Nanoparticles in Biosolids: Effect on Soil Health and Crop Growth

Nanoparticles are becoming popular from their use in medicine for therapy, diagnostics and imaging, in pharmacy for drug delivery, to its use in electronics, engineering and manufacturing industries. This wide application has increased their presence in the environment especially in wastewater from municipal and industrial sources. They end up in the fi nal product; biosolids which are treated sewage sludge from wastewater treatment plants. Due to limited space in landfi lls and cost effectiveness, biosolids are predominantly disposed in land applications as organic fertilizer for crop production or land reclamation. Nanoparticles have been detected in wastewater and biosolids raising concerns about their effect on soil health and crop growth. While a large number of studies have been conducted on effect of nanoparticles on seed germination and plant growth, few studies have been carried out using biosolids. The sole effect of nanoparticles may be different from when it's present in biosolids due to reaction with some components in biosolids. Hence more work is needed in this area to provide direction for regulation of biosolids. Studies have reported both positive and negative effects of nanoparticles on plant growth showing that it depends on plant species, type of nanoparticle, and dose of nanoparticle and method of application. There is also very little work on effect of nanoparticles on soil health. Most of the work done has shown the antimicrobial effect of some nanoparticles which could affect nutrient release from the organic matter fraction in the soil and disrupt some plant-microbe relationships that promote soil fertility. Although nanoparticles have proved benefi cial in many aspects of life, they need to be monitored due to their increasing use in the environment.