Research Papers by Raphael Semiat

Desalinated waters are poor in minerals thus, a certain degree of re-mineralization is essential so as to make the water palatable and non-corrosive as well as to meet health requirement. Selection of re-mineralization process is determined by regulatory water quality standards. This review summariz

Calcium phosphate precipitation, and in particular calcium hydroxyapatite (HAP)-Ca5(PO4)3OH scaling, is a major factor limiting high recovery in reverse osmosis (RO) of treated effluents. This study evaluated the feasibility of phosphate adsorption in continuous regime on granular ferric hydroxide (G

The present paper describes pilot plant development of a novel process enabling increase of water recovery in brackish water desalination without using any chemicals. This is achieved by precipitating the scaling salts of a carbonate-rich concentrate by increasing the pH through air stripping of CO2

Molecular dynamics simulation and Density Functional Theory were used to investigate the adsorption of two kinds of anti-scalant, ethane diphosphonic acid (EDPA) and polyether polyamino methylene phosphonate (PAPEMP), on the calcite (104) surface in order to increase the level of understanding of th

The possibility of alkaline scale precipitation and removal by electrolytic devices has long been recognized. The scale removal principle of the electrochemical technique is based on the creation of a high pH environment around the cathode by water and oxygen reduction reactions which release hydrox

Many scaling species such as CaCO3, Mg(OH)2 and Ca3(PO4)2 present in brackish and wastewater feeds can be removed by precipitation processes induced by raising the pH level of the raw water. These processes require dosage of alkaline chemicals such as NaOH, lime or magnesia. An interesting possibili

Desalination of brackish water containing silica at high recovery levels leads to a rapid flux decline, due to the precipitation of a colloidal solution consisting of polymerized silica nano-particles. The critical flux (CF) phenomenon postulates that there is a certain permeate flux level below whi

The potential of direct membrane filtration on either ultrafiltration (30, 200 and 400 kDa MWCO) or nanofiltration (200 Da MWCO) membranes was studied as a method of treatment of low load graywater for on site reuse. The graywater collected from a sports center’s public showers and characterized for

This paper describes laboratory techniques for characterizing the permissible water recovery fraction in RO desalination, which is limited by the need to avoid scale deposition on the membrane. The CaSO4 scaling system was adopted for the development of these techniques. An upper water recovery boun