Patent ID: 9718702
Date: 2017-08-01
CPC Classifications: B01D,C02F,F03B,Y02E,Y02P,Y02W

Claim:
1. A method for treating water extracted from Lake Kivu, said method comprising the steps of: (a) extracting water from an extraction depth of Lake Kivu to obtain extracted water; (b) degassing the extracted water so as to remove at least a portion of carbon dioxide gas from the extracted water and provide degassed water having a density lower than the extracted water and having a pH higher than the extracted water; (c) photosynthetic treatment of the degassed water by growth of an algal biomass to convert bicarbonate anions to carbon dioxide and hydroxyl anions, such that the pH of the degassed water is increased and magnesium and calcium precipitate out of the degassed water to provide de-densified water and precipitate; (d) separating the de-densified water from the algal biomass and the precipitate; (e) optionally adjusting the pH of the de-densified water by adding carbon dioxide thereto, wherein the carbon dioxide is obtained from the degassing step and by combustion of methane also obtained in the degassing step; and (f) reinjecting into Lake Kivu a return flow of the de-densified water separated from the biomass and precipitate, wherein the de-densified water is reinjected into Lake Kivu at a reinjection depth which is shallower than the extraction depth and which is density-matched with the de-densified water.