Design and Development of a Living Green Wall for Greywater Treatment

Master's Thesis , 2018 , 97 Pages , Grade: 1,0

Geography / Earth Science - Physical Geography, Geomorphology, Environmental Studies

Water scarcity and pollution represent key challenges which life on earth will have to face, considering the rapid population growth, and our water intensive societies, and global economy. On-site greywater treatment and reuse constitute ecologically and economically worthwhile solutions to counteract water scarcity and intelligently manage water resources.

Several modular living green wall prototypes were developed, which aim to remove man-made water pollution through a biotechnological approach similar to constructed wetlands. These designs however require far less valuable land by using a vertical, facade integrated design instead. The treatment units differed in terms of substrate and plant species compositions, as well as in their designated water-flow paths: i) vertical channels ii) cascading with 1° declining slope iii) cascading with 5° ascent angle.

Artificial greywater was introduced into these systems and effluents were analyzed regarding standard water quality parameters and nutrient contents. For all parameters except PO43-, no significant differences between the individual planted units were observed (p=0.05). Maximum removal rates were 28%, 28%, 29%, 40%, 88%, 37%, 51%, and 57% for BOD5, COD, DOC, NH4-N, PO43-, TOC, TSS, and turbidity, respectively. An in groups comparison of the channelized and cascading units revealed a significant difference in treatment performance in favor of the channelized units for the parameters BOD5 and PO43-. Shoot supporting structures, which were applied to the channelized systems, seemed to be the decisive structural element, as they promoted plant health and rhizosphere development.

Further investigations aimed to explore, if regulatory EU wastewater effluent quality standards can be met with a series of consecutive treatment units. With 19 mg/L and 93 mg/L, the effluent TSS and COD concentrations after five runs were below the thresholds.

Table of Contents

1. Introduction

2. Objectives

3. Fundamentals
3.1 Greywater: Quantity, Quality, Reuse, and Risks
3.2 Green Walls: Definition and State-of-the-Art
3.3 Constructed Wetlands as Reference Biotechnology
3.3.1 Surface Flow Wetlands
3.3.2 Horizontal Flow Wetlands
3.3.3 Vertical Flow Wetlands
3.4 Transformation and Elimination Processes in Constructed Wetlands
3.4.1 Carbon T ransformation
3.4.2 Nitrogen Transformation
3.4.3 Phosphorus Transformation and Retention
3.4.4 Suspended Solids Removal
3.4.5 Pathogen Removal

4. Material and Methods
4.1 Experimental Setup and Procedure
4.1.1 Design Concepts
4.1.2 Substrate
4.1.3 Plant Selection
4.1.4 Mean Residence Time Determination
4.1.5 Hydraulic Loading Regime and Sampling Procedure
4.1.6 On-site Measurements
4.2 Measurement Instruments
4.2.1 s::can spectra::lyser™
4.2.2 Hach-Lange DR-1900
4.2.3 WTW MultiLine® 3410 IDS
4.2.4 Thermo Scientific Eutech Expert CTS and HM Digital PH-200
4.3 Statistical Methods

5. Results and Discussion
5.1 Plant and Root Development
5.2 Mean Residence Time
5.3 Treatment Performance
5.3.1 Organic Pollutants
5.3.2 Total Suspended Solids and Turbidity
5.3.3 Nitrogen
5.3.4 Phosphate
5.4 Simulated Treatment Performance of a Five Meter High Living Green Wall
5.5 Hydraulic Loading Regime Modifications and its Effects on the Mean Residence Time

6. Conclusion and Outlook

7. Summary

8. References

9. Appendix
9.1 G reywater reci pe
9.2 Calibration data
9.3 Results
9.4 Test statistics

10. Curriculum Vitae

“A piece of nature to balance technology. A symbol of never ending cycle. A piece of genuine living and flowing nature which renews itself continually as an ambassador of the big empire of nature. [...]. The roots of the water plants emit oxygen and transform what we humans call dirty water into plant substance. We witness the never ending purification and renewal cycle in the smallest space in harmony with the laws of nature. This water purification plant is enriching us ecologically, optically and acoustically. It is a small step of the so called civilized man who is estranged from nature towards a peace treaty with nature. It helps to bring back to man what he is longing for and what technology cannot do. Man feels sheltered and safe again, there where nature and art reunite, and man can regain a tiny part of his good consciousness towards nature.”

Friedensreich Hundertwasser, July 1986

“The tree tenant symbolizes a turn in human history, because it regains its rank as an important partner to man. [...]. We suffocate in our cities through poison and lack of oxygen. We destroy systemically the vegetation which gives us life and lets us breathe. We walk alongside grey and sterile facades of houses. [...]. Cars have chased the trees up into the storeys of houses. We suffer daily from the aggressivity and tyranny of our vertical sterile high walls. But streets in the cities will become green valleys where man can breathe freely again.

The tree tenant is a symbol of reparation towards nature [...]. We restore to nature a tiny piece of the huge territories which man has taken away from nature illegally. The tree tenant is a giver. It is a piece of nature, a piece of homeland, a piece of spontaneous vegetation in the anonymous and sterile city desert, a piece of nature which can develop without the rationalist control of man and his technology.“

Friedensreich Hundertwasser, April 1991

Acknowledgements

This thesis was written under the supervision of Priv.-Doz. DI Dr. Günter Langergraber at the Institute of Sanitary Engineering and Water Pollution Control at the University of Natural Resources and Life Sciences in Vienna. In my first year he introduced me to the topic of constructed wetlands and ecological sanitation, which ignited a spark and motivated me to deepen my knowledge in these topics. I want to thank him and the team of alchemia-nova GmbH, who gave me the opportunity to write my thesis about such an interesting topic.

From the alchemia-nova team, I namely want to thank Heinz Gattringer and Carmen Zehetbauer. Thank you both for your steady counsel and help during the past year of elaborating this thesis.

I want to thank Prof. Dr. Dr. Erwin Lautsch for his time and helpful expertise during the statistical analysis.

I further want to thank my old friends Christoph Drexler and Jesse Bird for proofreading this thesis and for their helpful input. I want to thank Laura for cheering me up in the few demotivating moments, as well as for sharing all the good moments with me.

Finally, I want to thank my mother and father for the years of support since I started university. Without them I could not have lived and studied the way I did. Thank you for everything!

List of Figures

Figure 1: Greywater treating green walls. Water use and reuse scheme. Source: alchemia-nova GmbH

Figure 2: Total water consumption and greywater production. Source: adapted from Edwin et al. 2014, p. 47

Figure 3: Distinction of green wall systems. Source: (Manso and Castro-Gomes, 2015, p. 865)

Figure 4: Existing green wall-systems for greywater treatment. Left: multi-flowerpot approach. Right: surface biofilter bed with vines. Source: Masi et al. 2016, Fowdar et al. 2017

Figure 5: Classification of treatment wetlands. Source: adapted from Kadlec and Wallace (2009).

Figure 6: Scheme of a Surface Flow Wetland. Source: Tilley et al. (2014)

Figure 7: Scheme of a Horizontal Flow Wetland. Source: Tilley et al. (2014)

Figure 8: Scheme of a Vertical Flow Wetland. Source: Tilley et al. (2014)

Figure 9: Share of water-filled pore spaces and associated relative microbial activity regarding nitrogen transformation processes. Source: Vymazal and Kröpfelova (2008, p.39)

Figure 10: Visualization of the GreenINSTRUCT design approaches. Inner wall (grey), PU-foam (purple), cover plate (brown), mounts (yellow & orange), external green wall (green: modular cassette, blue: cascades, pink: channels, orange: cover plate). Source: Gianluca Vassallo

Figure 11: Technical drawing of "Chan" and "ChanPlus"

Figure 12: Technical drawing of "Pan_incl"

Figure 13: Technical drawing of "Pan_decl"

Figure 14: Irrigation and sampling scheme

Figure 15: spectra: :lyser™ scheme. Source: Günter Langergraber

Figure 16: Calibration curves for COD and BOD5

Figure 17: Plants under vertical stress. Photo by Gianluca Vassallo

Figure 18: Root network development near mentha aquatica in “Pan_decl”. Left: week 1, middle: week 8, right: week 12. Photos by Gianluca Vassallo

Figure 19: a) “ChanPlus” laid open, b) Root branch of “ChanPlus”. Visual comparison of root networks, left “Panjncl” right “ChanPlus”: c) Geranium palustre, d) Iris versicolor, e) Mentha aquatica, f) Carex acuta, g) Achillea millefolium. Photos by Gianluca Vassallo

Figure 20: MRT of the treatment unit "Panjncl" with a ‘15 minutes pumping - 60 minutes break’ interval

Figure 21: Pairwise comparison of BOD5 effluent concentrations. Kruskal-Wallis independent samples test, p=0.05

Figure 22: BOD5, COD, DOC, TOC, TURB, and TSS influent and effluent concentrations

Figure 23: LCK 303 NH4-N analysis. From left to right: Inflow, Control, Chan, ChanPlus, Pan_decl, Pan_incl. Green color indicating high NH4-N concentrations. Photo by Gianluca Vassallo

Figure 24: NH4-N and NO3-N influent and effluent concentrations

Figure 25: PO43 influent and effluent concentrations

Figure 26: BOD concentration reduction per cycle with trendline equation

Figure 27: MRT of Panjncl with a ‘1 minute pumping - 4 minutes break’ interval

Figure 28: MRT of greywater in "Control" during standard operation

Figure 29: MRT of greywater in "Chan" during standard operation

Figure 30: MRT of greywater in "ChanPlus" during standard operation

Figure 31: MRT of greywater in "Pan_decl" during standard operation

Figure 32: Pairwise comparison of COD effluent concentrations. Kruskal-Wallis independent samples test, p=0.05

Figure 33: Pairwise comparison of DOC effluent concentrations. Kruskal-Wallis independent samples test, p=0.05

Figure 34: Pairwise comparison of NO3-N effluent concentrations. Kruskal-Wallis independent samples test, p=0.05

Figure 35: Pairwise comparison of NH4-N effluent concentrations. Kruskal-Wallis independent samples test, p=0.05

Figure 36: Pairwise comparison of PO43- effluent concentrations. Kruskal-Wallis independent samples test, p=0.05

Figure 37: Pairwise comparison of TOC effluent concentrations. Kruskal-Wallis independent samples test, p=0.05

Figure 38: Pairwise comparison of TSS effluent concentrations. Kruskal-Wallis independent samples test, p=0.05

Figure 39: Pairwise comparison of TURB effluent NTU. Kruskal-Wallis independent samples test, p=0.05

Figure 40: BOD5 in groups comparison. Asymptotic sig. < 0.05, reject null hypothesis

Figure 41: COD in groups comparison. Asymptotic sig. > 0.05, retain null hypothesis

Figure 42: DOC in groups comparison. Asymptotic sig. > 0.05, retain null hypothesis

Figure 43: NH4-N in groups comparison. Asymptotic sig. > 0.05, retain null hypothesis

Figure 44: NO3-N in groups comparison. Asymptotic sig. > 0.05, retain null hypothesis

Figure 45: PO43- in groups comparison. Asymptotic sig. < 0.05, reject null hypothesis

Figure 46: TOC in groups comparison. Asymptotic sig. > 0.05, retain null hypothesis

Figure 47: TSS in groups comparison. Asymptotic sig. > 0.05, retain null hypothesis

Figure 48: TURB in groups comparison. Asymptotic sig. > 0.05, retain null hypothesis

List of Tables

Table 1: Literature review of greywater quality parameters from different sources

Table 2: Quality requirements for treated wastewater effluents to allow reuse

Table 3: Advantages and disadvantages of SF-Wetlands. Source: adapted from Tilley et al (2014)

Table 4: Advantages and disadvantages of HF-Wetlands. Source: adapted from Tilley et al (2014)

Table 5: Advantages and disadvantages of VF-Wetlands. Source: adapted from Tilley et al (2014)

Table 6: Dimensions, volume and weight of “Chan" and “ChanPlus”

Table 7: Dimensions, volume and weight of "Pan_incl"

Table 8: Dimensions, volume and weight of "Pan_decl"

Table 9: SERAMIS® specifications. Source: Seramis GmbH, 2015

Table 10: Plant selection per treatment unit

Table 11: Greywater dosing scheme during the plants’ adaption phase

Table 12: Mean residence times of all treatment units

Table 13: Mean influent and effluent concentrations of all measured parameters, including standard deviation and removal rate. BOD5, COD, DOC, TOC, TSS, and TURB n=30. NH4-N n=14. NO3-N n=11. PO43- n=8

Table 14: Mean pH and EC with STD of influent and effluents

Table 15: Significant differences (=orange) in favor of column “II” in terms of greywater treatment performance per water quality parameter. Pairwise comparison. Test procedure: Independent Samples Kruskal-Wallis Test, p=0.05

Table 16: BOD5/COD ratios of influent and effluents

Table 17: Treatment results of the “five meter” simulation with the unit “Chan". Comparison of other greywater treating green wall studies. Fowdar et al. (2017): varying removal rates with different plant species. Masi et al. (2017): mean concentrations and removal rates

Table 18: “alchemia-nova GmbH” greywater recipe per 50 L tap water

Table 19: Calibration data points and testing procedures

Table 20: Influent greywater compositions

Table 21: Treatment results of the prototype Control. Effluent concentrations in mg/L and the removal rates in % are shown

Table 22: Treatment results of the prototype Chan. Effluent concentrations in mg/L and the removal rates in % are shown

Table 23: Treatment results of the prototype ChanPlus. Effluent concentrations in mg/L and the removal rates in % are shown

Table 24: Treatment results of the prototype Pan_decl. Effluent concentrations in mg/L and the removal rates in % are shown

Table 25: Treatment results of the prototype Pan_incl. Effluent concentrations in mg/L and the removal rates in % are shown

Table 26: Five meter flow through simulation. Influent and effluent compositions after each cycle. 64 Table 27: Test for normality (p=0.05). If significance < 0.05, null hypothesis stating normality must be rejected

Table 28: Means medians and modes for all parameters and prototypes

Abstract

Water scarcity and pollution represent key challenges which life on earth will have to face, considering the rapid population growth and our water intensive societies and global economy. On-site greywater treatment and reuse constitute ecologically and economically worthwhile solutions to counteract water scarcity and intelligently manage water resources.

Several modular living green wall prototypes were developed, which aim to remove man-made water pollution through a biotechnological approach similar to constructed wetlands. These designs however require far less valuable land by using a vertical, facade integrated design instead. The treatment units differed in terms of substrate and plant species compositions, as well as in their designated water-flow paths: i) vertical channels ii) cascading with 1° declining slope iii) cascading with 5° ascent angle.

Artificial greywater was introduced into these systems and effluents were analyzed regarding standard water quality parameters and nutrient contents. For all parameters except PO43-, no significant differences between the individual planted units were observed (p=0.05). Maximum removal rates were 28%, 28%, 29%, 40%, 88%, 37%, 51%, and 57% for BOD5, COD, DOC, NH4- N, PO43-, TOC, TSS, and turbidity, respectively. An in groups comparison of the channelized and cascading units revealed a significant difference in treatment performance in favor of the channelized units for the parameters BOD5 and PO43-. Shoot supporting structures, which were applied to the channelized systems, seemed to be the decisive structural element, as they promoted plant health and rhizosphere development.

Further investigations aimed to explore, if regulatory EU wastewater effluent quality standards can be met with a series of consecutive treatment units. With 19 mg/L and 93 mg/L, the effluent TSS and COD concentrations after five runs were below the thresholds.

Kurzfassung

Angesichts des rasanten Bevölkerungsanstiegs und der wasserintensiven globalen Wirtschaft und Gesellschaft, werden Wasserknappheit und -verschmutzung wichtige zu überwindende Herausforderungen darstellen. Reinigung und Wiederverwendung von Grauwasser vor Ort sind sowohl ökologisch als auch ökonomisch vorteilhafte Lösungsansätze um die Ressource Wasser zu schonen.

Dafür wurden mehrere bepflanzte modulare Fassadenelemente entwickelt, welche durch ein Zusammenspiel aus Mikrobenaktivität, Sorption und Nährstoffaufnahme Grauwasser reinigen. Aufgrund ihres vertikalen fassadenintegrierten Designs, konkurrieren diese Reinigungsmodule nicht mit anderen Flächennutzungsarten. Die Prototypen unterschieden sich hinsichtlich ihrer Substrat- und Pflanzenzusammensetzung, sowie ihrer Wasserflussführung: i) vertikale Rohre ii) kaskadierend mit 1° Gefälle iii) kaskadierend mit 5° Steigung.

Die Reinigungsmodule wurden mit künstlichem Grauwasser getestet. Die Abwässer wurden hinsichtlich ihres Nährstoffgehalts sowie verbreiteter Wassergüteparameter analysiert. Ausschließlich für den Parameter PO43- wurde ein signifikanter Unterschied zwischen den einzelnen Reinigungsmodulen festgestellt (p=0.05). Die maximalen Reinigungswerte lagen bei 28% (BSB5), 28% (CSB), 29% (DOC), 40% (NH4-N), 88% (PO43-), 37% (TOC), 51% (AFS), und 57% (Trübung). Der gruppenbezogene Vergleich von kaskadierenden und kanalisierten Systemen, ergab für BSB5 und PO43- signifikante Unterschiede zugunsten der kanalisierten Systeme. Die in den kanalisierten Einheiten verbauten Stützvorrichtungen für Pflanzensprossen, scheinen dafür entscheidend gewesen zu sein, da diese ein besseres Pflanzen- und Wurzelwachstum ermöglichten.

Zudem sollte festgestellt werden, ob von der EU vorgeschriebene Ablaufgrenzwerte für Kläranlagen durch aufeinanderfolgende Einzelmodule erreicht werden können. Hinsichtlich der Parameter AFS und CSB wurden die Grenzwerte mit 19 mg/L und 93 mg/L nach fünf Modulen deutlich unterschritten.

Abbreviations

Abbildung in dieser Leseprobe nicht enthalten

1. Introduction

Two urgent challenges humanity will have to address in the near future, are water scarcity and water pollution. Global water demand is predicted to increase by 55% until 2050, with the main drivers being population growth, increases in manufacturing, thermal electricity generation, food production, as well as domestic consumption (Unesco, 2015, p. 42). By the same time, and promoted by globalized economy, two-thirds of the world population will be living in cities, as they open more job opportunities than the often structurally lagging rural regions (UNDESA, 2014). But these opened opportunities entail challenges. Regionally concentrated and steadily augmenting water demands impose pressure on the available water resources. Surface and groundwater sources are frequently overexploited.

Additionally, urbanization causes an increase in wastewater generation. Especially in the global south, were most of the urban population growth is expected, cities have limited resources to manage these rapidly increasing wastewater flows. 90% of the generated wastewater in developing countries, and 80% globally is estimated to be discharged untreated into the environment (Unesco, 2017, p. 2, 2015, p. 42). But also in urban areas with sewer systems and centralized treatment facilities, the pressure on these systems grows along with the cities. The same global trends endangering water supply also potentially contribute to the pollution of water resources, further compromising the ecosystems capacity to provide sufficient clean and safe water.

Beside the pressure on water supply and wastewater treatment, urbanization further increases the pressure on our finite land resources. As more people concentrate in cities, the loss of fertile land and urban biodiversity has risen along with the sealed surfaces. Land officially declared as building land is getting rare and more valuable. At the same time the urban population inhabiting unofficial settlements was at about 30% in 2015 and is projected to reach a total of 900 million by 2020 (Unesco, 2015).

Vertical spaces however, i.e. the building encasing roofs and facades, are so far largely unused, and unvalued. Their usage opens so far barely untouched opportunities, including starting points to counteract the increasing pressures on water and land resources, as well as urban air pollution and biodiversity loss. Green walls and roofs are such emerging and globally spreading starting points to make use of these untouched urban spaces, while additionally increasing the livability and sustainability of cities (Fowdar et al., 2017). Whereas certain beneficial properties like facilitated microclimate compensations are well-known (see chapter 3.2), their potential for greywater treatment has not yet been exploited. As also existing building stocks could be retrofitted, greywater treating green walls in particular represent a possibility for cities to meet their growing water demands by reclaiming and reusing it on-site, close to the points of usage (Figure 1).

Abbildung in dieser Leseprobe nicht enthalten

Figure 1: Greywater treating green walls. Water use and reuse scheme. Source: alchemia-nova GmbH

In cooperation with the Viennese Institute for innovative phytochemistry & closed loop processes, alchemia-nova GmbH, first prototypes of a facade integrated greywater treating green wall were developed in the period from March to November 2017. This thesis constitutes one of a few studies that investigated the greywater treatment performance of modular units with which existing buildings can be retrofitted (Fowdar et al., 2017; Masi et al., 2016). The work was carried out within the European Union (EU) funded project “GreenINSTRUCT” (grant agreement No 723825), which aims to develop a modular functional building block. By planning to prefabricate the building blocks out of over 70% construction and demolition waste (CDW), the project also addresses the waste challenge as CDW accounts for about 30% of the total generated waste in the EU (GreenINSTRUCT, 2018). While the interior layer of the module is associated with functions like light weight construction, building energy-efficiency and acoustic performance, the exterior layer is planned to hold the greywater treating living green wall.

2. Objectives

The objectives of this thesis corresponded to the preliminary GreenINSTRUCT project goals regarding the development of the exterior layer of the overall wall:

1. Design and development of different greywater treating living green wall prototypes
2. Assessment of the on-site greywater treatment performance of each prototype
3. Estimation of the amount of consecutive living green wall panels necessary to achieve regulatory water quality standards for reuse applications

The design and construction phase was initiated in spring 2017, followed by an outdoor planting and establishment phase of several weeks in the beginning of June of the same year. A spectrophotometer probe and a photometer were used to analyze a range of water quality parameters (BOD5, COD, DOC, TOC, TSS, TURB) and nutrients (NH4-N, NO3-N, PO43-). After calibration, the measurements were conducted in the period from August to September 2017 in the laboratory of alchemia-nova GmbH in Vienna.

In the subsequent chapter the fundamentals are summarized. First, green walls are defined and characterized, followed by an introduction about greywater quantity, quality, reuse, and risks. Constructed Wetlands as a reference biotechnology and their mode of operation, i.e. the transformation and elimination processes in wastewater treatment are presented.

Chapter four presents the materials and methods used. The design concepts, selected plants and substrates, the hydraulic loading regime and sampling procedure, and the mean residence time determination are described. All applied measurement instruments are presented, before this chapter closes with a description of the statistical methods.

The obtained treatment results are presented and discussed in the fifth chapter.

The thesis closes with a conclusion and suggestions for future improvements and investigations.

3. Fundamentals

3.1 Greywater: Quantity, Quality, Reuse, and Risks

Wastewater can be categorized regarding its different constituents into blackwater, yellow water, brownwater, and greywater (Tilley et al., 2014, pp. 10-11). The term blackwater summarizes fecal and urine wastewater including anal cleansing materials, while yellow water includes urine wastewater only. Brownwater contains fecal wastewater including anal cleansing materials. Greywater (GW), i.e. wastewater from sinks, showers, bath tubs, laundry machines, and dishwashers, is generally considered a low polluted wastewater stream which requires only little treatment. Although, greywater may still contain fecal pathogens from e.g. diapers.

The quantity of greywater production varies largely depending on lifestyle, habits, living standards, population structure, health, usage patterns and the degree of water abundance from as low as 20-30 L per person per day in low income countries with water shortage, up to 90-120 L per person and day (Li et al., 2009, p. 3440). Figure 2 shows the shares of the total household water consumption and greywater production. With about 62-65% greywater holds the biggest share of the total water consumption in households with flush toilets (Edwin et al., 2014, p. 45); (Tilley et al., 2014, p. 11). This makes it the most worthwhile wastewater stream to be treated and reused on-site, with a high potential of water savings. The biggest share of the greywater is produced using showers and bath tubs (49%), followed by laundry machines (27%), kitchen sinks and dishwashers (17%) and washing sinks (7%).

Abbildung in dieser Leseprobe nicht enthalten

Figure 2: Total water consumption and greywater production. Source: adapted from Edwin et al. 2014, p. 47.

The degree of greywater pollution depends largely on the source. GW from washing sinks, showers and bath tubs is considered the least polluted GW fraction, while GW from laundry machines, dishwashers and kitchen sinks drastically increase the pollution. Table 1 shows greywater pollution literature values for selected water quality parameters. For instance, BOD5, COD, TSS and turbidity values vary between 90-535 mg/L, 13-8000 mg/L, 17-300 mg/L and 15­240 NTU, respectively, for mixed greywater sources. Due to the high load of oil, grease, food particles and detergents, kitchen GW is considered the most polluted GW fraction. Although GW from kitchen only accounts for approximately 10-26% of total GW production, it contributes up to 42% of its COD and 48% of its BOD (Friedler, 2004, p. 1001).

Table 1: Literature review of greywater quality parameters from different sources.

Abbildung in dieser Leseprobe nicht enthalten

Considering that the least polluted bath GW fraction (sinks, showers, baths) accounts for the biggest share of the overall GW production, treating and reusing it directly on-site should be prioritized. Especially in urban areas where availability and therefore potential savings of freshwater are high. Treating and reusing GW on-site has multiple evident advantages. One is the reduction in freshwater demand for usages where a less clean water supply would be sufficient (e.g. toilet flushing). It would further reduce the hydraulic load on the sewer network and the centralized treatment facilities, allowing the possibility to scale down infrastructure and reduce costs.

Although solutions to fight water scarcity are sought after and awareness among governments and institutions has risen, legislation regarding water reuse is lacking behind in most parts of the globe. At present, there are no uniform international or national quality standards, laws or regulations regarding the treatment and reuse of GW specifically (Edwin et al., 2014, p. 42; Li et al., 2009, p. 3440; Unesco, 2017). The European Commission published quality standards for effluents which flow into surface waters from municipal wastewater treatment plants in the Urban Wastewater Directive, but no specific quality standards for reuse in households or industries were stated at the time (European Commission, 1991). Currently, the environmental board of the European Commission is working on a legislation proposal on minimum water quality requirements for reuse in aquifer recharge and irrigation (European Commission, 2018). Few guidelines were published on the state level of some countries or by research institutions. The state of California (USA) for instance officially allowed the reuse of greywater, and the state of Mumbai (India) even made it compulsory for all newly built commercial and residential buildings to implement GW reuse and rainwater harvesting systems (Edwin et al., 2014, p. 42). In the city of Tokyo, greywater recycling is mandatory for buildings with a potential reuse of 100 m 3 /d or an area over 30000 m 2 (Edwin et al., 2014, p. 42). One of the few known rules and standards specifically for greywater recycling, was published by the German Association for Process and Rainwater Usage (FBR) in the year 2005. It defines planning criteria and operation guidelines on how to manage greywater treatment for the reuse as process water and offers quality standards as shown in Table 2. Alcalde-Sanz and Gawlik (2014) summarized general water reuse standards from different EU countries. The range is also presented in Table 2, along with the United States Environmental Protection Agency (USEPA) and the Indian Central Pollution Control Board (CPCB) water reuse standards.

Table 2: Quality requirements for treated wastewater effluents to allow reuse.

Abbildung in dieser Leseprobe nicht enthalten

While reusing treated greywater for flushing toilets can already reduce the freshwater demand by 10-20% (Friedler, 2004, p. 997), the reduction in domestic water demand can reach up to 50%, if GW is reused for flushing water and garden irrigation together (Maimon et al., 2010, p. 3213). This can be a significant reduction especially in water stressed regions.

GW reuse is obviously not restricted to households, also an industrial or agricultural reuse is possible (e.g. as cooling or irrigation water). But despite the potential benefits, the reuse of treated GW has potential hazards. Some studies like Travis et al. (2010) concluded that treated GW can be irrigated without adverse effects on neither soil nor plant growth. Others instead point out the potential environmental risks associated with phosphorus rich effluents and demand a more intensive long-term research regarding the accumulation of micropollutants in soils and fruits (Edwin et al., 2014, p. 46).

In water stressed or water scarce regions, the physical necessity can raise reuse levels, such as the GW reuse as potable water. Edwin et al. (2014, p. 45) point out, that for instance in Singapore and Namibia, where freshwater resources are limited, highly treated greywater is mixed into the drinking water. Although, stringent quality parameters would have to be developed and the risks associated with different GW sources have to be kept in mind.

Finally it must be highlighted, that reuse is principally dependent on the development of legislations and economics. Once legislative obstacles are overcome and used water can be made available at comparable or even lower prices as regular freshwater, reuse rates could potentially rise.

3.2 Green Walls: Definition and State-of-the-Art

Artificial greening systems like green walls, have been frequently used as a functional and aesthetical feature throughout history as well as nowadays. Green walIs refer to “all systems which enable greening a vertical surface (e.g., facades, walls, blind walls, partition walls, etc.) with a selection of plant species [...], up or within the wall of a building” (Manso and Castro- Gomes, 2015, p. 864). They can further be divided into green facades, where ground rooted vines and ornamental plants grow directly on the wall or indirectly by applying a support structure, and living walls (Figure 3). Living walls allow a faster and more uniform coverage of vertical surfaces as well as the integration of a broader range of species. They can be divided into continuous systems (i.e. Vertical Gardens), where plants are inserted in lightweight permeable screens, and modular systems (Manso and Castro-Gomes, 2015, p. 865). Modular living wall systems are single units with specific dimensions and include the growing media for plants to grow in. Following the differentiation given in Figure 3, the green wall developed during this thesis is best described as a modular, building-integrated living wall with a box-like vessel.

Abbildung in dieser Leseprobe nicht enthalten

Figure 3: Distinction of green wall systems. Source: (Manso and Castro-Gomes, 2015, p. 865).

As initially mentioned, outdoor greening systems like green roofs and green walls, can contribute to revegetate cities without occupying valuable space at street level, and thus bring about synergetic environmental, economic, health and social benefits. In an urban context however, green wall systems have a higher potential than green roofs considering the vast extent of applicable facade on multistory buildings. Manso and Castro-Gomes (2015) list several beneficial effects, ranging from the contribution to urban biodiversity, air quality, temperature reduction (i.e. mitigation of the heat island effect) as well as acoustic and thermal insulation. Furthermore, they increase property value and can induce psychological wellbeing by the presence of vegetation.

Disadvantages of green walls, which are usually noted in literature and which could eventually impede their widespread application, are the high amounts of required freshwater (up to 20 L/m2/d for external applications) and energy needed to operate them (Department of Environment and Primary Industries DEPI, 2014; Fowdar et al., 2017, p. 219). However, both obstacles can be overcome. Transparent photovoltaic cells for instance, which are mounted in front of a green wall, allow 80% of the light to pass through them and thereby creating synergies (Aigner, 2014). The growing plants act as a cooling system for the photovoltaic cells, increasing their energy yield, whereas the partially shading cells regulate humidity. The application of freshwater to irrigate green walls can be prevented using alternative water sources. Using stormwater can be challenging due to its unpredictable occurrence and the consequential need for storage. Greywater instead is produced more regularly and, compared to stormwater, it is rich in nutrients to facilitate a healthy plant development. Fowdar et al. (2017, p. 219) point out, that although some systems currently use recycled greywater as feeding water, there is only little performance data regarding the use of green walls for greywater treatment. Some of the few scientific studies encountered which analyzed the treatment efficiency of green walls were Masi et al. (2016), Prodanovic et al. (2017) and Fowdar et al. (2017). Although, these types of green walls differ from the one developed during this thesis. Instead of a fagade integrated design approach, a hanging multi-flowerpot or a surface sand filter bed with vines were installed (Figure 4). Performance data of the three studies with the results obtained in this thesis are compared in chapter five. Combining green wall irrigation and greywater treatment would offer an added value, whereby making these systems more cost-effective and stimulate dissemination.

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Figure 4: Existing green wall-systems for greywater treatment. Left: multi-flowerpot approach. Right: surface biofilter bed with vines. Source: Masi et al. 2016, Fowdar et al. 2017.

Certainly, green walls are also installed indoor, where many of the above mentioned beneficial effects apply as well. Due to the more controlled environment, a more diverse selection of species can be planted regardless of the local climate. Commonly, the operation of these walls is automated (e.g. the irrigation and nutrient supply scheme), whereby costs are kept at a minimum. A regular maintenance must be realized for indoor and outdoor green walls either way.

3.3 Constructed Wetlands as Reference Biotechnology

In literature different classifications and definitions for Constructed Wetlands (CW) are suggested. One definition is given by Vymazal and Kröpfelova (2008, pp. 4-5):

“Constructed wetland treatment systems are engineered systems that have been designed and constructed to utilize the natural processes involving wetland vegetation, soils, and their associated microbial assemblages to assist in treating wastewater. They are designed to take an advantage of many of the same processes that occur in natural wetlands, but do so within a more controlled environment. [...] Constructed wetlands are essentially wastewater treatment systems and are designed and operated as such, though many systems do support other functional values.”

Which additional functional values apply depend on the type of CW and can include, for instance, the provision of a wildlife habitat, air quality improvements as well as an aesthetic value added. Although it must be mentioned, that potential adverse effects do exist as well (e.g. mosquito breeding habitats).

One classification to differentiate treatment wetlands based on the type of flow, is given by Kadlec and Wallace (2009, p. 5) and is presented in Figure 5. In the last decades, constructed wetlands have been applied for the treatment of various types of wastewaters. Vymazal (2008, p. 970) provides an overview of treated wastewaters by different types of CWs, which include industrial (petrochemical, textile, mining, etc.), agricultural (dairy, livestock, etc.) and municipal wastewaters.

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Figure 5: Classification of treatment wetlands. Source: adapted from Kadlec and Wallace (2009).

Regarding the treatment performance and the costs for operation and maintenance, constructed wetlands are regarded as one of the most eco-friendly and cost effective treatment technologies for greywater treatment (Li et al., 2009, p. 3447). However, the large space demand of up to 10 m 2 per person equivalent (PE) is probably the most decisive negative feature and makes them unfit for urban applications (Tilley et al., 2014, p. 116).

In the following, the three most frequently used types of CWs are shortly described: Surface Flow Wetlands (SF-Wetlands), Horizontal Flow Wetlands (HF-Wetlands) and Vertical Flow Wetlands (VF-Wetlands).

3.3.1 Surface Flow Wetlands

Of all CWs, SF-Wetlands (i.e. Free Water Wetlands; Figure 6) resemble natural wetlands like swamps or marshes the most, and therefore also attract wildlife (Kadlec and Wallace, 2009, p. 5). Wastewater flows into a sealed and controlled open-water pond with floating, submerged and/or emergent plants, where the interactions of flora and fauna facilitate the naturally occurring treatment processes. While slowly flowing through the wetland, wastewater constituents are filtered and degraded by physical, chemical and biological processes at the same time. Nutrients are used by flora and fauna to a limited extent, pathogens are being destroyed by UV irradiation and predation (Tilley et al., 2014, p. 114). Due to the limited capacity of transforming nutrients and supply oxygen (e.g. by plant roots), SF-Wetlands are rather used as a tertiary treatment step for low pollution loads, polishing, or for the treatment of stormwater runoff (Tilley et al., 2014, p. 115). Advantages and disadvantages of this type of CW are summarized in Table 3.

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3.3.2 Horizontal Flow Wetlands

HF-Wetlands, as shown in Figure 7, consist of a controlled and sealed pond filled with gravel or soil and emergent vegetation. Inflowing wastewater flows horizontally from the inlet, through the substrate and the rhizosphere, to the height variable outlet, which ensures the water to flow beneath the surface. This hinders the breeding of mosquitos as well as pathogenic infections, which both endanger human health. HF-Wetlands are most often used for secondary treatment of domestic wastewater, but industrial applications are widespread as well (Kadlec and Wallace, 2009, p. 6). A pretreatment is crucial to prevent clogging and to ensure treatment efficiency (see chapter 3.4.4). The design is based on the requirements, that apart from minor atmospheric interactions, plants create aerobic conditions by oxygen leakage in the rhizosphere to facilitate aerobic decomposition processes. Although, according to Vymazal and Kröpfelova (2008, p. 177), many studies have shown a limited plant induces oxygen transfer, resulting in anoxic and anaerobic zones and associated processes to take place as well. A possible solution is to aerate the bed artificially, which would require an additional constant energy supply.

The surface area demand of HF-Wetlands, is about 5-10 m 2 /PE (Tilley et al., 2014, p. 116). Advantages and disadvantages of HF-Wetlands are summarized in Table 4.

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Figure 7: Scheme of a Horizontal Flow Wetland. Source: Tilley et al. (2014).

Table 4: Advantages and disadvantages of HF-Wetlands. Source: adapted from Tilley et al. (2014).

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3.3.3 Vertical Flow Wetlands

In VF-Wetlands, wastewater is usually loaded intermittently from above while flooding the surface, but tidal or upflow regimes do exist as well. The sealed bed is filled with sand on top of gravel layer and planted with macrophytes. Wastewater slowly percolates down through the sand and gravel layers, passing the rhizosphere, and is collected by a network of drainage pipes as shown in Figure 8. When the water has drained completely, air is able to enter the substrate again. This periodic shift from a saturated, anaerobic environment to an unsaturated, aerobic one, facilitates carbon and in particular nitrogen transformation processes (see chapter 3.4). Because oxygen is supplied via the loading regime, the major purpose of plants in a VF-Wetland (in contrast to HF- Wetland) is to help maintain the hydraulic conductivity of the system (Vymazal and Kröpfelova, 2008, p. 179).

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Figure 8: Scheme of a Vertical Flow Wetland. Source: Tilley et al. (2014).

With about 1-3 m 2 /PE, the surface area demand of VF-Wetlands is significantly smaller compared to HF-Wetlands (Tilley et al., 2014, p. 118). Due to the higher oxygen supply and the consequential nitrification potential, this type of treatment wetland has been applied frequently for wastewaters with higher ammonia levels than municipal wastewaters (Kadlec and Wallace, 2009, p. 7). As for the other types of CWs described above, the advantages and disadvantages are summarized in the following.

Table 5: Advantages and disadvantages of VF-Wetlands. Source: adapted from Tilley et al. (2014).

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3.4 Transformation and Elimination Processes in Constructed Wetlands

Transformation and elimination processes largely depend on environmental conditions such as pH, temperature and oxygen supply. In the following chapters, the most relevant processes in greywater treatment are explained in detail.

3.4.1 Carbon Transformation

In treatment wetlands, the major processes of carbon transformation are aerobic respiration conducted by chemoheterotrophic microbes, and anaerobic respiration by facultative or obligate anaerobes. During aerobic respiration, organic substances are being degraded using oxygen as the main electron acceptor, into water, carbon dioxide, and energy which is stored as ATP (Kadlec and Wallace, 2009, p. 61):

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Under anoxic or anaerobic conditions, different carbon transformation reactions can take place. These include fermentation (Eq. 2 & 3), nitrate reduction (i.e. denitrification), and iron reduction. Sulfate-reducing and methane-forming bacteria instead, are active in anaerobic zones only (Vymazal and Kröpfelova, 2008, p. 21).

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Regarding the carbon parameters measured in treatment systems, COD, BOD, and TOC are of main importance. The COD does not distinguish between inert and biologically available organic matter. It is “the amount of a chemical oxidant, usually potassium dichromate, required to oxidize the organic matter’, while BOD is the “oxygen consumption of microorganisms in the oxidation of organic matter’ (Kadlec and Wallace, 2009, p. 237). BOD is generally surveyed as BOD5, the microbial oxygen consumption during five days. TOC is a measure for the total organic carbon content. Due to the intermittent loading, VF-Wetlands usually operate in an unsaturated downflow regime, which allows atmospheric oxygen to enter the pores during rest periods. This improves the aerobic carbon reduction and the associated BOD removal compared to HF-Wetlands. Although a sufficient oxygen supply should be ensured for aerobic decomposition of carbon to take place, anoxic or anaerobic reactions like denitrification consume carbon compounds as well.

Plants provide multiple beneficial functions in treatment wetlands. They exudate sugars, use nutrients in small amounts and are able to release oxygen to the rhizosphere, but above all provide living environments for microbes on their root surface (Brix, 1997). Tanner (2001, p. 10) repots a difference in BOD removal of 2-5 mg/L for planted Cw beds compared to unplanted ones, a small but measurable improvement.

3.4.2 Nitrogen Transformation

As for carbon transformations in biological treatment systems, microbes are as well involved in nitrogen transformation processes to a large extent. Chemoautotrophic bacteria like Nitrosomonas and Nitrosospira oxidize inorganic ammonium to nitrite (Eq. 5). Bacteria from the genera Notrobacter, Nitrococcus and Nitrospira are able to further oxidize nitrite to nitrate from which they derive energy for their cell metabolism (Eq. 6; Vymazal and Kröpfelova, 2008, p. 29). In both sub-processes, microbes use CO2 as carbon source for their cell synthesis (Kadlec and Wallace, 2009, p. 61). The oxygen needed for nitrification to take place can derive from the atmosphere, though Tanner (2001, p. 15) and Brix (1997, p. 13) point out, that rhizosphere oxygen release can further enhance nitrification processes.

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Additionally, also anaerobic respiration processes are of importance in these treatment systems. Under anaerobic or anoxic conditions, bacteria like Pseudomonas, Bacillus or Paracoccus denitrificans, substitute oxygen with nitrate or nitrite (Eq. 8) to oxidize carbohydrates in a process termed denitrification (Vymazal and Kröpfelova, 2008, p. 37). Nitrogen gas is produced via the intermediates nitric oxide and nitrous oxide (Eq. 9).

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It must be noted, that denitrification is strongly dependent on the availability of organic substances. A strong correlation was found especially regarding the supply of easily decomposable matter (Kadlec and Wallace, 2009, p. 38). Organic substances are usually present in soils or sediments, but can also be provided by root exudates to a limited extent (Vymazal and Kröpfelova, 2008, p. 38). In treatment wetlands, the major carbon inputs come from municipal wastewater, i.e. from blackwater and/or greywater.

Due to the anaerobic conditions needed for the denitrification process to take place, water saturated soils or substrates are reported to have higher denitrification levels (Figure 9).

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Figure 9: Share of water-filled pore spaces and associated relative microbial activity regarding nitrogen transformation processes. Source: Vymazal and Kröpfelova (2008, p.39).

3.4.3 Phosphorus Transformation and Retention

Because phosphorus might be a limiting factor for greywater reuse (Turner et al., 2013), phosphorus transformations are briefly describes as well.

In contrast to carbon or nitrogen, phosphorus does not show biologically induced fluxes from and to the atmosphere, nor is it used as a primary energy source during microbial oxidation (Vymazal and Kröpfelova, 2008, p. 54). In wetlands it occurs as inorganic and organic compounds, such as orthophosphate, which is present in ionic equilibrium (Eq. 10), and ATP (Vymazal and Kröpfelova, 2008, pp. 54-55).

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Although phosphorus is not being used as primary energy source, aquatic flora and fauna rapidly absorb it when entering the wetland. The absorption can reach up to 20% of total phosphorus sorption, however, the majority precipitates or is absorbed by iron and aluminum oxy-hydroxides, aluminosilicates, calcium and magnesium minerals, or clay depending on redox potential and pH (Kadlec and Wallace, 2009, p. 395; Turner et al., 2013, p. 288; Vymazal and Kröpfelova, 2008, p. 55). Turner (2013, p. 288) as well as Kadlec and Wallace (2009, p. 390) point out, that once all sorption sites have been saturated phosphorus sorption will stagnate. Additional phosphorus inflow would result in free phosphorus leaving the wetland, possibly entering groundwater or surface waters. Although, as long as concentrations stay low, phosphorus inflow can have a stabilizing effect on the hydrological ecosystem (Binder et al., 2016, p. 220) .To remove phosphorus in high amounts, bigger dimensioned CWs or other means of treatment would be needed.

3.4.4 Suspended Solids Removal

Constructed wetlands and other sand or gravel biofilters are effective in removing suspended solids by either settling, filtrating or intercepting them, which is of importance for their effluent water quality. Many wastewater pollutants are affiliated to the influent suspended matter, such as organic particles, organic chemicals and metals (Kadlec and Wallace, 2009, p. 203). Removal via filtration or interception can result in an accumulation of particles on the top layer of VF-Wetlands or the gravel inlet of HF-Wetlands. Although suspended solids entering a wetland are usually removed quickly by decomposers, the development of a biomat coat at the inlet could reduce the hydraulic conductivity or even plug the media if the biosolids bridge the pore voids, with adverse consequences on the system performance (Kadlec and Wallace, 2009, pp. 228-229). Kadlec and Wallace (2009, p. 229) point out, that the effluent TSS in HF-Wetlands are no product of the removal efficiency of the treatment system, but depend on internal biological processes, namely decomposition and resuspension of biomat particulates in the system .

3.4.5 Pathogen Removal

As indicated in Table 1, greywater can contain pathogens in high numbers. If intended for reuse, pathogen reduction in greywater treatment must be a prime goal to ensure human health.

Kadlec and Wallace (2009, p. 509) compared 54 HF and nine unsaturated downflow VF systems, for which a two logw reduction in total coliforms were achieved. They further compared studies regarding fecal coliform reduction in both types of wetlands, with logw reduction of 2.32 (HF) and 2.4 (VF). Although higher rates can be found in literature, these reduction rates are not constant throughout the year. Molleda (2008) for instance reported rates, with up to 99.9% removal in spring and autumn for E.Coli (3 log) and total coliforms (4 log), respectively. Removal mechanisms include high hydraulic retention times, filtration (depending on particle size of the substrate), and predation (Kadlec and Wallace, 2009; Vymazal and Kröpfelova, 2008).

4. Material and Methods

4.1 Experimental Setup and Procedure

4.1.1 Design Concepts

Before construction began, multiple design ideas were discussed considering water flow control i. e. control of hydraulic residence time, feasibility of production, assembly, root growth space, etc. Finally, three major design concepts for a modular greywater treating green wall were implemented:

1. Vertical channels
2. Inclining alternating cascades
3. Declining alternating cascades

In the early stage of the thesis, when the prototypes were built with the specification described in the following, the dimensions of the modular green wall were not yet finalized. Due to constructive difficulties the project consortium later agreed on different dimensions. To achieve satisfying thermal insulations values, the future internal and the external GreenINSTRUCT wall will have to sandwich a PU-foam layer (Figure 10). In order to be able to continue with a manageable modular green wall, a plate with 120 cm x 100 cm was added to the design. The plate will sandwich the PU-foam layer and hold three 40 cm x 100 cm cassettes.

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Figure 10: Visualization of the GreenINSTRUCT design approaches. Inner wall (grey), PU-foam (purple), cover plate (brown), mounts (yellow & orange), external green wall (green: modular cassette, blue: cascades, pink: channels, orange: cover plate). Source: Gianluca Vassallo

4.1.1.1 Vertical Channels

Although a short hydraulic residence time was estimated in advance due to the vertical design of the prototype, it was implemented either way due to multiple reasons:

1. The constructive effort and economic costs are minimal, as it can be constructed out of ready-made products. This allows to investigate different substrate compositions in parallel.
2. The final external green wall of the GreenINSTRUCT project is aimed to be made from minimum 70% CDW or other recycled materials. The extrusion of the green wall with a geopolymer which is being developed by the projects consortium is a possible manufacturing option. Extrusion could reduce the overall costs, and eventually stimulate dissemination of the product.

PVC based pipes were heated and warped into an elliptical shape with the dimensions noted in Table 6. The minor axis radius of approximately 3 cm was chosen to provide a comparably narrow root space as in the two other designs. A smaller radius could not be achieved without risking a material defect. Starting from 10 cm below the upper edge, five holes were drilled every 20 cm (Figure 11). The bottom was closed using an aluminum mesh with approximately 2 mm mesh size to inhibit substrate outflow.

For this prototype, a plant supporting structure was installed by mounting a polypropylene pipe which had been cut at a 45° angle on two sides. Two copies of the channelized design concept were built, but they were filled with different substrate compositions. The prototype “Chan” was filled with the substrate only, while coconut fibers were added to “ChanPlus” to approximately one-fourth of the volumetric content.

Table 6: Dimensions, volume and weight of “Chan” and “ChanPlus”.

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Figure 11: Technical drawing of "Chan" and "ChanPlus".

4.1.1.2 Inclining Alternating Cascades

In order to raise the flow length of the greywater and the associated hydraulic residence time, two cascading versions were implemented. Fowdar et al. (2017, p. 219) recommended the investigation of water saturated zones in the design of green walls to improve pollutants processing, especially to facilitate denitrification, and due to possible advantages for plants survival during water stressed periods.

The first cascading version was therefore built with an ascent 5° angle at each of the six cascades to create several small water retention basins (“Panjncl”). At first, the basins are filled up until a critical point is reached. Water then drips down to the next basin until it reaches the outflow or the following panel. With every new irrigation cycle, the incoming wastewater has to circulate through the basins, passing by the substrate, biofilm, and roots.

For first prototyping, both cascading panels were built out of wood, plastic liners, acryl glass and steel brackets with dimensions as shown in Table 7. Acryl glass was used as the cover plate to monitor the root growth, although its usage raised difficulties during construction regarding water tightness due to its low stiffness. Because plants had to be inserted in the panel, holes were drilled in the acryl glass cover plate in a parallel line with respect to the expected water level (Figure 12). The distance of the expected water level to the center of the drilled holes was 5 cm. With 12 cm, the horizontal distance from one hole to another was kept as wide as possible to prevent struggle for necessary root space among different plants.

Compared to the vertical channel design, this construction was more sophisticated regarding its construction and assembly, but with its box-like structure it was closer to the desired modular design. Additionally, more plants per panel can be planted, which eventually is beneficial regarding treatment performance as well as aesthetically. With three plants per cascade the total number of plants was 18.

Table 7: Dimensions, volume and weight of "Pan_incl".

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[...]

• College: University of Natural Resources and Applied Life Sciences, Vienna (Department of Water, Atmosphere and Environment Institute of Sanitary Engineering and Water Pollution Control)
• Grade: 1,0
• Author: Gianluca Vassallo (Author)
• Publication Year: 2018
• Pages: 97
• Catalog Number: V1334351
• ISBN (PDF): 9783346827111
• ISBN (Book): 9783346827128
• Language: English
• Tags: design, development, living, green, wall, greywater, treatment