Perspectives of surface plasmon resonance sensors for optimized biogas methanation

Abstract

Biogas production is becoming significantly viable as an energy source for replacing fossil‐based fuels. The further development of the biogas production process could lead to significant improvements in its potential. Wastewater treatment currently accounts for 3% of the electrical energy load in developed countries, while it could be developed to provide a source of nitrogen and phosphorus, in addition to energy. The improvement of anaerobic digestion (AD) detection technologies is the cornerstone to reach higher methane productivities and develop fully automatized processes to decrease operational costs. New sensors are requested to automatically obtain a better interpretation of the complex and dynamical internal reactor environment. This will require detailed systematic detection in order to realize a near‐optimal production process. In this review, optical fiber‐based sensors will be discussed to assess their potential for use in AD. There is currently a disparity between the complexity of AD, and online detection. By improving the durability, sensitivity, and cost of dissolved H2 (as well as H2S, acetic acid, ammonia, and methane) sensor technology, further understanding of the AD process may allow the prevention of process failure. The emergence of surface plasmon resonance (SPR) sensing with optical fibers coupled with the H2‐sensitive metal palladium, allows detection of dissolved hydrogen in liquid. By implementing these SPR sensors into AD, improvements to the biogas production process, even at small scales, may be achieved by guiding the process in the optimum direction, avoiding the collapse of the biological process. This review intends to assess the feasibility of online, cost‐effective, rapid, and efficient detection of dissolved H2, as well as briefly assessing H2S, acetic acid, ammonia, and methane in AD by SPR.

Detection of Hydrogen Dissolved in Liquid Media: A Review and Outlook

“…In dark-fermentation processes, monitoring dissolved hydrogen is necessary to ensure a total extraction from the liquid phase. [21,24,25] Moreover, it can be used to evaluate and probe the H 2 production capabilities of different algal strains and cyanobacteria in order to develop those with increased hydrogen yields. [26,27]…”

“…Limited hydrogen mass transfer rates render a system inaccurate and slow, which increases the risk of an excessive hydrogen buildup or diminishes the sensitivity in those systems where response times are critical, like anaerobic reactors. [22][23][24][25][50][51][52] Failures of the headspace method were reported by Kuroda et al, [24] whose hydrogen concentration measurement values turned out to be about 60-fold higher than theoretical values calculated with partial pressures and Henry's law. Pauss et al got similar results, reporting real dissolved hydrogen concentrations 40-70 times larger than calculated with headspace analysis.…”

“…They are also safer for monitoring systems in which hydrogen may escape the aqueous solution and become a gas because optical devices cannot ignite H 2 . [25,55] Their structures are relatively simple and suitable for commercial applications compared to other optical devices. [67] There are issues with the use of a Pd layer as the sensing component whose thickness represents a trade-off: thicker layers are more sensitive, but peel off easier.…”

“…A comprehensive review on the sensing properties of carbon nanotubes was written by Zaporotskova et al [82] Although all advances with regard to using carbon nanotubes for H 2 monitoring are directed toward gasphase sensors, they could be brought to the field of dissolved hydrogen sensing by the work of authors like Lamb et al and Sayago et al who used palladium-functionalized single-wall nanotubes to improve a sensor's sensitivity and affinity toward H 2 . [25,74] Their results indicate that the configuration is efficient and inexpensive because the amount of Pd used is minimal. [82] Finally, standardizing the characterization of dissolved hydrogen sensors would expedite comparisons between sensors and accelerate the growth of the field for scientists will be able to identify the best "stepping stones" upon which to base their own research.…”

Molecular Microbial Community Analysis as an Analysis Tool for Optimal Biogas Production

“…The acetogenic activity is thermodynamically affected in the high partial pressure of hydrogen; moreover, the conversion reaction of butyrate and propionate to acetate and hydrogen will only proceed in a low concentration of hydrogen in the system [34,35]. This can be avoided through balancing hydrogen production from acetogens and hydrogen consumption by methanogens [4,36].…”