Nitrogen and Phosphorus Loss Potential from Biosolids-Amended Soils and Biotic Response in the Receiving Water

Abstract

Application of municipal biosolids to agricultural soil can improve soil quality and improve crop yields. However, runoff or tile leachate from biosolids-applied fields may contribute to localized eutrophication of surface water. A laboratory experiment was conducted to determine loss potential of nutrients from soils amended with two different biosolids (anaerobically digested and chemically stabilized) relative to loss from a reference soil and to determine response in freshwater microcosms to nutrients lost from soils. Total phosphorus (TP) and total nitrogen (TN) were measured in runoff, and equivalent amounts were added to reference microcosms to determine if aquatic systems would respond similarly to TN and TP loading in bioavailable forms (PO, NH, NO) simulating loading related to inorganic fertilizer application. Nutrient concentrations (TP, TN, PO, NH, NO, and organic P and N) were similar in the runoff from the two biosolids-amended soils and higher than those in the runoff from the reference soil. Runoff from biosolids-amended soils stimulated algal growth and production (chlorophyll a and dissolved oxygen) relative to runoff from reference soil, but the response was weaker than in microcosms receiving equivalent amounts of inorganic N and P. Nutrient runoff from land-applied biosolids does have potential to increase algal production in receiving waters; however, this experiment suggests receiving waters may absorb a single large nutrient loading event associated with runoff from biosolids-amended soil without substantial impact. Moreover, the response to N and P in biosolids versus inorganic nutrient additions suggests biosolids may contribute relatively less to eutrophication than inorganic fertilizers, assuming equivalent TN and TP loading to aquatic systems.

Environmental Comparison of Biochar and Activated Carbon for Tertiary Wastewater Treatment

“…Although not included in this model’s scope, it is important to note that biosolids and artificial fertilizers could have different impacts after application. For example, nutrient runoff might be higher from artificial fertilizer, and biosolids land application can imply the risk of contaminating soil and adjacent waterways with heavy metals and persistent organic micropollutants. − …”

Vertical Phosphorus Migration in a Biosolids-Amended Sandy Loam Soil in Laboratory Settings: Concentrations in Soils and Leachates

“…Within the five months of the research, leachate from both biosolids-amended soil columns and reference soil columns demonstrated phosphorus concentrations around 0.039-0.054 mg/L. These concentrations were much smaller than the concentrations of phosphorus measured in runoff from biosolids-amended soils [17,20,29,[36][37][38]. but still exceeded concentrations suggested as optimal for limiting eutrophication potential (below 0.025 mg/L in streams and 0.01 mg/L in lakes) [39].…”

“…Runoff and erosion are important pathways of soil phosphorus loss [9,10], and the majority of studies on phosphorus loss from agricultural land are devoted to losses through runoff and erosion [11][12][13][14][15][16]. Application of municipal biosolids, specifically, can increase total phosphorus (TP) in runoff from soil in laboratory mesocosms [17], although loss of P in runoff in agricultural soils may be dependent on the stabilization method used to produce the biosolids [18][19][20]. These losses represent only horizontal migration of phosphorus through surface runoff, while vertical migration of phosphorus through the soil layers can also contribute to the phosphorus escape from agricultural lands [21].…”