Particulate Organic Carbon Solubilization in an Acid-Phase Upflow Anaerobic Sludge Blanket System

Abstract

The effects of operational and environmental parameters on particulate organic carbon solubilization during the acid-phase digestion of primary municipal sludge were studied using a bench-scale, upflow anaerobic sludge blanket (UASB), continuous-flow reactor. Short-chain volatile fatty acids (VFAs), the main products of the process, are preferred substrates for the bacteria involved in the biological removal of phosphorus. Both particulate organic matter solubilization [measured by filtered total organic carbon (TOC) increase or volatile suspended solids (VSS) reduction] and product formation (mainly VFAs) were affected by the changes in hydraulic retention time (HRT) from 6 to 15 h. Variation in solids retention time (SRT) from 5 to 20 days (at a constant HRT of 12 h) had a small effect on specific TOC solubilization rate and percent VSS reduction. In contrast, VFA production decreased sharply at the shortest SRT investigated. At an HRT of 12 h and a SRT of 20 days, a decrease in pH from 5.1 to 4.5 did not significantly influence system behavior. However, an increase in pH from 5.1 to 6.1 produced a higher specific TOC solubilization rate and a lower net VFA production. The settling properties of the UASB sludge blanket were excellent. Gas generation from the system was small. The amount of VFAs generated, in most runs, was large enough to support subsequent biological phosphorus removal processes.

Enzymatic hydrolysis of polysaccharide‐rich particulate organic waste

“…Dissociated acetate dominates at pH > 6. Therefore, 10 The effect of pH on the carbohydrate hydrolysis herein was generally consistent with that noted by others (Boon, as reviewed by Sanders et al, 2003;Elefsiniotis et al, 1996;: a low pH did not favor the hydrolysis of carbohydrate. However, 20 g/L of acetate inhibited carbohydrate hydrolysis by 30%, which value did not agree with those obtained by or Babel et al (2004) without inhibition.…”

“…Boon determined that the optimal pH in the hydrolysis of primary sludge was 6.5 (as reviewed by Sanders et al, 2003). Elefsiniotis et al (1996) determined that reducing the pH from 5.1 to 4.5 did not influence the hydrolysis or rate of acidogenesis of primary sludge, while an increase in pH from 5.1 to 6.1 increased the rate of hydrolysis but reduced the rate of acidogenesis. were the first to evaluate separately the roles of pH, total VFA and undissociated VFA in the hydrolysis of biowaste.…”

Kinetics of enzymatic hydrolysis of polysaccharide-rich particulates

“…Boon found that the optimal pH in the hydrolysis of primary sludge was 6.5 (as reviewed by Sanders et al, 2002). Elefsiniotis et al (1996) found that reducing the pH from 5.1 to 4.5 did not influence the hydrolysis or rate of acidogenesis of primary sludge, while an increase in pH from 5.1 to 6.1 increased the rate of hydrolysis but reduced the rate of acidogenesis. were the first to evaluate separately the roles of pH, total VFA, and undissociated VFA in the hydrolysis of biowaste.…”

Anaerobic digestion of cattail by rumen cultures

“…It can also be used to produce hydrogen by photosynthetic bacteria (Maeda et al, 2003), or to polyhydroxyalkanoates (Du and Yu, 2002). In addition, in municipal wastewater treatment applications, VFA can also be used as an energy and carbon source for microorganisms to enhance the removal of phosphorus and nitrogen (Elefsiniotis et al, 1996). Therefore, the main products from anaerobic degradation of cattail by rumen cultures have multiple utilities.…”