An attempt to learn about heavy metal levels in Municipal Waste Compost, especially "fluff", inspired by this worldchanging.org blog entry: I (heart) Fluff
Reminder: 1ppm equals 1 mg/kg
URLs of the studies and articles referenced by the Wastaway Company:
- Evaluation of composted household garbage as horticultural substrate, Auburn University
- Evaluation of composted municipal waste as amendment to pine bark in use for container ornamental production, Auburn University
- Byproduct of novel waste treatment system promotes plant growth, Public Works Digest, Volume XVI, No. 4
- Waste is a terrible thing to mind, Auburn University
- Horticultural substrate analysis, Composite Products of America
Table 4.28 in Waste Management Textbook (3rd german edition):
mg/kg normalized for 30% OS i. d. TS (organic substance in the dry substance) (bio compost = kitchen waste)
| Element | bio compost | bio compost and paper | plant compost | wet waste compost | unsorted municipal waste compost |
| Pb in mg/kg | 83.07 | 116.20 | 63.10 | 705.00 | 596 |
| Cd in mg/kg | 0.84 | 0.96 | 0.72 | 4.08 | 6.39 |
| Cr in mg/kg | 35.83 | 39.80 | 28.44 | 113.00 | 82.9 |
| Cu in mg/kg | 46.76 | 76.20 | 34.52 | 357.80 | 318 |
| Ni in mg/kg | 20.48 | 21.40 | 18.56 | 47.10 | 52.1 |
| Zn in mg/kg | 249.10 | 350.30 | 176.92 | 1334.00 | 1823 |
| Hg in mg/kg | 0.38 | 0.54 | 0.28 | 1.63 | 2.79 |
Table 4 in Waste is a terrible thing to mind, Auburn University (Table layout edited for clarity). Table header was: Element and soil analysis of Municipal Solid Waste Compost (MSCW) passing through a one-inch screen. Footer was: Analysis was conducted by Auburn University Soil Testing Laboratory using the saturated paste extract method, February 2004
| Measured quality | Measured quantity | unit |
| Ca | 88.9 | ppm |
| K | 580.9 | ppm |
| Ma | 18.4 | ppm |
| P | 9.2 | ppm |
| Al | 7.5 | ppm |
| B | 3.8 | ppm |
| Ba | 0.1 | ppm |
| Cd | <0.1 | ppm |
| Co | <0.1 | ppm |
| Cr | 0.6 | ppm |
| Cu | 20.9 | ppm |
| Na | 1154.3 | ppm |
| Ni | 0.7 | ppm |
| Pb | 0.9 | ppm |
| Zn | 4.1 | ppm |
| No3-N | 38.7 | ppm |
| EC | 9.5 | mmhos/cm |
| SS | 6650 | ppm |
| pH | 7,86 | |
| N | 1.22 | % |
| C | 31.55 | % |
| C:N | 26:1 | ratio |
Question: How can there be such a huge difference in measured lead content, between 0.9 ppm and over 500 ppm?
Theory: The Auburn study does not measure lead content correctly (0.9 ppm in the liquid phase, not in the compost dry mass?)
- Find out what the "saturated paste extract method" is.
Analysis Methods for lead according to EPA Document SW-846 Test Methods for Evaluating Solid Waste
- Method 6010 Inductively Coupled Plasma-Atomic Emission Spectrometry
- Method 6020 Inductively Coupled Plasma-Mass Spectrometry
- Method 7420 Lead (Atomic Absorption, Direct Aspiration)
- Method 7421 Lead (Atomic Absorption, Furnace Technique)