No abstract

This study highlights the scale-up of enzymatic hydrolysis of wheat starch from the phenomenological-based semiphysical model and control theory tools. The state variables involved were glucose concentration (L 1), maltodextrins (L 5), and temperature (L rL) for liquefaction and glucose concentration (S 1), maltodextrins (S 5), and temperature (L rS) for saccharification. The design variables included initial substrate concentration (S 0), reactor volume (V r), and initial enzyme concentrations for liquefaction (E 0L) and saccharification (E 0S). The hierarchy of low scale (LS) for the liquefaction and saccharification stage was L 1 > L 5 > T rL and S 1 > S 5 > T rS. The values of the design variables changed between LS and the high scale (HS) from 161 to 180 g/L, from 0.05 to 15.10 mL/L, and from 0.26 to 0.76 mL/L for S 0, E 0L, and E 0S, respectively. These values maintained the hierarchy in the saccharification stage but not in the liquefaction stage.

No abstract

No abstract

No abstract

The necessity to generate advances in the comprehension of modeling and simulation of enzymatic hydrolysis of lignocellulosic materials, based on experimentation, has attracted significant attention currently. This paper proposes a methodology for modeling and parameter estimation of the enzymatic hydrolysis process for sugarcane bagasse. The methodology is composed of three steps: experimental process, approach to the phenomenologically based semi-physical model, and parameter estimation. Experimentally, pretreated sugar cane bagasse was characterized, with 22.60, 13.39, and 23.71% for cellulose, hemicellulose, and lignin, respectively. The enzymatic hydrolysis of cellulose, cellobiose, and glucose concentrations was monitored using a commercial cellulase with an enzymatic activity of 96FPU/mL at 50 °C, pH 4.8, 130 rpm for 74 h. A model was proposed, which includes adsorption effects of the enzymatic complex, pH, temperature, transglycosylation, appearance of new cellulose, and product inhibition. Finally, a global mean percentage squared error cost function (% MSE Global ) was used, adjusting the glucose, cellobiose, and cellulose variables from the estimation of 29 kinetic parameters. It was possible to obtain a % MSE Global of 6.33%, which is lower than the proposed acceptable error of 10%. Thus, the methodology for modeling and parameter estimation achieved good results in this first approximation from experimental development and the formulation of a more complex model.

Biogas produced in municipal and industrial wastewater treatment facilities (BWWF) is a resource wasted in several socio-economic contexts. BWWF-based projects are compared against energy projects using conventional electricity or natural gas (NG), following strict economic considerations that usually tip the balance in favour of conventional energy supply. This is because the economic gain associated with the environmental benefits of using small biogas sources like BWWF does not overcome the technical and financial effort required in these types of project. This paper shows a broader application of life cycle assessment (LCA) methodology to explore opportunities for positive (or effective) utilization of BWWF in the Colombian context. LCA has been used to evaluate the supply-chain of NG which is the direct competitor of BWWF, in three different Colombian regions, in order to identify those where higher NG environmental impacts offer increased environmental added-value to BWWF use. LCA was also applied to study two BWWF valorization scenarios in the poultry processing industry. It shows how valorization options for BWWF are more realistic and effective when specific-regional loads are applied to the environmental assessment of NG supply-chain and BWWF valorization.

An analysis of the enzymatic hydrolysis of wheat starch was performed. The gelatinization stage was carried out between 90-95°C for 15min. In the liquefaction stage, a commercial α-amylase was used with an enzyme-substrate ratio (E/S ratio) 0.036%w/w at 60°C and pH 5.8 for 4h. In the saccharification stage, a commercial amyloglucosidase was used with an E/S ratio of 0.11% w/w at 60°C and pH 4.3 for 6h. A second hydrolysis was evaluated using a E/S ratio of  0.18%w/w in the saccharification stage. Two methods of enzymatic deactivation, boiling temperatures and pH were evaluated. Inhibitory effects were studied by adding 180g/L of glucose to the process. It is concluded that increases in the E/S ratio decrease reaction times but reaches similar concentrations than lower ratios, the most efficient enzymatic deactivation method is pH. In the inhibition tests, it was determined that there are no glucose inhibitory effects.