A significant fraction of phosphorus (P) consumed by human is converged into municipal wastewater and removed into sewage sludges through various biological and physicochemical processes. Associations between P and heavy metals (HMs) such as Fe contribute to P removal into sludges. Understanding their dynamic coupling during wastewater and sludge treatments has important implications to resource recovery from wastewater and sludge management, while is not well understood. Recent progresses were achieved from experimental investigations using advanced spectroscopic techniques, while they possess limitations: 1) experimental studies can measure limited numbers of sludge samples and the results may be specific to the sludge source and handling process, and 2) spectroscopic methods have intrinsic analytical uncertainties and great variations between studies were found.<br/>To obtain a comprehensive understanding of the dynamic transformation of P and related HMs and the underlying processes during wastewater and sludge treatments, spectroscopic analysis and chemical modeling were complementarily used to speciate the elements across a broad range of conditions. We revealed the specific wastewater conditions (i.e., composition and redox conditions) that are conducive to the formation/prevalence of main chemical species identified spectroscopically. Discrepancies between modeling and spectroscopic results were also identified and can be related to characteristics of wastewater treatment processes. Findings from this work significantly advance our understanding of the behaviors of multiple coupled elements in the municipal wastewater system and provide a predictive insight on their speciation in sewage sludges generated/processed under varying conditions.

Toward a comprehensive understanding of elemental speciation in sewage sludges through combined spectroscopic and modeling analysis

ACS Fall 2021

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