Abstract: A hybrid membrane aerated biofilm reactor (MABR) and activated sludge (AS) system and process are described herein. At least a portion of the AS system includes aerobic mixed liquor, for example in an aerobic tank or zone downstream of a tank or zone containing membrane aerated biofilm modules. The flow of air to the membrane aerated biofilm is modulated considering the ammonia loading rate to the system or to the aerobic mixed liquor, for example according to a diurnal cycle. For example, air flow to the membrane supported biofilm can be below an average or initial air flow rate during a period of low ammonia loading. Air flow to the aerobic mixed liquor may remain essentially constants during the same period. Optionally, mixed liquor around the membrane aerated biofilm modules may be aerated during a period of high ammonia loading.

Abstract: A hybrid membrane aerated biofilm reactor (MABR) and activated sludge (AS) system and process are described herein. At least a portion of the AS system includes aerobic mixed liquor, for example in an aerobic tank or zone downstream of a tank or zone containing membrane aerated biofilm modules. The flow of air to the membrane aerated biofilm is modulated considering the ammonia loading rate to the system or to the aerobic mixed liquor, for example according to a diurnal cycle. For example, air flow to the membrane supported biofilm can be below an average or initial air flow rate during a period of low ammonia loading. Air flow to the aerobic mixed liquor may remain essentially constants during the same period. Optionally, mixed liquor around the membrane aerated biofilm modules may be aerated during a period of high ammonia loading.

Abstract: Wastewater with high ammonia concentration is pre-treated before discharging it into a wastewater treatment plant treating lower strength wastewater, for example an activated sludge plant treating municipal sewage. The high strength wastewater is pre-treated to oxidize ammonia by contact with a fixed film supported on gas transfer membranes in a membrane aerated biofilm reactor. The pre-treatment may be a batch or continuous process. The pre-treatment can be controlled to remove ammonia to about the point of material alkalinity depletion. One or more parameters such as alkalinity, pH, or membrane exhaust oxygen concentration can be monitored to determine if alkalinity depletion has occurred or is about to occur. In some examples, the high strength wastewater is blended with wastewater having less ammonia and more alkalinity, for example municipal sewage or primary effluent. In some examples, the high strength wastewater is a liquid fraction of one or more sludges.

Abstract: A media bed reactor may be used to remove selenium from water. An exemplary reactor has a fluid injection system with one or more outlets located within the media bed. The fluid injection system may be connected to a source of gas, liquid or both. In a selenium treatment process, a denitrification zone forms above a selenium-reducing zone in the media bed. Operation of the reactor includes a step of flowing a fluid upwards through only an upper part of the bed. This upper part of the bed preferably contains at least most of the denitrification zone.

Abstract: A media bed reactor may be used to remove selenium from water. An exemplary reactor has a fluid injection system with one or more outlets located within the media bed. The fluid injection system may be connected to a source of gas, liquid or both. In a selenium treatment process, a denitrification zone forms above a selenium-reducing zone in the media bed. Operation of the reactor includes a step of flowing a fluid upwards through only an upper part of the bed. This upper part of the bed preferably contains at least most of the denitrification zone.

Abstract: A liquid treatment plant has sets of membrane trains and processing trains with flow between them through channels. Means of withdrawing permeate and sludge from the trains are described. Cyclic aeration is provided to the membrane trains. Methods of foam control, backwashing and chemical cleaning are described. Single membrane trains or process trains may be isolated for various functions. An isolated membrane train may be used to thicken sludge.

Abstract: A liquid treatment plant has sets of membrane trains and processing trains with flow between them through channels. Steps of withdrawing permeate and sludge from the trains are described. Cyclic aeration is provided to the membrane trains. Methods of foam control, backwashing and chemical cleaning are described. Single membrane trains or process trains may be isolated for various functions. An isolated membrane train may be used to thicken sludge.

Abstract: A liquid treatment plant has sets of membrane trains and processing trains with flow between them through channels. Flow configurations for withdrawing permeate and sludge from the trains are described. Cyclic aeration is provided to the membrane trains. Methods of foam control, backwashing and chemical cleaning are described. Single membrane trains or process trains may be isolated for various functions. An isolated membrane train may be used to thicken sludge.

Abstract: A static screen used upstream of a membrane assembly within a water treatment system has a screening surface with a number of openings distributed over its area. Liquid flows through the screening surface to reach the membrane assembly. Various shapes of screening surfaces are described including three-dimensional bodies with openings at or near their lower ends. Methods for cleaning the screen are described including aeration, backwashing and lowering down the water level in an upstream section by partially or completely draining a tank. Various treatment systems or process designs incorporating the screen are described. Screen elements may be made in two or more parts comprising a supporting structure and a separation layer and may be mounted on a conduit or pan.