Veolia Water Solutions&Technologiesa Aqua Services&Engineering(ASE)has secured a contract to upgrade and refurbish a 400 m3/day seawater desalination plant in Walvis Bay,Namibia.The project will help increase potable water supply for domestic use,and provide process water for a Walvis Bay factory. Because of the source seawater's high organic content,ASE has to adapt the air flotation filtration system design,making it suitable for use as a pre-treatment step."Our engineers will introduce a vortex mixer to generate micro bubbles,which are fed into the flocculated raw seawater stream,"said Christian Stock,ASE managing director."This will help lighter organic particles float to the surface,and allow for heavier particles to settle." These settled particles will then be filtered by an ultrafine filtration bed where,unlike with an additional pumping step,minimal break-up of the flocculated particles will occur.This pre-treatment will ensure that the raw seawater,often affected by red tide and sulphur eruptions,meets the required standards for effective desalination in reverse osmosis membranes. ASE will install an energy recovery system to the reverse osmosis membrane system to help the plant optimise its energy consumption."This high-end technology will help the plant reduce its reliance on municipal power sources by up to 42%,"said Stock. The plant should be operational within 5–6 months.
