While wastewater can be recycled into valuable sources of water, nutrients, and energy, the water treatment byproducts, also known as sewage sludge, became a major waste product in most advanced societies. Today, more than 80% of sludge disposal is either incinerated or landfilled causing 2.8% of global greenhouse emissions, costing more than 150 MCHF per year in Switzerland (165 Bn globally) to Sewage Treatment Plants, and having potential harmful effects. Our catalytic hydrothermal gasification system was developed for the disposal of different types of liquid wastes that are usually incinerated or landfilled and instead, turns them into by-products such as clean water, biogas and mineral salts that can further be upgraded into Phosphoric Acid. This not only makes the sludge a new form a revenue instead of a cost but also reduces the contamination effects. Our main objective for the next 2 years is to scale up our lab-scale prototype to an industrial level and commercialize it in the Global Sewage Treatment Plant market. We plan to build our first commercial unit by 2020, with treatment capacity of 10 tons per day of sewage sludge.

Opportunities addressed:
It is now well established that population and economic growth are placing water resources under increasing strain. Major regions of the world will face a massive water challenge in the coming decades if current trends continue – with potentially devastating consequences for human life and health, business and agriculture, international relations, and the environment if they do not adapt. The growing volumes of municipal wastewater are increasing demand for efficiencies in treatment technologies to improve water reuse and recycling. Today there is an urgent need to develop innovative solution for a better management of sewage sludge. Regulations are crucial in this domain and evolve quickly. Within 2026, all Swiss facilities will have to recover Phosphate, a non-renewable resource essential to grow crops. We believe we have the right solution to meet with this new regulation. Many actual technologies focused on recovering phosphate out of incineration ashes, but today they are economically not viable. We know that if we can provide a cheaper solution to recover phosphate, we can get a huge market share since the need today is a reliable method to dispose the sludge, which can fulfill all regulations, and turn this waste into valuable byproducts.

Innovative side of the project:
Our sewage sludge disposal solution is unique since it is developed to turn sewage sludge into valuable by-products such as clean water, biogas and mineral salts.
Not only the TreaTech solution is 51% cheaper than current alternatives like incineration, but it does not produce CO2 emissions from burning the sludge. Moreover, we designed a technology that is installed on STP sites, and hence no longer requires any sludge transport to incinerators (20% of total sludge management costs).
Paradigm shift toward cleaner methods of wastewater treatment. Government legislation is now focused on maximizing the recovery of resources and is the most important driver of growth for sale of wastewater control technologies. All of the current solutions are unsustainable due to the loss of recyclable by-products such as Phosphate. TreaTech solves all critical legislative issues faced by STP’s today. Our technology is a clean alternative that offers a cost-efficient, eco-innovative and on-site solution for a high variable liquid waste disposal, promoting sustainability and green economy.

We divided tasks of our project in 3 work packages (WP):
WP1 was dedicated to the computer aided design and physical construction of the lab-scale semi-batch reactor that operates in supercritical conditions.
WP2 was dedicated to testing typical compositions of wastewaters from industrial and municipal streams. Several designs of our industrial scale plant were performed taking into account properties of the feedstock and the sewage treatment plants.
Finally, WP3 considered the screening of different feedstocks and determining the salt separation and biogas production potential. We effectively managed to perform a 4- days campaign, treating sewage sludge under supercritical conditions, avoiding clogging by semi-continuous removal of the solid fraction (minerals) and delivering a liquid effluent whose carbon compounds can be converted at >99.9% into biogas. In addition, the processed water meets Swiss legal standards for STPs. Overcoming this milestone was decisive in order to validate our technology at lab-scale and to pursue our venture towards the construction of a pilot unit.

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Peng, G.; Steib, M.; Gramm, F.; Ludwig, C.; Vogel, F. Synthesis Factors Affecting the Catalytic Performance and Stability of Ru/C Catalysts for Supercritical Water Gasification. Catal. Sci. Technol. 2014, 4 (9), 3329;
Peng, G.; Gramm, F.; Ludwig, C.; Vogel, F. Effect of Carbon Surface Functional Groups on the Synthesis of Ru/C Catalysts for Supercritical Water Gasification. Catal. Sci. Technol. 2015, 5 (7), 3658;
Peng, G.; Ludwig, C.; Vogel, F. Ruthenium Dispersion: A Key Parameter for the Stability of Supported Ruthenium Catalysts during Catalytic Supercritical Water Gasification. ChemCatChem 2016, 8 (1), 139;
Peng, G.; Ludwig, C.; Vogel, F. Catalytic Supercritical Water Gasification: Interaction of Sulfur with ZnO and the Ruthenium Catalyst. Appl. Catal. B Environ. 2017, 202, 262;
Reimer, J.; Peng, G.; Viereck, S.; De Boni, E.; Breinl, J.; Vogel, F. A Novel Salt Separator for the Supercritical Water Gasification of Biomass. J. Supercrit. Fluids 2016, 117, 113;
De Boni, E.; Reimer, J.; Peng, G.; Zöhrer, H.; Vogel, F. Salt Precipitator and Method for Generating a Gas Mixture Containing Methane from Biomass Using a Salt Precipitator. EP 2918549 A1, 2014;
Haiduc, A. G.; Brandenberger, M.; Suquet, S.; Vogel, F.; Bernier-Latmani, R.; Ludwig, C. SunCHem: An Integrated Process for the Hydrothermal Production of Methane from Microalgae and CO2 Mitigation. J. Appl. Phycol. 2009, 21 (5), 529;
Peng, G.; Vogel, F.; Refardt, D.; Ludwig, C. Catalytic Supercritical Water Gasification: Continuous Methanization of Chlorella Vulgaris. 2017, submitted;
Bagnoud-Velásquez, M.; Brandenberger, M.; Vogel, F.; Ludwig, C. Continuous Catalytic Hydrothermal Gasification of Algal Biomass and Case Study on Toxicity of Aluminum as a Step toward Effluents Recycling. Catal. Today 2014, 223, 35;
Schubert, M.; Regler, J. W.; Vogel, F. Continuous Salt Precipitation and Separation from Supercritical Water. Part 2. Type 2 Salts and Mixtures of Two Salts.
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Rodríguez, G. Incinération Des Boues D’épuration: Énergie Gagnée Ou Perdue; 2008;
New publications will be issued within the coming months considering results obtained during our sewage sludge processing campaign.