Increasing numbers of filter materials have been proposed as suitable media for P removal in on‐site wastewater treatment systems. The phosphorus sorption capacity (PSC) of the material can be estimated in batch experiments and is commonly used as the criterion for material selection. However, there is no standard procedure and batch experimental parameters are arbitrarily established, thus leading to difficulties in comparing the results. The main parameters affecting the batch adsorption system are the form and amount of material, material‐to‐solution ratio, nature, pH and initial concentration of P solution, contact time, agitation, and temperature. This paper critically reviews a number of relevant studies that used batch experiments to estimate the PSC of different filter materials. The nature and form of the materials vary significantly and there is broad variation in the batch experimental parameters set in the selected studies. Analysis of the data from selected studies showed a relationship between particle size or pH of the material and its PSC. The initial P concentration of the solution and the material‐to‐solution ratio in the batch system were found to be correlated with the estimated PSC, suggesting that batch parameters have a great influence on the results. Based on the analysis of the selected studies, the difficulties of using batch experiments are outlined, recommendations for batch experiment procedure are suggested and a classification system for filter materials according to their PSC and particle size is presented.

Argon oxygen decarburisation (AOD) slag may be used for phosphorus (P) removal, as its high pH and weatherable calcium (Ca) minerals provide sufficient Ca(2+) and OH(-) for calcium phosphate (Ca-PO4) precipitation. This study examined the P removal performance of AOD slag for use as wastewater treatment material. Batch experiments were carried out using both synthetic P solution and real wastewater, followed by chemical modelling and X-ray absorption near edge structure (XANES) spectroscopy. The influences of initial P concentration, slag dose and modification by polyethylene glycol (PEG), an effective agent for generation of porous materials, were investigated to determine the optimal conditions for P removal by AOD slag. It was found that virgin AOD slag removed 94.8% of P from a synthetic P solution in 4 h and 97.8% in 10 h. This high P removal was accompanied by a rapid increase in pH from 7.0 to 10.74. The maximum P removal capacity (PRC) from synthetic P solution ranged from 1.3 to 27.5 mg P g(-1). The optimal AOD dose for P removal from wastewater, determined in 8-h batch experiments, was 25 g L(-1). PEG modification increased the reaction rate and resulted in higher final pH, increasing PRC by 47.9%. Combined Visual MINTEQ and XANES analysis for detailed examination of P removal mechanisms revealed that the main P removal mechanism was precipitation of calcium phosphate. According to the XANES analysis, the main Ca-PO4 precipitate formed on virgin AOD slag under low initial P concentration and high pH was apatite, while brushite was the dominant product at high initial P concentration and low pH.