Aerobic, Sewer Sludge

The Technical Research Center of Finland (VTT) has developed a headspace test that like the Sturm test, is also based on the measurement of carbon dioxide under aerobic conditions. The VTT test is performed in headspace bottles (volume 125 mb) containing 50 mb of a mineral nutrient medium and sewage 

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D 5209-91 Standard Test Method for Determining the Aerobic Biodegradation of Plastic Materials in the Presence of Municipal Sewer Sludge. 

The heterotrophic biomass in wastewater is typically not a limiting factor for the aerobic transformations in a sewer. The limitation is typically caused by the supply of the electron acceptor (oxygen), i.e., the reaeration. Contrary to what has been proposed by several authors, it would typically serve no useful purpose to inject biomass (sludge) in a sewer line to enhance the treatment processes unless a significant amount of oxygen is continuously supplied to the wastewater (cf. Example 5.1). 

FIGURE 5.4. The flow of substrate and biomass according to the activated sludge concept for aerobic, heterotrophic transformations. The three major pathways of the flow, biomass growth, hydrolysis and biomass decay, were included in the first attempt to describe the corresponding processes in the sewer. The components are defined in Section 3.2.6. 

The main part of the WWTP is usually the aerobic biological activated sludge process. Around this central facility a complex of preparatory and subsequent separation operations is grouped. The facility may be a dedicated plant on the site of the polymer installation, a central facility in the site containing the polymer installation, or an external urban WWTP connected by dedicated pipeline or a sewer with little risk of storm overflow prior to the WWTP. The central waste water plant is normally equipped with ... 

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