It can indicate the performance of sludge, such as purification ability, aging, sedimentation effect and concentration effect. For example, normal sludge rotifers and bell worms are evenly distributed, and the sludge is flocculent and yellowish brown, while aging sludge rotifers appear in large numbers, bell worms disappear, and the sludge is fine and grayish brown. In logarithmic growth period, microbial activity is high, but sedimentation performance is not good.
Microorganisms that play a major role in activated sludge;
Activated sludge is a yellowish brown flocculate formed by mixing microorganisms (mainly bacteria and micro-animals) with suspended solids and colloidal substances. Among them, microorganisms are mainly composed of bacteria, including bacteria micelle and filamentous bacteria, accounting for about 90.95% of the total number of microorganisms in sludge, and bacteria play the most important role in organic wastewater treatment.
Activated sludge:
Activated sludge is a general term for microbial communities and organic and inorganic substances attached to them. It was discovered by Clark and Gage in England in 19 12. Activated sludge can be divided into aerobic activated sludge and anaerobic granular activated sludge, which are mainly used to treat sewage and wastewater. Activated sludge process is an aerobic treatment method to treat organic wastewater by using suspended microbial flocs.
Working principle of activated sludge;
Complex microorganisms in activated sludge and organic nutrients in wastewater form a complex food chain. Heterobacteria and saprophytic fungi are the first to undertake the task of purification, and bacteria, especially spherical bacteria, play the most critical role. Activated sludge with excellent operation is a bacterial micelle composed of spherical bacteria with filamentous bacteria as the skeleton. With the normal operation of activated sludge, bacteria multiply and begin to grow protozoa, which are the primary predators of bacteria. Common protozoa in activated sludge are flagellates, meat caterpillars, ciliates and tube jellyfish. When activated sludge matures, fixed ciliates and species are dominant; Metazoa are secondary predators of bacteria, such as rotifers and nematodes, which only appear when dissolved oxygen is sufficient, so when metazoa appear, it shows that the water quality is improving. Its performance indicators include: mixed liquor suspended solids (MLSS), sludge sedimentation ratio (SV), sludge index [sludge volume index (SVI), sludge density index (SDI).