Greywater treatment using lab-scale systems combining trickling filters and constructed wetlands with recycled foam glass and water spinach

Abstract

A low energy-consuming system for greywater treatment was developed with a trickling filter (TF) followed by constructed wetlands (CWs). Roles of substrates, plants, and microorganisms were intentionally explored. TFs and CWs were filled with recycled foamed glass. Water spinach and parsley planted in the CWs provided additional value. Microorganisms in the system were characterized through carbon-utilization tests and 16S rRNA gene next-generation sequencing. In 5.5 months, TOC, TN, and TP removals from greywater were, respectively, 83.5, 85.5, and 92.1 %. TOC was removed in the TF at 22.6 g-C/m²/d. The CWs exhibited TN and TP removals at 0.44 g-N /m²/d and 0.19 g-P/m²/d. Water spinach was harvested at 792 g-wet/m²/week, accounting for 7.1 % and 12.6 % for TN and TP removals. Denitrification, microbial diversity, and carbon source utilization potentials were enhanced by water spinach. This is a sustainable wastewater treatment model by using recycled materials and edible plants.