If we apply 5 tons of dry biosolids then:
Metal added/acre = lb per ton X application rate. (may need to convert lb/A to Kg/ha, use conversion factor 0.00224)
|
Example: Cu added = 5 tons X 0.566 lb per ton Cu Cu added = 2.83 lb Cu Ni added = 5 tons X 0.072 lb per ton Ni Zn added = 5 tons X 0.92 lb per ton Zn Cd added = 5 tons X 0.002 lb per ton Cd Pb added = 5 tons X 0.14 lb/ton Pb Mo added = 5 tons X 0.146 lb/ton Mo Arsenic added = 5 ton X 0.00478 lb/ton Se added1= 5 ton X 0.00538 lb/ton |
If we wanted to calculate the amount of biosolid we could apply and still meet our annual pollutant loading rate (APLR), then we could utilize the following example:
|
APLR tons/A
Conc. In biosolids/ton |
= tons/A dry
|
|
Arsenic = 1.8
(APLR) 0.00478 lb/ton |
=
|
376.57
tons could be applied |
* (Most permits restrict sludge application to 5 tons/A dry. Exceptions are made for reclaimed areas.) The APLR is the maximum amount of regulated pollutants in biosolids that can be applied to a site in any one year. CPLR is cumulative pollutant loading rate, the maximum amount of regulated pollutants in biosolids that can be applied to a site considering all biosolids applications made after July 20, 1993. Different classes of biosolids have different restrictions. Refer to the latest EPA guidelines.
Cadmium annual application should not exceed 2 lb/acre in most cases.
Max tolerable heavy metals accumulation depends on Soil Cation Exchange Capacity (CEC) of each soil. The OEPA regulates the concentrations of heavy metals that may be applied and all application sites must be authorized.
pH > 6.5 minimizes metal uptake by plants. The OEPA limits application of biosolids to crop land with a pH of 5.5 or greater (accurate at the time of printing).