. This is especially the case in the UK where we have a high
rainfall and plenty of precipitation and groundwater contribution to
baseline dry weather flows throughout most summers to provide dilution
at river discharge points.

Admittedly, for example, refractive COD may remain after such
treatment , but if a risk assessment approach shows that such
remaining parameters will have negligable impact, then these lower
cost alternatives which allow some refractive COD to remain, may well
prove very much to be the BAT.

This is quite different from the national discharge consent
requirements applied by environment agencies in many nations,
including much of Europe. The application of a national consent
standard (or perhaps two or three classifications for different types
of watercourses) no doubt keeps the cost of regulation low and simple
to administer , where only one (or two or three) sets of rules exist
for all sites. National discharge consents no doubt provide lots of
work for "high-tech" environmental industries, but ultimately are not
environmentally defensible (or sustainable) in my view, where within
market economies cost bears a close correlation to use of resources
and overall environmental impact.

Also, to take what amounts to the
"purer-treated-effluent-must-always-be-better" viewpoint I have often
heard voiced (most often outside the UK), to its ultimate conclusion,
just let's think about the environmental impact of discharging pure
distilled water as a major component of any natural watercourse flow!
This would certainly not be zero, with no nutrients or salts present
at all - certainly this form of discharge would not be "natural" nor
ecologically neutral in its impact  at all.

So, in the UK the selection of BAT will necessarily be in the context
of Site Specific Risk Assesment, and compliance with the UK (and EU)
system of EQSs (Environmental Quality Standards for Controlled Waters)
for all receiving watercourses, whether the leachate is pumped to a
Public Sewage Works, and then discharges, or it is treated on site to
a standard suitable for direct watercourse discharge.

Is it BAT for example to discharge to a public sewage treatment works
a leachate high in ammoniacal nitrogen when although there is
sufficient dilution available at the STW to achieve the STW's
discharge quality, there is a low percentage nitrification removal
capability, or practically non at all! The sewage works undertaker may
be keen to accept the revenue from such a waste stream, particularly
if he applies a multiplier under the charging formula for NH4-N,
because an older low BOD leachate may cost him little to treat. Should
this be outlawed under BAT?

This is even more difficult when it is realised that it is often a
matter of degree how much nitrification /denitrification which takes
place, and it is only the operating company which will know the %age
nitrification and denitrification - and will also consider this to be
commercial-in-confidence information to be known only to the Water Plc
operating the Public Sewage Works. So how does the landfill operator
(or his leachate management plan consultant) even find out to what
extent his leachate would be nitrified and/or denitrified at the STW?

We hope you will visit www.leachate.co.uk , find out a little more by
seeing the types of SBR biological leachate plants commonly built in
the UK, and comment on these issues, plus perhaps suggesting more for
discussion, to help us create these important UK BAT guidelines!