Nitrogen release and leachable organic matter decomposition of anaerobically digested biosolids with variable pre-treatments

Sarah Fischer; Greg McCarty; Mark Ramirez; Alba Torrents

doi:10.1016/j.wasman.2019.12.049

Nitrogen release and leachable organic matter decomposition of anaerobically digested biosolids with variable pre-treatments

Waste Manag. 2020 Mar 1:104:82-93. doi: 10.1016/j.wasman.2019.12.049. Epub 2020 Jan 20.

Authors

Sarah Fischer¹, Greg McCarty², Mark Ramirez³, Alba Torrents⁴

Affiliations

¹ Marine, Estuarine, and Environmental Sciences Program, University of Maryland, College Park, MD 20742, USA; Department of Civil and Environmental Engineering, University of Maryland, College Park, MD, USA. Electronic address: sarahj.fischer@colorado.edu.
² USDA Agricultural Research Service, Hydrology & Remote Sensing Laboratory, Beltsville, MD, USA.
³ District of Columbia Water and Sewer Authority (DC Water) Blue Plains, 5000 Overlook Avenue, Washington, District of Columbia, USA.
⁴ Marine, Estuarine, and Environmental Sciences Program, University of Maryland, College Park, MD 20742, USA; Department of Civil and Environmental Engineering, University of Maryland, College Park, MD, USA. Electronic address: alba@umd.edu.

PMID: 31972456
DOI: 10.1016/j.wasman.2019.12.049

Abstract

Thermal hydrolysis pretreatments (THP) coupled to anaerobic digestion (AD) are implemented to treat municipal solids, but limited study indicates whether THP-AD materials merit different land application rates than AD biosolids without THP. Three AD biosolids types with either no pretreatment, THP, or two-hour fermentation were evaluated for differences in leachable dissolved organic matter (DOM), DOM decomposition, and nitrogen (N) releases in biosolids incubated in sandy loam soil. DOM characterizations of size exclusion chromatography, FTIR, and fluorescence maxima > Ex: 400 nm indicated similarities in among AD-DOM that contrasted waste activated sludge Milorganite and Suwannee River Organic Matter (SRNOM). Fluorescence peak picking was a more adaptable analysis for shifted leachate spectra than fluorescence regional integration (FRI). Peak ratio analysis is recommended over FRI for biosolids-DOM. The 3-month net inorganic N produced in biosolids-soil incubations was 155 ± 12.1, 149 ± 18.2, 140 ± 17.4, and 354 ± 15.1 mg N/kg for AD biosolids with no pretreatment, fermentation-AD, THP-AD, and Milorganite respectively. Overall, there was limited evidence of differences in leachable organic matter quality or net mineral N release after 105 days for AD solids with or without THP. Red-shifted fluorescence of leachates decayed by day 45 in aerobic biosolids-soil incubations, suggesting that larger, complex carbon sources liberated during solids stabilization may decompose readily in soils. Overall, other variables (source material, AD operation) may have a greater influence on final nutrient releases and organic matter quality than full-scale pretreatments to AD alone. Critical and targeted application of DOM spectroscopy specific to biosolid-leachates will improve use in advanced stabilization studies.

Keywords: Anaerobic digestion; Biosolids degradation; Dissolved organic matter; Fluorescence spectroscopy; Land-application; Leachates; N mineralization; Thermal hydrolysis.

MeSH terms

Biosolids*
Hydrolysis
Nitrogen*
Sewage
Soil

Substances

Biosolids
Sewage
Soil
Nitrogen