I have a hard time with this finding the concept for the below: plz help

How and in what way does the input of organic matter, such as sewage, effect the O2 content of a river or stream? A pond or lake?

Does the organic matter get digested by bacteria, microbes et al? Do they multiply rapidly? Do they use oxygen?

As an alternative thought, how does aerobic digestion work in a sewage plant?

As a side point, another outcome of the digestion process is large amounts of carbon dioxide produced, in rivers and ponds, this then results in massive algae formations, which causes environmental problems of its own.

The input of organic matter, such as sewage, can have a significant impact on the oxygen content of a river, stream, pond, or lake. Here's how it generally works:

When organic matter enters the water, it serves as a food source for bacteria, microbes, and other decomposers. They break down the organic matter through a process called decomposition. During decomposition, bacteria and other microbes consume the organic matter and release enzymes to break it down further. This breakdown process requires oxygen and is known as aerobic digestion.

As the decomposers feed on organic matter, they multiply rapidly to take advantage of the available food source. This increase in microbial population can deplete the dissolved oxygen in the water, especially in cases where the influx of organic matter is substantial.

Since the decomposers use oxygen during their digestion process, they can consume significant amounts of dissolved oxygen from the water. This can lead to a decrease in the oxygen content, which can negatively impact aquatic organisms like fish and other wildlife that rely on oxygen to survive.

To address the side point about aerobic digestion in a sewage plant, it is a process specifically designed to treat sewage and minimize the environmental impact. In aerobic digestion, sewage is mixed and aerated with oxygen. This promotes the growth of aerobic bacteria, which digest organic matter more efficiently and produce less sludge compared to anaerobic digestion. The increased oxygen availability in the treatment process helps support the growth of beneficial bacteria that break down organic matter more effectively.

Regarding the formation of massive algae growth as a result of the digestion process, this is commonly known as an algal bloom. When excessive nutrients, such as carbon dioxide, are present in the water, it can fuel the rapid growth of algae. The excess organic matter from sewage can contribute to elevated levels of nutrients like nitrogen and phosphorus, encouraging algal blooms.

These algal blooms can have detrimental effects on the ecosystem. As algae multiply, they can block sunlight from reaching submerged aquatic plants, depriving them of photosynthesis and leading to their demise. Additionally, when the algae eventually die and decompose, it further depletes oxygen from the water, leading to the creation of low-oxygen or even completely oxygen-deprived areas, which can harm fish and other organisms.

In summary, the input of organic matter, such as sewage, affects the oxygen content of water bodies by fueling decomposition by bacteria and microbes, which consume oxygen in the process. This can lead to reduced oxygen levels, negatively impacting aquatic life. Moreover, excessive organic matter and resulting nutrient imbalances can contribute to algal blooms, causing additional environmental problems.