Aerobic treatments processes

Table 11.2 provides a summary of the main features of aerobic and anaerobic wastewater treatment. Aerobic treatment processes are generally restricted to BOD < 1000 mg/liter unless pure oxygen is used for aeration. 

Combined Anaerobic-Aerobic Treatment Processes 4.1 Mechanism of Decolorization... 

Aerobic Treatment Process. Effluent from edible oil refineries has been shown to be amenable to biological treatment, both anaerobic and aerobic processes (74,75). The application of activated sludge process or aerated lagoon in this context is well established in the edible oil industry (71, 73, 76). Figure 14 shows the process flow of a typical activated sludge process. 

Aerobic treatment process works by introducing organic waste into a reactor where an aerobic bacterial culture is maintained in suspension. Here the bacteria carry out the conversion of organic compounds in accordance with the following equations. 

In comparison with aerobic treatment processes, in anaerobic digestion biodegradation occurs in the presence of oxygen the advantages and disadvantages of anaerobic digestion are summarised in Table 19.2. As indicated in this table, anaerobic treatment can play an important role in cost-effective waste management and environmental protection. 

Remediation of TNT-contaminated soil by humification of di- and trinitrotoluenes through an anaerobic-aerobic treatment process will require careful analysis of the treated... 

Another advantage of the MFC process versus an aerobic treatment process, such as AS, is a reduced production of solids from the bioreactor. The subject of cell yields from MFCs is addressed in Chapter 7. As noted there, estimated cell yields from an MFC process with acetate are thought to be on the order of Yxjs = 0.16g-COD-cell/g-COD. This... 

Aerobic treatment is generally appHed to lower strength wastewaters, whereas anaerobic treatment is employed as a pretreatment for high strength wastewaters. The choice of process depends both on the concentration of organics and the volume of wastewater to be treated. 

The four most common aerobic biological treatment processes are stabilization ponds, aerated lagoons, trickling filters, and activated sludge (see... 

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 ... 

In a typical plant operation the pollutants dissolved in the wastewater or that would not settle in the primary clarifiers flow on in the wastewater to the Secondary treatment process. Secondary treatment further reduces organic matter (BOD,) through the addition of oxygen to the wastewater which provides an aerobic environment for microorganisms to biologically break down this remaining organic matter. 

Aerobic Treatment. The activated sludge process depends on aerobic biological action. In this case the microorganisms, in searching for food, break down the complex organic substances into simple stable substances. This process results in the removal of soluble and suspended organic matter from wastewater. 

The well-known aerobic downflow process is a trickled bed filter. Attached growth is used in the biological treatment of wastewater. Air passes through the bed while the liquid is forced to down by gravity. Figure 13.2 shows the liquid gas system for the mass transfer... 

Composting. This is an aerobic, thermophilic treatment process in which contaminated material is mixed with a bulking agent it can be carried out using static piles or aerated piles. 

Some kraft mills use basins without mechanical aerators. Known as stabilization basins, this is the simplest form of aerobic treatment. This process uses shallow basins that cover very large areas and relies on natural diffusion of air into the wastewater and algae to create aerobic conditions. At depths greater than 1.2 m (4 ft), anaerobic microorganisms will become active in lower depths thus, stabilization basins are shallow. Typically, the basin is earthen although some are lined with compacted clay. Wastewater retention time may last up to 30 d to achieve up to 90% BOD5 removal. 

Annachhatre, A.P. and Bhamidimarri, S.M.R., Aerobic treatment of meat industry wastewater COD removal and nitrification, process industries power the Pacific rim Sixth conference of the Asia Pacific confederation of chemical engineering Twenty first Australasian chemical engineering conference Official proceedings of combined conference 1993 137-142, 1993. 

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