The self-purification capacity of water bodies is beyond reproach. The self-purification capacity of water mainly includes oxidation-reduction, dilution and diffusion, sedimentation and accumulation, as well as the decomposition ability of organic matter by microorganisms in water, etc. In this chapter, let’s explore the process of water self-purification together with Modi-Tech. It can mainly be divided into four stages:

1.Contaminated section. It is because a large amount of pollutants enter the water body, but the self-purification capacity of the water body itself is limited, which leads to the deterioration of the water quality. The dissolved oxygen in the water is getting less and less, and apart from bacteria, there are very few other organisms. Autotrophic organisms almost do not exist.

2.Decomposition stage. At this stage, organisms that decompose organic matter will gradually multiply, and the biological decomposition activities will be very intense. This will consume a large amount of dissolved oxygen, making it difficult for fish to survive. Instead, more algae and some protists with low oxygen demand will appear. After the BOD (Domestic Oxygen Demand) gradually decreases, the dissolved oxygen in the water will gradually increase.

3.Recovery stage. At this time, algae, fish and other large organisms will become active, and the water quality will gradually change.

4.When the water body returns to normal and the dissolved oxygen approaches saturation, the water quality becomes crystal clear, and the self-purification process is considered complete.

Another thing to remind everyone is that we all know that water bodies have their own self-purification ability. So, do we think it’s okay to constantly discharge a large amount of wastewater, sewage pollution or garbage into rivers, seas, streams and other water bodies? Because water bodies themselves will always be self-purified. This idea is clearly incorrect. Although water bodies themselves have the ability to self-purify, this ability is also limited. Just like us humans, there are certain limits to our physical abilities in all aspects. If we exceed this range, we will feel unwell and even fall ill. In fact, the self-purification capacity of water bodies is the same. If it exceeds its capacity range, it will cause pollution and harm to the water body. So, all major enterprises still need to carry out water quality testing work. For example: online monitoring of drinking water, process water, medical wastewater, agricultural sewage, industrial wastewater, etc. This way, the safety of the water quality is further guaranteed!