Constructed Wetlands for greywater reuse
Sustainable management: Grey water reuse
For the treatment and reuse of grey water, IRIDRA proposes the following solutions
Classical constructed wetlands
- Horizontal subsurface flow systems (HF)
- Vertical subsurface flow systems (VF)
- Free water surface systems (FWS)
- Hybrid systems (HF + VF, HF + FWS, HF + VF + HF + FWS)
Green architectural nature-based solutions
- Roof wetlands
- Vertical gardens o Green Walls
- Green roofs
Combination with water saving devices in buildings
- Hand basins and shower water saving devices
- Water saving solutions for toilet flushing
- Low water footprint scelta appliances
Greywater represents about 70% of the water consumed in houses. In comparison with blackwater, greywater is less polluted and easier to be treated and reused.
Greywater reuse
Since greywater is easy to be treated, they are valuable non-conventional water for uses not requiring potable water quality, such as:
- irrigation
- flushing toilet
- fire prevention system
- pavement cleaning
The role of constructed wetlands
Constructed wetlands are one of the most promising nature-based solutions for the treatment and reuse of greywater, due to the following advantages:
- high removal efficiencies of organic pollutants and pathogens
- simple realization and functioning
- simple maintenance
- low CAPEX in comparison to compact technological solutions
- very low OPEX
- multiple possibilities of landscaping: gardens, terraces, roofs
Horizontal flow constructed wetland (HF) is one of the most adopted solutions for treatment and reuse of greywater, providing:
- organic load removal efficiencies of 80–90%, absolutely adequate for greywater treatment
- efficient disinfection
- simple construction and management
Due to the low pollutant load of greywater, nature-based solutions do not give any odour issue and are suitable for both indoor and outdoor application. Therefore, indoor CW can be also seen as an interesting occasion for aesthetic improvement of indoor spaces.
Example of outdoor CW for treatment and reuse of greywater (WC flushing), serving a small residential area of 280 inhabitants (Preganziol - TV, Italy), designed by IRIDRA
Example of indoor CW for treatment and reuse of greywater (WC flushing and gardening), San Francisco Public Utilities Commission: the “Living Machine” (USA)
Green wall pilot plant sited in Maharashtra Jeevan Pradhikaran head office (Pune - India) for treatment and reuse of greywater. Designed by IRIDRA and realized under the European funded project NaWaTech
Residential area in Preganziol (TV - Italy)
Treated person equivalent: 280 PE
Chosen Nature-based solution : HF
Peculiarity: Separation, treatment, and reuse of greywater for toilet flushing
Year of realization: 2009
Beduin village in Westbank (Palestine)
Treated person equivalent: 70-120 PE
Chosen Nature-based solution: VF
Peculiarity: Separation, treatment with a constructed wetland, and reuse of greywater from a Beduin village in Palestine. The treated greywater is reused for irrigation of olive trees and fodder. The nature-based solution was designed by IRIDRA, commissioned by the NGO OXFAM Italy, and funded by EU ECHO, FAO, and Sardinia Region
Year of realization: 2011-2012
Margarita beach, Marina di Ragusa (RG - Italy)
Maximum trated greywater quantity: 0.5 l/s (Pilot plant)
Chosen Nature-based solution: Green wall
Peculiarity: Gardening reuse of treated greywater. Designed by IRIDRA for Svi.med, partner of the project CONSUME-LESS (Interreg MED)
Year of realization: 2018
The aim of the "green wall" realization project is the environmental and economic sustainability obtained through the purification of grey water, their recovery and their reuse for less noble uses such as the rinsing of the toilets or the irrigation. This is possible through a wall that exploits the purifying power of plants and substrate to remove impurities, typical of constructed wetlands. The green wall aims to save about 300/400 liters of drinking water per day.
The Green wall was designed by Iridra for Svimed Centro Euromediterraneo per lo Sviluppo Sostenibile, partner of the ConsumelessMed project.
Restoration of a residential area in Alliste (LE - Italy)
Treated person equivalent: 100 PE
Chosen Nature-based solution: HF + VF
Peculiarity: Irrigation reuse of treated greywater.
Year of design: 2010
"La Cava" camping, Arezzo (AR - Italy)
Treated person equivalent: 80 PE
Chosen Nature-based solution: HF
Peculiarity: Separation, treatment with a constructed wetland, and reuse of greywater for irrigation. Nature-based solution realiazed under the EU funded project SWAMP
Year of realization: 2004
Hostel campus of the College of Engineering, Pune (India)
Treated greywater quantity: 40 m3/day
Chosen Nature-based solution: VF
Peculiarity: Separation, treatment with a constructed wetland, and reuse of greywater for toilet flushing. Nature-based solution realiazed under the EU funded project NaWaTech
Year of realization: 2015
The derivation from the sewer will be realized intercepting the main collector with a pumping station that will permit to load the AT with the selected flow; the overflow will continue to go in the same collector that is connected to the public sewer.
The scheme is the following:
- Pumping station fro wastewater derivation
- AT treatment
- pumping station for VF tertiary treatment loading
- VF constructed wetland divided into three basins, with a net surface (bottom of the basin) of 135 m2 each and a total surface of 405 m2
- Connection to disinfection, using chlorination and treated effluent collection tank
The wastewater of the right part of the campus, for an amount of 40 m3/day, will be treated in a Anaerobic treatment and discharged in the sewer with a better water quality.
The greywater of the GH building will be instead separated from the main sewer and treated in Constructed wetland system as following:
Degreaser 10 m3
pumping station for VF loading
VF constructed wetland divided into two equal sectors, with a net surface (bottom of the basin) of 133 m2
Connection to disinfection, using chlorination and treated effluent collection tank
To load VF for greywater treatment, a pump controlled by a timer and a time switch is installed in a reinforced concrete tank. The pump is controlled by a control panel, contained in a Box. Every day the loading on the bed is in a batch mode, controlled by Timer and time switch to program pump start and duration of pumping (or alternatively by switch level regulators), ensuring a resting period between every flush of approximately 1.6-2 h. Flush volume will be 2700-3300 L
San Carlo settlement, San Vincenzo (LI - Italy)
Treated wastewater quantit: 30 m3/day
Chosen Nature-based solution: HF + VF
Peculiarity: Tertiary treatment for reuse purposes. Treated wastewater is reused to irrigate vegetation used for restoration of a dismissed querry.
Year of design: 2010
Resort in Grumenti community, Serengeti (Tanzania)
Treated greywater quantity: 4 m3/day
Chosen Nature-based solution: roof wetland
Peculiarity: Irrigation reuse of treated greywater.
Year of realization : 2015
Maharashtra Jeevan Pradhikaran head office, Pune (India)
Treated person equivalent: 0.125 - 0.25 m3/day (Pilot plant)
Chosen Nature-based solution: Green wall
Peculiarity: Investigation of possible reuse of greywater treated by a green wall. Nature-based solution realiazed under the EU funded project NaWaTech
Year of realization: 2014
Wedding facility "Luna Nuova", Sternatia (LE - Italy)
Treated person equivalent: 615 PE
Chosen Nature-based solution: HF + VF + HF + FWS
Peculiariy: Irrigation reuse of treated greywater.
Year of realization: 2004
Centro di ricerche Kerakoll, Sassuolo (MO)
Tipologia di impianto: Vasche d'acqua
Peculiarità: Recupero acque meteoriche ed inserimento paesaggistico
Anno di realizzazione: 2012
Restoration of a residential area in Alliste (LE - Italy)
Treated person equivalent: 100 PE
Chosen Nature-based solution: HF + VF
Peculiarity: Rainwater harvesting for irrigation and toilet flushing
Year of design: 2010
Residential buildings in Località ex oratorio del Monte, Vicchio (FI - Italy)
Treated person equivalent: 30 PE
Chosen Nature-based solution: HF
Peculiarity: Rainwater harvesting for irrigation integrated with nature-based solution for black and greywater treatment
Year of design: 2008
Private house, Treviso (TV - Italy)
Chosen Nature-based solution: Green roof
Peculiarity: Rainwater harvesting for irrigation and aestethic improvement
Year of realization: 2012
Residential area in Preganziol (TV - Italy)
Chosen SuDS solution: Rain Garden
Peculiarity: Rainwater harvesting for irrigation and aestethic improvemen
Year of realization: 2009
