Model behaviour

Modelling can be applied to almost every aspect of industrial operations, whether

the goal is to minimise use of resources, introduce new processes or expand

existing facilities. In addition, so-called ‘intelligent equipment’, incorporating

embedded software, is set to make a significant contribution to improved control

and monitoring of production in many sectors of industry.

A sizable proportion of these costs has necessarily been passed on to customers.

Many companies are struggling to reduce the impact of these increased water

charges and comply with effluent discharge limits imposed under the Local Authority

Pollution Control regime.

A new mantra is emerging for companies wishing to cushion the impact of these

increased charges: ‘reduce water consumption, optimise processes, and minimise

effluent generation’. It applies to most industry sectors, but particularly

to those, such as the dairy, brewing, pharmaceutical and metals industries,

that use large quantities of water – and hence generate potentially large amounts

of effluent.

For example, many breweries discharge, as effluent, up to 70 per cent of the

water that is supplied to their sites. Advice on saving water and reducing effluent

is available from the water utilities and government agencies, such as Envirowise,

but there is also a growing band of consultants offering software solutions

that can help optimise processes and minimise effluent arisings.

The international water and environment consultancy, WRc, has developed a range

of practical, cost-effective solutions for water, wastewater and industrial

effluent treatment challenges. Software solutions are available for odour management,

risk and reliability modelling, and water and wastewater treatment processes.

Model roles

Packages such as Polecat and Plan-It-STOAT (Plan-It) can help

companies improve their waste treatment processes, reducing water consumption

and effluent generation, thereby making worthwhile savings on water charges.

Both Polecat and Plan-It are Windows-based modelling tools with wide ranging

applications.

Polecat has been used successfully to model the effluent from fermenters and

waste tanks at a brewery site in the North-East of England. The model can estimate

waste arising in terms of a range of parameters, such as flow and chemical oxygen

demand (COD). This enables the user to assess the possibility of re-using wastewater

in applications where mains quality is not essential. It can be used to schedule

tank cleaning and reduce water consumption, thereby optimising cleaning cycles

to reduce peak flow and improve operational efficiency. At one brewery it has

even been used to modify wastewater treatment, resulting in reduced discharge

costs.

Plan-It-STOAT was also conceived as a tool for modelling the load and flow

of waste arisings from industrial processes. It can be used in any industrial

application where the waste is biodegradable, though it was initially proven

in sewage treatment. The package has a detailed hydraulic capability allowing

it to even out loads – in this instance the flow rate and biological oxygen

demand (BOD) – of the effluent. ‘Smoothing out’ the flow in this way brings

the maximum flow rate closer to the average flow, achieving a steadier flow

rate and avoiding large surges that can overload the treatment plant.

Turn the tide

This ‘smoothing’ capability means that, in the event of needing to expand the

plant, the scale of expansion can be optimised to accommodate actual need, rather

than building in unnecessary overcapacity. Plan-It can determine the point at

which increasing the load would exceed the capacity of the plant’s pipe systems

to transport effluent, and when the whole plant would reach overload, and can

also be used to demonstrate the relative investment benefits of, for example,

activated sludge versus anaerobic

treatment methods.

Many leading industrial companies are already reaping the benefits of using

software to solve the challenges of industrial effluent treatment. Others will

inevitably follow their example in a bid to turn back the rising tide of higher

charges for water and wastewater services.