Submitted to: Soil and Water Conservation Society
Publication Type: Abstract Only
Publication Acceptance Date: 1/28/2015
Publication Date: N/A
Technical Abstract: Excess soil phosphorus (P) beyond the assimilative capacity of soils is a major factor to discontinue application of biosolids to land nearby municipal wastewater treatment plants. For this reason, municipalities incur in hefty fees for transportation and landfilling biosolids that otherwise could be used as soil amendment. A new treatment process, called “quick wash” was developed and patented by the USDA-ARS for recovery of P from manure solids. Additional research showed the approach is very effective to recover P from municipal biosolids prior to land application. This process was developed for rapid wet extraction of P from raw waste and recovery of P in solid concentrated form, improving the nitrogen (N) and P balance in the waste. This process consists of selectively extracting P from organic wastes using mineral or organic acids, and recovery of P from the extract by adding lime and an organic polymer forming a calcium-containing P precipitate. The quick wash process can recover more than 80% of the P from the waste stream, while leaving most of the N in the washed solid residue. Consequently, the washed solid residue has a more balanced N:P ratio for crop production and is safe for land application. Because the quick wash process is conducted at ambient temperature, it avoids loss of oxidizable organic carbon (C) and N from washed residues. Thus, the land application of washed solid residues contribute with C and N to maintaining soil health while reducing the environmental risks of excess soil P. The concentrated P materials contain more than 90% of its P in plant available form that provides a recycled P source for use as crop fertilizer. The inclusion of this treatment process in municipal wastewater treatment systems offers both rural and urban communities an opportunity to minimize P losses into the environment and sustain soil health while recovering and recycling P as a valuable product.