Phosphorus Removal from Wastewater: The Potential Use of Biochar and the Key Controlling Factors

Abstract

In recent years, a large volume of literature has been published regarding the removal of phosphorus (P) from wastewater. Various sorbing materials, such as metal oxides and hydroxides, carbonates and hydroxides of calcium (Ca) and magnesium (Mg), hydrotalcite, activated carbon, anion exchange resins, industrial solid wastes and organic solid wastes, have been suggested for P removal. Many of these sorbents are expensive and/or may cause some environmental problems. In contrast, biochar, as an economical and environmentally friendly sorbing material, has received much attention in recent years and has been used as a novel sorbent for the removal of different organic and inorganic pollutants. Biochar is a type of sustainable carbonaceous material that is produced from the thermal treatment of agricultural organic residues and other organic waste streams under oxygen free conditions. This paper reviews the potential use of biochar and the key controlling factors affecting P removal from wastewater. The ability of biochar to remove P from wastewater depends on its physical and chemical properties. Some of the most important physicochemical properties of biochar (structural characteristics, electrical conductivity (EC), mineral composition, pH, zeta potential, cation exchange capacity (CEC) and anion exchange capacity (AEC)) are affected by the feedstock type as well as temperature of pyrolysis and the P sorption capacity is highly dependent on these properties. The P removal is also affected by the water matrix chemistry, such as the presence of competing ions and bulk pH conditions. Finally, several recommendations for future research have been proposed to facilitate and enhance the environmental efficiency of biochar application.

Adsorption and desorption of nutrients from abattoir wastewater: modelling and comparison of rice, coconut and coffee husk biochar

“…Chemical sorption is dependent on the type of biochar, the number and type of functional groups, and the chemical composition of the biochar, while physical sorption is related to the structure and surfaces of the biochar. A similar finding was reported by Nobaharan et al (2021). The authors reported that the biochar physical properties were affected by the P sorption from wastewater, structural properties derived from different biochar original feedstocks.…”

Water Resource Recovery Facilities (WRRFs): The Case Study of Palermo University (Italy)

“…Once exhausted, zeolites will be removed from the column and applied to soil as conditioner. The columns with biochar do not provide for a backwash because P is mainly retained irreversibly and only slightly adsorbed, thus making the desorption not economically recommended [47]. However, when biochar is exhausted, it will be applied to soil as both slow-release fertiliser and CO 2 sink [48].…”

Roadmapping the Transition to Water Resource Recovery Facilities: The Two Demonstration Case Studies of Corleone and Marineo (Italy)

“…On the other hand, the biochar column is not provided with a backwash system, because P is mainly irreversibly retained. When the biochar is exhausted, it will be directly applied to soil as both the CO2 sink and slow-release fertilizer [25]. This pilot plant is aimed at enhancing the state-of-the-art PHA production from urban wastewater with the use of high SRT waste activate sludge (WAS) as the substrate for VFA production [21,22].…”

“…On the other hand, the biochar column is not provided with a backwash system, because P is mainly irreversibly retained. When the biochar is exhausted, it will be directly applied to soil as both the CO 2 sink and slow-release fertilizer [25].…”