Melbourne Water pumps up environmental efforts New sewage treatment processes improve Solutions final effluent quality—with Rockwell A new control philosophy for activated sludge process comprised Automation’s Integrated Architecture playing • Six intelligent motor control centres a key role in control of the facility. incorporating – Allen-Bradley ControlLogix – CompactBlock I/O with DeviceLogix – 1336 variable speed drives – Redundant DeviceNet networks – PanelView 550 HMI – Allen-Bradley Powermonitor • MCCs connected via dual-redundant EtherNet/IP on fibre • ControlLogix gateway to provide connectivity to plant-wide SCADA

Control system controls and monitors all aspects of the activated sludge plant • Multiple pumping stations and recycle flows • Oxygen levels • Duty cycle for aeration blowers • Flow meters and level sensors The majority of the world’s population gives little thought to the massive infrastructure required to process raw sewage into an effluent suitable for ocean discharge or water recycling. For Melbourne Water’s Western Treatment Results Plant at Werribee, adoption of an ‘Environment Improvement Plan’ has meant greater focus than normal. The Rockwell Automation control system permits When a 1990’s environmental study revealed the prudence of reducing nitrogen loads into Victoria’s Port Phillip Bay, Melbourne Water started • Fully automated plant (unmanned) progressively upgrading the sewage treatment processes at the 11,000-hectare • Local manual control (for redundancy) Western Treatment Plant. The main goal was to improve nitrogen removal from the treated effluent, most of which is discharged into the bay. The • Reduced programming and resulting project has involved the transformation of two existing lagoon commissioning time systems into ‘enhanced lagoons’ and the cessation of traditional land filtration • Ongoing benefits for maintenance and methods. Just a year after the second upgraded lagoon system—known as 25 diagnostics West (25W)—was commissioned, the annual amount of nitrogen discharged has been reduced by the targeted 1000 tonnes. Development of the enhanced lagoons has been no small feat. Traditional lagoon treatment involves the gravitational flow of sewage through a series of shallow ponds, during which a natural progression of ultraviolet (UV), microbiological and biological treatment processes break down organic waste Six distributed outdoor motor control centres, linked by a dual-redundant EtherNet/IP fibre optic communications backbone, control different sections of the activated sludge plant. and other micro-organisms. This system is sewage treatment is the anaerobic area, around the basin at any time,” says still in place; however, in order to ‘beef also known as Pond 1, where 60 percent Gulovsen. The third zone of the 25W up’ the nitrogen-removal capability, an of the pollutant load is removed in the activated sludge plant comprises five ‘activated sludge process’ has been added form of gases such as methane, carbon gravity-fed clarifying tanks. Here, the to the front end of the 55 East (55E) and dioxide and hydrogen sulphide. “From bacteria settles to the bottom to be 25W lagoon systems. The activated sludge here it gets pumped at a rate of around recycled into the front of the process as process involves pumping the sewage 180 ML per day to the activated sludge the RAS, and the clear effluent at the top between a series of oxygenated and plant, where the nitrogen content is overflows into Pond 2 to make its way deoxygenated zones loaded with bacteria reduced from about 60 mg to 15 mg per through the original lagoon system. to speed up natural processes. litre,” he says. The Rockwell Automation control system After the successful 2001 upgrade of 55E, Upon entering the main activated sludge at 25W ensures the entire process operates Melbourne Water identified a number of plant basin, the sewage is mixed with effectively and automatically. “The most areas in which the plant could be further brown ‘return activated sludge’ (RAS) critical part of the process is the improved at 25W. One was the from the end of the process. This provides oxygenation zone,” says Gulvosen. “The introduction of large blowers to provide the bacteria for the treatment, which bacteria will die if the dissolved oxygen diffused oxygen into the process, instead begins in the deoxidised anoxic zone. levels are wrong, so the levels are of surface mechanical aerators. Another From here, the sewage moves into the measured via direct oxygen probes. Based advance was the incorporation of a adjoining aerobic zone, where oxygen is on this, the control system will allocate different control philosophy. This utilised added via submerged diffusers to promote the duty cycle for the blowers. There are the latest distributed process and the conversion of ammonia to nitrates. In five control zones with different air Intelligent Motor Control technology order to transform the nitrates into distribution along the length of the from Rockwell Automation’s Integrated atmospheric nitrogen, sewage from the basin.” Architecture suite. aerobic zone is pumped at high volumes The automation system also monitors a back into the anoxic zone, where this myriad of flow meters and level sensors reaction takes place. Sewage and Sludge located throughout the plant. The flow Melbourne Water’s Trevor Gulovsen, a “The recycle rate is three to four times the measurements are integral to the variable process engineer at Western Treatment inflow rate, which means that there is speed control of the various pumping Plant, explains that the first stage of about 900 to 1080 ML per day flowing stations, which direct sewage from stage to stage, along with the various recycle DeviceLogix program holds the drive Ethernet on Fibre flows. These flows are all balanced by the interlock and safety functions that would Master control of the 25W plant is control system to ensure the optimum traditionally have been implemented in provided by a central ControlLogix and flow throughout the plant. the PLC and duplicated in hard wiring PanelView 1400 HMI located in a small for redundancy. If communications to the control building near to Pond 1. Also PLC are lost, for any reason, the Split the Code located here is technology provided by DeviceLogix program continues to The Melbourne division of systems Rockwell Automation Encompass Partner, execute, maintaining full manual drive engineering group, SEMF (formerly Hirschmann, to ensure integrity of the functionality.” known as Austek), worked closely with dual-redundant EtherNet/IP Rockwell Automation and Melbourne According to David Ellis, process control communications network, which is Water to deliver the control solution for and instrumentation specialist with established in a ‘hiper-ring’ configuration. the 25W activated sludge plant. This was Melbourne Water, this manual control “The Hirschmann ring-manager switch based on a conceptual design by Sinclair functionality is an essential feature for a sends out a signal in one direction, and so Knight Merz, founded on Rockwell critical public infrastructure plant. long as it returns on the other side, the Automation’s powerful hybrid controller, “Manual control is important for switch creates an artificial break in the Allen-Bradley ControlLogix, along with redundancy,” he says. “If the PLC fails, network,” says SEMF’s Manners. Allen-Bradley DeviceLogix to provide we can still put the drive into ‘run’ via the “However, if a break in Ethernet Intelligent Motor Control. The design CompactBlock. It has also simplified the communications is detected, the ring also included dual-redundant EtherNet/IP number of components in the motor manager removes the barrier and restores communications on optical fibre and starter, as we’ve eliminated a heap of the connection.” The EtherNet/IP network redundant DeviceNet fieldbus networks. relays that used to provide the between the control building and the redundancy function.” James Manners, SEMF mechatronics various MCCs is provided on two optical engineer, explains that the dual- Not only is ControlLogix adept at fibre cables, buried metres apart. Similarly, redundant, industrially hardened handling the sequential control aspects of each ControlLogix includes two Ethernet EtherNet/IP communications backbone the plant, its hybrid nature makes it also cards to integrate it with the dual networks. connects a series of six motor control ideal for the essential process control Ellis says that Melbourne Water has centres (MCCs) located outdoors around parameters—such as dissolved oxygen adopted the dual-redundant Hirschman the extensive plant. These take levels and numerous flow and level loops. hiper-ring arrangement across the whole responsibility for controlling different “When it came to this project,” says Ellis, Western Treatment Plant. Individual sections of the activated sludge plant: “we investigated ControlLogix and talked EtherNet/IP hiper-ring architectures have diffused aeration system including three with others who were very happy with the been deployed at 55E and various other 750-kW blowers, mixers (to ensure there equipment. It has proven itself a robust pump stations and new plants around the is sufficient turbulence in the basin to system, and we were happy to adopt the site. These are now linked via a central keep the bacteria suspended) and the technology.” ControlLogix gateway, also located in the various pump stations. Each MCC control building. incorporates at least one ControlLogix and a redundant DeviceNet network to connect a local Allen-Bradley PanelView 550 human-machine interface (HMI), local Allen-Bradley Powermonitor and CompactBlock I/O. To provide local manual motor control, independent of the control system, the unique Allen-Bradley DeviceLogix was utilised. “A small DeviceLogix program is downloaded into each CompactBlock I/O, which has a mini processor inside,” Manners says. “Each CompactBlock I/O is paired with either a variable speed drive (VSD) or the electronic overload relay in a direct on-line (DOL) motor starter—as well as hard-wired analog process instrumentation. “During normal operation,” Manners Trevor Gulovsen, Melbourne Water senior continues, “ControlLogix sends process engineer, inspects the HMI inside one of the motor control centre shelters. commands to and receives information from each drive and motor starter via the DeviceLogix program. In this case, the Intelligent motor control from Rockwell Automation is a critical redundancy feature permitting full manual operation of the pumps.

The ControlLogix gateway allows both the hardware and software. “This the recently completed biogas seamless connectivity between different means, for example, that the starter for regeneration and water recycling plants. sections of the facility, plus it provides a every pump in a pump station has Both are also important elements of the direct connection to the site-wide identical code, identical wiring and Environment Improvement Plan. The SCADA system located in the main site identical configuration,” he says. biogas plant converts the emitted gases operations centre at one end of the vast “Duplication was child’s play, as it was from the anaerobic stage into electricity, Western Treatment Plant site. This possible to replicate the starter to any while the water recycling plant further SCADA terminal is Western Treatment number of other drives in the MCC, treats the high-quality effluent from 25W Plant’s link to the outside world, and where there might be as many as 10 and 55E to make it suitable for irrigation. Melbourne Water’s numerous other plants pumps. It also meant that we only had to and pumping stations around the city. debug one module of code, instead of 10. The new 25W activated sludge plant was In the end, commissioning only took four commissioned in September, 2004. Both Child’s Play months, and the MCCs were fully 25W and 55E now have capacities of 180 commissioned inside two days.” ML per day (increased from 100 ML per SEMF first became involved in the 25W day). This means that the old land and upgrade project in early 2003, after This modular approach, enabled by grass filtration systems, which originally successfully completing the similar 55E Rockwell Automation’s RSLogix 5000 treated around 30 percent of the 500 ML project using Rockwell Automation programming software, not only reduced of sewage received per day at Western technology. “We began development work programming and commissioning time Treatment Plant, could be on the software and bench-testing for 25W but also provides ongoing benefits for decommissioned and transformed into in about August 2003,” says Manners. maintenance and diagnostics. In addition, irrigated pasture. Moreover, Melbourne it has allowed SEMF to extend the Manners explains that a modular Water has met its targeted nitrogen load of control system philosophy to subsequent approach was adopted for development of 3100 tonnes per year into Port Phillip Bay. projects carried out at the site—namely,

Publication WATER-AP008A-EN-P – February 2007 Copyright ©2006 Rockwell Automation, Inc. All Rights Reserved. Printed in Australia.