| مستخلص: |
Alginate like extracellular polymers (ALE) recovered from excess sludge have been evaluated as an eco-friendly, cost effective and sustainable alternative to highly valued materials. However, the ALE extraction from flocculent sludge ranges normally from 90 to190 mg/g VSS, which is only equivalent to the lowest edge of the ALE production from aerobic granular sludge (AGS). As flocculent sludge is much higher in production than AGS, it is worth investigating the key factors controlling the ALE formation in flocculent sludge for potential applications. For this reason, some influent characteristics & operational parameters and the associated mechanisms were experimentally investigated with flocculent sludge in lab-scale sequencing batch bioreactors (SBRs). The results indicate that flocculent sludge with starch being a substrate contained the highest ALE production (220.3±8.0 mg/g VSS). Low temperature was more favorable to enriching ALE, up to 303.3±21.5 mg/g VSS at 12 oC. Moreover, ALE reached up to 137.8±13.2 mg/g VSS at C:N=5:1 and slightly declined with increased or decreased C/N. The specific ALE yield was 63.7 mg ALE/(g BOD5) at a low organic load, which was twice as high as those with high organic loadings. However, SRT had a minor effect on the ALE formation. Although a band of the factors controlling the ALE formation in flocculent sludge needs to be further studied, different parameters would exert significant influence on the composition and chemical properties of ALE, which also implies that the parameters could be controlled to directionally cultivate ALE with the unique structures. In a word, adjusting or optimizing the influent characteristics and operational parameters could improve the formation, production and characteristics of ALE for wide applications |
