Activated sludge plant

Under optimum conditions of anaerobic and aerobic treatment in activated sludge plants, up to 90% removal of phosphorus can be achieved. Biological removal can, at best, achieve efffnent concentrations of about 0.2 mg total phosphorus but more usually reduces phosphorus to about ImgUh... 

Aluminum based chemicals have been used for many years in wastewater treatment applications for suspended solids removal. These include dry and liquid alum, with sodium aluminate used in activated sludge plants for phosphorus removal. 

One way of implementing the UV disinfection process at existing activated sludge plants involves suspending the UV lights (in the form of low-pressure mercury arc UV lamps with associated reflectors) above the secondary clarifiers. The effluent is exposed to the UV radiation as it rises over the wire in a thin film. 

Diffused Air Aeration A diffused air activated sludge plant takes air, compresses it, and then discharges the air below the water surface of the aerator through some type of air diffusion device. 

In a specific activated sludge plant, the organic load is carried out at 0.8 kg BOD per kg MLSS-day 1 with an 80% BOD removal efficiency. Values for the above mathematical model are as follows. 

Flores X, Rodriguez-Roda I, Poch M, Jimenez L, Banares-Alcantara R (2007) Systematic procedure to handle critical decisions during the conceptual design of activated sludge plants. Ind Eng Chem Res 46(17) 5600-5613... 

Zagomaya and colleagues22 reported the complete biodegradation of 2300 mg/L of formaldehyde in wastewater treated in an activated sludge plant, whereas Gerike and Gode26 observed that 30mg/L... 

FIGURE 19.7 Schematic representation of a nitrification-denitrification activated sludge plant. 

FIGURE 21.11 Process flow diagram of upgrade activated sludge plant at apaper mill using a DAF cell. 

This new concept is applied for improving the operation of an existing overloaded activated sludge plant, or for the expansion of the hydraulic capacity to handle additional wastewater flow. 

Sludge bulking is another phenomenon that often occurs in activated sludge plants whereby the sludge occupies excessive volumes and will not settle rapidly. 

Maddock, J.E.L. and Tomlinson, E.J., The clarification of effluent from an activated sludge plant using dissolved air flotation, Water Pollution Control, 85 (1), 114-127, 1980. 

Schneeberg, E., Increase of Efficiency of an Activated Sludge Plant in Paper Manufacturing Industry by Application of a Fluidized Bed System, Wat. Sci. Tech., 29(12) 177 (1994)... 

Nielsen PH, Roslev P, Dueholm TE, Nielson JL (2002) Microthrix parvicella, a specialized lipid consumer in anaerobic-aerobic activated sludge plants. Wat Sci Technol 46 73-80... 

Nitrate and oxygen also may play an important role in determining the rate of azo dyes reduction. Wuhrmann et al. demonstrated that obligate aerobes might actually decolorize azo dye compounds under temporary anoxic conditions. However, high nitrite concentrations in the mixed liquor of activated sludge plants could significantly inhibit dye removal. 

LINPOR [Linde porous medium] A biological waste water treatment process, using an open-pore plastic foam for retaining the biomass. Its use enables the capacity of an activated sludge plant to be increased without adding extra tanks. Invented at the Technische Universitat, Munich, and further developed by Linde, Munich. See also CAPTOR. 

In a study of the removal of 16 FMs from wastewater, Simonich et al. [11] conducted their studies at 17 wastewater treatment plants with plant flows of 1.4x106-1.0x108 L day-1. Twelve of the plants were located in different states and regions of the U.S. and five plants were located in Europe. In addition, five of the 17 plants were activated sludge plants, two were carousel plants, two were oxidation ditch plants, five were trickling filter plants, one was a rotating bio-... 

Surfactants retain their foaming properties in natural waters in concentrations as low as 1 mg/L, and although such concentrations are nontoxic to humans [24], the presence of surfactants in drinking water is esthetically undesirable. More important, however, is the generation of large volumes of foam in activated sludge plants and below weirs and dams on rivers. 

There are a number of full-scale activated sludge plants that are in operation in countries such as the United States, Canada, and Finland, which treat effluents from Kraft, sulfite, TMP, CTMP, and newsprint mills [22]. SchneU et al. [70] reported the effectiveness of a conventional activated sludge process operating at an alkaline-peroxide mechanical pulping (APMP) plant at Malette Quebec, Canada. The full-scale plant achieved 74% reduction in filterable COD and nearly complete elimination of BOD5, resin acids, and fatty acids in the whole mill effluent. The treated effluent tested nontoxic as measured by a Microtox assay. Saunamaki [71] reported... 

Two common operational problems encountered during the treatment of pulp and paper wastewaters in activated sludge plants are ... 

Limiting concentrations of nitrogen and phosphorus (N and P) that are vital for maintenance of active microbial population in an activated sludge plant. 

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