For a novel approach of resource-efficient water reuse, a municipal wastewater treatment plant was extended at pilot scale for advanced wastewater treatment, i.e., ozonation and biological activated carbon filtration, and a hydroponic system for reclaimed water driven lettuce cultivation. The treatment specific wastewater lines with the corresponding lettuce plants, differentiated into roots and shoots, were monitored for priority wastewater micropollutants, i.e., acesulfame (sweetener), caffeine (stimulant), carbamazepine, diclofenac, ibuprofen, sulfamethoxazole with acetyl-sulfamethoxazole (human pharmaceuticals), 1H-benzotriazole, and 4/5-methylbenzotriazole (industrial chemicals). As clearly demonstrated, conventional tertiary treatment could not efficiently clean up wastewater. Removal efficiencies ranged from 3% for carbamazepine to 100% for ibuprofen. The resulting pollution of the hydroponic water lines led to the accumulation of acesulfame, carbamazepine, and diclofenac in lettuce root systems at 32.0, 69.5, and 135 μg kg−1 and in the uptake of acesulfame and carbamazepine into lettuce shoots at 23.4 and 120 μg kg−1 dry weight, respectively. In contrast, both advanced treatment technologies when operating under optimized conditions achieved removal efficiencies of > 90% also for persistent micropollutants. Minimizing the pollution of reclaimed water thus met one relevant need for hydroponic lettuce cultivation. Graphical abstract
Within the research project HypoWave, a hydroponic system for plant production was investigated. The hydroponic system was fed with wastewater that had undergone specially adapted treatment. The principal aim was to develop a combined system for water treatment and hydroponic plant production, where water and nutrients were reused efficiently to produce marketable food products. Another goal was to find out whether the reuse of pre-treated wastewater for plant growth in a hydroponic system could also present an additional alternative wastewater treatment step for enhanced nutrient removal. A pilot plant, consisting of various treatment steps such as activated sludge process, ozonation and biological activated carbon filtration, was used to produce lettuce with irrigation water of different qualities. The hydroponic pilot plant was operated in two different modes – flow-through and feed & deplete. This paper focuses on the influence of the various modes of operation and accordingly varying nutrient concentrations (N, P, K) on plant growth. Furthermore, heavy metal content in the various types of treated wastewater and in the produced plants was investigated. In addition, the results of the different modes of operation were verified by mass balances for N, P and K.
Based on three pilot- and demonstration-scale projects investigating agricultural irrigation practices with reclaimed water, risks associated with these water reuse practices are highlighted and processes and strategies to minimize associated microbial risks were evaluated. A number of treatment processes and combinations were tested regarding their efficacy for pathogen removal, representing the biggest threat to the quality of products from reuse irrigation practices. In addition, the importance of regrowth potential and different methods for monitoring risks associated with pathogens were discussed. One method for online monitoring is flow cytometry. The results of an exemplary quantitative microbial risk assessment (QMRA) were discussed to determine the significance of microbial risks. Multi-barrier approaches comprised of technical and administrative barriers can reduce the risks of water reuse significantly. Quality management also needs to address all stakeholders involved in a reuse project, starting from source control in the sewershed to marketing of the final products. In addition, environmental risks of water reuse need to be addressed by quality management as well.
Developed more than a century ago, the potential of vacuum sewerage systems remains underexploited. At the same time, the rapid urbanization in Asia brings about major challenges for municipal utilities. In this context, the GIZ (Deutsche Gesellschaft fuer Internationale Zusammenarbeit) project ‘Integrated Resource Management in Asian Cities: the Urban Nexus’ gives technical advice to stakeholders in the partner cities. Fraunhofer IGB, having operated a vacuum sewer system for more than ten years in the context of a research project, carried out a survey regarding current experiences with vacuum sewer systems and the transferability to countries of the Global South. In an environment with existing infrastructure, it is often not economically reasonable to install an additional sewer system. Nevertheless, with aging infrastructure and an increasing importance of circular economy concepts including water reuse, nutrient recovery and biogas generation, vacuum sewers can pose a viable alternative for refurbishments or new developments in semi-decentralized sanitation approaches involving local treatment and resource recovery.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.