Formation of soluble microbial products (SMP) in an anaerobic sludge system

A bench-scale experiment has been carried out to investigate the formation of soluble microbial products in an anaerobic baffled reactor (ABR) treating buffered synthetic glucose substrate (about 500mg COD/L) under mesophilic temperatures. Generally, SMP production increased with decreasing temperature. A higher SMP to soluble chemical oxygen demand (SCOD) ratio was found at high temperature because of complete volatile fatty acid degradation. SMP accounted for amount to 0.85 of the SCOD in the effluent of the ABR. The performance of each compartment under organic load shock was different. In general, the fluctuation of SMP concentration in acidogenesis zone was bigger than in methanogenic zone which probably due to more SMPs are produced during acidogenesis than during methanogenesis. The other reason probally was the microorganisms in the rear compartment extremely deficient in nutrients and the SMP was partially consumed as a secondary metabolite.