Liquid clarifier and method for clarifying liquid, comprising a liquid reactor which comprises an cylindrical tank having an upper vertical section and a lower tapered section, an inner cylinder extending along at least part of the upper section of the tank and an outlet for clarified liquid at the top of the tank, where the liquid clarifier further comprises a gas compressor adapted to inject compressed gas into the lower region of the cylinder and an inlet for an unclear liquid at the upper region of the cylinder, and at least one partition wall inside the cylinder, where the at least one partition wall create flow channels in the lower region of the inner chamber, where the compressed gas is adapted to be injected through gas inlets in flow channel/s in order to create an upward flow in the flow channel/s having gas inlets, which will create a downward flow in the flow channel/s without gas inlets, where the at least one partition wall extends out of the lower region of the cylinder. The advantage of the invention is that different kinds of liquids can be clarified in an efficient and fast way without the need of specific additives.