Hamworthy Water Systems has delivered its largest ever Membrane Bioreactor (MBR) wastewater treatment plant for installation on board a cruise ship. The twin process tank system, delivered to Meyer Werft’s Papenburg yard, Germany, is being installed on board a 5,600 passenger capacity cruise ship due delivery to an unspecified ship owner later in 2010.
Featuring 64 membranes, the system has the capability to treat all of the ship’s black and grey water, which is expected to be in the region of 1,800m3 per day. Its two process tanks each have a capacity of 250m3. Strict restrictions imposed by the yard required Hamworthy to deliver tanks weighing no more than 40 tonnes apiece, necessitating the incorporation of an internal ‘space frame’ for good structural stiffness and load distribution of minimum weight.
Finite Element Analysis techniques were used to optimise the design in terms of stress distribution, with particular consideration being given to stresses during lifting the tanks onto the ship. Other than the internal ‘space frame’ there are no stiffeners inside the tank, giving 'clean', accessible internal surfaces for the epoxy coating.
Based on biological degradation and membrane separation, the MBR process achieves the highest quality discharge without requiring any addition or generation of chemicals hazardous to the maritime or shipboard environment. Since introducing its MBR technology in 2000, Hamworthy has supplied over 100 MBR units to a range of new and existing cruise ships, ferries, offshore rigs, naval ships, and super yachts.