Anaerobic process

The inability to produce high-quality effluents is one significant disadvantage. Another disadvantage is that anaerobic processes must be maintained at temperatures between 35 and 40°C to get the best performance. If low-temperature waste heat is available from the production process, then this is not a problem. 

In all types of biological processes, excess sludge is produced which must be disposed of. The treatment and disposal of sludge are major problems which can be costly to deal with. Anaerobic processes have the advantage here, since they produce considerably less sludge than aerobic processes (on the order of 5 percent of aerobic processes for the same throughput). 

In Situ Bioremediation. In situ bioremediation can be an aerobic or anaerobic process, or a combination of the two. In designing an in situ bioremediation system, one should consider the types of microorganisms available (naturally in place or added), the stmctural and chemical makeup of the soil matrix, types of contaminants, oxygen and nutrient addition and distribution, and temperature. These factors are discussed prior to introducing the individual techniques for in situ bioremediation. 

ADI Process. The ADI is a low rate anaerobic process which is operated ia a reactor resembling a covered football field. Because of the low rate, it is less susceptible to upset compared to the high rate processes. Its disadvantage is the large land area requirement. 

With the exception of the ADI process, anaerobic processes usually operate at a temperature of 35°C. In order to maintain this temperature, the methane gas generated ia the process is used to heat the reactor. Anaerobic processes are shown ia Figure 18. Anaerobic treatment performance data are shown ia Table 14. 

There are two methods of biological treatment aerobic and anaerobic (217). The aerobic systems use free oxygen dissolved in the wastewater to convert wastes in the presence of microorganisms to more microorganisms, energy required for their existence, and carbon dioxide. The anaerobic process occurs in the absence of free oxygen and converts the waste to methane and carbon dioxide, generally in deep tanks or basins, and can produce odor problems when sulfides or sulfates are present in the wastewater. 

TABLE 25-44 Anaerobic Process Performance on Industrial Wastewater UASB/ Submerged filter (SF)/ FBR... 

Another emerging area m biofuels is pyrolysis, which is the decomposition of biomass into other more usable fuels using a high-temperature anaerobic process. Pyrolysis converts biomass into charcoal and a liquid called biocrude. This liquid has a high energy density and is cheaper to transport and store than the unconverted biomass. Biocrude can be burned in boilers or used in a gas turbine. Biocrude also can be chemical by altered into other fuels or chemicals. Use of pyrolysis may make bioenergy more feasible in regions not near biomass sources. Biocrude is about two to four times more expensive than petroleum crude. 

A bioreactor is a vessel in which an organism is cultivated and grown in a controlled manner to form the by-product. In some cases specialised organisms are cultivated to produce very specific products such as antibiotics. The laboratory scale of a bioreactor is in the range 2-100 litres, but in commercial processes or in large-scale operation this may be up to 100 m3.4,5 Initially the term fermenter was used to describe these vessels, but in strict teims fermentation is an anaerobic process whereas the major proportion of fermenter uses aerobic conditions. The term bioreactor has been introduced to describe fermentation vessels for growing the microorganisms under aerobic or anaerobic conditions. 

Chlorhexidine has been shown to inhibit the membrane ATPase and could thus inhibit anaerobic processes. 

Presence of other organic contaminants may inhibit biodegradation Degradation pathways for anaerobic processes not as well understood as aerobic pathways anaerobic processes typically slower... 

Anaerobic processes that produce methane from waste solve 2 problems at once waste and energy. Anaerobic processes provide some of the simplest and most practical methods for minimizing public health hazards from human and animal wastes. Pathogens such as schistosome eggs, hookworm, flat/tape worm, dysentery Bacillus, poliovirus, Salmonella, and... 

The emission of N20 from manure occurs directly by both nitrification and denitrification of nitrogen contained in the manure. This emission mainly depends on the N and C content of the manure during various types storage and treatment. The nitrification process strictly needs oxygen, while subsequent denitrification is an anaerobic process. 

The aim of this review is to present a comprehensive evaluation of the presence of three classes of emerging contaminants in sludge alkylphenols, hormones, and pharmaceuticals. In particular, the fate of these compounds during sewage and sludge treatment by aerobic and anaerobic processes is addressed. 

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