Can biosolids pollute or contaminate surface and groundwater?
Biosolids pose little risk to groundwater or surface water quality. As with any fertilizer, the chief groundwater concern is use of nitrogen, the application of which is regulated. Unlike commercial fertilizers, about 95 percent of the nitrogen in biosolids is present in a slow-release organic form, making biosolids less likely to cause groundwater pollution from the release of nitrates (the mobile form of nitrogen). Regulations limit the use of biosolids on agricultural land to strict agronomic loading rates, the rate that is necessary for crop growth but which minimizes passage beyond the root zone. In addition, when biosolids are applied to land with the adequate soil pH, the solubility of metals is controlled, preventing them from moving into groundwater. Most state regulations require that the soil pH be maintained at 6.0 or higher, to ensure that metals do not contaminate soil and groundwater.
Biosolids pose little risk to ground or surface water quality if applied and managed correctly. As with any fertiliser the chief water quality concern is the use of nitrogen and phosphorus, the application of which is regulated. Unlike commercial fertilisers about 85 per cent of the nitrogen in biosolids is present in a slow-release organic form, making biosolids less likely to cause water pollution from the release of nitrates (the mobile form of nitrogen) or phosphates. Regulations limit the use of biosolids on agricultural land to strict agronomic loading rates, the rate that is necessary for crop growth but which minimises passage beyond the root zone. In addition, when biosolids are applied to land with appropriate soil pH the solubility of metals is controlled, preventing them from moving into groundwater. State regulations require that the soil pH be maintained at 5.
