Household Scale Treatment and Reuse of Laundry Greywater Through a Hybrid Wetland System

Abstract

The reuse of greywater on a domestic scale allows not only to reduce the consumption of drinking water but also the volume of domestic wastewater generated, aspects that are relevant in regions with water scarcity and lack of sanitation. However, uses such as irrigation or simple storage of treated water for toilet flushing usually require prior treatment in order to improve its quality. In the present work, the operation of a hybrid system for the treatment of laundry greywater with a high organic load was evaluated. It consisted of a first treatment stage through a vertical flow wetland followed by a phytoremediation stage with floating macrophytes (Eichhornia crassipes and/or Salvinia minima). The system allowed to remove a large part of suspended solids (up to 90 %), COD (up to 91 %) and nitrogen (up to 90 % as TN), improving the quality of the water for its storage and reuse in some non-drinking purposes. The first stage of the treatment also made it possible to retain microplastics. Due to the duration of the second stage (4 days), evaporation increased the concentrations of dissolved salts, decreasing its water quality for later use in irrigation. The sole application of the first treatment stage is recommended in this case.