Let's talk about the proliferation of activated sludge today! At first glance, the term "activated sludge" may seem unfamiliar and dirty, but it is a definite "star employee" in the sewage treatment industry, and its proliferation principle is like a brilliant microbial "survival game".
First, let's talk about what activated sludge is. Simply put, it is a group of microorganisms that form clumps and are then coated with organic and inorganic impurities, forming flocculent mud particles. Among these microorganisms, there are bacteria, fungi, protozoa, and metazoa, which are like a super complex "community" with each member having their own division of labor. Bacteria are the main force responsible for decomposing organic matter in wastewater; Fungi deal with some difficult "hard bones", such as complex carbohydrates and proteins; Protozoa and metazoa are like "cleaners" in the community, devouring excess bacteria and organic debris to keep the entire system clean and tidy.
Why does activated sludge need to proliferate? In fact, the principle is similar to that of human reproduction, which is to survive and strengthen the "team". The organic matter in sewage is a delicious "buffet" for the microorganisms in activated sludge. When microorganisms discover that there is sufficient food, they will "rub their fists" and start a big fight. Take bacteria as an example. Bacteria reproduce mainly through dichotomies. In short, one bacterium divides into two and becomes two identical bacteria. This process is like cells playing 'copy and paste', with astonishing speed. Under suitable environmental conditions and sufficient food, some bacteria can complete a division in about 20 minutes, and their numbers can grow exponentially in just a few hours.
Speaking of which, we need to mention the key factors that affect the proliferation of activated sludge. Firstly, it is the concentration of organic matter in food, which refers to the wastewater. This is like eating, having enough food, being in a good mood and state, naturally growing strong. Microorganisms are the same. A high concentration of BOD (biochemical oxygen demand, an indicator of organic matter content) in sewage means there is more food. After eating and drinking enough, microorganisms will focus on "having children", and the amount of activated sludge will also increase rapidly. But if there is not enough food, microorganisms can only "tighten their belts", slow down their proliferation rate, and even start to consume their stored energy in order to survive. At this time, activated sludge not only does not grow, but may also decrease.
In addition to food, oxygen is also an important factor in determining the proliferation of activated sludge. The microorganisms in activated sludge are mostly aerobic microorganisms, just like us who cannot do without air, they need oxygen to 'breathe'. In the aeration tank of sewage treatment, air is continuously introduced into the water to deliver oxygen to microorganisms. If there is insufficient oxygen supply, microorganisms will suffer from hypoxia and suffocation, slowing down their metabolic rate and severely affecting their proliferation. But more oxygen is not necessarily better. Excessive oxygen may damage the structure of activated sludge, causing previously clustered microorganisms to "disperse", which is also detrimental to the proliferation of activated sludge and the effectiveness of sewage treatment.
Temperature is also the "driving force" behind the proliferation of activated sludge. Different microorganisms have their own preferred temperature range, just like some people prefer warmth like spring, while others prefer coolness and comfort. For microorganisms in activated sludge, the most suitable temperature is generally between 15-35 ℃. Within this temperature range, various enzymes in microorganisms have the highest activity, fast metabolic rate, and the most active proliferation. If the temperature is too low, the enzyme activity inside the microbial body is inhibited, just like being pressed a "slow key", metabolism and proliferation become slow; However, if the temperature is too high, it may damage the protein and enzyme structures inside microbial cells, leading to microbial death and the proliferation of activated sludge.
The pH value cannot be ignored either. Activated sludge microorganisms prefer to live in neutral or weakly alkaline environments, with a generally suitable pH value between 6.5-8.5. If the pH value is too low and the acidity is too strong, the membrane structure of microbial cells may be damaged, affecting the absorption of nutrients; A high pH value and strong alkalinity can also affect the activity of enzymes in microorganisms, causing them to 'strike'. This is like living in extreme weather conditions, which are definitely uncomfortable, let alone working hard and reproducing offspring.
The process of activated sludge proliferation is actually a dynamic equilibrium process. The staff of sewage treatment plants are like "commanders", constantly paying attention to various factors such as sewage quality, dissolved oxygen, temperature, pH value, etc. By adjusting the aeration time, aeration amount, inflow rate, etc., they create the most suitable living environment for activated sludge microorganisms. In the early stage of operation of the activated sludge system, microorganisms have just entered a new environment and will have a period of adaptation. At this time, they grow slowly and are busy familiarizing themselves with their "new home"; When the adaptation is almost complete, it enters the logarithmic growth period, during which there is sufficient food and suitable environment, microorganisms proliferate wildly, and the amount of activated sludge rapidly increases; As the number of microorganisms increases and food gradually decreases, competition becomes fierce, and a stable period is entered. At this time, the growth and consumption of activated sludge basically reach a balance; If the environment deteriorates further and there is a severe shortage of food, microorganisms will enter a period of decline and their numbers will begin to decrease.
Understanding the principle of activated sludge proliferation is crucial for wastewater treatment. Only by mastering these knowledge can sewage treatment plants better regulate operating parameters, maintain the "combat effectiveness" of activated sludge, efficiently decompose organic matter in sewage, clean dirty water, and protect our water environment. Next time you pass by a sewage treatment plant, don't underestimate those dark activated sludge. They are the "unsung heroes" who silently protect the environment, and there are hidden questions about the proliferation principle behind them!
