Workshop
Resolutions
A workshop was held in Melbourne recently between state regulators, researchers and the water industry to examine the issue of cadmium additions to soils in organic fertilisers and recycled wastes e.g. biosolids.
Agreement was reached on the following actions:
- Controls
at source (i.e. trade waste policies) to be reviewed. Traceback
of Cd in biosolids in treatment works with high Cd concentrations
to determine where additional controls are needed on influent
concentrations;
- Maximum
annual loading rate of 30g/ha/yr averaged over 5 years (150g/ha/5yr);
- Maximum
soil concentration 1.0 mg/kg, unless local data indicate lower
limit;
- Biosolid
cadmium grading – national guideline to be adopted (when
finalised);
- Research
to suggest soil/biosolid bioavailability index & what is
a sustainability system;
- An
analytical quality assurance program be encouraged through the
Australasian Soil and Plant Analysis Council; and
- Controls
on Cd in wastes other than biosolids to be considered e.g. other
animal and urban wastes and composts.
US
EPA issues final rule on maximum permissible
contaminants in zinc fertilisers
"The
US EPA has issued their final regulation
on recycling of zinc wastes as fertilisers,
and has set maximum cadmium, and other
contaminant, concentrations in zinc
fertilisers. The maximum permitted concentration
for cadmium is 1.4 mg/kg per percentage
zinc content. For further information
see http://www.epa.gov/epaoswer/hazwaste/recycle/fertiliz/index.htm"