Design and Development of a Living Green Wall for Greywater Treatment
Gianluca Vassallo
Master's Thesis from the year 2018 in the subject Geography / Earth Science - Physical Geography, Geomorphology, Environmental Studies, grade: 1,0, University of Natural Resources and Applied Life Sciences, Vienna (Department of Water, Atmosphere and Environment Institute of Sanitary Engineering and Water Pollution Control), language: English, 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.
