Parameter and process significance in mechanistic modeling of cellulose hydrolysis (original) (raw)

Biodegradation study of cellulose bearing synthetic wastewater in activated sludge system

2019

Due to the inert nature of cellulose, decomposition of cellulose present in food processing industry wastewater and digestate generating from organic solid waste treatment units is a key aspect in abetting global industrial pollution. The present study describes the performance of an aerobic bioreactor treating cellulose bearing synthetic wastewater. Complete acclimation with cellulose bearing synthetic wastewater was achieved within 10–12 weeks of initiating the acclimation batch runs. Maximum removal of the introduced chemical oxygen demand (COD) was recorded to be 70.4% mid-way through the acclimation phase. An average COD removal percentage in between 64% and 67% was noticed at the end of the acclimation phase. Inhibition of the bioreactor was noticed when the percentage of cellulose in the synthetic wastewater was increased above 70%. This resulted in sharp fall in system pH along with pronounced lowering of MLSS and percentage COD removal. Stability in the reactor performance ...

Impacts of biofilms on the conversion of cellulose

Applied Microbiology and Biotechnology

Lignocellulose is a widely available renewable carbon source and a promising feedstock for the production of various chemicals in biorefineries. However, its recalcitrant nature is a major hurdle that must be overcome to enable economic conversion processes. Deconstruction of lignocellulose is part of the global carbon cycle, and efficient microbial degradation systems have evolved that might serve as models to improve commercial conversion processes. Biofilms—matrix encased, spatially organized clusters of microbial cells and the predominating lifestyle in nature—have been recognized for their essential role in the degradation of cellulose in nature, e.g., in soils or in the digestive tracts of ruminant animals. Cellulolytic biofilms allow for a high concentration of enzymes at the boundary layer between the solid substrate and the liquid phase and the more complete capture of hydrolysis products directly at the hydrolysis site, which is energetically favorable. Furthermore, enhanc...

Enhancement of solubilization rate of cellulose in anaerobic digestion and its drawbacks

Process Biochemistry, 2011

Hydrolysis is widely acknowledged as the rate-limiting step in anaerobic digestion of solid cellulose to biogas (methane), and pretreatment is generally considered to facilitate the process. However, few studies have investigated how such pretreatment may affect the rest of this complex process. The present study compared the solubilization rate in anaerobic digestion of cotton linter (high crystalline cellulose), with that of regenerated cellulose (amorphous cellulose), using pretreatment with NMMO. Batch digestions were performed, with the initial cellulose concentrations ranging between 5 and 40 g/l, and during 30 days of incubation, biogas and VFAs production as well as pH and COD changes were measured. The lag time before digestion started was longer for the high crystalline cellulose than for the amorphous one. The maximum solubilization rates of treated cellulose were 842 and 517 mg sCOD/g cCOD/day at the initial cellulose concentration of 5 and 30 g/l, respectively, while the solubilization rate of untreated cellulose never exceeded 417 mg sCOD/g cCOD/day. The difference between the two cellulose types was a direct result of the high rate of hydrolysis inhibiting the acetogenesis/methanogenesis microorganisms, a drawback to the rest of the process.

The hydrolysis and biogas production of complex cellulosic substrates using three anaerobic biomass sources

Water Science & Technology, 2012

In this study, the ability of various sludges to digest a diverse range of cellulose and cellulose-derived substrates was assessed at different temperatures to elucidate the factors affecting hydrolysis. For this purpose, the biogas production was monitored and the specific biogas activity (SBA) of the sludges was employed to compare the performance of three anaerobic sludges on the degradation of a variety of complex cellulose sources, across a range of temperatures. The sludge with the highest performance on complex substrates was derived from a full-scale bioreactor treating sewage at 37 °C. Hydrolysis was the rate-limiting step during the degradation of complex substrates. No activity was recorded for the synthetic cellulose compound carboxymethylcellulose (CMC) using any of the sludges tested. Increased temperature led to an increase in hydrolysis rates and thus SBA values. The non-granular nature of the mesophilic sludge played a positive role in the hydrolysis of solid substr...

Optimized operational parameters of anaerobic cellulosic-wastewater treatment for bioenergy recovery and effluent quality improvements

Current Science International, 2019

A series of standardized batch experiments were carried out to optimize the biogas production from cellulosic-rich wastewater treatment. The experimental results showed that the best result was produced under C/N ration of 20 with 80.94 % COD removal and cumulative biogas production reached 44.55 ml/g COD added. The maximum cellulose degradation was achieved at 10 g/L with a cumulative biogas production of 6.13 L/L. Based on the response surface model, the most significant operational parameter was cellulose concentration and C/N ratio with Log Worth values reached 2.112 and1.131, respectively. As for biological pretreatment, the experimental results showed that the pretreatment under shaking cultural conditions produced better results in COD removal efficiency however, the biogas production was negatively affected as well as the soluble by-products concentrations were significantly decreased. The experimental results showed that the changing in the soluble by-product concentrations could explain the effect of operational factors and the best condition was reported.

Identification of metabolite and protein explanatory variables governing microbiome establishment and re-establishment within a cellulose-degrading anaerobic bioreactor

PloS one, 2018

Proteins, metabolites, and 16S rRNA measurements were used to examine the community structure and functional relationships within a cellulose degrading anaerobic bioreactor. The bioreactor was seeded with bovine rumen fluid and operated with a 4 day hydraulic retention time on cellulose (avicel) as sole carbon and energy source. The reactor performance and microbial community structure was monitored during the establishment of the cellulose-degrading community. After stable operation was established in the bioreactor, the mixing intensity was increased in order to investigate the effect of a physical disruption of the microbial community structure. Finally, the original conditions were re-established to understand the stability of the microbial community after a perturbation. All factors measured were found to be inter-correlated during these three distinct phases of operation (establishment, perturbation and re-establishment). In particular, the return of community structure and fu...

Cellulose biodegradability and its impact on enhanced biological phosphorus removal

2021

Cellulose from toilet paper contributes approximately one third of the influent organic suspended solids (TSS) to wastewater treatment plants and is a key target for resources recovery. Cellulose recovery is beneficial as it reduces the required energy for treatment and biosolids treatment cost. Hence, understanding the hydrolysis of cellulose in wastewater which is mainly affected by temperature and the solids retention time (SRT), is a major key to determine the optimum location for its recovery. In order to assess the impact of temperature and SRT on cellulose degradation, this study investigated the biological aerobic degradation of cellulose in four laboratory-scale sequencing batch reactors (SBR) at four different temperatures (10-33°C) and two different sludge retention times (SRT of 15 days and 3 days). The degradation efficiency of cellulose was observed to increase with temperature and was slightly dependent on sludge retention time (80%-90% at an SRT of 15 days, and 78%-8...