Supercritical water gasification of effluents from composted human excreta and recycling of the aqueous phases for microalgae cultivation

Dorian Tosi Robinson
2017
Student project

Effluents from composted human excreta were sampled and characterized. Results show a constancy in the characteristics and nutrient content of these effluents. Then, these effluents were treated with supercritical water gasification, producing hydrogen rich gas (67-69%). Carbon efficiencies of 41-43% were achieved. Microalgae Chlorella vulgaris (CV) and Phaeodactylum tricornutum (Ph.t) cultivation were studied in the gasification aqueous phase (AP). No growth was observed in the raw AP even with adjusted pH. CV could grow in the activated carbon treated AP with similar results for cell concentration and pigment content, but with higher biomass production than in its control medium. Ph.t was unable to grow even in the treated AP. These results show promising development in recuperating energy and nutrients from effluents from composted human excreta, combining energy production, microalgae valorization and contributing to close the nutrient loop.

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Dorian Tosi Robinson
2017
Student project

Abstract

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https://infoscience.epfl.ch/record/231900?ln=en

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Related concepts (14)

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Supercritical fluid

A supercritical fluid (SCF) is any substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist, but below the pressure required to compress it into a solid. It can effuse through porous solids like a gas, overcoming the mass transfer limitations that slow liquid transport through such materials. SCF are much superior to gases in their ability to dissolve materials like liquids or solids.

Microalgae

Microalgae or microphytes are microscopic algae invisible to the naked eye. They are phytoplankton typically found in freshwater and marine systems, living in both the water column and sediment. They are unicellular species which exist individually, or in chains or groups. Depending on the species, their sizes can range from a few micrometers (μm) to a few hundred micrometers. Unlike higher plants, microalgae do not have roots, stems, or leaves. They are specially adapted to an environment dominated by viscous forces.

In chemistry, pH (piːˈeɪtʃ ), also referred to as acidity, historically denotes "potential of hydrogen" (or "power of hydrogen"). It is a scale used to specify the acidity or basicity of an aqueous solution. Acidic solutions (solutions with higher concentrations of hydrogen () ions) are measured to have lower pH values than basic or alkaline solutions. The pH scale is logarithmic and inversely indicates the activity of hydrogen ions in the solution. where [H+] is the equilibrium molar concentration (mol/L) of H+ in the solution.

Water quality and the biogeochemical engine

Learn about how the quality of water is a direct result of complex bio-geo-chemical interactions, and about how to use these processes to mitigate water quality issues.