A method of water treatment comprising: providing an electrolysis device comprising: an electrolysis vessel; a pair of electrodes arranged in the electrolysis vessel, the pair of electrodes respectively serving as a positive electrode and a negative electrode; and a cell unit arranged between the positive and negative electrodes, the cell unit comprising a bipolar membrane element and at least one cation exchangeable membrane, the bipolar membrane element having a cation exchangeable side and an anion exchangeable side, the cation exchangeable side being closer to the negative electrode than the anion exchangeable side, said at least one cation exchangeable membrane being arranged between the anion exchangeable side of the bipolar membrane element and the positive electrode, so as to define an alkalic between the bipolar membrane element and the cation exchangeable membrane, said cation exchangeable membrane is selective; an anion exchangeable membrane between the negative electrode and the cation exchangeable side of the bipolar membrane element, an acidic chamber being defined between the anion exchangeable membrane and the bipolar membrane element, said anion exchangeable membrane is selective; a first salt water chamber defined between said negative electrode and anion exchangeable membrane, a second salt water chamber defined between said positive electrode and said cation exchangeable membrane; and a first inlet providing a feed stream to said first salt water chamber, a second inlet providing a feed stream to said second salt water chamber, a third inlet providing a feed stream to said acidic chamber, and a fourth inlet providing a feed stream to said alkalic chamber; providing feed streams to said first salt water chamber, second salt water chamber, acidic chamber, and alkalic chamber, said acidic chamber producing an acidic solution and said alkalic chamber producing an alkalic solution; directing at least a portion of the contents of said first and second salt water chambers into a precipitation tank; directing at least a portion of the alkalic solution into said precipitation tank, thereby increasing the pH in said precipitation tank to produce precipitate; and removing said precipitate from said precipitation tank. an electrolysis vessel; a pair of electrodes arranged in the electrolysis vessel, the pair of electrodes respectively serving as a positive electrode and a negative electrode; and a cell unit arranged between the positive and negative electrodes, the cell unit comprising a bipolar membrane element and at least one cation exchangeable membrane, the bipolar membrane element having a cation exchangeable side and an anion exchangeable side, the cation exchangeable side being closer to the negative electrode than the anion exchangeable side, said at least one cation exchangeable membrane being arranged between the anion exchangeable side of the bipolar membrane element and the positive electrode, so as to define an alkalic between the bipolar membrane element and the cation exchangeable membrane, said cation exchangeable membrane is selective; an anion exchangeable membrane between the negative electrode and the cation exchangeable side of the bipolar membrane element, an acidic chamber being defined between the anion exchangeable membrane and the bipolar membrane element, said anion exchangeable membrane is selective; a first salt water chamber defined between said negative electrode and anion exchangeable membrane, a second salt water chamber defined between said positive electrode and said cation exchangeable membrane; and a first inlet providing a feed stream to said first salt water chamber, a second inlet providing a feed stream to said second salt water chamber, a third inlet providing a feed stream to said acidic chamber, and a fourth inlet providing a feed stream to said alkalic chamber; providing feed streams to said first salt water chamber, second salt water chamber, acidic chamber, and alkalic chamber, said acidic chamber producing an acidic solution and said alkalic chamber producing an alkalic solution; directing at least a portion of the contents of said first and second salt water chambers into a precipitation tank; directing at least a portion of the alkalic solution into said precipitation tank, thereby increasing the pH in said precipitation tank to produce precipitate; and removing said precipitate from said precipitation tank.