Phosphorus removal from wastewater by field-scale fortified filter beds during a one-year study

Abstract

Due to low availability of alternative technologies, rural communities are unable to comply with national wastewater discharge limits. This study tested the effectiveness of filter bed fortification with biochar on phosphorus removal. Water-tight down-flow beds of sand and gas concrete, constructed alongside a reference sand bed (all 0.8 m deep and 0.75 m(2) surface area), were topped with a 0.2 m biochar layer. Pre-treated domestic wastewater with mean concentrations of 6.4 mg/L [Formula: see text] and 142.6 NTU, was infiltrated at 4 cm/d hydraulic loading rate. Ultimately, the biochar-sand was relatively outstanding in turbidity reduction, achieving <5 NTU. The biochar-gas concrete exhibited superior performance in [Formula: see text] removal, trapping 32.3 g (40.2%), compared with 20.5 g (25.6%) and 15.5 g (19.3%) by biochar-sand and reference bed respectively. However, statistical analysis revealed a weak correlation between pH and biochar-gas concrete removal efficiency (r(2 )= 0.2). The relationship was stronger for biochar-sand [Formula: see text] (r(2 )= 0.5) than reference (r(2 )= 0.4) bed. Paired samples t-tests showed that incorporating biochar into the sand bed significantly (p = .04) improved its [Formula: see text] removal efficiency. In conclusion, sand bed fortification with biochar could be an important measure for improving P removal and wastewater clarification efficiency.

Filter Media-Packed Bed Reactor Fortification with Biochar to Enhance Wastewater Quality

“…3− sorption in the C and SaC effluent, respectively, was explained by the variation in their pH measure while only 53% did for Sa. Except for turbidity, P-removal in an earlier field-scale study [27] related to this current study was a bit lower. The warmer room conditions (17-25 • C), less-mixed influent wastewater, small loaded wastewater volumes (0.021 L) per dose, etc., and smaller particle sizes (2-4 mm) used in the current study are believed to have contributed largely to the higher efficacies of the media.…”

“…Scientific investigations have provided insights suggesting that the chemical content and porosity of biochar contribute to its capability to interact with and thus trap P. For instance, the 73% of P removal efficiency by the biochar studied by Yao et al [26] was attributed to its content of periclase (MgO). Various studies reported through investigations with Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and solid-state 13C nuclear magnetic resonance (NMR), the development of aromatic functionality and porosity in biochar produced under pyrolysis conditions of >400 • C. Therefore, it is possible that, if added to sand or soil filters, it could boost their performances, which we previously tested in a field pilot-scale treatment system [27]. In order to control and measure the treatment performance of certain parameters we also arranged a laboratory column experiment with real wastewater.…”

A Review of Phosphorus Removal Structures: How to Assess and Compare Their Performance

“…Consider now the calcareous oil-shale ash used by Vohla et al [41] versus the P removal structure utilizing laterite [42]. The former removed only 5.6% of P after a loading of nearly 12,000 mg kg −1 dissolved P. This translated to a cumulative P removal of 656 mg kg −1 , which is a relatively large mass of P removal.…”

Potential of Biochar Filters for Onsite Wastewater Treatment: Effects of Biochar Type, Physical Properties and Operating Conditions

“…According to the supplier of the sand used in the studies, it had been mixed with 5% lime. The presence of Ca, Fe, Al and Mg, which have an affinity for soluble reactive P, is an important feature of a filter medium, as adsorbed PO 4 3− will precipitate to form surface complexes and hence be immobilised [25]. Based on the elemental composition, activated biochar and sand can be predicted to have the highest potential for P adsorption from wastewater.…”