Most plants are not optimised for power or process efficiency and are designed and manufactured to meet a standard and operated to meet compliance. OEM providers and Infrastructure providers usually only make minor changes to plant during defects liability. For this reason, new plants do not appear to have optimisation of the aeration and other stages of the plant.
In conjunction with City West Water, Parasyn embarked on a series of small, non-capex initiatives to optimise the process control at the Altona Treatment Plant for the purpose of reducing the energy consumption (improved blower performance), improve the plants stability (e.g. consistent and controlled Ammonia) and provide operator assurance of meeting the plants Ammonia permit conditions (greater visibility into the process performance).
The initiatives included the following;
- Improving the control of the Dissolved Oxygen set-point using on-line effluent Ammonia measurement
- Optimising the secondary effluent Ammonia based on downstream recycled water requirements and permit limits
- Aerator PID loop control and Blower Energy use optimisation post a review of existing controls
The outcome is OPEX reduction in energy costs of approx. 13% per annum, reduced performance monitoring of secondary treatment by operator, greater plant stability due to better loop tuning and ammonia management and lower and more predicable chemical consumption.
The investment for this undertaking was extremely small but led to significant OPEX savings. The control system changes are rudimentary, meaning they were optimised without introducing any new control system methodologies like Advanced Process Control or replacing inefficient plant components or instrumentation. What was there was used.
Parasyn considers this Stage One of Plant Optimisation, the low hanging fruit. Stage Two would include improvements in process management, further energy savings, and improved automated management of process disturbances like environmental fluctuations.