Study On ICP And ECP's Formation In Activated Sludge And Their Impact On The Performance Of Sludge

To environment engineers, activated sludge process is the most popular process in water treatment. In this process, sludge settling and mud-water separating is a committed step if we want to get a perfect result. To gain a good settleability, good activated sludge floc must be formed first of all. So far, there have been a lot of studies and results on the mechanism of the formation of floc, but none of these can summarize all case because of the complex component and structure of the activated sludge, it needs a further study to perfect them.Intracellular polymers (ICPs) are storages of carbon source and energy in bacteria, including glycogen, PHB, polyphosphate, sulfur globules, etc. Extracellular polymers (ECPs) are materials enclosed the cell membrane, including polysaccharides, protein, nucleic acids, lipoid, humus, fibre, etc. It's considered that these polymers don't have direct relation in biosynthesis, but from the type of medium, synthesis and degradation, they have relation. Especially in the aspect of the activated sludge's flocculability and settleability, ICPs'synthesis and degradation impacted ECPs'synthesis and degradation, forming a competition, accordingly impacted the flocculability and settleability of the activated sludge.This study on the biosynthesis and degradation of ICPs (glycogen and PHB) and ECPs (glycogen and protein) during the aeration was carried out to get a better insight in their influence on the activated sludge's performance. With glucose, acetate, glucose and acetate together as substrates respectively, five sequencing-batch-reactors (SBR) of different activated sludge's performance were utilized to investigate the biosynthesis and degradation of ICPs and ECPs. The two ICPs were observed with glucose and acetate as substrates respectively, indicating that about 15.2% of COD translated into glycogen with glucose as substrate, and 14.4% of COD translated into PHB with acetate as substrate. It was important for a good settlement performance that accumulated ICPs were degraded in time. Besides ICPs, overabundance of ECPs would cause deterioration of the settlement performance of the activated sludge. These was a competition growth between ICPs and ECPs as well as their great quantity gap...