widely applied in different fields of engineering and are a modelling approach based
on how biological neural systems are believed to work. Li et al. review the applicability of ANNs to urban hydraulics and hydrology. An area that could be usefully
explored includes using ANN models to predict flows at treatment works.
With the advent of event duration monitors and performance targets on up-time
on the weirs to and from storm tanks, there is a push within the industry to manage
flows at the front end of the treatment works. This would both protect and reduce risk
to the environment (in using storm tank capacity) a lot more stringently.
The system as a whole can be seen in Fig. 3. It is slightly overcomplicated with
the addition of flow monitoring on the feed pumping stations and on the storm tank
return and yet could be considered slightly simplified as large works could potentially have many more than just two feed pumping stations. However, the principal is
there insofar as there is no control over the gravity feed to the works, but there is
control over the two feed pumping stations that could hold back feed flows.
However, this would be dependent upon the capacity in the network upstream of
the pumping stations, and in the pumping station wet wells themselves.
This is the point where the inlet works of the WTW becomes an integral part of
the wastewater collection network and vice versa.
After flows pass forward to treatment, the first stage that they will typically pass
through is primary settlement. Although not always present as a treatment stage on
the larger works, it is normal practice. This is because the separation of gross solids
in the sewage is a valuable energy source that, if not removed, is simply load, and
therefore an energy loss, to be treated in the next stage of the process. As it is a
simple physical settlement stage, there is very little to control, but measurement of
the wastage of primary solids is something that should be considered in an energy/
resource factory, as it is a major source of energy. Primary settlement tanks can be
used as a thickening stage using type 3 (hindered) settlement and type 4 (compression) settlement. In this way there is the potential to use a combination of both sludge
blanket level and flow/solids measurement on the primary de-sludge line from the
settlement stage to manage the sludge inventory. In reality, flows and loads coming
into a sewage treatment works are ultimately predictable, and with predictability the
primary sludge inventory can be managed with the right measurement. This also
needs to feed forward to sites with anaerobic sludge digestion to create an almost on
demand availability of sludge allowing for the correct blend of import and secondary
sludges to maximise the energy output of the wastewater treatment facility.
3.2.2 Measuring and Controlling Secondary Treatment
The biological (or secondary) stage of wastewater treatment very much depends
upon the size and the type of the plant and what the treatment goals are. Biological
filters are still the predominant type of wastewater treatment, especially on small and
medium treatment works, and, apart from simple recirculation flow control to keep
biological filters wet, there is very little measurement and control needed in this type
of secondary treatment. As the process is so simple, there is also very little that can
Monitoring and Controlling a Smarter Wastewater Treatment System: A UK. . .
129
on how biological neural systems are believed to work. Li et al. review the applicability of ANNs to urban hydraulics and hydrology. An area that could be usefully
explored includes using ANN models to predict flows at treatment works.
With the advent of event duration monitors and performance targets on up-time
on the weirs to and from storm tanks, there is a push within the industry to manage
flows at the front end of the treatment works. This would both protect and reduce risk
to the environment (in using storm tank capacity) a lot more stringently.
The system as a whole can be seen in Fig. 3. It is slightly overcomplicated with
the addition of flow monitoring on the feed pumping stations and on the storm tank
return and yet could be considered slightly simplified as large works could potentially have many more than just two feed pumping stations. However, the principal is
there insofar as there is no control over the gravity feed to the works, but there is
control over the two feed pumping stations that could hold back feed flows.
However, this would be dependent upon the capacity in the network upstream of
the pumping stations, and in the pumping station wet wells themselves.
This is the point where the inlet works of the WTW becomes an integral part of
the wastewater collection network and vice versa.
After flows pass forward to treatment, the first stage that they will typically pass
through is primary settlement. Although not always present as a treatment stage on
the larger works, it is normal practice. This is because the separation of gross solids
in the sewage is a valuable energy source that, if not removed, is simply load, and
therefore an energy loss, to be treated in the next stage of the process. As it is a
simple physical settlement stage, there is very little to control, but measurement of
the wastage of primary solids is something that should be considered in an energy/
resource factory, as it is a major source of energy. Primary settlement tanks can be
used as a thickening stage using type 3 (hindered) settlement and type 4 (compression) settlement. In this way there is the potential to use a combination of both sludge
blanket level and flow/solids measurement on the primary de-sludge line from the
settlement stage to manage the sludge inventory. In reality, flows and loads coming
into a sewage treatment works are ultimately predictable, and with predictability the
primary sludge inventory can be managed with the right measurement. This also
needs to feed forward to sites with anaerobic sludge digestion to create an almost on
demand availability of sludge allowing for the correct blend of import and secondary
sludges to maximise the energy output of the wastewater treatment facility.
3.2.2 Measuring and Controlling Secondary Treatment
The biological (or secondary) stage of wastewater treatment very much depends
upon the size and the type of the plant and what the treatment goals are. Biological
filters are still the predominant type of wastewater treatment, especially on small and
medium treatment works, and, apart from simple recirculation flow control to keep
biological filters wet, there is very little measurement and control needed in this type
of secondary treatment. As the process is so simple, there is also very little that can
Monitoring and Controlling a Smarter Wastewater Treatment System: A UK. . .
129