sludge along the bottom to the center of the clarifier wherein it is evacuated via conduit 17 floating skimmings are collected into a bean 18 and are removed via line 30 together with the bottom sludge via line 17 the module 19 can have all previously described elements and provisions and can be operated as previously described skilled in art are familiar with operation of clarifiers with peripheral influent feed it is obvious that a secondary clarifier with central feed can be upgraded by installing filtration modules connected to the existing peripheral effluent collection trough fig6 is a section of the upper portion of the combined clarification filtration apparatus 1 showing multiple means for collecting effluent positioned at different elevations other elements of the system had already been described and the descriptions will not be repeated here this embodiment is advantageous in cases of very high range of flows for example significantly variable dry weather flows and significant influent increase during storm events as an example possible water elevations el 1 el 2 and el 3 can correspond to a certain probability percentile for dry influent flow e g 80 the maximum design dry weather flow 100 and the maximum design wet weather flow e g 25 years probable rain coinciding with the maximum dry weather flow for municipal influent as an example the lowest level effluent collection means 9 a will be operated in the range of elevations from el 1 or lower but above the means 9 a to el 2 when the flow exceeds 80 percentile or as otherwise selected the next level collection means 9 b becomes submerged and starts taking in the effluent and yet at wet weather events and.