activated sludge


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Related to activated sludge: Trickling filter, activated sludge method

ac·ti·vat·ed sludge meth·od

a method of sewage disposal in which sewage is treated with 15% bacterially active liquid sludge, which is produced by repeated vigorous aeration of fresh sewage to form floccules or sediment; when this flocculation process is complete, the resulting activated sludge contains large numbers of bacteria, together with yeasts, molds, and protozoa, which actively effect the oxidation of organic compounds; this mixture is piped to a sedimentation tank, the effluent from which is completely treated sewage.

activated sludge

any living material used in sewage treatment, consisting mainly of bacteria and protozoans, that breaks down organic matter in the sewage and increases by multiplication during the process. Part of the new sludge is used in the continuing treatment of the sewage.
References in periodicals archive ?
The activated sludge process used In the modernisation process is still the same basic one devised by Arden and Lockett, but the way in which it is controlled has been massively enhanced, resulting in a much better controlled and energy-efficient treatment of the sewage.
The higher dose in the tertiary treatment was most likely due to the small concentration of suspended solids and the low sorption, whereas in the case of APAC, the circulation of unreacted PAC in the return activated sludge and the additional sorption by biomass were ensured.
At its basic level, the activated sludge process (ASP) is composed of two interconnected tanks which are a bioreactor and a settler as shown in Figure 1.
At present, the aerobic activated sludge process is used to remove ammonium from leachate.
The sludge concentration (MLSS) was adjusted to 4000 mg/L (typical concentration in activated sludge tank of a municipal wastewater treatment plant) with prepared experimental water and a certain amount of mixed PAE standard solution.
Biological treatment of dairy wastewater using activated sludge. Science Asia, 39: 179-185.
Disintegration of excess activated sludge by hydrogen peroxide oxidation, Desalination, 246: 275-284.
For municipal wastewater characteristics of TN-TP values were minimum 28; maximum 38 mg/L minimum 3.0; maximum 5.5 mg/L TN- TP removal performances of SBR were 61%-61% 81%-95% and 83%- 97% without organic carbon source with acetic acid addition with waste activated sludge alkaline fermentation liquid addition respectively [28].
The aerated sludge mixture is supplied from the aeration tanks to the secondary sedimentation tanks designed to separate the activated sludge from the fluid being treated.
In this condition a link between rheological properties (relative viscosity) of activated sludge and its solid concentration (TSS%) by means of a mathematical model of [[eta].sub.r] = f (TSS%, [??]) type was proposed.
The presence of unfavorable conditions in the activated sludge system, such as toxic conditions (pH below 6.5 or above 9.0), insufficient dissolved oxygen (DO), nutrient deficiencies, or seasonal temperatures may contribute to the foaming.

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