Effects of glucose and phenol on soluble microbial products (SMP) in sequencing batch reactor systems

Soluble microbial products (SMP) are ubiquitously present in the effluents of biological wastewater treatment systems. In sequencing batch reactor (SBR) systems, effects of influent concentration and temperature on the amount and the molecular weight (MW) distribution of SMP were investigated for the two substrates, glucose and phenol. The values of effluent SMP/S0 of phenol were higher than those of glucose at different influent concentrations and temperatures. It was found that the effluent SMP (Se) was linearly correlated to the influent total organic carbon (TOC) (S0) for both substrates. The slope and intercept of the equation were affected by the temperature. According to the analysis of the MW distribution, it was shown that there exists a bimodal pattern with the majority of SMP having a MW<1 kDa or >10 kDa. The low MW fraction (<1 kDa) amounts to 47.3–70.4% of the effluent SMP. The high MW fraction (>10 kDa) slightly fluctuates in the range of 21.2–32.8% of the effluent SMP.