ProMinent DULCOMETER PH-501 Assembly And Operating Instructions Manual page 513

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Mixed liquor is pumped from the post-anoxic tank to the membrane tanks (TNK-601 and TNK-
602). The membrane tanks serve as additional volume for aerobic biological treatment to
remove any excess MicroC (which would other cause BOD in the effluent) and house the
membrane filters used for solid-liquid separation. Treated effluent is drawn through the
membranes by vacuum pumps.
Since the solid-liquid separation process results in an accumulation of solids in the membrane
tank, the mixed liquor (containing both solids and filtrate) is continuously recycled to the first
aeration tank (TNK-501). This prevents excessive solids build-up in the membrane tank, and
maintains sufficient biomass in the anoxic and aeration tanks. The solids that accumulate in the
system consist of biomass that have grown from the influent organics and ammonia, as well as
non-biodegradable solids from the influent wastewater. In order to maintain an optimal
concentration of mixed liquor suspended solids (MLSS) (typically 10 g/L), a portion of the mixed
liquor is periodically wasted by pumping from the Aeration Tank (TNK-501) to the sludge holding
tank (TNK-901). Wasted sludge in the sludge holding tank is thickened by decanting
supernatant back to the screen tank. Thickened sludge accumulates in the sludge holding tanks
until it is eventually pumped out for disposal.
newterra O&M Manual 46
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