Aerobic treatment, wastewater

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. 

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. 

U.S. Environmental Protection Agency, Process Control Manualfor Aerobic Biological Wastewater Treatment Facilities, Office of Water Program Operations, Washington, D.C., EPA-430/9—77—006, 1977. 

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. 

Different kinds of bioreactors and configurations have been used to treat wastewater containing formaldehyde and urea, and three different kinds of treatments can be applied anaerobic treatment, aerobic treatment, and combined nitrification and denitrification treatments. 

Canto and colleagues52 operated an integrated anoxic-aerobic treatment of wastewaters from a synthetic resin producing factory (Figure 19.9). These authors managed to treat up to 2.01 kg/m3 d COD and up to 0.93 kg/m3 d TKN with removal efficiencies of 80 to 95% and 58 to 93% for COD and TKN, respectively. 

Rittstieg, K., Robra, K.H., and Somitsch, W., Aerobic treatment of a concentrated urea wastewater with simultaneous stripping of ammonia, Appl. Microbiol. Biotechnol., 56, 820-825, 2001. 

Canto, M., Gomez, J., Kennes, C., and Veiga, M.C., Integrated anoxic-aerobic treatment of wastewaters from a synthetic resin producing factory, European Conference on New Advances in Biological Nitrogen and Phosphorus Removal for Municipal or Industrial Wastewaters, Narbonne, France, October 12-14,1998. 

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. 

Aerobic treatment systems can be used for the food industry wastewater treatment as well. However, if the organic strength is very high, the use of aerobic systems may not be effective. A combination of anaerobic/aerobic treatment may be necessary. 

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. 

Zaoyan Y, Ke S, Guangliang S et al (1992) Anaerobic-aerobic treatment of a dye wastewater by combination of RBC with activated sludge. Water Sci Technol 26 2093-2096... 

Seshadri S, Bishop PL, Agha AM (1994) Anaerobic/aerobic treatment of selected azo dyes in wastewater. Waste Manage 14(2) 127-137... 

Combined Anaerobic-Aerobic Treatment of Azo Dye-Containing Wastewaters in... 

As stated earlier, the biodegradation of azo dyes requires an anaerobic and aerobic phase for the complete mineralization. The required condition can be implemented either by spatial separation of the two sludge using a sequential anaerobic-aerobic reactor system or in one reactor in the so-called integrated anaerobic-aerobic reactor system. In recent years, combined anaerobic-aerobic treatment technologies are extensively applied in the treatment of azo dye-containing wastewaters. Table 1 lists the systems based on combined anaerobic-aerobic treatment in separate reactors. Table 2 lists SBR based on temporal separation of the anaerobic and the aerobic phase. Table 3 lists the other systems, either hybrids with aerated zones or micro-aerobic systems based on the principle of limited oxygen diffuse in microbial biofilms [91]. 

Each type of technique can be applied in several modifications. Microbiological degradation processes offer the possibility to purify wastewater streams which contain a wide range of organic pollutants. In contrast, physical/chemical techniques are much more specific. The quality of the purified water regarding residual amounts of soluble organic pollutants, and colloidal and suspended particle pollutants, strongly depends on the type of treatment process and the applied treatment conditions. Very often a combination of different types of treatment techniques is necessary to satisfy the effluent quality required (for example a combination of anaerobic and aerobic treatment). 

Process Control Manual Aerobic Biological Wastewater Treatment... 

In many cases, anaerobic filter treatment was found to successfully treat pharmaceutical industry wastewater. This can be an excellent alternative for conventional aerobic treatment, which is energy intensive and requires the disposal of sludge. The anaerobic filter, on the other hand, can produce energy in the form of biogas and does not require... 

Fox, P. Venkatasubbiah, V. Coupled anaerobic/aerobic treatment of high-sulfate wastewater with sulfate reduction and biological sulfide oxidation. Water Sci. Technol. 1996, 34 (5/6), 359-366. 

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