The improved treatment solution
Listening to you
We reviewed the process design of the treatment works and this identified a more suitable process for the removal of high amounts of fats, oils and greases that are anticipated at the facility.
We also looked at ways of addressing some of the concerns raised at the public inquiry, particularly about construction nuisance and the risk of odour.
What we're doing
Decision has been made now to use an alternate process of Aeration Lanes and Final Settlement Tanks because they handle fat, oil and grease more effectively than the first proposed design (Lamella Plant).
Growing, thriving communities
This, combined with further population growth since original design and from our experience working with other WWTWs, has led to the decision for this alteration as best solution for Scottish Water customers.
The waste disposal process
The new treatment works consists of:
- fine screening to remove rags and other larger suspended solids,
- a grit plant to remove excess grit,
- a conventional activated sludge plant utilising a fine bubble diffuser system in order to efficiently remove biodegradable material
The sludge plant effluent flows into two final settlement tanks for sedimentation. The sludge is returned back to the process and the treated effluent is directed to the outfall. Excess sludge is removed periodically from the process, thickened and stored for further disposal.
This process does not require primary settlement, which is a principle cause of odour, and the system is not as prone to be affected by fats, oils, and greases as the original proposed process was, resulting in less risk of odour with the new process. The design also allows us to make better use of the quarry site, to facilitate a reduction in the amount of rock that is required to be removed.
Project Benefits
This treatment works is conventional, robust, simpler to operate and more flexible than the one we had previously planned. It will also better accommodate the population fluctuations in a seasonal holiday town such as Dunoon.
This proposal minimises the disruption to the local environment whilst providing a robust and effective treatment facility for the future.
