Powdered activated carbon augmented double react-settle sequencing batch reactor process for treatment of landfill leachate

Three types of sequencing batch reactors (SBRs) were used in the treatment of landfill leachate in Kulim, Malaysia. These SBRs were a non-powdered activated carbon SBR (NPAC-SBR), powdered activated carbon SBR (PAC-SBR), and double react-settle SBR (DRS-SBR). Powdered activated carbon was used to augment the SBR process in the PAC and DRS reactors. The first two reactors operate on five conventional phases (i.e., fill, react, settle, draw, and idle), whereas the third operates on seven phases (i.e., fill, react I, settle I, react II, settle II, draw, and idle). Raw landfill leachate was treated in 20 experiments. The PAC- and DRS-SBRs exhibited better performance, improved sludge characteristics, and superior aeration energy savings compared with the NPAC-SBR. Results for mean sludge volume index, total dry solids in sludge, saved aeration energy, removed ammonia, chemical oxygen demand, color, and total dissolved salts were 334.4 mL/g, 1.06%, 0%, 89.4%, − 42.9, 10.2%, and 35.9% , respectively, for the NPAC-SBR, and 27.5 mL/g, 2.01%, 64.03%, 85.5%, 50.4, 45%, and 38.3%, respectively, for the DRS-SBR. The PAC-augmented DRS-SBR exhibited a significant improvement in the treatment of landfill leachate compared with the NPAC-SBR. ► Three types of sequencing batch reactors (SBRs) were used for treatment of raw landfill leachate. ► The SBRs were non-powdered activated carbon (NPAC-SBR), powdered activated carbon (PAC-SBR) and double react–settling augmented PAC (DRS-SBR). ► PAC-SBR and DRS-SBR showed better performance, improved sludge, and greater ability to save aeration energy (> 50 %). ► Both the PAC dosage and the supplied air had a significant effect on the SBR performance. ► The DRS-SBR that operates in seven phases commonly offered better results than the conventional five-phase SBR.