Biosorbent, a promising material for remediation of eutrophic environments: studies in microcosm

Abstract

Eutrophication is considered a global environmental problem that causes economic and biodiversity loss. Together with excess phosphorus in some aquatic environments, there is the depletion of phosphate rock deposits, which can directly affect fertilizer production and therefore global food security. Thus, the present work aimed to study a new remediation technique for eutrophic environments that enables the recovery of these environments through phosphorus adsorption in sawdust, creating the possibility to apply the phosphorus-enriched material as an agricultural fertilizer. The study was conducted in 36 microcosm flasks with water and sediment samples from a eutrophic reservoir in Ibirité/MG. The experiment was carried out using 18 control flasks and 18 others as treatment, consisting of water and eutrophic environment sediment and, additionally, two bags, containing 10 g of sawdust in each bag. The phosphorus adsorption on sawdust was more intense after 49 days of immersion in the microcosm, and reductions of 90% in the concentration of reactive soluble phosphorus were observed in the water column of the microcosm treatment at 159 days of the experiment. Based on the results, it can be concluded that, although the phosphorus concentration adsorbed on sawdust (16.2 μg g) is considered low, the use of the biosorbent is a particularly promising technique for remediation of eutrophic environments, as well as the possible reuse of the adsorbed phosphorus as a fertilizer in agriculture.

Remediation of Eutrophic Aquatic Ecosystems: Evaluation of Phosphorus Adsorption by Sawdust

“…This value is considered low for future agricultural applications and even to apply this technique on a real scale. This value does represent a gain, however, because it is higher than that determined by Pantano, Aquino et al () (16.2 µg/g) when using smaller sawdust particles (particle size, 0.2‐2.0 mm).…”

“…Under oxidizing conditions (positive values for E H ) the adsorption of P is favored by the formation of Fe(III) oxyhydroxide biofilm (Rentz et al ; Mort et al ; Gault et al ; Pantano, Aquino et al ; Wang et al ). The values determined in the water column of the control microcosms ranged from –27 to 305 mV; for the treatment, this variation was –35 to 351 mV.…”

“…Pantano, Aquino et al () conducted laboratory experiments with water and sediment samples from a eutrophic aquatic body. They showed that the sawdust ( Pinus caribaea var hondurensis ), with a particle size under 2 mm, was a promising biosorbent for P, with an adsorption capacity of 16.2 μg P g –1 at 159 d of incubation time.…”

“…A well known correlation is proven between Fe and P compounds; one that iron hydroxides have a high ability to trap phosphorus, in a process involving the oxidation of dissolved Fe(II) and consumption of Fe minerals that is mostly dominated by the Fe-oxidizing bacteria action. Therefore, the use of the biosorbent is founded on the biogenic oxidation of Fe(II), resulting in the formation of Fe (III) oxy-hydroxides, whose main characteristic is a high capacity of phosphate ion adsorption, thus promoting its removal from the water column (Rentz et al 2009;Mort et al 2010;Takeda et al 2010;Gault et al 2011;Benyoucef and Amrani 2012;Pantano, Ferreira et al 2017;Wang et al 2019). conducted laboratory experiments with water and sediment samples from a eutrophic aquatic body.…”

Microcosm Study: Effect of Fe(II) Addition in Sawdust for Phosphorous Recovery from Eutrophic Aquatic Ecosystems

“…The study of phosphorus recovery techniques in eutrophic aquatic ecosystems is very important considering water scarcity and food production. The use of sawdust for removal of this excess from eutrophic systems for further use as soil fertilizer is a possible solution to ensure water and food security [18][19][20].…”