This disclosure relates to physical selection, deselection or outselection for smaller, less dense, sheared or compressed particles in sludge, wherein the first deselection step occurs at the reactor or at a clarification step, by separately deselecting for such particles and then a second deselection step occurs in an external selector. This double deselection promotes the more efficient removal of slow settling particles, while simultaneously allowing for maintenance of multiple solids residence times for fast and slow growing organisms. The deselection in a clarifier occurs typically at the periphery of the tank or at the surface of a blanket using a positive or negative pressure device. Structures such as slotted or perforated plates, pipes or manifolds can be used to assist in such deselection. Baffles can also be used for such deselection.

A system for mixing and mixing processes and structures are disclosed. In addition a nozzle used for mixing is disclosed.

A system for mixing and mixing processes and structures are disclosed. In addition a nozzle used for mixing is disclosed.

A method of generating hydrogen gas includes providing a colony of sulfur-reducing bacteria and a colony of sulfur-oxidizing bacteria. The colonies can be submerged in a body of water. The colony of sulfur-reducing bacteria can be used to convert at least a portion of sulfates present in the body of water to hydrogen sulfide. The colony of sulfur-oxidizing bacteria can be used to convert the hydrogen sulfide to sulfuric acid. The sulfuric acid can react with manganese to produce hydrogen gas and manganese sulfate.

A method of generating hydrogen gas includes providing a colony of sulfur-reducing bacteria and a colony of sulfur-oxidizing bacteria. The colonies can be submerged in a body of water. The colony of sulfur-reducing bacteria can be used to convert at least a portion of sulfates present in the body of water to hydrogen sulfide. The colony of sulfur-oxidizing bacteria can be used to convert the hydrogen sulfide to sulfuric acid. The sulfuric acid can react with manganese to produce hydrogen gas and manganese sulfate.

A method of separating oxygen from a body of water includes providing a colony of denitrifying bacteria submerged in the body of water. The colony of denitrifying bacteria can be used to convert at least a portion of nitrogen oxides present in the body of water to nitrogen gas. The method can also include collecting the nitrogen gas and bubbling the nitrogen gas through a portion of water from the body of water to remove dissolved oxygen from the portion of water. This can form a mixture of the nitrogen gas and oxygen gas.

A wastewater treatment device has: an ozone generator which supplies ozone; a mixer which mixes ozone supplied from the ozone generator with wastewater and supplies ozone mixed wastewater; an ozone oxidation unit which progresses ozone oxidation in the ozone mixed wastewater while passing the ozone mixed wastewater therethrough and discharges wastewater in which the ozone has been consumed; a biological treatment unit which performs biological treatment on the wastewater discharged from the ozone oxidation unit using microorganisms; and an adjusting device which adjusts the amount of ozone to be mixed with the wastewater by the mixer so that ozone in an amount that inhibits the microorganisms of the biological treatment unit does not remain in the wastewater discharged from the ozone oxidation unit.

A wastewater treatment device has: an ozone generator which supplies ozone; a mixer which mixes ozone supplied from the ozone generator with wastewater and supplies ozone mixed wastewater; an ozone oxidation unit which progresses ozone oxidation in the ozone mixed wastewater while passing the ozone mixed wastewater therethrough and discharges wastewater in which the ozone has been consumed; a biological treatment unit which performs biological treatment on the wastewater discharged from the ozone oxidation unit using microorganisms; and an adjusting device which adjusts the amount of ozone to be mixed with the wastewater by the mixer so that ozone in an amount that inhibits the microorganisms of the biological treatment unit does not remain in the wastewater discharged from the ozone oxidation unit.

A combined sedimentation tank including a flocculation tank, a transition zone and a sedimentation tank which are sequentially connected along a direction that water flows. The sedimentation tank includes a sloping plate zone and a horizontal flow zone. The length of the sloping plate zone is a quarter of the total length of the sedimentation tank. A return pipe is arranged at the bottom of the sloping plate zone. Some of sludge in the sloping plate zone is returned to the flocculation tank through the return pipe to increase the concentration of the suspended solids in the flocculation tank, thereby forming the sediments.

A combined sedimentation tank including a flocculation tank, a transition zone and a sedimentation tank which are sequentially connected along a direction that water flows. The sedimentation tank includes a sloping plate zone and a horizontal flow zone. The length of the sloping plate zone is a quarter of the total length of the sedimentation tank. A return pipe is arranged at the bottom of the sloping plate zone. Some of sludge in the sloping plate zone is returned to the flocculation tank through the return pipe to increase the concentration of the suspended solids in the flocculation tank, thereby forming the sediments.