Variation of the element composition of municipal sewage sludges in the context of new regulations on phosphorus recovery in Germany

Abstract

Phosphorus (P) recovery is obligatory for all sewage sludges with more than 20 g P/kg dry matter (DM) from 2029 in Germany. Nine wastewater treatment plants (WWTPs) were chosen to investigate variations of phosphorus contents and other parameters in sewage sludge over the year. Monthly sewage sludge samples from each WWTP were analyzed for phosphorus and other matrix elements (C, N, H, Ca, Fe, Al, etc.), for several trace elements (As, Cr, Mo, Ni, Pb, Sn) and loss of ignition. Among the nine WWTPs, there are four which have phosphorus contents both above and below the recovery limit of 20 g/kg DM along the year. Considering the average phosphorus content over the year, only one of them is below the limit. Compared to other matrix elements and parameters, phosphorus fluctuations are low with an average of 7% over all nine WWTPs. In total, only hydrogen and carbon are more constant in the sludge. In several WWTPs with chemical phosphorus elimination, phosphorus fluctuations showed similar courses like iron and/or aluminum. WWTPs with chamber filter presses rather showed dilution effects of calcium dosage. As result of this study, monthly phosphorus measurement is highly recommended to determine whether a WWTP is below the 20 g/kg DM limit. Graphical Abstract

Valuable elements in sludge from eight municipal wastewater treatment plants in relation to their recovery potential

“…The spectrometer was optimized to provide minimal values of the ratios CeO + /Ce + and Ba 2+ /Ba + and optimal intensity of the analytes. The concentrations of the elements were determined using the isotopes as follows: 7 Li, 11 B, 24,25,26 Mg, 27 Al, 31 P, 39 K, 42,44 Ca, 46−49 Ti, 51 V, 52 Cr, 54,57 Fe, 55 Mn, 59 Co, 60,62 Ni, 63,65 Cu, 64,66 Zn, 69 Ga, 75 As, 86,88 Sr, 96, 98 Mo, 105, 108 Pd, 107,109 Ag, 112,114,116 Cd, 121,123 Sb, 197 Au, 200,202 Hg and 206,207,208 Pb. Due to the presence of spectral polyatomic interferences on the isotopes of As and Pd, their concentrations were determined in DRC mode [36,37].…”

“…, minimum and maximum values of the macro-and microelement content in mg per kg of sludge DW from all studied WWTP a[16,[20][21][22][40][41][42][43] …”

Multi-sectorial assessment of phosphorus in Ontario, Canada: Mapping flows and analysis of the potential for recovery and reuse

“…In addition, the European Union is setting specific targets to reduce the use of non-renewable materials in fertilizer production (European Comission, 2018) and to promote the use of waste-based fertilizers (European Comission, 2022). More ambitious regulations for the particular case of wastewater are currently being discussed for adopting minimum recovery and recycling rates for phosphorus at water resource recovery facilities (WRRFs) (European Sustainable Phosphorus Platform, 2022), and some countries such as Germany and Switzerland already approved regulations enforcing phosphorus recovery from sewage sludge (Sichler et al, 2022). These efforts supporting the circular economy of phosphorus might serve as a guideline to develop phosphorus recovery strategies in other regions.…”

Keu Contamination in Tuscany: The Life Cycle Assessment of Remediation Project as a Decision Support Tool for Local Administration

“…In recent years, the problem of "Keu" has emerged in Tuscany, a waste derived from the processes of pyrolysis and sintering of sewage sludges produced from the wastewater treatment plant of the tannery district of Santa Croce dell'Arno, as note rich in chromium. Generally, the chromium concentration for sewage sludges is typically less than 50 mg/kg [7]. Part of the waste produced every year has been destined for the construction sector and used as backfill material.…”