Wastewater treatment plant construction work

Description

Irish Water is currently planning to upgrade the existing Ringsend Wastewater Treatment Plant (WwTP) to provide for the introduction of a treatment process using Enhanced Biological Phosphorus Removal (EBPR). There are currently other upgrade works underway with the objective of increasing the plant capacity to 2 400 000 Population Equivalent. Irish Water is considering inviting tenders for a contract which will comprise the design, construction, commissioning, and operation of a new facility which will provide for the fixation and recovery of Phosphorus (P) in a form suitable for use as an agricultural fertiliser or as a raw material for mineral fertiliser formulations. The Ringsend WwTP treats most of the wastewater arising in the Greater Dublin Area. Irish Water is currently planning an upgrade to the Ringsend Treatment Plant based on the application of aerobic granular sludge technology (Nereda®) which will provide for nutrient removal, including biological P removal as noted above. The introduction of aerobic granular sludge and EBNR will be carried out in phased upgrades of the Ringsend plant, with the aim (inter alia) of reducing the Phosphorus concentration in the treated wastewater in compliance with relevant legislation. The capacity of the Upgraded plant will be approximately 2 400 000 Population Equivalent (PE), where 1 PE is taken as 60 g BOD / day. This project is to provide for the recovery of Phosphorus from liquors generated from the dewatering of sludges arising at the plant. This project will specifically provide for recovery of phosphorus from these liquors (most likely) in the form of a Magnesium Ammonium Phosphate (Struvite) precipitate, with stated minimum removal / recovery efficiencies. The existing Ringsend plant is noted as providing for Thermal Hydrolysis, Mesophilic Anaerobic Digestion and thermal drying of sewage sludges arising. The P fixation plant is to be constructed within the confines of the existing wastewater treatment plant site. It is intended that this tender competition will provide for the design and construction of the P fixation facility and for the operation of that facility for a period following commissioning under a Design Build and Operate form of contract. The scope of the services to be provided by the appointed Contractor, may include the management of the sale and distribution of the recovered struvite product on behalf of Irish Water. This new facility will receive influent sludge liquors from the main wastewater treatment plant at Interface points with the existing works. The interface points will also provide for the return of the treated liquors for onward (further) treatment at the existing works. The existing Ringsend WwTP is operated and maintained by a company on behalf of Irish Water. This company will not be participating in the tender competition for the new P fixation facility as above.