Linking Phosphorus Extraction from Different Types of Biomass Incineration Ash to Ash Mineralogy, Ash Composition and Chemical Characteristics of Various Types of Extraction Liquids

Abstract

Phosphorus (P) rich ash from biomass incineration is a potential promising alternative for non-renewable phosphate rock. This study considered the P recovery potential of poultry manure ash, sewage sludge ash and meat and bone meal ash through wet chemical extraction. XRD analysis showed that these three ash types had a distinct P mineralogy. If inorganic acids were used for the extraction, the P extraction efficiency was not or only slightly affected by the P mineralogy. Contrarily, for the organic acids, alkaline extraction liquid and chelating agents considered, the P extraction efficiency was highly affected by the P mineralogy, and was also affected by the elemental composition of the ash and/or the chemical characteristics of the extraction liquids. Alkaline extraction liquids showed in general low heavy metal co-extraction, in contrast to the inorganic acids. From an economic point of view, of all extraction liquids considered, sulfuric acid was the most interesting to extract P from all three ash types. Oxalic acid could be a more sustainable option for P extraction from sewage sludge ash. In addition, extraction of poultry manure ash with ethylenediaminetetraacetic acid showed a relatively high P extraction efficiency combined with relatively low heavy metal co-extraction.

Sugarcane bagasse ash as fertilizer for soybeans: Effects of added residues on ash composition, mineralogy, phosphorus extractability and plant availability

“…In this study, P was extracted with 2% citric acid, yielding similar values for gBM ash (96.8%) as for TSP (98.0%), while cBM ash (85%), gB ash (78%) and cB ash (49%) contained less extractable P (% of P from total P; Figure 1B). This extractability of P was higher than in 0.5 M HCl, probably due to complexing agents in citric acid (Herzel et al, 2020;Luyckx et al, 2021). The lowest amount of P extracted with 2% citric acid was measured in cBS ash (30%; Figure 1B).…”

Recovery of phosphorus from sewage sludge ash: Influence of incineration temperature on ash mineralogy and related phosphorus and heavy metal extraction

“…Figure 3 shows that the P extraction efficiency with sodium hydroxide gradually decreased with increasing incineration temperature, which is related to the decreasing mass fraction of Al/Fe-phosphates in the SSA (see Figure 2). In general, Al-and/or Fe-phosphates dissolve well in alkaline extraction liquids such as sodium hydroxide, whereas Caphosphates do almost not dissolve in alkaline environment [14,30,54,55]. However, the P extraction efficiency with sodium hydroxide was generally lower than the mass fraction of Al/Fe-phosphates in the SSA samples obtained from the SMT protocol.…”

“…Hydrochloric acid was selected because it is available on an industrial scale, and upon extraction, no additional solid residue is formed, only the ash extraction residue remains. Sodium hydroxide was selected because previous work showed that it co-extracts less heavy metals during P extraction compared to the beforementioned acids [13,14,29,30]. The experiments were carried out at the optimal extraction conditions determined in previous work of the authors [13]: sulfuric acid, hydrochloric acid and oxalic acid were applied at a concentration of 0.5 N, an L/S ratio of 10 ml/g ash and a contact time of 2 h; sodium hydroxide was applied at a concentration of 0.5 N, an L/S ratio of 50 ml/g ash and a contact time of 2 h.…”

“…In contrast, oxalic acid showed lower co-extraction of heavy metals compared to sulfuric acid and hydrochloric acid (respectively, about 17% of heavy metals extracted compared to about 23%, see Figure 4.g). However, from an economic point of view, it might be most interesting to use sulfuric acid because it is cheaper than oxalic acid and hydrochloric acid [13,14,77].…”

“…Many experts prefer P recovery from SSA by wet chemical extraction over thermochemical treatment and other recovery methods because of the high efficiency, low costs and because it is similar to the process currently used for extraction of P from phosphate rock [3,5]. In previous work of the authors, it was found that the type of extraction liquid, extraction liquid concentration, liquid/solid (L/S) ratio, contact time, pH, ash composition and ash mineralogy all affect P and heavy metal extraction efficiency from SSA [13,14]. Moreover, other literature shows that the temperature at which the SS is incinerated can alter the P mineralogy of the SSA and in this way can also affect the P extractability [3,8,15,16].…”