Befesa Water Projects was awarded to develop the Seawater Desalination Plant in Qingdao in 2008 under 25-years BOT contract.It is located in the city of Qingdao,in the Shandong province,in Eastern China and it has a production capacity of 100,000 m3/d.Seawater intake is situated a few kilometers away in a lagoon that is shared with other industries.Water is conducted to the lagoon through a pipe,which is completely submerged at high tide.Due to this,raw water is difficult to treat because it has a high total suspended solid concentration,high turbidity values and different pollutants.Additionally,the challenge of operating with large variations in temperature exits in different seasons.In order to confirm the selection of the pretreatment to ensure the water supply,ultrafiltration and conventional pre-treatment pilot tests was carried out.This paper reviews the main results and conclusions obtained during the pilot scale experiments in order to validate and optimize the pre-treatment for Qingdao Desalination Plant.