Biomass selection and control for continuous flow granular/flocculent activated sludge processes
A continuous flow granular/flocculent sludge wastewater process selects for granule biomass capable of nitrogen and phosphorus removal and controls granule size and concentration of granular and flocculent sludge for optimal nutrient, organic, and solids removal in a smaller footprint. A series of biological process zones lead to a secondary clarifier. Mixed liquor sludge, preferably from an aerobic zone, goes through a classifier or separator processing flow from the aerobic zone, to the secondary clarifier. In a sidestream process that can be included a portion of sludge preferably from an aerobic zone goes through a classifier or separator to selectively produce a granular-rich effluent, and the clarifier may also have a separator to further concentrate granular biomass, most of which is cycled back to an initial multi-stage anaerobic process zone. The anaerobic zone is structured and operated to encourage growth of granules in subsequent process zones.
1. A system including a separator within a clarifier in biological treatment of wastewater including organic sewage, with activated sludge flowing continuously into and exiting the clarifier, the activated sludge having both floc and granular biomass, comprising:
a clarifier tank with an inflow pipe configured to receive said activated sludge from upstream liquid process zones of the system,
the separator including an energy dissipating inlet connected to the inflow pipe and configured to receive said activated sludge having both floc and granular biomass,
the energy dissipating inlet having a bottom plate and internal baffles configured to direct the sludge in generally even distribution outwardly into liquid volume of the clarifier, configured to cause sludge solids to settle by gravity to a tank floor sloped downwardly toward the center of the clarifier, with granular sludge settling faster than floc sludge and the floc sludge settling slower and more outwardly,
the separator further including a granular sludge exit through the clarifier tank floor, near the center of the clarifier, and a floc sludge exit through the tank floor spaced outwardly from the granular sludge exit, and
the separator further including an annular sludge dividing deflector plate extending up only part way from the tank floor and positioned radially inwardly from the floc sludge exit, leaving an annular space above the deflector plate thus configured to cause floc sludge, which to travel over the deflector plate to settle more slowly and travel farther outwardly in the clarifier than granular sludge, tends to settle on the tank floor outwardly of the dividing deflector plate while the denser granular sludge tends to settle inwardly of the dividing deflector plate,
whereby sludge exiting the granular sludge exit has a higher concentration of granular sludge than sludge exiting at the floc sludge exit of the clarifier.
2. The system as in claim 1 , wherein the clarifier has a rotating sludge removal arm positioned on and movable on the clarifier floor in a sweeping motion to bring settled granular sludge to the granular sludge exit, and including a floc sludge removal arm on the clarifier floor and movable in a sweeping motion to bring floc sludge to the floc sludge exit.
3. The system as in claim 1 , wherein the energy dissipating inlet is submerged and further including an upper deflector plate in an annular configuration above and outward from the energy dissipating inlet, positioned to deflect sludge emerging from the energy dissipating inlet away from a liquid surface in the clarifier and outwardly in the clarifier.
4. The system as in claim 1 , wherein the energy dissipating inlet has a downflow configuration, with said internal baffles configured to direct floc biomass in generally even distribution radially outwardly to exit a floc discharge opening into liquid volume of the clarifier and faucet baffles to direct granular biomass in generally even distribution radially inwardly and downwardly into the liquid volume.