Treatability Trials -
the Enviros “Wheely Bin” method

Why a Wheely?

We use wheely bins (as used for household domestic solid waste collection), for our biological SBR treatability trials.

Clearly, it is always worthwhile reducing the risk of process design errors by spending on trials, when several hundreds of £1,000‘s, and possibly up to a £million or more are to be spent.

We think that laboratory bench scale trials have been shown to be too small to be fully reliably “scaled up” to a full scale plant.

We also believe that a fully fledged pilot scale plant based upon an ISC (International Standard Container) as used by many, or the on site “scale model“
approach, to be unnecessarily expensive, and time consuming to set-up.

So the use of the wheely bin is, we have found, a sensible compromise. They are readily available, easy to move when empty, and sufficiently deep to facilitate aeration.

Reliable results
In practise we have found the results to be highly scaleable, and reliable, far as can be judged given the high variability of landfill site leachates in the first place.

The “wheely” idea was pioneered by Howard Robinson more than 18 years ago.

Our policy is to carry out a treatability trial on all landfill leachates, if possible. With very few exceptions, no matter how familiar we are with a leachate, or simple we believe a particular leachate will be to treat, or lax the discharge consent, we still prefer to carry out a trial.

Experience has shown that any leachate can throw surprises, and for the cost of a trial, it is worth doing.

Hazardous Substances (Prescribed List etc)
An often overlooked advantage of a trial is to be able to show the extent of removal of hazardous

substances which may be present in the raw leachate, but which will be prohibited from discharge*

Of course, there will be sites for which there is no characteristic leachate available, and for new sites, there may be little point in conducting a trial on a very new highly acetogenic leachate which will change rapidly over the first few years of the site in operation.

If nothing else, the treatability trial will provide peace of mind, that such parameters as dosing rates, optimum sludge density, and nutrient balance requirements have been verified from experience, rather than from theory.

Timetable
A simple nitrification process treatability trial takes about 6 to 8 weeks to complete. Reporting takes another 4 or 5, depending on the return period for the final water quality analyses results.

At present (January 2004) we have two treatability trials in operation for different sites/ clients. We also perform trials

for a new breed of plants. Namely, “denitrification” type biological plant trials, and these take an additional 4 to 6 weeks to complete, once the nitrification trial has been completed.

A Well Run Trial
The mark of a well run treatability trial will be a trial fully and accurately documented, showing an acclimatisation phase, an optimisation stage, and then a stage of stable operation at the optimum/maximum design throughput.

The results should show consistent treatment quality trends, and any unexpected changes should be explained, with the corrective actions taken.

Beware of One-Off Trials!
In the real world, one-off pilot plants will need an extensive de-bugging (or “teething“) period, before a trial of any value can be run. Beware the one-off trial carried out while plant teething problems persist! The actual trial results can be very hard to decipher when plant and equipment failures ensue!

Our treatment technicians (leachate busters!) are continually running these trials, and are the most experienced there are.

Two simple nitrification plant treatability trials in progress in South Africa, with acknowledgements to Durban Solid Waste (DSW).

Ask us:

We would be pleased to quote for carrying out a wheely bin trial on your leachate, or industrial effluent. Whether or not we carry out the process design.

If necessary trials can be set up abroad under our supervision, and run remotely, and very cost effectively. See the picture above, which is an example of such work.

We will be pleased to provide an expert detailed trial report which can be used by any process designer.

*We have been working for the
Environment Agency UK, for more than two years to update leachate source-term data for UK leachates, and can provide data on request derived from this work, which shows the hazardous substance removal rates achievable by biological treatment.

Our lab technicians were once known as the “leachate busters”, and are not all as ugly as this guy!