Microbial growth curve and its significance in biological treatment of wastewater
Microbial growth curve and its significance in biological treatment of wastewater The growth law of microorganisms: The growth law of microorganisms is generally reflected by the growth curve. According to the growth rate of microorganisms, its growth can be divided into four growth stages. 1 , stagnation period If the activated sludge is inoculated into wastewater different from the original growth conditions ( change in nutrient type, sludge cultivation and acclimation stage ) , or if the sewage treatment plant is interrupted after running for some reason, a stagnation period may occur. In this case, the sludge needs to wait for a certain period of time to adapt to the new wastewater, or to return to normal from the aging state. Whether the stagnation period exists or the length of the stagnation period is related to the amount of activated sludge, the nature of the wastewater, and the growth conditions. 2 , logarithmic period When the concentration of organic matter in the wastewater is high and the culture conditions are appropriate, the activated sludge may be in the logarithmic growth phase. The sludge in the logarithmic growth period is poorly flocculated and dispersed. Microscopic examination can see more free bacteria. After the mixture is precipitated, the upper layer is turbid. It contains high concentration of organic matter, and it is difficult to precipitate strongly. When filtering, the filtration rate is very slow. 3 , stationary period When the concentration of organic matter in the sewage is low and the concentration of sludge is high, the sludge may be in a stationary phase, and the activated sludge in the stationary phase has good flocculation property. After the mixture is precipitated, the supernatant liquid is clear, and the filtration speed is fast when filtered by filter paper. . In the activated sludge structure with good treatment effect, the sludge is in a stationary phase. 4 , aging When the concentration of organic matter in the sewage is low and the nutrients are obviously insufficient, the aging period may occur. The sludge in the aging period is loose and the sedimentation performance is good. After the mixture is precipitated, the supernatant is clear, but there is fine mud. When filtering with filter paper, the filtration speed is fast. Note the synthetic yield coefficient and the observed yield factor. 5. Significance in biological treatment of wastewater: In the biological treatment of wastewater, microorganisms are a mixed group, and they also have certain growth patterns. When there are many organic substances , the bacteria with organic matter are dominant , and the number is the most; when there are many bacteria, the protozoa with bacteria as the food material appears ; then the metazoans that use bacteria and protozoa as foodstuffs appear. In the biological treatment process of sewage, if the conditions are appropriate, the growth process of activated sludge is similar to that of pure single-cell microorganisms. However, since activated sludge is a mixed group of various microorganisms, its growth is affected by various environmental factors such as the nature, concentration, water temperature, pH , and dissolved oxygen of the wastewater. Therefore, only one of the growth curves usually appears in the treated structure. Two stages. The sludge at different stages has a very different characteristic. For more information, please pay attention: Yingnuo Instrument (Shanghai) Co., Ltd. Website: http:// Safety Raincoat Reflective,High Visibility Raincoat,Safety Raingear,Class 3 Raincoat Ningbo Staneex Imp. & Exp. Co., Ltd. , https://www.staneex.com