Vertical constructed wetland for embedded grey water treatment

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1 Vertical constructed wetland for embedded grey water treatment Matjaz Nekrep Perc (1) 1. (1) Faculty Of Civil Engineering, University of Maribor, Slovenia Abstract Vertical green façade systems are gaining their popularity because of many benefits among them are improved aesthetics, regulation of temperature, biodiversity improvements, better air quality, etc. Constructed wetlands on the other side are treatment systems that use natural processes to improve water quality with many benefits and few weaknesses. If we join two related concepts together with a little help of potential energy the result can be natural, efficient, good looking and almost automatic system for grey water treatment and reuse in buildings. Our effort was to design and test easy to build solution that links both of the concepts, and integrate result into façade or solitary green wall. Keywords grey water, constructed wetlands, embedded sanitary systems, bio filtration, and green walls

2 1 Basics We are dealing here with two exciting concepts. Green walls with many known benefits for urban places and constructed wetlands nature like wastewater treatment. We will try to tie them together in quite unique way to serve also as domestic grey water treatment system. First of all, we will discuss some basic concepts. 1.1 Green walls Green walls are bringing reaches of nature into the urban environment on the envelope or inside the buildings. They can benefit to the buildings from the aesthetics point of view, protect the building and increase indoor air quality and climatic conditions in the building. Figure 1. Green wall in hotel lobby; Antibes France Green walls are elements of reach flora and creating natural habitat for favna in the urban environment. They can benefit even to the mental health of the people. Envelope of the building is protected against heavy rain and green walls act as retainers during heavy showers. 1.2 Constructed wetlands Constructed treatment wetlands are used for wastewater treatment for decades and natural wetlands in nature since beginning of time.

3 Constructed treatment wetlands are a natural, low-cost, eco-technological biological wastewater treatment technology designed to mimic processes found in natural wetland ecosystems, which is now standing as the potential alternative or supplementary systems for the treatment of wastewater (UN-HABITAT 2008). Figure 2. Constructed treatment wetland; Ponikva Slovenia Constructed treatment wetland is a shallow basin filled with some sort of filter material (substrate), usually sand or gravel, and planted with vegetation tolerant of saturated conditions. Wastewater is introduced into the basin and flows over the surface or through the substrate, and is discharged out of the basin through a structure, which controls the depth of the wastewater in the wetland. Advantages of constructed wetlands are that they are less expensive, utilize natural processes, construction, operation and maintenance are simple and cost effective. Main limitation of the constructed treatment wetland is large area requirement. 1.3 Domestic greywater Average domestic consumption of drinking water in Slovenia is 117 l per person per day (Čuček 2012). On third of that water is used for toilet flushing, only 1-3 % for drinking and around 10% in kitchen (Sakkas 2012). As result 2/3 of the domestic water is greywater. Treated greywater can be reused in not potable uses like toilet flush and irrigation.

4 1.4 Additive manufacturing systems as possible key to embedded elements in walls Additive manufacturing in building industry allows advanced and brave design and free form nature inspired constructions. Micro inner design of the walls can follow design and structural demands together with many additional possibilities including all building utilities. New demands and opportunities will challenge water supply and drainage in building. Not only pipe lines but also active elements of networks could be embedded in time of building creation on site. 2 Vertical constructed treatment wetland = green wall If we use principles from constructed treatment wetlands and green walls the result is Vertical constructed wetland. Our goal to preserve all benefits from both systems and use green wall as a constructed treatment wetland limited to the greywater. Important parameter in constructed treatment wetland operation is Hydraulics loading rate (HLR), which refers on a water volume per unit area (Davis, 1994). Vertical constructed treatment wetland must have as much as horizontal surface as possible. Figure 3. Green wall BIM system (WallGreen 2014) In case of horizontal constructed treatment wetland 2 m 3 (2m2 100 cm depth) is needed per person in case of greywater (3m 2 in case of black water).

5 Converted to vertical area, we can expect that vertical constructed treatment wetland can treat around 25 l of greywater per square meter per day. 3 Conclusions Vertical constructed treatment wetland in form of green wall can enable us in house greywater reuse in case of off-greed building or even more usual sustainable buildings. We need 5 m 2 off green wall per habitant to treat greywater for reuse. In case of high raised buildings, treated water can be reuse few floors below. The Soft Machine garden by Slovenian designer Tomaž Bavdež has been designed based on principles of vertical garden to provision ecosystem services, processing and recycling waste within an attractive setting. The human body plays its part in the processing, helping to pump waste water to the top of the modular living walls and filtering units, whilst training on the exercise bike nothing is wasted. Marsh planting predominates and both the planting and landscape materials serve as additional water filters. Figure 4. Prized experemental green wall treatment system The Soft Machine at Chelsea Flower Show 2012 by Tomaž Bavdež and Humko (Bavdež 2013) Another testing facilities are of vertical constructed treatment wetland are planning on our building.

6 5 References 1. Bavdež, Tomaž. "The Soft Machine." Web. 23 July < 2. Davis, Luise, ed. A Handbook of Constructed Wetlands: A Guide to Creating Wetlands For--agricultural Wastewater, Domestic Wastewater, Coal Mine Drainage, Stormwater in the Mid-Atlantic Region. Washington, DC: U.S. G.P.O., Supt. of Docs., Print. 3. Humko, d.o.o. "WallGreen." Web. 21 July < 4. Sakkas, Panos. "Domestic Greywater Treatment through the Integration of Constructed Wetlands in Living Wall Systems." Master Thesis (2012). TU Delf. Web. 5. Szymkiewicz, Adam. Modeling Water Flow in Unsaturated Porous Media Accounting for Nonlinear Permeability and Material Heterogeneity. Berlin: Springer, Print. 6. Čuček, Saša. "Svetovni Dan Voda 2012." Statistični Urad Republike Slovenije. 20 Mar Web. 11 July UN-HABITAT. Constructed Wetlands Manual. Nepal, Kathmandu: United Nations Human Settlements Programme, Print.

7 6 Presentation of Authors Matjaz Nekrep Perc is a Researcher, Teacher and Head of Centre for Hydraulics at the University of Maribor, Slovenia