Modular walls for use in building liquid tank

A wall module assembly comprising:

• a first wall module comprising a top surface, a bottom surface and a first side, the first wall module further comprises two insulating layers and a first sealing layer located between the two insulating layers, the first side comprising a upper side surface and a lower side surface, the first wall module further comprising a first sealing flange extending from the first sealing layer outwardly beyond both the upper and lower side surfaces, the first sealing flange comprising a first rippled edge portion;
• a second wall module comprising a top surface, a bottom surface and a second side, the second wall module further comprises two insulating layers and a second sealing layer located between the two insulating layers, the second side comprising an upper side surface and a lower side surface, the second wall module further comprising a second sealing flange extending from the second sealing layer outwardly beyond at least one of the upper and lower side surfaces, the second sealing flange comprising a second rippled edge portion, wherein the first wall module and the second wall module are arranged such that the first side opposes the second side with no wall module intervening between the first side and the second side;
• and
• a coupler located between the first and second sides, the coupler configured to liquid-tightly couple the first rippled edge portion and the second rippled edge portion such that the first wall module and the second wall module are liquid-tightly connected.