Hydrogen production automatic control in continuous microbial electrolysis cells reactors used in wastewater treatment.

In this paper, two control laws are proposed and applied in a model for a continuous Microbial Electrochemical Cells system. The used model is based on mass balances describing the behavior of substrate consumption, microbial growth, competition between anodophilic and methanogenic microorganisms for the carbon source in the anode, hydrogen generation, and electrical current production. The main control objective is to improve the electrical current generated and thus the production of bio-hydrogen gas in the reactor, using the dilution rate and the applied potential as individual control input variables.

Evaluation of alkalinity spatial distribution in an up-flow fixed bed anaerobic digester.

In this paper, an experimental study upon alkalinity and hydrodynamic behavior in an anaerobic up-flow fixed bed reactor for the treatment of tequila vinasses is presented. Measurements of volatile fatty acids, pH, alkalinity and bicarbonate were obtained at three sampling points in the reactor in the axial axis. Then, the spatial distribution of alkalinity is studied and discussed.

Anaerobic treatment of Tequila vinasses in a CSTR-type digester.

Tequila industries in general produce great volumes of effluents with high pollutant loads, which are discharged (untreated or partially treated) into natural receivers, thus causing severe environmental problems. In this contribution, we propose an integrated system as a first step to comply with the Mexican ecological norms and stabilize the anaerobic treatment of Tequila vinasses with main design criteria: simple and easy operation, reduce operating time and associated costs (maintenance), integrated and compact design, minimal cost of set-up, start-up, monitoring and control. This system is composed of a fully instrumented and automated lab-scale CSTR-type digester, on-line measuring devices of key variables (pH, temperature, flow rates, etc.

Multiple response optimization analysis for pretreatments of Tequila's stillages for VFAs and hydrogen production.

The objective of this work was study the effect of three pretreatments (alkalinization, thermical treatment, and sonication) on Tequila's stillages hydrolysis process in acidogenesis stage, through the following response variables: soluble chemical oxygen demand (CODs), total sugar and volatile fatty acids profile and the hydrogen production at the time. The stillages were subject to these pretreatments (according to a 2(3) factorial design); afterward they were transferred to a batch reactor at 35 degrees C and inoculated with an anaerobic digestor sludge. Multiple response optimization (MRO) analysis was done to find the global optimum for the response variables described above.

A tunable multivariable nonlinear robust observer for biological systems.

This paper presents a robust nonlinear asymptotic observer with adjustable convergence rate with a great potential of applicability for biological systems in which the main state variables are difficult and expensive to measure or such measurements do not exist. This observer scheme is based on the classical asymptotic observer, which is modified to allow the tuning of the convergence rate. It is shown that the proposed observer provides fast and satisfactory estimates when facing load disturbances, system failures and parameter uncertainty while maintaining the excellent robustness and stability properties of the classical asymptotic observer.