There's always lots of people suggesting, offering advice, regarding what you should do.
That's important and also necessary, needless to say.
However, at times it's also important to fully understand what you ought to not do, what you ought to stay away from.
The reasoning behind giving out this information is to help you and AD Plant designers and operators understand in what areas you might generate Anaerobic Digestion odors and avoid the mistakes which could cause them by showing you the 5 odour hot spots you will need to avoid, and why you need to avoid them.
Plus we will tell you those actions which you should do as an alternative, in order to understand in what areas you might generate anaerobic digestion odors and avoid the mistakes which could cause them.
Anaerobically digesting organic materials are by their nature odorous.
Production of hydrogen sulphide, organosulphur compounds and mercaptans occur naturally under reducing conditions and that is a necessary part of the AD process.
The "hot spot" odour locations for potential odour generation are: 1.
Waste input storage bays: Take care not to allow waste in the (waste input storage bays to stand around for too long.
These can cause odours, especially during the warm seasons when the organic content of the waste can begin decaying before it is even collected for disposal.
So don't leave odorous wastes lying around.
The reason you ought not do this is that these odours are very unpleasant and travel a long way before they are no longer offensive.
Instead, you should not store any wastes which you cannot prevent producing an odour outside and instead place these wastes inside or in a container which can be sealed.
2.
Avoid odors from the AD pre-sorting plant.
Proprietary designs for biogas digesters can require that the operator carries out mixing with digestate to enable sorting of inorganic and organic material to be carried out.
Always ensure that the possible odor production from this activity can be controlled, again.
this may require enclosing the space and filtering the vented air to remove odors.
This is because the pre-sorting stage can be the source of further unpleasant smells.
Alternatively, just enclose the whole digestion process in a large building, ensure that the air pressure through any door openings is always held below the air pressure outside by extraction fans, and filter all vented air to remove all significant odour before it is discharged.
3.
Avoid odors from mixing tanks if these are separated from the presorting area.
This is where digestate is mixed with separated organic material prior to charging the digester.
Clearly this really is quite a potentially smelly activity on all AD plants.
And what you want to do instead is design and operate the plant in a way which avoids becoming a bad neighbour due to smells.
4.
Planned equipment maintenance of the digestor, and vessel cleaning.
Although the digestor must be sealed during operation for process reasons, it requires to be cleaned out occasionally, when its contents may be exposed to the air.
Why this could be a mistake is odours may then escape.
Alternatively you really want to plan ahead and make sure that all such odours are contained and do not become a nuisance.
5.
Finally, avoid odours at the digestate draw-off and dewatering plant.
Although digested material is significantly less odorous than raw organic material, there is an odorous element of digested waste which may be considered unpleasant.
It will be sometimes hard to avert this but all good biogas digester operators succeed in doing this to the satisfaction of local residents and the planning authorities alike.
Instead, do not forget that anaerobically digested organic materials are by their nature odorous.
But, by responsible plant design and operation such odours must and can be avoided.
Carefully and conscientiously avoid these 5 common "odour hot spot" errors, embrace the alternatives offered instead, and your local reputation, cash flow and long term prosperity are going to be much the better because of it.