Chapter Three - Small Solutions to Large Problems? Nanomaterials and Nanocomposites in Effluent, Water, and Land Management

Abstract

The development of nanoscience and nanotechnologies, involving research and technology development at the atomic, molecular, or macromolecular levels in the length scale of approximately 1–100 nm, has been heralded as a potential solution to many key water purification, waste water and effluent treatment, and soil and groundwater management issues. The use of nanotechnology in effluent, water, and soil clean-up applications largely makes use of the enhanced reactivity, surface area, and/or enhanced mobility of nanoparticles. Serious concerns have, however, been raised concerning the health implications of widespread nanoparticle use and release, deriving largely from the small size, and high reactivity and potential mobility (in both environmental and biological systems) of engineered nanoparticles. There are also serious cost issues related to bulk use of many novel nanomaterials, and questions over the scalability of treatment processes. This chapter discusses current applications of nanotechnology relevant to the treatment of agricultural and food production wastes and effluents, and outlines recent research on nanocomposites and nanostructured materials aimed at producing scalable, low-cost, and nontoxic devices for effluent and water treatment and land remediation and regeneration. Prototype devices based on reactive nanoparticles incorporated into stable polymer, silica, and carbon-based “scaffolds,” or on carbons with “tailored” nanostructure, show considerable utility in the rapid removal of a range of problem contaminants from water and effluent streams, including problem agricultural pesticides such as metaldehyde, atrazine, and malathion. The use of a flexible (and low-cost) scaffold as a host for the reactive nanoparticles allows the devices to be produced in a range of geometries, which permits their use in a variety of configurations at point of treatment or as decentralized solutions, for example, as a high-throughflow filter for liquids, in a column, membrane or bed reactor, or as permeable reactive barrier materials. The potential advantages of the nanocomposite approach are discussed and evaluated, and the potential for wider application of these and similar devices in effluent, waste and water treatment, and land management, critically evaluated.