Waste Secondary Clarifiers

The fluidized-bed bioreactor (FBBT) (26) increases the capacity of existing plants. Primary effluent is passed upward through the columnar reactor filled with sand or carbon with sufficient velocity to fluidize the bed. An attached biomass develops on the bed particles. Intimate contact between the biomass and waste is provided and improved removals are reported. Oxygen is provided by a deep U-tube reactor. No biomass recirculation is required and a secondary clarifier is not necessary. 

Trickling filter An attached culture,wastewater treatment system. A large tank generally filled with rock or rings (see Bio-Tower). Wastewater is sprayed over the top of the media, providing the opportunity for the formation of slimes or biomass to remove wastes from the wastewater, through revolving arms which have spray nozzles. Water is pumped from the bottom of a trickle filter to a secondary clarifier. 

Underflow rate of flow from the secondary clarifier Rate of flow of sludge wasting... 

Secondary waste water clarifieation Cationic PAM High High... 

Modak reported that com sugar waste (reducing sugars) fi om a starch manufacturing operation is useful for sulfur dye reduction [53]. In one reported case, textile wastewater sulfide concentration was reduced from 30 to 2 ppm, with associated reduction in aquatic toxicity. An increase in BOD resulted but was easily handled by the textile wastewater treatment system, whereas the sulfide waste was not amenable to waste treatment. The zone settling velocity in the secondary clarifiers improved as a result of the decrease in sulfide, thus increasing waste treatment efficiency. Odors were reduced. The com starch manufacturer saved 12,000 on waste treatment system expansion and 2400 in operating expenses, had the waste stream not been reused [53]. 

Fig. 9.2 Biological treatment process consisting of a bioreactor and secondary clarifier. (A) Activated sludge process with aeration basin, siudge recycle, and waste sludge lines (B) Trickling filter process consisting of biotower, solids contact tank, biotower effluent recycle and sludge recycle lines.

Flow rate of waste sludge from the existing secondary sedimentation clarifier, volume... 

The WRS includes two clarifiers, two thickeners, two filter presses, and auxiliary equipment. The ICB effluent is transferred to the WRS clarifiers, where a polymer will be injected to provide chemical coagulant for enhancing removal of suspended solids. The clarified effluent will be transferred to the BRS. The clarifier sludge will be pumped to the WRS thickeners, where a polymer may be added to enhance thickening. Thickener overflow is recycled to the clarifiers, and underflow is pumped to the dewatering filter presses. The Alter press separates the solids from the liquid stream. The liquid is recirculated to the clarifiers, and the filter cake, containing 20-25 percent dry weight sohds, is a secondary waste. 

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