Mining iron and phosphate from sludge
Leon Korving of Wetsus presented a new technology to recover or ‘mine’ iron and phosphate from sludge. The technology uses mining technology to remove phosphate from sludge, creating an alternative to chemical precipitation. Wetsus research shows that 90% of phosphorus in sludge is in the form of vivianite. In the pilot project, the technology has an 80% efficiency rate in recovering vivianite from sludge. The biggest advantages of this new technology are a 10% to 15% less sludge production, more than 50% phosphorus recovery and the reuse of iron. Click here for more information (in Dutch).
Recovering metals from sewage sludge and fly-ash
Julian Muñoz Sierra from KWR showed their TKI funded research project on resource recovery from water, sludge and fly-ash. The research focuses on recovering heavy metals from the water cycle and exploring technologies to recover metals from sewage sludge and fly-ash. Combining the technologies developed by KWR in this project could optimise the purity and recovery of metals and minimise the use of chemicals for the extraction of metals from sludge, water and fly-ash. Click here for more information: (in Dutch).
Sjoerd Kersten of Royal HaskoningDHV explained the development of the Nereda technology and Kaumera biopolymer. Kaumera is produced from granular sludge that originates from the adjacent Nereda wastewater treatment plant. Kaumera is a valuable raw material and a viable alternative to a variety of oil-based materials. It offers a range of new applications like coatings, an absorbent biopolymer or bio-agent and several other applications. Furthermore, the Nereda granules are made up of 15% to 20% Kaumera, therefore reducing the sludge treatment and disposal costs. Click here for more information.
Netherlands-Balkan region cooperation
Finally, Maarten Schaafsma of the Energie en Grondstoffenfabriek (energy and raw materials factory) and Darja Kragić Kok of the Netherlands Water Partnership highlighted the opportunities in the Netherlands and the Balkan region. Wastewater contains about eight times more energy than it takes to process it, and it contains valuable resources. According to the Energie en Grondstoffenfabriek, the top six resources recovered from wastewater in The Netherlands are: cellulose, Kaumera, phosphate, bioplastics, biomass and the water itself. These resources also present the biggest opportunity. If all the sludge in the Netherlands were collected, at least 12,000 tons of phosphate could be recovered in the form of struvite, bio granules and phosphorus, and 25,000 tons of bioplastics could be recovered. At present, less than one ton of bioplastics is recovered. There is also a lot to gain in terms of resources like cellulose and green gas. At present, 1,500 tons of cellulose are recovered and only 10 million cubic metres of green gas produced, while both have the potential for 180,000 tons and 70 million cubic metres respectively a year.
In the Balkan region, the greatest potential for sludge recovery are in the countries that are in the process of accession to the EU. The Environmental Chapter is a big issue in the accession process. A lot of water is collected in these countries that goes untreated, so there is a lot of potential. In Slovenia especially, where much is already being done to treat wastewater and recover resources from sludge, resource recovery from wastewater offers a lot of potential.