Assessing the suitability of solid aggregates for nutrient recovery from aqua systems

Since the bourgeoning interest in solid phase recovery of nutrient from wastewater, a large number of solid phase materials have been investigated, either as adsorbents or reactive materials in nutrient recovery technologies. The theoretical basis for the choice of these material are often shrouded and not teased-out, which made it difficult to understand the underlying mechanism of the recovery process. In this treatise, an overview of the theoretical basis for the choice of solid phase material for nutrient recovery from wastewaters was provided. The primary consideration for the choice of a solid phase material for nutrient recovery include the nutrient adsorption capacity, the pore size, pH values, chemical and mineralogical assemblage and surficial physiognomies. In order to ensure the sustainability of the process, the material must be readily available, low-cost, ecofriendly, and ease of nutrient release for plant growth. Good hydraulic conductivity, to minimize the risk of clogging, when applied as barriers or filters was also identified. Furthermore, an evaluation of the concentration and bioavailability of possible contaminants leached from the solid phase material is required. Despite the plethora of materials that have been investigated as solid phase material they can be easily classified as green and non-green materials. This classification can be further sub-divided into organic, inorganic and composite solid phase materials.