Biological treatment of waste

One aspect of the basic equation describing biological treatment of waste that has not been referred to previously is that biomass appears on both sides of the equation. As was indicated above, the only reason that microorganisms function in waste-treatment systems is because it enables them to reproduce. Thus, the quantity of biomass in a waste-treatment system is higher after the treatment process than before it. 

In water, neither volatilization nor sorption to sediments and suspended particulates is expected to be an important transport mechanism. Using the Henry s Law constant, a half-life of 88 days was calculated for evaporation from a model river 1 m deep with a current of 1 m/second, and with a wind velocity of 3 m/second (Lyman et al. 1982). The biological treatment of waste water containing phenol has shown that less than 1% of phenol is removed by stripping (Kincannon et al. 1983 Petrasek et al. 1983). 

Measurement of toxicity (biological analyses) The development of toxicity during chemical/biological treatment of waste waters was seldom assessed. Only in the last few years has the application of toxicity testing been reported more frequently (e. g. Diehl et al., 1995 Moerman et al., 1994 Jochimsen, 1997 Sosath, 1999). Moerman etal. (1994) showed that a toxicity balance around the whole process is important for combined chemical/biological treatment. It is not sufficient to assess the effect of ozonation alone (cf. chapter A 1). 

Biological treatment of wastes. If available. Is recognized as being less expensive and as producing a better-quality outflow than physico-chemical methods. 

For mixed culture microorganisms used for biological treatment of waste water, the general range of values used are BOD 1.43 X BOD5 Approximately 1.4-1.5 kg Oj/kg BOD5. 

Precisely the same fate can be seen in neighboring area, the biological treatment of waste water and solid wastes (Fig. 1.1). The pressure of environmental problems has grown so great that here too the methods of thinking that have been successfully used in conventional biotechnical processes are being applied. One can now speak of the biotechnology of waste water treatment. 

M. A Winkler, Biological Treatment of Waste-Water, Ellis Howard, Ltd., New York, 1981, Chap. 7. 

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