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Activated sludge tank at Beckton sewage treatment plant, UK.The white bubbles are due to the diffused air aeration system. The activated sludge process is a type of biological wastewater treatment process for treating sewage or industrial wastewaters using aeration and a biological floc composed of bacteria and protozoa.
Sludge Volume Index (SVI) is a process control parameter used to describe the settling characteristics of sludge in the aeration tank of an activated sludge process. [1] It was introduced by Mohlman in 1934 and has become one of the standard measures of the physical characteristics of activated sludge processes.
Enhanced biological phosphorus removal (EBPR) is a sewage treatment configuration applied to activated sludge systems for the removal of phosphate. [1]The common element in EBPR implementations is the presence of an anaerobic tank (nitrate and oxygen are absent) prior to the aeration tank.
The sludge age may be too low to enable nitrification. The typical control band for the concentration of MLSS is 2 to 4 g/L for conventional activated sludge, or up to 15 g/L for membrane bioreactors. One of the easiest control procedures for activated sludge systems is the Constant Mixed Liquor Suspended Solids method.
In facultative ponds, sludge removal may be necessary only in intervals around 15 to 25 years. In maturation ponds, sludge accumulation is very low. [6] Sludge removal, also called desludging, may be done in two basic ways: (i) interrupting the operation of the pond for desludging or (ii) keeping the pond in operation while desludging. [6]
The quantity or “age” of sludge within the tank is closely monitored, as this can have a marked effect on the treatment process. The sludge is allowed to settle until clear water is on the top 20 to 30 percent of the tank contents. The decanting stage most commonly involves the slow lowering of a scoop or “trough” into the basin.
In most conventional activated sludge processes or aerobic granular reactor, the microorganisms grow in flocs. Flocs are defined as a mass of microorganisms that are held together by slime or fungal filaments, which help with aerobic decomposition and trapping particles (et al. Wilen). [3] Activated sludges are built with two physical separate ...
Sewage sludge treatment is the process of removing contaminants from wastewater.Sewage sludge is produced from the treatment of wastewater in sewage treatment plants and consists of two basic forms — raw primary sludge and secondary sludge, also known as activated sludge in the case of the activated sludge process.