Continuous micro-current stimulation to upgrade methanolic wastewater biodegradation and biomethane recovery in an upflow anaerobic sludge blanket (UASB) reactor

Abstract

The dispersion of granules in upflow anaerobic sludge blanket (UASB) reactor represents a critical technical issue in methanolic wastewater treatment. In this study, the potentials of coupling a microbial electrolysis cell (MEC) into an UASB reactor for improving methanolic wastewater biodegradation, long-term process stability and biomethane recovery were evaluated. The results indicated that coupling a MEC system was capable of improving the overall performance of UASB reactor for methanolic wastewater treatment. The combined system maintained the comparatively higher methane yield and COD removal efficiency over the single UASB process through the entire process, with the methane production at the steady-state conditions approaching 1504.7 ± 92.2 mL-CH L-reactor d, around 10.1% higher than the control UASB (i.e. 1366.4 ± 71.0 mL-CH L-reactor d). The further characterizations verified that the input of external power source could stimulate the metabolic activity of microbes and reinforced the EPS secretion. The produced EPS interacted with Fe liberated during anodic corrosion of iron electrode to create a gel-like three-dimensional [-Fe-EPS-] matrix, which promoted cell-cell cohesion and maintained the structural integrity of granules. Further observations via SEM and FISH analysis demonstrated that the use of bioelectrochemical stimulation promoted the growth and proliferation of microorganisms, which diversified the degradation routes of methanol, convert the wasted CO into methane and accordingly increased the process stability and methane productivity.

Enhanced nutrient removal from mixed black water by a microbial ultra-low weak electrical stimulated anaerobic-two stage anoxic/aerobic process

“…As MUlWES increased, the LB/TB decreased. These results were consistent with the phenomenon that the sludge LB/ TB reduced from 0.66 to 0.62 after microcurrent stimulation reported by [60]. LB-EPS decreased and TB-EPS increased under weak electrical stimulation at 0.2 V, but the total amount of LB-EPS and TB-EPS proteins changed very little [10].…”

Bioremediation of industrial effluents: A synergistic approach

“…The microorganisms attach to the sludge particles and aggregate to form dense compact biofilms called the sludge granules [78][79][80]. By anaerobic digestion, microbes present in the sludge breakdown and transform organic matter into a gas [81]. Gases are allowed to extract by baffles located at the top of the reactor (Figure 3).…”

Biotechnology for Gas-to-Liquid (GTL) Wastewater Treatment: A Review

“…Among several anaerobic reactors, the up-flow anaerobic sludge blanket (UASB), is the most commonly used reactor in the area of wastewater treatment. Basically, this reactor can convert the soluble organics present in wastewater into value-added bioenergy during waste the treatment [71]. The treatment of several wastewater streams combined with biogas production were investigated using UASB reactors and achieved varying efficient degradation such as 76.3% COD reduction from refinery wastewater, and biogas production rate of 0.25 L biogas/L feed [72], 71% COD and 75% phenol reduction from coal gasification wastewater [1], reduction phenols and m-cresol of 98% and 20%, respectively for wastewater stream contained 900 mg/L of phenol and 320 mg/L of m-cresol [73].…”