Organic waste disposal methods

Since the emergence of a civilized society, it has always faced the problem of environmental protection. As a result of industrial, agricultural and domestic human activities, there have been constant changes in the physical, chemical and biological properties of the environment, and many of these changes were very unfavorable here.

Waste products of animals and humans, as a rule, have always been used to increase soil fertility. This is not a problem if there are few of them. In the case of the creation of industrial livestock complexes, the area of ​​the surrounding land may be insufficient for the disposal of animal waste products. As a result, groundwater surrounding water bodies and wells can be polluted.

The waste products of some animals can not always be applied directly to the soil, because they are often carriers of pathogens and parasites, which humans can also get sick with. These animals include, first of all, pigs. Cases of avian influenza are reported at regular intervals. Therefore, the waste of these animals must first be disinfected.

The same applies to the wastewater of large cities, consisting mainly of human waste products, lipids and sugars, which get there from public catering enterprises and home kitchens. Wastewater from industrial plants also needs to be treated before it is reused or released into rivers and bodies of water.

Organic waste, consisting mainly of water, protein, fat, carbohydrates and minerals, can be broken down to its primary constituents under the influence of microorganisms. Moreover, the process of decomposition of organic waste can occur both in the presence of oxygen and in an oxygen-free environment.

If oxygen is present in the medium that undergoes decomposition, then organic matter decomposes under the action of aerobic microorganisms (bacteria and micromycetes). In this case, the process will be called composting.

Other natural processes of aerobic breakdown are, for example, digestion, fermentation. If the process of decomposition of biomass occurs without oxygen, it is called anaerobic. Anaerobic bacteria take part in this process, and as a result of their effect on organic matter, a high-quality organic fertilizer and a mixture of gases (mainly methane (60-80%) and carbon dioxide (20-40%)), as well as a small amount of hydrogen sulfide ( up to 3%), hydrogen, ammonia, nitrogen oxides, etc.). This gas mixture is called biogas. The anaerobic process of decomposition of organic biomass is also called decay – it can be observed in swamps, lakes, bogs, etc. It is in this way that natural gas is formed over a very long period of time, which differs from biogas in its high methane content (90-95%).

It should be noted that the energy released by the anaerobic process is not lost like heat from composting. Due to the vital activity of methanogenic bacteria, it turns into methane molecules, the energy value of which is 50 MJ / kg.

The processes of decay have been known for a very long time, they already took place even when our atmosphere had a completely different composition. Methanogenic bacteria are among the oldest and most adapted living things on planet Earth.

Rotting processes are widespread: in the mud of seas, rivers and lakes, they occur in the same way as in bogs, swamps, soil layers where oxygen does not penetrate, in garbage dumps, in heaps of manure, in the stomach of ruminant cloven-hoofed animals (they produce about 200 liters of methane per day).

In water, the formation of methane is noticeable by gas bubbles that rise to the surface. Depending on the place of origin, we can talk about swamp, rotten, landfill, sewage gas, wastewater gas, or, as it is commonly called in agriculture, biogas.

In general, biogas can be obtained from any organic matter in the absence of oxygen. The bacteria only need to have enough time to deal with material that is difficult to break down (for example, lignified plants). This process is purposefully used in wastewater treatment in order to decompose compounds of harmful substances. However, some substrates have proven to be the most suitable for such a process. Fluid, mushy, and generally substrates that retain a significant amount of water are best suited for the methane digestion process, since they can easily withstand anaerobic conditions, while material from large, whole pieces is better decomposed by composting or otherwise.

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