Membrane Autopsy Techniques

Purpose

Resilience is a system’s ability to maintain routine function even under unexpected circumstances.It is an essential factor in ensuring continuous process throughput whilst remaining compliant with strict water discharge guidelines.
Resilience modelling tools have been widely used in the Petrochemical, Oil and Gas, and Aviation industries to model process reliability and safety over the last 15 years.
No standard resilience modelling method has been developed for a potable reuse scheme.

Study used a resilience modelling tool from the Oil and Gas industry, GL Noble Denton’s (GLND) OPTAGON Simulation Package
OPTAGON is GLND’s Monte Carlo-based Reliability, Availability and Maintainability (RAM) simulation tool which is capable of modelling the performance of asset.
With user-variated real-time data, OPTAGON is able to accurately predict equipment failure and system resilience.

Develop a mechanical resilience model for dual membrane plants (MF/UF + RO) using data from large scale (>10 MLD) plants with long operating history (7-10 yrs)
Develop “What-if” scenarios for resilience model’s sensitivity based on confirmed cases of drinking water plant failure resulting in pathogen infection
Quantify process resilience and predict process equipment failure using resilience model.

GIDEON database catalogued >2000 confirmed pathogenic outbreaks from 2003 to 2013.
30% of the outbreaks were associated with protozoan parasites.
The most common type of failure was an incident in the catchment area in conjunction with an inadequate process design.
Second most common type of failure occurred in the distribution system followed by an inadequate management framework and operational error.
Poor asset management and failures highlight the need and importance of resilience modelling in the water industry.

Equipment failure and performance data is sourced from 7 water recycling plants worldwide.
Relevant information is collected from a wide array of data sources.

Cataloged equipment data is sorted and mapped according to process equipment specified in the model (Reference Plant).
Equipment arranged with design and operational capacities based on functional location.
Operation & Maintenance (O&M) Manuals provide vital information on equipment availability.
MTBF and MTTR are also calculated if not previously provided.
Equipment criticality is determined based on failure and maintenance data.

Mapped data becomes input variables for OPTAGON to model asset’s mechanical resilience.
Monte Carlo simulations of 10,000 realisations ensure confidence of modelling results.
Results also demonstrate equipment interdependency.
Modelling results would quantify the asset’s overall reliability and resilience.
Sensitivity analysis would further highlight which input variable would have the greatest impact on the system.
“What-if” scenarios would test the robustness of the reference plant and aid with process optimisation.

Resilience = ƒ (Availability, Performance)
Availability = ƒ (Reliability, Maintainability)
Risk = ƒ (Likelihood, Consequence)

OPTAGON can model complex water recycling systems with high level of accuracy and consistency.
Modelling results would be able to quantify asset resilience, criticality and risk.
Resilience modelling can predict and improve asset performance throughout asset’s lifespan.
Sensitivity analysis would support asset management decisions and aid in efficiency and profitability.
Reference model can also be used to provide insight to specific failure modes and resulting effects.