Abstract: An underdrain assembly in a wastewater filtration unit for providing even distribution of liquid and gas during filter backwashing operations and the uniform collection of filtered water during the normal operation of the filtration unit is provided. The underdrain assembly is provided with a flat, concrete plate with a perimeter matching the shape of the filtration unit. The concrete plate has a plurality of holes with individual PEX tubes in each hole extending from the concrete plate top surface through and protruding below the plate.

Abstract: A biological reactor which is intermittently aerated to create an environment that alternates from aerobic to anoxic. A programmable logic controller controls the amount and timing of air flow to the biological reactor linking aeration to incoming load.

Abstract: In a wastewater treatment system comprised of an anoxic tank outputting to a biological reactor and outputting from the reactor to a clear well, a process for controlling the rate and timing of flow through the reactor by means of a floating pump within the anoxic tank. Further enhancement of denitrification is achieved by sending internal recycles into the sludge zone of the anoxic tank via a baffle positioned within the sludge layer.

Abstract: A single submerged attached growth bioreactor interconnected to an equalization tank and a clear well. The equalization tank receives raw wastewater and provides primary settling of solids from the waste water. The output from the equalization tank is sent into the bioreactor. The wastewater flow path through the bioreactor biofilter is serpentine. Wastewater enters the first cell of the biofilter and flows downward to an opening at the biofilter bottom that hydraulically connects the first cell to a biofilter second cell. In the second cell the wastewater flows up from the bottom to an opening above the media within the cell, which connects the second cell with a third biofilter cell. Wastewater then flows downward through the third cell to the bottom and exits the biofilter through a pipe connected to a pump in the clear well. The hydrostatic pressure created by the differential liquid levels drives forward flow through the cells and into an effluent pipe at the bottom of the third cell.

Abstract: In a biological wastewater treatment system, the addition of an intermittently aerated second bioreactor to accomplish ammonium oxidation to predominately nitrite and then to achieve denitrification by introducing the effluent, containing nitrite, from the second bioreactor into the influent collection system or the head works of a wastewater treatment plant. Denitrification from nitrite occurs in the collection pipe using the influent organics as a carbon source.

Abstract: a wastewater treatment system having a submerged attached growth bioreactor connected to an equalization tank and a clear well. The bioreactor has a deep-bed sand filter. the wastewater flow through the filter is in two directions, i.e., down flow (forward flow) and up flow (reverse flow). The hydrostatic pressure created by the differential liquid levels within the tanks creates a forward flow from the equalization tank, into the bioreactor and out into the clear well. Reverse flow is accomplished by pumping from the clear well back up through the bioreactor. The reverse flow fills the headspace within the bioreactor, stops, and then begins to flow forward again. The flow through the bioreactor alternates between down flow and up flow. In an alternative embodiment, process air required for the oxidation of organics and nitrification is accomplished by aerating the clear well. The oxygen rich water is pumped into the filter from the clear well during the reverse flow.

Abstract: The process and apparatus of the present invention provides an anoxic pretreatment tank, a granular fixed film denitrification reactor and a membrane bioreactor. Raw waste flows into the anoxic pretreatment tank, through a denitrification filter and then to a membrane bioreactor for nitrification and micro filtering. Contents of the membrane bioreactor are periodically recycled to the anoxic tank and the denitrification filter for BOD reduction, denitrification and coarse filtration.

Abstract: A media used in conjunction with any system than is comprised at least of a septic or anoxic tank followed by an aerobic or alternating aerobic/anoxic treatment unit that is providing nitrification. The media enhances denitrification of effluent that has been recycled from the nitrification unit to the anoxic tank. The is comprised of a number of synthetic cords with a specific gravity less than the specific gravity of the effluent. The cords are attached to the bottom of the septic or anoxic tank. The cords will float in the liquid flow stream of the septic/anoxic tank providing a number of surfaces for fixed film organisms.

Abstract: A process and apparatus for treating wastewater containing nitrogen compounds is disclosed. The process includes passing the wastewater to be treated through a biologically active material in one direction to treat the wastewater and passing the treated wastewater through the biologically active material in a second direction to further treat the wastewater under alternating aerobic and anoxic conditions, converting nitrogen compounds to nitrates and nitrites, and converting nitrates and nitrites to gaseous nitrogen.