An investigation of submerged aerated filter for high-rate organics removal from greywater

Greywater (GW) separation and treatment targeting water recycling is widely accepted as a sustainable wastewater management approach. Removal of organics is a major objective of GW treatment systems. Biological aerated filter (BAF) is well-known to be a compact (high-rate) and efficient process for treatment of different wastewaters. However, clogging is the biggest drawback of BAF, which reduces operational efficiency and increases energy demands. Submerged aerated filter (SAF) – utilising media with high specific surface area and bed porosity – can offer high biological oxidation rates and be less vulnerable to clogging. In a first, this preliminary study investigated the application of SAF for high-rate organics removal from GW. Trials were carried out using a lab-scale up-flow SAF and synthetic GW over 80 days, wherein volumetric organic loading rate (OLR) was gradually increased from 1 to 6 kg COD/(m 3 ∙d). The reactor was not subjected to backwashing during the study period. At OLRs of about 6 kg COD/(m 3 ∙d) [hydraulic retention time of 1.9 h], the SAF showed COD removal efficiencies of 90–95% with about 24 mg COD/L in the effluent. Such SAFs can be an attractive and promising organics removal method for realising compact and efficient GW treatment systems.