Abstract:
This
study focussed on extending and applying techniques to measure hydrodynamic
characteristics in treatment units at sewage works. Use was made of tracer dye studies
and a
spreadsheet based analysis tool. The resulting infonnation about residence time,
tank
conguration and pathological behaviour was linked to other infonnation from
respirometry and flow and load studies. Characterising the wastewater process will
become
increasingly important as the economic and compliance drivers in the
operation of wastewater treatment facilities become increasingly pronounced.
Case studies at
Royton WWTW, Chorley WWTW, Preston WWTW and Montebello
WWTW were used to
develop, improve and apply the methodology. Tests at Royton
and
Chorley were used to develop the practical side of conducting tracer studies. The
Preston case
study was used to improve the diagnostic methodology. It was
demonstrated that consent failures as a result of events are usually a result of a
number of
(linked) factors, in the case of Preston influenced by the tank
conguration.
The
response of a pulse of dye was measured at Preston in vessel outlet throughout
the works. The tracer
dyeresponse was used to predict the response to a discharge of
high ammoniacal leachate liquor and compared to measured data. This type of
calibration
experiment facilitated the simulation of different discharge event
scenarios.
The tracer and
modelling techniques were incorporated in a general diagnostic
methodology, which caters for a phased approach in diagnostic studies. A series of
diagnostic tables take the user through cause - effect hypotheses and possible
measurement
techniques to use in the diagnostic investigation.
Although the diagnostic methodology proved to be a versatile asset optimisation tool,
which
required considerable less effort than deterministic models, implementation in
United Utilities' AMP3 Capital Investment Programme was problematic. The size of
the
programme and lack of resources forced the company to implement standard
rather than tailor-made solutions. However, the diagnostic methodology can easily be
applied elsewhere in the wastewater industry.
