Availability and Environmental Impact of Phosphorus in Soils Amended with Biosolids: Effect of Wastewater Treatment Processes on the Forms, Solubility, and Biological Availability of Phosphorus in Municipal Biosolids

Legislation in the Mid-Atlantic area, and elsewhere globally is shifting nutrient management planning efforts in the direction of mandating controls on phosphorus (P) losses to surface waters and shallow ground waters, in addition to the established focus on potential nitrogen (N) losses. A systematic assessment of the risks of biosolids-P application to soils becomes essential. When biosolids are applied to soils, it is apparent that the availability of the P should be considered when determining appropriate loadings, but this may vary according to the type of biosolids used. Accordingly, this study examined various biosolids samples to compare these properties, including many different biosolids and a set of P fractionations. An initial drying procedure at 60 C instead of 105 C was first developed in order to preserve fractionation characteristics. Findings include the general uniformity of P fractionation in terms of total P, across a suite of samples, but variability of soluble vs. insoluble fractions according to the use of biological P removal vs. chemical precipitant usage. A cationic polymer was indicated to remove some P from the soluble fraction.