A method of controlling an enhanced primary treatment (EPT) system that includes an EPT settling tank. A sludge drain discharges a sludge including BOD from the EPT settling tank and a clarified effluent discharge recovers decanted fluid from the EPT settling tank. A controller has at least one computer processor. A sludge sensor is communicatively coupled to the controller. The sludge sensor provides a sludge BOD concentration measurement, or a measurement from which the sludge BOD concentration is calculated. A process algorithm controls the sludge valve to control the discharge of the sludge by gravity or by pumping in response to data from the sludge sensor of the sludge BOD concentration.

An operating point for control of an acoustic transducer can drift during operation and be compensated. A model for the transducer and/or environment frequency response is provided and used to compensate feedback from the transducer to determine an adjustment for the operating point. The model can be recalibrated during operation.

A separator, for separating solids from a liquid, comprises a hydrodynamic separator, a first filtration device, a first backwash device, a second filtration device, and a second backwash device. The first filtration device comprises a first inlet at a first level for receiving at least a first portion of the liquid from the hydrodynamic separator, and a first filter for filtering the first portion of the liquid received via the first inlet. During filtration of the first portion of the liquid, the first portion of the liquid passes through the first filter away from the first inlet and a first portion of solids is retained by the first filter. The first filter is located between the first inlet and the first backwash device. The first backwash device is configured to alternately prevent and allow the passage of the first portion of the liquid through the first backwash device such that, when the passage of the first portion of the liquid through the first backwash device is prevented, the first portion of the liquid that has passed through the first filter passes back through the first filter toward the first inlet so as to remove the first portion of solids from the first filter. The second filtration device comprises a second inlet at a second level higher than the first level for receiving a second portion of the liquid from the hydrodynamic separator, and a second filter for filtering the second portion of the liquid received via the second inlet. During filtration of the second portion of the liquid, the second portion of the liquid passes through the second filter away from the second inlet, and a second portion of solids is retained by the second filter. The second filter is located between the second inlet and the second backwash device. The second backwash device is configured to alternately prevent and allow the passage of the second portion of the liquid through the second backwash device such that, when the passage of the second portion of the liquid through the second backwash device is prevented, the second portion of the liquid that has passed through the second filter passes back through the second filter toward the second inlet so as to remove the second portion of solids from the second filter.

A method and a system for purification of contaminated oil. Said method comprises the steps of: —providing contaminated oil and a separation aid in a tank (3); —waiting for allowing a sludge phase comprising the separation aid together with impurities from the oil to settle in a bottom part (4) of the tank (3); —reusing the sludge phase for purification of new contaminated oil.

Methods and systems for treating tailings at an elevated pH using lime are disclosed herein. In some embodiments, the method comprises (i) providing a tailings stream comprising bicarbonates and a pH less than 9.0, (ii) adding a coagulant comprising calcium hydroxide to the tailings stream to form a mixture having a pH of at least 11.5 and a soluble calcium level no more than 800 mg/L, and (iii) dewatering the mixture to produce a product having a solids content of at least 40% by weight. In some embodiments, the pH and soluble calcium level of the mixture cause chemical modification of clay materials of the mixture via pozzolanic reactions. In some embodiments, the undrained shear strength of the product increases over a period of time of at least two days.

Methods and systems for treating tailings at an elevated pH using lime are disclosed herein. In some embodiments, the method comprises (i) providing a tailings stream comprising bicarbonates and a pH less than 9.0, (ii) adding a coagulant comprising calcium hydroxide to the tailings stream to form a mixture having a pH of at least 11.5 and a soluble calcium level no more than 800 mg/L, and (iii) dewatering the mixture to produce a product having a solids content of at least 40% by weight. In some embodiments, the pH and soluble calcium level of the mixture cause chemical modification of clay materials of the mixture via pozzolanic reactions. In some embodiments, the undrained shear strength of the product increases over a period of time of at least two days.

Methods and systems for treating tailings at an elevated pH using lime are disclosed herein. In some embodiments, the method comprises (i) providing a tailings stream comprising bicarbonates and a pH less than 9.0, (ii) adding a coagulant comprising calcium hydroxide to the tailings stream to form a mixture having a pH of at least 11.5 and a soluble calcium level no more than 800 mg/L, and (iii) dewatering the mixture to produce a product having a solids content of at least 40% by weight. In some embodiments, the pH and soluble calcium level of the mixture cause chemical modification of clay materials of the mixture via pozzolanic reactions. In some embodiments, the undrained shear strength of the product increases over a period of time of at least two days.

Methods and systems for treating tailings at an elevated pH using lime are disclosed herein. In some embodiments, the method comprises (i) providing a tailings stream comprising bicarbonates and a pH less than 9.0, (ii) adding a coagulant comprising calcium hydroxide to the tailings stream to form a mixture having a pH of at least 11.5 and a soluble calcium level no more than 800 mg/L, and (iii) dewatering the mixture to produce a product having a solids content of at least 40% by weight. In some embodiments, the pH and soluble calcium level of the mixture cause chemical modification of clay materials of the mixture via pozzolanic reactions. In some embodiments, the undrained shear strength of the product increases over a period of time of at least two days.

A settling or sedimentation tank including inlet structures arranged, through whose inlet opening the suspension to be separated flows to the tanks, the height of which can be variably adjusted. In addition to the height variability of the inlet opening, the volumetric flow flowing out of the inlet structure can, depending on the actual load, be directed by forming a horizontally flow-through inlet opening or a vertically flow-through inlet opening and can optionally be divided into horizontal and vertical partial flows Q.sub.I and Q.sub.II. As a result of the horizontal inflow, the capacity of the sedimentation tank increases at high loads, and as a result of the vertical inflow, the volume flow through the sedimentation chamber and the turbulent energy in the sedimentation chamber decrease at low loads, so that the retention of fine suspension in the sedimentation tank is increased and thus the effluent quality is improved.

A scum removal system for use with a wastewater treatment clarification tank containing wastewater is provided and includes a debris intake conduit, a debris discharge conduit, and a pump article. The pump article is configured to be in flow communication with the debris intake conduit and the debris discharge conduit, wherein the pump article and debris intake conduit are configured to generate a suction within the debris intake conduit and wherein the debris intake conduit is configured to be located proximate the wastewater. Additionally, the debris intake conduit is sloped downwardly at a debris intake conduit angle β, and the second discharge conduit is sloped downwardly at a debris discharge conduit angle Ω.