Maximising renewable energy generation from anaerobic digestion
Process modelling with Anglian Water
The issue
Anglian Water wanted to improve their
gas yields and energy production conversion
rates from their nine anaerobic
digester sites. They needed to combine
proficiency in digital twin software platforms
with expertise in wastewater plant
operations so they could undertake extensive
simulation modelling for treatment
centres.

The solution
Anglian Water worked with Aqua Enviro,
the SUEZ wastewater specialist
company. The Aqua Enviro experts employed
a process simulator, which combines biological,
chemical and physical process
models to accurately simulate the operation
and performance of Anglian Water’s
sludge treatment assets. The team drew
upon a variety of techniques, including the
use of BioWin based digital twins (Figure
1), to conduct an in-depth review. Using
a controlled environment enhances confidence
and limits implementation risk
on-site. The digital twin facility enabled
the team to identify improvements that
otherwise might not have been identified.
Figure 1: Building the model and asking the relevant questions at every stage

How it worked
1. Developed a good working relationship
with team at the utility company
2. Understood the specifics of each of the AD processes at all nine sites. The process flow schematics for the individual sites were developed and then the operational parameters were incorporated
3. Replicated each one with a digital twin. The trained technicians use their knowledge of the Envirosim BioWin software to create the replicas (Figure 2)
4. Validated the replicas in coordination with the Anglian Water team. This involved data collection and sampling over three weeks to calibrate and validate the model
5. Adjusted all the potential parameters. Once modelled, a range of dynamic simulations with various operational considerations and scenarios were conducted to identify key areas for improvement to enhance power output (Figure 3), bespoke for each site. Understanding of the subtleties of wastewater treatment plant operations is a distinct advantage here. The team:
a) Questioned and reviewed every stage of operations
b) Established the capacity of each
type of sludge to generate energy
c) Understood the conversion rates
for each type of AD process (CAMBI, Monsal, HpH)
6. Repeated this process multiple times to find the solutions that cost the least but gives the most benefit
7. Identified the optimal list of operational improvements for each of the nine sites.
2. Understood the specifics of each of the AD processes at all nine sites. The process flow schematics for the individual sites were developed and then the operational parameters were incorporated
3. Replicated each one with a digital twin. The trained technicians use their knowledge of the Envirosim BioWin software to create the replicas (Figure 2)
4. Validated the replicas in coordination with the Anglian Water team. This involved data collection and sampling over three weeks to calibrate and validate the model
5. Adjusted all the potential parameters. Once modelled, a range of dynamic simulations with various operational considerations and scenarios were conducted to identify key areas for improvement to enhance power output (Figure 3), bespoke for each site. Understanding of the subtleties of wastewater treatment plant operations is a distinct advantage here. The team:
a) Questioned and reviewed every stage of operations
b) Established the capacity of each
type of sludge to generate energy
c) Understood the conversion rates
for each type of AD process (CAMBI, Monsal, HpH)
6. Repeated this process multiple times to find the solutions that cost the least but gives the most benefit
7. Identified the optimal list of operational improvements for each of the nine sites.
Figure 2: The BioWin model

The results
As well as the improved energy production,
the project successfully evaluated
conversion rates for different AD
processes (CAMBI, Monsal, HpH) and
identified the Anglian Water HpH process
as being industry-leading with
conversion rates of >1 MW/tds. Much of
what was achieved has been through operational
optimisation (i.e., without further
investment), around:
The modelling pointed to the need for improved process control, monitoring and better mixing, all of which have contributed to enhanced performance and output.
- better sludge conditioning
- better management of thickening process efficiency
- control of mixing sludges
The modelling pointed to the need for improved process control, monitoring and better mixing, all of which have contributed to enhanced performance and output.
✓ Improved operational efficiency |
✓ Higher gas yields |
✓ Improved energy output |
✓ Raised awareness of operating factors to improve conversion rates |
Figure 3: Outputs

Differentiating factors
EXPERIENCE:
The Aqua Enviro team have decades of wastewater treatment operational experience, gained across UK and overseas plants.
EXPERTISE:
Expertise in using digital twin BioWin software, which is used worldwide to design, upgrade, and optimize wastewater treatment plants of all types.
COLLABORATIVE APPROACH:
The Aqua Enviro team collaborated with the client, helping to mitigate risks around KPIs and business targets, reducing operational costs from chemical consumption and enhancing energy output and revenue.
The Aqua Enviro team have decades of wastewater treatment operational experience, gained across UK and overseas plants.
EXPERTISE:
Expertise in using digital twin BioWin software, which is used worldwide to design, upgrade, and optimize wastewater treatment plants of all types.
COLLABORATIVE APPROACH:
The Aqua Enviro team collaborated with the client, helping to mitigate risks around KPIs and business targets, reducing operational costs from chemical consumption and enhancing energy output and revenue.
The future
The models developed by the Aqua Enviro
team can be reviewed and updated,
thereby used as a metric to evaluate,
and monitor the impact of improvements
made on site. New enhancements and algorithms
in the modelling programme now
extend to include emissions from digestate
(methane) and NOx from wastewater
treatment processes.

A retrospective view of the project demonstrates that BioWin modelling is an invaluable enabler of innovation and optimisation at a strategic level. Given the complexity of the task of comparing efficiency on multiple integrated STCs, BioWin, along with the framework developed with the team at Aqua Enviro, is a powerful tool in providing successful efficiency gains and process insights.
David Inman , Innovation Projects Manager, Anglian Water