TECHNOLOGY FOCUS - ENVIRONMENT - Preferred Method: Treating wastewater comprises subjecting the filamentous biomass to alternating feast and famine conditions; and where separating the filamentous biomass from the wastewater is performed by a dissolved air flotation process, a screening process or a filtration process. Aerobic famine condition includes an oxygen supply rate less than the aerobic feast condition. At least one of the micronutrients in form of ions of potassium (K), sulfur (S), magnesium (Mg), calcium (Ca), iron (Fe), zinc (Zn), manganese (Mn), cobalt (Co), copper (Cu), molybdenum (Mo), boron (B), chlorine (Cl), vanadium (V) and sodium (Na) is maintained on a level that is limiting for growth of non-filamentous biomass in the process. The feast and famine conditions give rise to feast treatment and famine treatment, and where the feast treatment is performed in a first reactor and where the famine treatment is performed in a second reactor where the second reactor is located downstream of the first reactor or in a side stream. Filamentous biomass is subjected to alternating periods of feast treatment and famine treatment, and where the feast treatment is less than or equal to 25% of the of the combined feast and famine period to which the biomass is cyclically exposed. The concentration of the readily biodegradable organic substrate under feast conditions is at least approximately 10 mg-readily biodegradable organics (RBCOD)/L, and the concentration of the readily biodegradable organic substrate under famine conditions is approximately 2 mg-RBCOD/L or less. The maximum concentration of the readily biodegradable organic substrate available to the filamentous biomass under feast conditions is approximately 10 to approximately 5000 mg-RBCOD/L, and the concentration of the readily biodegradable organic substrate available to the filamentous biomass under famine conditions is approximately 0 to 2 mg-RBCOD/L. Concentration of the readily biodegradable organic substrate made available to the filamentous biomass under feast conditions is at least 50 mg-RBCOD/L. Selecting filamentous biomass includes controlling sludge retention time to between approximately one day and approximately eight days. Selecting filamentous biomass includes controlling the sludge retention time to less than 4 days. The method is performed in a sequencing batch reactor and includes: directing the wastewater into the reactor; mixing the wastewater with the filamentous biomass in the reactor under aerobic conditions to form mixed liquor; separating the filamentous biomass from the mixed liquor; and removing an effluent from the reactor leaving a concentrated filamentous biomass. The method further includes after removing the effluent, leaving the concentrated filamentous biomass in the reactor, and subjecting the concentrated filamentous biomass to famine conditions. It comprises selecting the filamentous biomass by controlling sludge retention time by removing portions of the filamentous biomass from the reactor; and using removed filamentous biomass for further processing towards extracting accumulated PHA. The method also comprises selecting the PHA producing filamentous biomass and treating the wastewater with the filamentous biomass in a sequencing batch reactor. It comprises mixing the wastewater and the filamentous biomass in a sequencing batch reactor; subjecting the filamentous biomass to feast conditions in the sequencing batch reactor; separating the filamentous biomass from the wastewater and withdrawing a substantial portion of the wastewater from the sequencing batch reactor, leaving a concentrated filamentous biomass in the sequencing batch reactor; and subjecting the concentrated filamentous biomass to famine conditions in the sequencing batch reactor. Selecting filamentous biomass is achieved in part at least by controlling sludge retention time, and where sludge retention time is controlled by withdrawing portions of the filamentous biomass from the sequencing batch reactor. The method comprises controlling sludge retention time by maintaining sludge retention time to approximately 1 day to approximately 8 days. Separation of the filamentous biomass from the wastewater in the sequencing batch reactor is conducted with a dissolved air flotation process. The method comprises selecting PHA producing filamentous biomass and treating the wastewater with the filamentous biomass in a system having at least two separate reactors, the method includes mixing the wastewater and filamentous biomass in a first reactor to form mixed liquor; subjecting the filamentous biomass to feast conditions in the first reactor by maintaining the concentration of available organic substrate in the first reactor at approximately 10 mg-RBCOD/L and higher; separating the filamentous biomass from the mixed liquor; transferring the separated filamentous biomass to a second reactor; subjecting the separated filamentous biomass to famine conditions by maintaining the concentration of available biodegradable organic substrate in the second reactor to 2 mg-RBCOD/L and less; and after subjecting the filamentous biomass to famine conditions in the second reactor, returning at least a portion of the filamentous biomass and mixing the filamentous biomass with the wastewater. Selecting the filamentous biomass includes controlling sludge retention time by withdrawing portions of the filamentous biomass such that the sludge retention time is maintained between approximately 1 day and approximately 8 days. The method comprises subjecting the withdrawn filamentous biomass to further PHA accumulation or extraction. Biologically treating wastewater comprises subjecting the biomass to feast conditions in the main stream; and subjecting the biomass to feast conditions in the main stream before the biomass is concentrated and directed to the side stream. In biologically treating wastewater with a biomass and producing PHA-storing biomass in sequencing batch reactor, the mainstream includes at least one feast reactor for subjecting the biomass to feast conditions and at least one additional biological treatment reactor disposed downstream of the feast reactor; and where the method includes subjecting the biomass to feast conditions in the feast reactor prior to further treating the wastewater in the additional biological treatment reactor. The method further includes directing the wastewater and biomass from the biological treatment reactor to a downstream separator disposed in the mainstream and separating the biomass from the wastewater in the separator to form a treated effluent and a concentrated biomass; and directing the concentrated biomass to the famine reactor in the sidestream. The wastewater includes RBCOD, and where the method includes removing substantially all of the RBCOD in the feast reactor prior to the biomass being transferred from the feast reactor to the downstream biological treatment reactor. The wastewater includes OBCOD, and where the method includes removing substantially all of the OBCOD from the wastewater in the biological treatment reactor before the biomass is subjected to famine conditions. The mainstream includes a feast reactor and an additional biological treatment reactor, and where there is at least one separator disposed between the feast reactor and the other biological treatment reactor for separating at least some of the biomass from the wastewater so as to produce a concentrated biomass that is subsequently subjected to famine conditions in the sidestream. The mainstream includes at least two separators, one separator disposed downstream of the feast reactor, and one separator disposed downstream of the biological treatment reactor. The sidestream includes at least two famine reactors connected in series. The mainstream includes a feast reactor, at least one additional biological treatment reactor, and two separators for separating biomass from the wastewater, and where one separator is disposed between the feast reactor and the additional biological treatment reactor, and the other separator is disposed downstream of the additional biological treatment reactor; and where the sidestream includes two famine reactors connected in series with one famine reactor operative to receive concentrated biomass that is separated from the wastewater by the separator disposed between the feast reactor in the additional biological treatment reactor, and where the other famine reactor receives concentrated biomass separated from the wastewater by the separator disposed downstream of the biological treatment reactor. EXAMPLE - No suitable example given.