A flocculation and sedimentation apparatus has: sedimentation tank that causes flocs in raw water to be sedimented and separated; sludge concentration tank that is surrounded by sedimentation tank and that collects and concentrates the flocs; and raw water supply mechanism having center line that passes through sludge concentration tank, wherein raw water supply mechanism rotates about center line and supplies the raw water to sedimentation tank. Raw water supply mechanism includes: raw water introducing portion that is located on center line and to which the raw water is introduced, raw water supply port that is open at a lower portion of an inner space of sedimentation tank and that supplies the raw water to sedimentation tank, and pipe portion that communicates both with raw water introducing portion and with raw water supply port and that extends above sludge concentration tank in a direction away from center line.

A flocculation and sedimentation apparatus has: sedimentation tank that causes flocs in raw water to be sedimented and separated; sludge concentration tank that is surrounded by sedimentation tank and that collects and concentrates the flocs; and raw water supply mechanism having center line that passes through sludge concentration tank, wherein raw water supply mechanism rotates about center line and supplies the raw water to sedimentation tank. Raw water supply mechanism includes: raw water introducing portion that is located on center line and to which the raw water is introduced, raw water supply port that is open at a lower portion of an inner space of sedimentation tank and that supplies the raw water to sedimentation tank, and pipe portion that communicates both with raw water introducing portion and with raw water supply port and that extends above sludge concentration tank in a direction away from center line.

An apparatus for wasting flocculant sludge from a clarifier is provided including a wasting pipe fluidly connectable to a waste conduit, a manifold fluidly connectable to the wasting pipe, an upper header for collecting the flocculant sludge fluidly connectable to the manifold, a return sludge pipe fluidly connectable to a return sludge well, a lower header for collecting settled sludge fluidly connectable to the return sludge pipe, and a drive mechanism for rotating the upper header and the lower header about a center axis. A wastewater treatment system is provided including the clarifier fluidly connectable to a source of a mixed liquor and the apparatus for wasting flocculant sludge. A method of separating settled sludge from a clarifier is provided including withdrawing flocculant sludge and withdrawing settled sludge. A method of retrofitting a clarifier is also provided including providing the manifold, the upper header, and the drive mechanism.

An apparatus for wasting flocculant sludge from a clarifier is provided including a wasting pipe fluidly connectable to a waste conduit, a manifold fluidly connectable to the wasting pipe, an upper header for collecting the flocculant sludge fluidly connectable to the manifold, a return sludge pipe fluidly connectable to a return sludge well, a lower header for collecting settled sludge fluidly connectable to the return sludge pipe, and a drive mechanism for rotating the upper header and the lower header about a center axis. A wastewater treatment system is provided including the clarifier fluidly connectable to a source of a mixed liquor and the apparatus for wasting flocculant sludge. A method of separating settled sludge from a clarifier is provided including withdrawing flocculant sludge and withdrawing settled sludge. A method of retrofitting a clarifier is also provided including providing the manifold, the upper header, and the drive mechanism.

A process for producing alumina trihydrate includes a digestion step, a separation step, and a precipitation step the separation step including: b1) pretreating a slurry from the digestion step by adding a flocculant to said slurry and mixing the flocculant and the slurry, b2) settling the resulting flocculated slurry in a gravity settler vessel, b3) determining a measured value representative of the concentration of solid particles in the resulting clarified liquor, b4) comparing the measured value with a predetermined threshold, b5) feeding said clarified liquor directly to the precipitation step, while the measured value is less than said predetermined threshold, and b6) redirecting said clarified liquor to the pre-treatment step b1), when the measured value is more than said predetermined threshold. An installation may be configured for operating said process.

A process for producing alumina trihydrate includes a digestion step, a separation step, and a precipitation step the separation step including: b1) pretreating a slurry from the digestion step by adding a flocculant to said slurry and mixing the flocculant and the slurry, b2) settling the resulting flocculated slurry in a gravity settler vessel, b3) determining a measured value representative of the concentration of solid particles in the resulting clarified liquor, b4) comparing the measured value with a predetermined threshold, b5) feeding said clarified liquor directly to the precipitation step, while the measured value is less than said predetermined threshold, and b6) redirecting said clarified liquor to the pre-treatment step b1), when the measured value is more than said predetermined threshold. An installation may be configured for operating said process.

An apparatus for wasting flocculant sludge from a clarifier is provided including a wasting pipe fluidly connectable to a waste conduit, a manifold fluidly connectable to the wasting pipe, an upper header for collecting the flocculant sludge fluidly connectable to the manifold, a return sludge pipe fluidly connectable to a return sludge well, a lower header for collecting settled sludge fluidly connectable to the return sludge pipe, and a drive mechanism for rotating the upper header and the lower header about a center axis. A wastewater treatment system is provided including the clarifier fluidly connectable to a source of a mixed liquor and the apparatus for wasting flocculant sludge. A method of separating settled sludge from a clarifier is provided including withdrawing flocculant sludge and withdrawing settled sludge. A method of retrofitting a clarifier is also provided including providing the manifold, the upper header, and the drive mechanism.

An apparatus for wasting flocculant sludge from a clarifier is provided including a wasting pipe fluidly connectable to a waste conduit, a manifold fluidly connectable to the wasting pipe, an upper header for collecting the flocculant sludge fluidly connectable to the manifold, a return sludge pipe fluidly connectable to a return sludge well, a lower header for collecting settled sludge fluidly connectable to the return sludge pipe, and a drive mechanism for rotating the upper header and the lower header about a center axis. A wastewater treatment system is provided including the clarifier fluidly connectable to a source of a mixed liquor and the apparatus for wasting flocculant sludge. A method of separating settled sludge from a clarifier is provided including withdrawing flocculant sludge and withdrawing settled sludge. A method of retrofitting a clarifier is also provided including providing the manifold, the upper header, and the drive mechanism.

A clarifier tank insert assembly configured to be inserted into a frac tank. The clarifier tank insert assembly includes a housing that defines a housing interior and includes a bottom opening, at least a first plate pack assembly disposed in the housing interior, and at least a first pipe positioned within the housing interior and above the first plate pack assembly. The first plate pack assembly includes at least first and second parallel plates and the first plate defines a plate angle with the bottom surface of the housing. The first pipe includes a plurality of inflow openings defined therein. A water path extends through the bottom opening, between the first and second parallel plates and into the inflow openings in the pipe.

A clarifier tank insert assembly configured to be inserted into a frac tank. The clarifier tank insert assembly includes a housing that defines a housing interior and includes a bottom opening, at least a first plate pack assembly disposed in the housing interior, and at least a first pipe positioned within the housing interior and above the first plate pack assembly. The first plate pack assembly includes at least first and second parallel plates and the first plate defines a plate angle with the bottom surface of the housing. The first pipe includes a plurality of inflow openings defined therein. A water path extends through the bottom opening, between the first and second parallel plates and into the inflow openings in the pipe.