Aerobic digestion

In attached growth film) methods, as with aerobic digestion, the microorganisms can be encouraged to grow attached to a support medium such as plastic packing or sand. In anaerobic digestion, the bed is usually fluidized rather than a fixed-bed... 

Sludge Stabilization. Organic sludges need to be stabilized before ultimate disposal except in the case of incineration. This is usually achieved by either aerobic or anaerobic digestion. In aerobic digestion, the degradable volatile soHds are Hquefted and oxidized to CO2 and H2O. In anaerobic digestion the soHds are Hquefted and fermented to CH and CO2. 

Fig. 3. Process components for the activated-sludge process, with aerobic digestion at plants <473.1 m /h and two-stage anaerobic digestion at plants...

Addition of a thickener-clarifier before aerobic digestion greatly reduces this difference. 

Table 3. Comparison of Filters on Aerobically Digested Sludges ...

Stabilization (Anaerobic Digestion, Aerobic Digestion, High Lime... 

A new concept is to use an on/oFf air supply cycle. During aeration, nitrates are produced. When the air is shut off, nitrates are reduced to nitrogen gas. This prevents acid buildup and removes nitrogen from the sludge. High power cost for aerobic digestion restricts the applica-bihty of this process. 

The primary advantage of aerobic digestion is that it produces a biologically stable end product suitable for subsequent treatment in a variety of processes. Volatile solids reductions similar to anaerobic digestion are possible. Some parameters affecting the aerobic digestion process are ... 

Aerobically digested sludge usually has good dewatering characteristics. When applied to sand drying beds, it drains well and redries quickly if rained upon. 

Air Requirement 15 - 20 cfnt per 1,000 cubic feet of digester capacity is adequate. The air supplied must keep the solids in suspension this requirement may exceed the sludge oxidation requirement A dissolved oxygen concentration of 1 to 2 ppm should be maintained in the aerobic digestion tanks. 

Aerobic microbes Microbes used in a biofiltration process in which gaseous pollutants are removed from a process gas stream by aerobic digestion. 

Aerobic digested sludge 0.02-0.4 0.11 1 Activated sludge + nitrification/ denitrification Australia [9]... 

A measure of the total organic material present in slurries can be obtained by determining chemical oxygen demand (COD) or biological oxygen demand (BOD) (3) and the latter measure is used by Water Authorities in relation to the pollution of water courses where oxygen tension in the water is a prime concern. In studies to evaluate aerobic digestion as a means of odour reduction, the dissolved volatile fatty acids are a useful measure of the potential odour nuisance (2). 

Aerob digesting period Daily produced amount of gas Utilizable gas amount per day... 

Fig. 12.17 Breakthrough curves for a conservative tracer (Ck) and lime-stabilized biosolid (LSB), aerobically digested biosolid (ADB), and poultry-manure biosolid (PMB) colloids eluted from intact (a) Maurry, (b) Woolper, and (c) Bruno soil monoliths (C, effluent concentration, C, influent concentration, (after Karathanasis et al. 2005)...

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