Rathkeale Wastewater Treatment Works was constructed and commissioned circa 1992-1993 for a design PE of 4,000.The plant consisted of inlet works, 2 No. oxidation ditches (east & west), 2 No. settlement tanks (east & west), picket fence thickener and a sludge press. The network discharging to the plant is a combined foul and surface water sewer.
In order to reduce the overall energy demand of the WWTP the Contract was to commission the east stream (which was not in operation) by installing a more efficient aeration system there. The aeration system consisted of an Aquaconsult Aerostrip fine diffuser array was installed in each of the two lanes in oxidation tank no. 2, fitted to stainless steel lift out grids. The Aquaconsult Aerostrip ultra-fine diffusers transfer oxygen to effluent more efficiently than any other type of diffuser.
The contract also required the following ancillary works:
- Removal and disposal of existing redundant aeration equipment in east ditch.
- Design, supply and installation of fully functional FBDA system.
- Control system for the aeration system
- Control panel for all new electrical equipment.
- 2 No. new dissolved oxygen monitors installed in the oxidation ditch.
- Complete refurbishment of two no. Clarifiers, manufacturing and replacement of all mechanical equipment with stainless steel
- Design, manufacture and installation of splitter chamber and pipework to ensure 50/50 split of flows from oxidation ditch to the two no. clarifiers
- DMI of screw auger inlet screen to cater for flows of up to 80 l/s, operating on a level differential sensor and timer with manufacture of screened overflow chamber. Permanent diversion of inlet pipework to cater for new installation.
- Design of RAS system which resulted in installation of 2 no. RAS pumps in sludge return chambers and stainless steel pipework to return sludge at the most effective point in oxidation tank to ensure process efficiencies were maximized.
- DMI of new flow measurement flume embedded in concrete, top of which at 300mm above ground level and fitted with open steel decking.
- Relocate existing composite sampler from the splitter chamber to the new flume chamber. Ultrasonic flowmeter installed at the flume and connected to control panel.
- Control panel containing motor controllers, ammeters, power meters (with display showing kW/kWhs, power factor etc).
- Power metering
- Dissolved Oxygen levels displayed on control panel