Production and Effect of Soluble Microbial Product£¨SMP£©in Effluent of Wastewater Treatment Plant

Nearly half of the organic matters in secondary effluent from biological wastewater treatment come from autochthonous soluble microbial product (SMP), which consists of utilization associated product (UAP) from exogenous substrate metabolism, biomass associated product (BAP) from extracellular polymer substances (EPS) hydrolysis and cell lysates. Due to the similar structure to natural organic matter (NOM) and its complicated composition, SMP is difficult to be quantitatively expressed and so its content could only be roughly predicted by some mathematical models. SMP has a potential biotoxicity, which might cause microbial mutation and becomes the precursors of disinfection by-products (DBPs) due to photodegradation and microbial subsequent metabolism for longª²term retention in receiving waters. Therefore, monitoring SMP has led to many academic studies. Among them, controlling the optimum sludge retention time (SRT) and organic load rate (OLR) are the most effective methods, and municipal wastewater with low carbon source along could reduce SMP to a large extent in denitrifying phosphorus removal processes. From the viewpoint of controlling oxygen consumption of black and smelly water, it is not necessary to blindly reduce effluent COD, but only to strictly control BOD₅ and NH₄⁺. Activated carbon adsorption plus filtration can effectively remove SMP when the safety of reclaimed water reuse is considered.