From now on, municipal sewage sludge is sanitized and recycled into phosphorus fertilizer on site in Lorsbach, a climate protecting and cost-saving manner.
In the applied PYREG process, the sewage sludge is first dried using the belt drying system from Eliquo Stulz and then carbonized by the PYREG reactor temperature of 500°C to 700°C. This carbonization eliminates any organic pollutants such as critical pharmaceutical residues, microplastics, PAH, PCDD/F, PCB and hormones. The resulting process gas is freed from dust and carbon particles by a process gas filter and transferred to the combustion chamber. Combustion takes place with a FLOX® burner at temperatures of around 1,000 °C. The hot exhaust gases arising there heat the reactors indirectly via the outer shell of the reactors. It is therefore an autothermal process and the generated renewable energy is used for the drying of the sewage sludge.
The carbon contained in the sewage sludge is permanently bound in the generated biochar from biosolids. Used as a phosphorus fertilizer in agriculture that biochar closes the material cycle. And it furthermore acts as a stable carbon sink for over 1000 years.
The PYREG PX 750 processes 5000 t of dewatered sewage sludge per year (or 16 t per day at 7500 operating hours) with 25% dry matter, or 1250 t per year of dried sewage sludge. As a valuable output, the association generates up to 625 t of biochar form biosolids per year with a phosphorus content of about 15%.

With the commissioning of this plant, Abwasserverband Main-Taunus is taking a resource-saving approach to the legally required recovery of phosphorus from sewage sludge. The goal is to use the recovered biochar form biosolids for agricultural purpose

Der Beitrag The wastewater association Main-Taunus chooses a climate-protecting and cost-saving way to recycle phosphorus from sewage sludge erschien zuerst auf PYREG.

In a 2019 study by the German Federal Environmental Agency, the result is that conventional fertilizer production in Germany emits about +1.2 kg CO₂ eq/kg P₂O₅. Furthermore, phosphate recovery processes like precipitation (in digested sludge or centrate) or sewage sludge ash also demonstrably cause CO₂ emissions.

In comparison to the global warming potential (GWP) of these processes, PYREG biochar from biosolids has a negative GWP of –4,01 kg CO₂ eq / kg P₂O₅. Consequently, the recovery of phosphate within the PYREG process and the final application of the carbonizate contributes to fight global warming and reaching net zero.

In addition to that the phosphate recovery rate of PYREG biochar from biosolids is nearly 80 %, which is in the range of other thermal treatments and far better than precipitation processes with <40 % recovery rate.

Sources:
UBA TEXTE 13/2019: Ökobilanzieller Vergleich der P-Rückgewinnung aus dem Abwasserstrom mit der Düngemittelproduktion aus Rohphosphaten unter Einbeziehung von Umweltfolgeschäden und deren Vermeidung, Forschungskennzahl 3716 31 330 0 UBA-FB 002759, ISSN 1862-480
Kratz, Schnug (2009): Zur Frage der Löslichkeit und Pflanzenverfügbarkeit von Phosphor in Düngemitteln JOURNAL FÜR KULTURPFLANZEN, 61 (1). S. 2–8, 2009, ISSN 0027-7479 VERLAG EUGEN ULMER KG, STUTTGART
Koch, Bernhard (2021): Gefäßversuch zur Phosphorverfügbarkeit aus Klärschlammrecyclaten, Landesbetrieb Landwirtschaft Hessen, DPP Forum 2021 Frankfurt
EVS 2019: Experimenteller Nachweis der Cadmiumentfrachtung während des Karbonisierungsprozesses von Klärschlamm
Kuzyakov 2015: Biochar stability in soil: Meta-analysis of decomposition and priming effects, GCB Bioenergy, DOI:10.1111/gcbb.12266
EBI Whitepapaper

Der Beitrag Biochar from biosolids: the climate-positive alternative to conventional phosphorus fertilizer erschien zuerst auf PYREG.