Experimental evaluation of compost leachates.

Details

• Creators:
  Flury, Markus ; Mullane, Jessica M. ; Chahal, Maninder K. ; Cogger, Craig G.
• Corporate Creators:
  Washington State University. Dept. of Crop and Soil Sciences
• Corporate Contributors:
  United States. Federal Highway Administration
• Subject/TRT Terms:
  • Compost
  • Leachate
  • Evaluation
  • Runoff
  • Particulates
  • Nitrates
  • Phosphorus
  • Copper
• Publication/ Report Number:
  WA-RD 848.1
• Resource Type:
  Tech Report
• Geographical Coverage:
  Washington
• Corporate Publisher:
  Washington (State). Dept. of Transportation. Office of Research and Library Services
• Abstract:
  Compost is often used in raingardens, roadsides, and bioretention systems, not only because of ; its beneficial properties on soil quality, but also because compost improves water infiltration and ; retains stormwater contaminants. However, when compost is freshly applied, materials from ; compost can leach out when rain or stormwater seep through compost or compost-amended ; bioretention media. The goal of this research project was to experimentally evaluate and ; characterize leachates from compost. We quantified and characterized the leachate composition ; of compost following intermittent, simulated storm events. We used municipal compost of ; different ages and different source materials. Compost was filled into columns and then irrigated ; with deionized water and stormwater. Stormwater was spiked with copper to increase copper ; concentrations. Six-month, 24-hour rain storms were applied every two weeks for a total of up to ; 18 rain storms. Outflow was analyzed for pH, electrical conductivity (EC), particulate ; concentration, surface tension, dissolved organic carbon (DOC), nitrogen, phosphorus, and ; copper. Particulate and dissolved organic matter was further characterized for molecular structure ; by Nuclear Magnetic Resonance (NMR) and Fourier-Transformed Infrared (FTIR) Spectroscopy. ; Our results showed that concentrations of dissolved and particulate organic carbon and electrical ; conductivity in the leachate where high at the onset of each storm, but decreased as the storm ; progressed. However, each new storm released another peak of constituents. Leaching from ; mature compost was less a function of age and type, but more a function of number and ; frequency of storms and leaching history. Concentrations of nitrogen, phosphorus, and copper were high in the initial few storms, and then decreased. Only a small fraction (3%) of the copper ; present in the compost leached out, but nonetheless, the copper concentrations in the leachate ; remained above the regulatory waste discharge standards. NMR and FTIR analyses revealed that ; dissolved organic carbon consisted mainly of aliphatic and aromatic components typical of fulvic ; and humic acids. Our results show that municipal compost can serve as a sustained source of ; leaching of nutrients and metals, regardless of compost age and source. However, the copper ; concentrations observed in our experiment are likely not toxic due to the presence of elevated ; DOC, as DOC readily forms complexes with dissolved copper thereby reducing its toxicity to ; aquatic organisms. The DOC plays a dual role in terms of copper fate and transport: DOC can ; enhance leaching of copper by forming aqueous complexes, but at the same time, reduces toxicity ; of copper because copper-DOC complexes are less bioavailable.
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• Format:
  PDF
• Funding:
  T1462-03
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/29510/dot_29510_DS1.pdf
• File Type:
  [PDF - 3.08 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:dce3b6ef295f1f271f69396a09965df02d044ae29a8f9db0983e0d3944579952