| Biological treatment is one of the most widely used wastewater treatment processes. Soluble microbial products (SMP) are produced by the microorganisms in wastewater treatment bioreactors when organic materials presented in wastewater are consumed. SMP constitute a major part of the residual chemical oxygen demand (COD) in effluent for most well-operated biological treatment system. Hence, the presence of SMP is a matter of great interest not only because they effectively control the removal efficiency for COD, but also in terms of achieving current discharge standards. In this paper, the formation rule and influencing factors of SMP were explored. Cheating characteristics of SMP were also studied in depth. The preliminary research on the adsorption characteristics of typical pharmaceuticals and personal care products (PPCPs) on activated sludge and EPS was developed as well. Main contents and results are as follows:1. RSM coupled with GRA were used to evaluate both the individual and interactive effects of substrate concentration, NH4+-N concentration, temperature and aeration rate on SMP production. Results show that a minimum SMP production of 7.5 mg/L was obtained under the optimum conditions: substrate concentration 654.8 mg COD/L, NH4+-N concentration 23.9 mg/L, temperature 13.7oC, aeration rate 0.1 m3/h. GRA analysis results show that the influential priority of the four factors on the SMP production is: temperature> substrate concentration> aeration rate> NH4+-N concentration. Carbonhydrates were found to be the major component of SMP in SBR system.2. The interactions between three metals and SMP of the effluent from wastewater biological treatment plant were investigated by fluorescence quenching combined with EEM fluorescence spectroscopy and SWATLD analysis. The main conclusions are as follows: Both protein- and humic-like substances in SMP were strong ligands for the three metals, with an order of Cu2+>Al3+>Fe3+. All the three metals had a better affinity to protein-like substance compared to humic-like substance in SMP; The complexation between metals and SMP could be significantly affected by solution pH values. SMP had relatively higher affinity to the metals at neutral condition than those at acidic or alkaline conditions. However, ionic strength influenced the complexation of SMP by a complicated mechanism. Different effects occurred at various ionic strength region.3. The adsorption characteristics of triclosan on activated sludge and EPS were studied mainly based on thermodynamics and dynamics. In addition, some preliminary explorations on biotoxiacity of TCS to the biological wastewater treatment were carried out. It was found out that the adsorption process of activated sludge floc tailed with Lagergren dynamical model and Freundlich adsorption model. The adsorption of TCS on EPS is physical adsorption attributed to the interaction between hydrophobic functional groups. The functional groups which interacted with TCS vary between LB and TB, and TB has a relatively higher affinity to TCS compared with LB. This interaction is slightly influenced by the pH of the solution. Biotoxiacity of TCS to microorganisms is not clear, however, the metabolism of the activated sludge is enhanced to a certain degree. At the same time, more SMP is produced reflecting a response to the outside pressure.
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