Abstract: A waste treatment process utilizes a two-stage digestion process with a thermophilic digester, a heat exchanger, and a mesophilic digester. The pH of the thermophilic digestate is increased by removal of carbon dioxide with an air stripper, or by adding a pH increasing reagent upstream of the heat exchanger. The pH adjustment of the digestate protects the heat exchanger and downstream equipment and processes from struvite formation. A struvite reactor may be located in various locations downstream of the heat exchanger to produce a treated digestate or effluent that contains struvite, which can optionally be recovered for beneficial use.

Abstract: A waste treatment process utilizes a two-stage digestion process with a thermophilic digester, a heat exchanger, and a mesophilic digester. The pH of the thermophilic digestate is increased by removal of carbon dioxide with an air stripper, or by adding a pH increasing reagent upstream of the heat exchanger. The pH adjustment of the digestate protects the heat exchanger and downstream equipment and processes from struvite formation. A struvite reactor may be located in various locations downstream of the heat exchanger to produce a treated digestate or effluent that contains struvite, which can optionally be recovered for beneficial use.

Abstract: A method of processing biological solids includes blending a sludge with calcium oxide and delivering the blended sludge and calcium oxide to a pressurized container; injecting, into the blended sludge and calcium oxide in the pressurized container, an additive capable of exothermic reactions with the calcium oxide; regulating pH in the pressurized container to produce class A biological solids from the sludge; and pumping the blended sludge, calcium oxide, and additive from the pressurized container to a reactor. A system used for this process include sources of calcium oxide and biological solids, an additive injector, and a pressurized reactor.

Abstract: A sludge flow monitoring system and method measures volume of sludge pumped by a positive displacement pump through a pipeline by determining a fill percentage during each pumping cycle. The start and end of each piston stroke are identified by hydraulic system sensors. The fill percentage is determined based upon a first summation of periodic piston speed command values from the start of a pumping stroke to the end of a pumping stroke, and a second summation of periodic piston speed command values from a poppet valve opening indicating output flow from the pump to the end of the pumping stroke.

Abstract: A drying system includes a fluidized bed dryer and fluidizing gas loop. The system is a closed loop so that fluidizing gas used to dry particulate matter can be reconditioned and recycled to fluidize and dry additional particulate matter. The fluidizing gas is reconditioned by removing fine particulates and water vapor. The drying system includes oxygen control features to prevent oxygen from entering the system. A method for drying particulate matter includes fluidizing the particulate matter in a dryer with a fluidizing gas, heating the particulate matter to remove water, removing water vapor and fluidizing gas from the dryer, removing fines and water vapor from the fluidizing gas, recirculating the fluidizing gas to the dryer to fluidize additional particulate matter and removing dried particulate matter from the dryer. A modular drying system reduces the amount of construction necessary at the installation site.

Abstract: One embodiment includes an assembly with a movable column with an upper end and a lower end, wherein the lower end includes a recessed opening. The assembly also includes a locking foot assembly with a base foot and a locking mechanism. The locking mechanism includes a latch which is spring biased and at least partially extends outward from the base foot such that the latch comes into contact with the lower end of the movable column and is retractable inward into the base foot when the spring is compressed, such that the latch of the locking mechanism can both engage and disengage the recessed opening in the lower end of the movable column.

Abstract: One embodiment includes an assembly with a movable column with an upper end and a lower end, wherein the lower end includes a recessed opening. The assembly also includes a locking foot assembly with a base foot and a locking mechanism. The locking mechanism includes a latch which is spring biased and at least partially extends outward from the base foot such that the latch comes into contact with the lower end of the movable column and is retractable inward into the base foot when the spring is compressed, such that the latch of the locking mechanism can both engage and disengage the recessed opening in the lower end of the movable column.

Abstract: A system for reducing wear includes a receptacle having at least one wall and a floor for holding material within the receptacle. An opening is located in the floor for accessing material held in the receptacle. A sliding frame is located above and parallel to the floor for agitating material held in the receptacle. At least one component is included inside the receptacle to reduce wear on the floor and/or sliding frame, and/or a wear indicator is located outside of the receptacle to monitor wear on the floor and/or the sliding frame.

Abstract: A pump system for pumping a viscous material that includes N positive displacement pumps, where N is an integer greater than two, and a hydraulic drive. Each pump has an inlet and an outlet therefrom, and a pair of cylinders each with a piston movable in a reciprocating stroke cycle therein. The hydraulic drive is connected to the N positive displacement pumps to reciprocate the pistons within the cylinders. The stroke cycle includes a discharging stroke and a filling stroke. The discharging stroke and the filling stroke of the N positive displacement pumps are staggered from one another by 1/N stroke positions such that no two pumps have pistons in the same stroke position at the same time.

Abstract: A method for clearing obstructions in a silo having a reciprocating frame uses an obstruction clearance mode. The method includes driving at least one frame in a reciprocal motion across a silo floor until sensing an indication that at least one frame has encountered an obstruction. Upon sensing the indication of obstruction, an obstruction clearance mode is initiated in an attempt to clear the obstruction.

Abstract: A silo includes a stuffing box forming for use with a reciprocating frame. A push-rod extends from a hydraulic cylinder through a stuffing box and a silo wall to actuate a reciprocating frame. The stuffing box forms a floating seal around the push-rod capable of moving with the push-rod to accommodate misalignment.

Abstract: A system for reducing wear includes a receptacle having at least one wall and a floor for holding material within the receptacle. An opening is located in the floor for accessing material held in the receptacle. A sliding frame is located above and parallel to the floor for agitating material held in the receptacle. At least one component is included inside the receptacle to reduce wear on the floor and/or sliding frame, and/or a wear indicator is located outside of the receptacle to monitor wear on the floor and/or the sliding frame.

Abstract: A pump system for pumping a viscous material that includes N positive displacement pumps, where N is an integer greater than two, and a hydraulic drive. Each pump has an inlet and an outlet therefrom, and a pair of cylinders each with a piston movable in a reciprocating stroke cycle therein. The hydraulic drive is connected to the N positive displacement pumps to reciprocate the pistons within the cylinders. The stroke cycle includes a discharging stroke and a filling stroke. The discharging stroke and the filling stroke of the N positive displacement pumps are staggered from one another by 1/N stroke positions such that no two pumps have pistons in the same stroke position at the same time.

Abstract: A silo includes a stuffing box forming for use with a reciprocating frame. A push-rod extends from a hydraulic cylinder through a stuffing box and a silo wall to actuate a reciprocating frame. The stuffing box forms a floating seal around the push-rod capable of moving with the push-rod to accommodate misalignment.

Abstract: A method for clearing obstructions in a silo having a reciprocating frame uses an obstruction clearance mode. The method includes driving at least one frame in a reciprocal motion across a silo floor until sensing an indication that at least one frame has encountered an obstruction. Upon sensing the indication of obstruction, an obstruction clearance mode is initiated in an attempt to clear the obstruction.

Abstract: A silo with a reciprocating frame includes a blanking plate that is capable of limiting the amount of material released from the silo. A blanking plate is attached to at least one reciprocating frame and is configured to substantially cover an opening in a floor when the reciprocating frame is centered above the opening in the floor.

Abstract: A reciprocating frame for a silo has outside bevels located on outer surfaces of a rim. Outside bevels slide under material as the reciprocating frame moves across a silo floor. The reciprocating frame has inside bevels located on inner surfaces of the rim. The inside bevels contact material at an angle that provides downward force to the reciprocating frame as it moves across the silo floor.

Abstract: A reciprocating frame for a silo has a rim and at least one support extending across an interior of the rim. A first composite blade is located on the rim and includes a filler material. A method of manufacturing a composite blade for a reciprocating frame includes forming an angle base to define a pocket, filling the pocket with a filler material, and forming the angle base and filler material into a composite beveled cutting surface for reciprocating frame.