A POTW facility that operates an anaerobic digestion process generates 2200 tones of waste water sludge per year. The solids content of the raw sludge is 4% by weight. The dry weight concentrations (mg/Kg) of cadmium, copper and lead in the sludge are 50, 1250, and 250, respectively. Two options for the sludge are being considered:
1. First, it is thought that the sludge can be incinerated. If the heat value of dried sludge is 12,804KJ/Kg dry solid and the heat of vaporization of water is 40.656KJ/mol of water, what does the water content of the sludge need to be in order to "break even" in energy?
2. Second, it is thought that the sludge could be used for land application. What is the permitted application rate of this bio-solid to a hectare of land? How many hectares of land can be fertilized at this rate? Assuming no losses of these metals to the land, how many years can land application be performed?
Type no more than a 1 page description of which alternative you would recommend and why.