h reinforced bearing V Gear unit sizeType HVH B4-CH-10-D Bevel-helical speed reducers B4

Flender/Flender Gear Units/Bevel-helical speed reducers B4

th cells of the aerobic reactor which could have contributed to the poor nitrification. The plant also failed to comply with the TSS limit. From October to December when the flow diversion was stopped, the sl udge age was increased to about 2 days and the plant was nitrifying sufficiently to meet the final effluent limit. The summer sludge age was however too high thus wasting energy. The 3-stage Phoredox process design anoxic mass fraction of 0.0 is too low to achieve denitrification to meet the nitrate/nitrite limit of 6 mgN/. Site meas urements indicate average final effluent values of around 2 mgN/ while model predictions indicate much higher values of about 1 mgN/. The possibility of analytical error is unlikely since 1 values were recorded and out of these only 2 exceeded the limit of 6 mgN/. The most feasible explanation is that si gnificant denitrification occurs in unaerated pockets within the bioreactors due to uneven aeration pattern. Operators also report that they occasionally turn off some of the aerators if portab le DO measurements indicate high concentrations thus creating higher anoxic mass fraction. The -recycle rate is not known since no data was collected from the - recycle pump flow meter. The two old DO sensors that were out of service in 2 were replaced with new ones in 2. Both sensors are located in the last aerobic cell; the same location as the old ones. Locating both sensors in 5-1 the last cell is not optimal for DO monitoring and co ntrol and model predictions show that one of the sensors should be located at the end of the 2nd aerobic cell. Operators will get better indication of the DO along the reactor and use this together with effluent quality to determine the depth of immersion for the aerators by raising or lowering the adjustab le weir or when and which aerators to manually switch off as stipulated in the engineering design. The new nitrate, FSA, and TSS sensors in the last aerobic cell will greatly