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 Transformation
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 spectro::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 Greywater recipe
9.2 Calibration data
9.3 Results
9.4 Test statistics
10. Curriculum Vitae
Objectives & Core Topics
The primary goal of this research is to design and develop modular, facade-integrated living green wall prototypes for on-site greywater treatment. The study assesses the treatment performance of different configurations regarding their substrate, plant species, and water-flow dynamics, ultimately evaluating if consecutive treatment units can meet regulatory water quality standards for potential reuse.
- Design and development of modular greywater treatment prototypes.
- Assessment of treatment efficiency for pollutants such as BOD, COD, and nitrogen.
- Investigation of plant growth and root network development in vertical setups.
- Analysis of hydraulic residence time and its influence on purification performance.
- Evaluation of consecutive modular units for achieving regulatory effluent quality requirements.
Auszug aus dem Buch
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.
Summary of Chapters
1. Introduction: This chapter highlights global challenges such as water scarcity and urbanization, introducing green walls as a modular, facade-integrated solution for on-site greywater treatment.
2. Objectives: The research aims are defined, focusing on the design of prototypes, performance assessment, and the estimation of necessary serial configurations to reach water quality standards.
3. Fundamentals: Provides a theoretical basis by defining greywater, green wall systems, and established constructed wetland biotechnology regarding treatment processes.
4. Material and Methods: Details the experimental construction of the prototypes, the selection of substrates and plants, the hydraulic loading regimes, and the analytical methods used.
5. Results and Discussion: Presents the analysis of plant health, mean residence times, and pollutant removal performance, discussing the differences between channelized and cascading prototype designs.
6. Conclusion and Outlook: Synthesizes findings, emphasizing the importance of support structures for root development and suggests future optimizations for material choice and loading regimes.
Keywords
Greywater Treatment, Living Green Walls, Constructed Wetlands, Sustainability, Urban Water Management, Facade Integration, Biofiltration, Water Reuse, Hydraulic Residence Time, Environmental Engineering, Nutrient Removal, Modular Design, Wastewater Quality, Urban Ecosystems, Rhizosphere Development
Frequently Asked Questions
What is the core purpose of this research?
The research focuses on developing and testing modular, facade-integrated green wall systems capable of treating greywater on-site to help mitigate urban water scarcity.
Which green wall prototypes were tested?
The study tested prototypes using vertical channels, inclining alternating cascades, and declining alternating cascades, compared against an unplanted control system.
What is the primary objective regarding water quality?
The goal is to determine if these systems can treat greywater to meet EU regulatory standards for reuse applications like irrigation or toilet flushing.
What methodology was employed for analysis?
The performance was analyzed using an UV/Vis spectrophotometer probe and chemical photometers, alongside statistical evaluation using the Kruskal-Wallis test.
What are the main topics discussed in the main body?
The body covers materials and methods, design concepts, plant root development, residence time calculations, and the performance of the system in a simulated multi-stage setup.
Which keywords best describe the study?
Key terms include greywater treatment, living green walls, constructed wetlands, urban water management, and ecological sanitation.
Why did the plant selection prioritize specific species?
Plants were selected based on their suitability for artificial treatment wetlands and their ability to thrive in the narrow, vertical root space provided by the developed prototypes.
How does the substrate influence the treatment performance?
The substrate contributes significantly to pollution removal through adsorption and provides the necessary surface area for biofilm development essential for microbial treatment.
- Quote paper
- Gianluca Vassallo (Author), 2018, Design and Development of a Living Green Wall for Greywater Treatment, Munich, GRIN Verlag, https://www.grin.com/document/1334351
