2 Domestic Emuents
2.1 Biodegradable Organic Substances
Man, like all animals, consumes organic foodstuff and leaves undigested organic
remains behind in his feces. In the preparation of his food organic substances are also
left over as garbage, whether in the commercial processing of foodstuffs or as household waste. In natural environments, decomposers exist: organisms which specialize
in the breaking-down of a dead organic substance. More precisely, they are organisms
which satisfy their energy needs from a dead organic substance. For the most part,
they are bacteria and micro-fungi.
Under ideal conditions, the cycle of carbon and oxygen is balanced in nature (Fig. 1).
When effluents from a city are introduced into a body of water, this means an additional supply of dead organic substances, and the question is whether or not it can be
absorbed by nature. The number of bacteria in bodies of water can respond to the
amount of available organic substance (to their food). However, bacteria consume
oxygen in their respiration process. To serve as a rule of thumb, the Population-Equivalent Unit has been created; one unit represents the amount of oxygen that is consumed to break down during a 5-days' experiment the readily degradable fraction of
the feces and garbage produced by I person per day. This figure is called Biochemical
Oxygen Demand (BODs), and it differs according to life styles: in the Federal Republic of Germany a couple of years ago it was 54 g, and now it is 60 g of oxygen per
day; in the U.S.A. it is 75 g of oxygen per day. Such a quantity of oxygen is contained in 6-10 m 3 of seawater saturated with oxygen (Table 3).
I ~
algae
... used by
domestic effluents
contain;
6
oxygen
nutritional elements
Nand P
Fig. I. Greatly simplified
schematic of the circulation
of oxygen and of nutrients.
The role of animals in the
circula tion of substance has
been omitted. Attention is
focused on the contribution
of dead organic material
and nutrients which domestic
effluents may support
2.1 Biodegradable Organic Substances
Man, like all animals, consumes organic foodstuff and leaves undigested organic
remains behind in his feces. In the preparation of his food organic substances are also
left over as garbage, whether in the commercial processing of foodstuffs or as household waste. In natural environments, decomposers exist: organisms which specialize
in the breaking-down of a dead organic substance. More precisely, they are organisms
which satisfy their energy needs from a dead organic substance. For the most part,
they are bacteria and micro-fungi.
Under ideal conditions, the cycle of carbon and oxygen is balanced in nature (Fig. 1).
When effluents from a city are introduced into a body of water, this means an additional supply of dead organic substances, and the question is whether or not it can be
absorbed by nature. The number of bacteria in bodies of water can respond to the
amount of available organic substance (to their food). However, bacteria consume
oxygen in their respiration process. To serve as a rule of thumb, the Population-Equivalent Unit has been created; one unit represents the amount of oxygen that is consumed to break down during a 5-days' experiment the readily degradable fraction of
the feces and garbage produced by I person per day. This figure is called Biochemical
Oxygen Demand (BODs), and it differs according to life styles: in the Federal Republic of Germany a couple of years ago it was 54 g, and now it is 60 g of oxygen per
day; in the U.S.A. it is 75 g of oxygen per day. Such a quantity of oxygen is contained in 6-10 m 3 of seawater saturated with oxygen (Table 3).
I ~
algae
... used by
domestic effluents
contain;
6
oxygen
nutritional elements
Nand P
Fig. I. Greatly simplified
schematic of the circulation
of oxygen and of nutrients.
The role of animals in the
circula tion of substance has
been omitted. Attention is
focused on the contribution
of dead organic material
and nutrients which domestic
effluents may support