Land application of biosolids refers to the spreading of biosolids on or just below the soil surface for beneficial use. The practice includes applying to:
• Agricultural land, such as fields used for the production of food, feed, and fiber crops
• Pasture- and rangeland
• Public contact sites, such as parks and golf courses
• Nonagricultural land, such as forests
• Disturbed lands, such as mine spoils, construction sites, and gravel pits
• Superfund sites for reclamation (Henry and Brown, 1997)
• Dedicated land disposal sites
• Home lawns and gardens
Biosolids are applied to the land at agronomic rates, that is, rates designed to provide the amount of such macronutrients as nitrogen, phosphorus, and potassium needed by the crop or vegetation grown on the land while minimizing the amount that passes below the root zone. Land-applied biosolids are subjected to further destruction of pathogens and destruction of many toxic organic substances from the combined effect of sunlight, soil microorganisms, and desiccation.
To qualify for land application, biosolids or materials derived from biosol-ids must meet at least the pollutant ceiling concentrations, class B pathogen requirements, and vector attraction reduction requirements. Biosolids that are sold or given away in bags or other containers for application to lawns and home gardens must meet the exceptional quality pollution concentration limits, class A pathogen requirements, and vector attraction reduction require ments. Because of the continuing concern with wastewater sludge disposal, many farmers accept only class A sludge, forcing wastewater treatment plant operators to modify their sludge treatment schemes (Vesilind, 2003).
Was this article helpful?