Design and configuration criteria for wetland systems treating greywater

Abstract

Design and configuration for wetlands treating greywater are usually based on literature data obtained from domestic wastewater operating wetlands. It is very important to determine proper criteria for design and configuration to provide efficiency and minimum maintenance, avoiding bad odour and clogging amongst others, ensuring the acceptance of householders. The aim of this work was to design a wetland system treating greywater for a household and determine whether the chosen criteria were appropriate. Some of the criteria taken into consideration for design and configuration were: quantitative and qualitative characteristics, desired removal of biochemical oxygen demand (BOD) and suspended solids (TSS), substrate and ornamental aspect of the system. The system was composed of a grease trap (kitchen), sedimentation tank, a horizontal flow constructed wetland (HF-CW), intermittent feeding system, and a vertical flow constructed wetland (VF-CW). The results showed that the suggested design and configuration were in accordance with the expected efficiency. Being a compact system, it was susceptible to peak flows, temporarily deteriorating the performance of the HF-CW. The hybrid system, however, showed to cope well with influent fluctuations. The overall performance of the system shows that the removal of turbidity, TSS, COD and BOD were over 88%, reaching 95% removal for both BOD and turbidity.

A modified constructed wetland system for greywater treatment

“…As greywater typically has a lower pathogen content and lower organic matter load than combined domestic sewage, it has been considered a potential source of water to meet current and future needs even though it is mostly considered for nonpotable use (Benami et al, 2015;Ghunmi et al, 2011;Maimon et al, 2014;Teodoro et al, 2014). This holds true especially for the light grey water (GW L ) fraction, which apart from excluding the toilets also excludes the kitchen sink and dishwasher fractions, which are the greywater fractions that carry the highest COD loads and have the highest content of suspended solids (Abu Paulo et al, 2009). Greywater can be highly variable in composition and volume generated per person, being heavily dependent on the dynamics and behaviour of individuals, sanitary standards, age, lifestyle, water use, eating habits, personal care and household products choice and water availability, among others.…”

“…Natural systems are considered sustainable ecotechnologies for small scale treatment of domestic wastewater and its fractions (Mahmood et al, 2013;Paulo et al, 2013;Morel and Diener, 2006). In this view, filters (planted or unplanted) and several variations of constructed wetlands have been used for greywater treatment (Ramprasad and Philip, 2016;Ghunmi et al, 2011;Hoffmann et al, 2011;Li et al, 2009;Paulo et al, 2009;;Gross et al, 2007). One advantage of these ecotechnologies is that they can be totally integrated into the gardens (if individual) or into the landscaping of available common areas, increasing the green sites in urban zones, and contributing to an improvement of the microclimate, where an improvement of thermal and environmental comfort is expected.…”

The implications of household greywater treatment and reuse for municipal wastewater flows and micropollutant loads

“…However, related research has largely been restricted to studies of standard water quality parameters such as total organic carbon, biological oxygen demand, chemical oxygen demand and faecal and total coliforms (e.g. Pidou et al, 2008;Paulo et al, 2009). In contrast, there has been very little greywater research investigating the loads and dynamics of micropollutants.…”

Seasonal Performance of an Outdoor Constructed Wetland for Graywater Treatment in a Temperate Climate

“…Despite varying hydraulic loading rates and water temperatures, the studied wetlands all performed well, with COD removal rates ranging from 75 to 90%. Another group of researchers operated a horizontal flow followed by vertical flow wetland system in Campo Grande, Brazil (Paulo et al, 2009) to treat high-load graywater, and realized BOD and total nitrogen removals of 95 and 82%, respectively. Of note is the warm climate in which these wetlands were operated.…”