Ashes from Sewage Sludge and Bottom Sediments as a Source of Bioavailable Phosphorus

Abstract

Phosphorus is an element necessary for the growth of plants. As phosphate rock gets depleted, it becomes an increasingly scarce resource. Therefore, it seems necessary to implement simple methods of cheap and effective phosphorus recovery from waste. The ashes of municipal sewage sludge and bottom sediments constitute particularly valuable sources of phosphorus. However, these materials usually carry significant amounts of pollutants, including heavy metals. Optimization of ash phosphorus sequential extraction methods from a thermal conversion of sewage sludge and bottom sediments allows to select an effective and simple technology of phosphorus recovery, while maintaining low heavy metal pollution, which is one of the main restrictions in use of ashes. Determination of an amount of bioavailable phosphorus is therefore a basis for estimation of the possibility of using it from waste. Extraction using the Golterman method or shaking out with calcium lactate or Trougs reagent indicates that the ashes from sewage sludge and bottom sediments are rich sources of bioavailable phosphorus, which could find use under field conditions as a viable alternative to fertilizers containing fossil phosphorus.

Inorganic Fertilization at High N Rate Increased Olive Yield of a Rainfed Orchard but Reduced Soil Organic Matter in Comparison to Three Organic Amendments

“…The Ash + N treatment tended to show values that rarely stood out in comparison to the treatments of inorganic or organic fertilization, which seems in accordance with its initial composition. In general, bottom ashes are fertilizing materials that can be valued for their content in nutrients such as P, K, Ca or Mg [20][21][22], but which can also present toxicity problems as they may contain high levels of heavy metals, such as Cd, Cr or Pb [23][24][25][26]. In this study, neither aspect deserves to be highlighted, perhaps reflecting, once again, its initial mineral composition and the moderate rates in which it was applied.…”

“…Fly and bottom ashes from burnt wood biomass in thermal power plants are materials of varied elemental composition, but with potential to be used in agriculture. These fertilizing materials can contain high levels of some valuable nutrients, such as calcium, phosphorus, potassium and/or magnesium [20][21][22], but also high levels of heavy metals [23][24][25][26] Nonetheless, several studies have shown benefits in soil properties or in the growth of agricultural and forestry plants through the application of wood ash [27][28][29][30].…”

Archives of Environmental Protection

“…All technologies and solutions are focused on use of waste as an alternative source of raw materials (Ciesielczuk et al, 2018) in fertilizer industry should be evaluated from economic (Generowicz et al 2011, Kowalski et al 2012, Jóźwiakowski et al 2015, Makara et al 2016, environmental (Feng andReisner 2011, Koneczna andMoghim and Garna 2019) and social points of view. The impact of the above technologies on the environment can be evaluated using environmental assessment methods (Kowalski et al, 2007, Gaska et al, 2017.…”