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RECOWATING is a project financed by Water JPI on “Water challenges for a changing world” aiming to tackle the ambitious grand challenge of “Achieving sustainable water systems for a sustainable economy in Europe and abroad”. Water is vital and essential for a smart, sustainable and inclusive growth.
The primary goal: developement of a front-end engineering (technical) design of a modular and transportable installation for the staged recovery of an agricultural water from dewatering and drying of high moisture fermentation products, working according to Plug and Produce (PnP) principle and turning by-products into useful/marketable products.
Wroclaw University of Science and Technology
Faculty of Mechanical and Power Engineering
Wybrzeże Wyspiańskiego 27
50-370 Wrocław, Poland
Head of the Project
PhD Eng. Halina Pawlak Kruczek, WUST Prof.
halina.pawlak@pwr.edu.pl
+48 71 320 39 42
The main goal of the project implemented by a consortium of Polish partners (PWr, AGH, ZGO Gać) and partners from KTH-Royal Institute of Technology, HoSt Bioenergy Installations, and University of Twente, the Netherlands, was to develop a multi-stage process of post-fermentation processing to solid hyrochars and first of all, treatment of the separated water, i.e. its purification by many methods in order to reuse it in agriculture.
An important goal was to determine the final method of water purification that meets the requirements of water useful for agriculture. The parameters of the components of the post-digestate conversion treatment processes (using membranes) were estimated from the research, which enabled the production of usable water and solid residue (hydrochars).
The techniques and processes proposed in the project may contribute to the development of effective technologies that will reduce water scarcity through the use of water recovered from wet products of anaerobic fermentation of organic waste in agriculture. The implementation of the project confirmed that it is possible to use digestates, process them, obtain valuable products, and thus reduce the amount of waste produced, which is in line with the idea of a circular economy. As part of the work carried out in the project, design guidelines were developed and a preliminary design of a self-sufficient, multi-stage water recovery system from highly hydrated fermentation products for agricultural purposes was developed, including a hydrothermal carbonization module, a leachate treatment module after dewatering, a drying module, and a CHP installation using gasification, gas turbines and heat exchangers for heat recovery.
Based on the conducted tests, a significant reduction of pollutants contained in leachates was demonstrated as a result of treatment using a cascade system of flat membranes. Based on the analyses of the produced hydrochars, it was found that dried hydrochar could be used as a fuel, providing heat necessary for its drying and HTC process, along with some surplus electricity that could be sold to the grid.
Overall, positive energy balance is encouraging. The plant sized for a typical municipal waste sorting plant in Poland, producing biogas from wet sorted fraction of municipal solid waste, could achieve internal return rate of 11.4% with NPV 10 550 722 EUR by investing in the installation developed within the scope of this project. Such installations are even easier to be applied for agricultural biogas plants. In Poland, over 3.3 million tons of digestate is produced annually. This means that wide application of such technology would result in generating additional 400 GWh of green electricity per year as well as 350 million liters of agricultural water per year.
Socio-economic impact of wide implementation of such technology would include:
