A liquid treatment device provided at a carbon block, the carbon block having an upper cover, the liquid treatment device being used for post-treating a liquid treated by the carbon block, characterized in that the liquid treatment device comprises: a housing having an accommodation space, a liquid inlet being opened in the housing for the liquid to flow into the accommodation space, and the liquid inlet at least comprising a first inlet located in a sidewall of the housing; a cover located at an upper end of the housing, the cover being fixedly connected to the housing, covering the upper end of the housing, having a liquid outlet for the liquid to flow out of the accommodation space, being detachably covering an upper surface of the upper cover of the carbon block and a radially outer surface of the upper cover, and a radial size of the cover being larger than a radial size of the upper cover of the carbon block; a sealing portion, the sealing portion being located between the cover and the upper cover of the carbon block, being used to seal between the cover and the upper cover of the carbon block, and being an annular protrusion provided on the upper surface of the upper cover of the carbon block, or being a sealing ring provided between a radially internal side of the cover and a radially internal side of the upper cover of the carbon block; a lower treatment unit disposed in the accommodation space and configured to treat the liquid entering the lower treatment unit; and an upper treatment unit disposed in the accommodation space and configured to treat the liquid entering the upper treatment unit, the upper treatment unit being located above the lower treatment unit; wherein the liquid inlet further comprises a second inlet located in the housing, the liquid enters the lower treatment unit through the second inlet and is treated by the lower treatment unit, and the liquid treated by the lower treatment unit is guided to the liquid outlet through an upper liquid flow path located in the upper treatment unit, and the liquid enters the upper treatment unit through the first inlet and flows out from the liquid outlet after being treated by the upper treatment unit. a housing having an accommodation space, a liquid inlet being opened in the housing for the liquid to flow into the accommodation space, and the liquid inlet at least comprising a first inlet located in a sidewall of the housing; a cover located at an upper end of the housing, the cover being fixedly connected to the housing, covering the upper end of the housing, having a liquid outlet for the liquid to flow out of the accommodation space, being detachably covering an upper surface of the upper cover of the carbon block and a radially outer surface of the upper cover, and a radial size of the cover being larger than a radial size of the upper cover of the carbon block; a sealing portion, the sealing portion being located between the cover and the upper cover of the carbon block, being used to seal between the cover and the upper cover of the carbon block, and being an annular protrusion provided on the upper surface of the upper cover of the carbon block, or being a sealing ring provided between a radially internal side of the cover and a radially internal side of the upper cover of the carbon block; a lower treatment unit disposed in the accommodation space and configured to treat the liquid entering the lower treatment unit; and an upper treatment unit disposed in the accommodation space and configured to treat the liquid entering the upper treatment unit, the upper treatment unit being located above the lower treatment unit; wherein the liquid inlet further comprises a second inlet located in the housing, the liquid enters the lower treatment unit through the second inlet and is treated by the lower treatment unit, and the liquid treated by the lower treatment unit is guided to the liquid outlet through an upper liquid flow path located in the upper treatment unit, and the liquid enters the upper treatment unit through the first inlet and flows out from the liquid outlet after being treated by the upper treatment unit.