Concern over dwindling water supplies for urban areas as well as environmental degradation from existing urban water systems has motivated research into more resilient and sustainable water supply ...strategies. Greywater reuse has been suggested as a way to diversify local water supply portfolios while at the same time lessening the burden on existing environments and infrastructure. Constructed wetlands have been proposed as an economically and energetically efficient unit process to treat greywater for reuse purposes, though their ability to consistently meet applicable water quality standards, microbiological in particular, is questionable. We therefore review the existing case study literature to summarize the treatment performance of greywater wetlands in the context of chemical, physical and microbiological water quality standards. Based on a cross-section of different types of wetlands, including surface flow, subsurface flow, vertical and recirculating vertical flow, across a range of operating conditions, we show that although microbiological standards cannot reliably be met, given either sufficient retention time or active recirculation, chemical and physical standards can. We then review existing case study literature for typical water supply disinfection unit processes including chlorination, ozonation and ultraviolet radiation treating either raw or treated greywater specifically. An evaluation of effluent water quality from published wetland case studies and the expected performance from disinfection processes shows that under appropriate conditions these two unit processes together can likely produce effluent of sufficient quality to meet all nonpotable reuse standards. Specifically, we suggest that recycling vertical flow wetlands combined with ultraviolet radiation disinfection and chlorine residual is the best combination to reliably meet the standards.
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•Constructed wetlands are a low energy treatment process with potential to adequately treat greywater for nonpotable reuse•Greywater contaminant removals are complex and reductions vary depending on the contaminant and operating conditions•With right disinfection measures, constructed wetlands may be a safe, low energy option for decentralized, nonpotable reuse
Climate change, population expansion, water shortages, soil erosion, and food security are some of the primary concerns facing the world today. Hydroponic, aquaponic, and aquaculture systems may help ...to address these difficulties. Hydroponics is a closed-loop system for growing plants in nutrient-rich water rather than soil. Aquaponic systems combine hydroponics and the growing of fish or other aquaculture species in addition to plants. This review aims to evaluate the challenges encountered by aquaponic and aquaculture farming operations and identify which issues still need to be addressed. The review is organized as follows: recent previous studies on hydroponics, aquaponics, and aquaculture were collected and investigated; water quality and energy issues were addressed; technologies to improve water quality in these systems were discussed; and challenges to the implementation of large-scale aquaponics were discussed. The study found that a commercial reverse osmosis filtering system that provides excellent water quality control is a good method for removing harmful contaminants from water in small-scale aquaponics and aquaculture. Recirculation systems are more sustainable and effective in managing the volume of effluent in aquaculture units because only 10% of the total volume of water is refilled daily. Constructed wetland systems are a low-cost, high-efficiency treatment solution for nitrogen-containing wastewater, with removal efficiencies of up to 98% for NH4-N and above 98% for NO2-N. The use of aquaponics in desert settings with water constraints constraint is viewed as a possible sustainable food production approach.
Floating treatment wetlands planted with emergent macrophytes (FTWs) provide an innovative option for treating urban stormwaters. Emergent plants grow on a mat floating on the water surface, rather ...than rooted in the bottom sediments. They are therefore able to tolerate the wide fluctuations in water depths that are typical of stormwater ponds. To better understand the treatment capabilities of FTWs, a series of replicated (
n
=
3) mesocosm experiments (12
×
0.7
m
3 tanks using 0.36
m
2 floating mats) were conducted over seven day periods to examine the influence of constituent components of FTWs (floating mat, soil media, and four different emergent macrophyte species) for removal of copper, zinc, phosphorus and fine suspended solids (FSS) from synthetic stormwater. The presence of a planted floating mat significantly (
P
<
0.05) improved removal of copper (>6-fold), fine suspended particles (∼3-fold reduction in turbidity) and dissolved reactive P (in the presence of FSS) compared to the control. Living plants provided a large submerged root surface-area (4.6–9.3
m
2 of primary roots m
−2 mat) for biofilm development and played a key role in the removal of Cu, P and FSS. Uptake of Cu and P into plant tissues during the trials could only account for a small fraction of the additional removal found in the planted FTWs, and non-planted floating mats with artificial roots providing similar surface area generally did not provide equivalent benefits. These responses suggest that release of bioactive compounds from the plant roots, or changes in physico-chemical conditions in the water column and/or soils in the planted FTWs indirectly enhanced removal processes by modifying metal speciation (e.g. stimulating complexation or flocculation of dissolved fractions) and/or the sorption characteristics of biofilms. The removal of dissolved zinc was enhanced by the inclusion of a floating mat containing organic soil media, with reduced removal when vegetated with all except one of the test species. The results indicate that planted FTWs are capable of achieving dissolved Cu and Zn mass removal rates in the order of 5.6–7.7
mg
m
−2
d
−1 and 25–104
mg
m
−2
d
−1, respectively, which compare favourably to removal rates reported for conventional surface flow constructed wetlands treating urban stormwaters. Although not directly measured in the present study, the removal of particulate-bound metals is also likely to be high given that the FTWs removed approximately 34–42% of the turbidity associated with very fine suspended particulates within three days. This study illustrates the promise of FTWs for stormwater treatment, and supports the need for larger-scale, longer-term studies to evaluate their sustainable treatment performance.
Constructed wetland treatment systems (CWTS)s can be used to treat various wastewaters. The main constituent in oil sands process-affected water (OSPW) with uncertain treatment by CWTS are naphthenic ...acid fraction compounds (NAFC)s. The NAFCs are also among the primary contributors of toxicity to aquatic organisms. While there is preliminary evidence that some CWTSs are capable of treating OSPW for future potential discharge, there is little information comparing the effectiveness and efficiencies of different CWTS designs.
Obtaining large volumes of OSPW for testing can be difficult, and while it is known that synthetic NAFCs are simpler and have different toxicity than OSPW-NAFCs, it is unknown whether they could serve as a proxy for optimization of CWTS design and operation. This study presents a comprehensive comparison of CWTS performance operated with both synthetic OSPW and OSPW for four CWTS designs differing in plant type, aeration, flow path, water depth, and substrate type. This study evaluated the potential biodegradation of NAFCs including: (1) decrease in total NAFC concentration, (2) shifts in Ox-NAFC fractions from O2- to O3-, O4-, and O5-NAFC, (3) decrease in carbon number, (4) decrease of the double bond equivalencies (DBE), and (5) change in toxicity of the waters to test organisms.
CWTS planted with Sedge achieved the greatest extent of NAFC treatment and detoxification regardless of design. Although CWTSs planted with Cattail and Bulrush also degraded NAFCs and decreased toxicity, a greater hydraulic retention time was required, and the total extent of treatment was less than the CWTSs planted with Sedge. While synthetic OSPW was more toxic and experienced faster degradation rates, it showed similar trends to OSPW in terms of CWTS design efficiencies and function. Although synthetic OSPW would not be appropriate for modelling or scaling of CWTSs, it can be useful for testing designs and operating conditions.
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•Treatment of oil sands process waters varied with constructed wetland design.•Efficiency evaluated through analytical chemistry, rates, extents, and toxicity.•Constructed wetlands with aquatic Sedges more effective than Cattail or Bulrush.•Treatment was associated with plant type and evapotranspiration.
► Two wet ponds were studied pre- and post-floating treatment wetland (FTW) retrofit. ► No significant improvement in TN concentration was observed with addition of FTWs. ► Results suggested a ...minimum percent coverage of 18% for improvement in TP and TSS. ► Mean and median pond temperature was the same beneath the FTWs versus open water. ► Below mat N, P, and K plant concentrations were higher than above mat concentrations.
Thousands of existing wet retention ponds have been built across the United States, primarily for the mitigation of peak flow and removal of sediment. These systems struggle to mitigate soluble nutrient loads from urban watersheds. A simple retrofit for improvement of pond performance for nitrogen and phosphorus removal could become popular. Floating treatment wetlands (FTWs), one such retrofit, are a hydroponic system that provides a growing medium for hydrophytic vegetation, which obtain nutrients from the stormwater pond. Installation of FTWs does not require earth moving, eliminates the need for additional land to be dedicated to treatment, and does not detract from the required storage volume for wet ponds (because they float). To test whether FTWs reduce nutrients and sediment, two ponds in Durham, NC, were monitored pre- and post-FTW installation. At least 16 events were collected from each pond during both monitoring periods. The distinguishing characteristic between the two ponds post-retrofit was the fraction of pond surface covered by FTWs; the DOT pond and Museum ponds had 9% and 18%, respectively, of their surface area covered by FTWs. A very small fraction of N and P was taken up by wetland plants, with less than 2% and 0.2%, respectively, of plant biomass as N and P. Temperature measurements at three depths below FTWs and at the same depths in open water showed no significant difference in mean daily temperatures, suggesting little shading benefit from FTWs. The two ponds produced effluent temperatures that exceeded trout health thresholds. Both the pre- and post-FTW retrofit ponds performed well from a pollutant removal perspective. One pond had extremely low total nitrogen (TN) effluent concentrations (0.41mg/L and 0.43mg/L) during both pre- and post-FTW retrofit periods, respectively. Floating treatment wetlands tended to improve pollutant capture within both ponds, but not always significantly. Mean effluent concentrations of TN were reduced at the DOT pond from 1.05mg/L to 0.61mg/L from pre- to post-retrofit. Mean total phosphorus (TP) effluent concentrations were reduced at both wet ponds from pre- to post-retrofit 0.17mg/L to 0.12mg/L (DOT pond) and 0.11mg/L to 0.05mg/L (Museum pond). The post-retrofit effluent concentrations were similar to those observed for bioretention cells and constructed stormwater wetlands in North Carolina. The DOT pond showed no significant differences between pre- and post-retrofit effluent concentrations for all nine analytes. The Museum pond had a statistically significant improvement post-retrofit (when compared to the pre-retrofit period) for both TP and total suspended solids (TSS). Wetland plant root length was measured to be approximately 0.75m, which had the benefit of stilling water flow, thereby increasing sedimentation. Results suggested that greater percent coverage of FTWs produced improved pollutant removal.
This is the first study looking at the wastewater treatment system created at Basrah University, Iraq. This study aims to investigate the effectiveness of horizontal subsurface flow (HSSF) ...constructed wetland (CW) system for treating municipal wastewater, and to understand the inner processes presented in the wetland to distinguish and define the function of each component of the treatment and to create wastewater treatment built using MATLAB programming language to represent the biochemical phenomena systems similar to the treatment system and implement them throughout Iraq. To do this, a mathematical model based on one dimensional constructed wetland model number 1 (CWM1) matrix and the optimum CWs operational parameters was occurring in the CWs. The CWM1 was used to simulate processes in horizontal subsurface flow (HSSF) constructed wetlands. Results of the simulation had a very good fit to measured NH4-N as well as a good fit to measured chemical oxygen demand (COD) concentration after changing the values of the concentration autotrophic nitrifying bacteria (XA) and acetotrophic methanogenic bacteria (XAMB).
The application of direct mass spectrometry techniques to the analysis of complex samples has a number of advantages including reduced sample handling, higher sample throughput, in situ process ...monitoring, and the potential for adaptation to on-site analysis. We report the application of a semi-permeable capillary hollow fibre membrane probe (immersed directly into an aqueous sample) coupled to a triple quadrupole mass spectrometer by a continuously flowing methanol acceptor phase for the rapid analysis of naphthenic acids with unit mass resolution. The intensity of the naphthenic acid-associated peaks in the mass spectrum are normalized to an internal standard in the acceptor phase for quantitation and the relative abundance of the peaks in the mass spectrum are employed to monitor compositional changes in the naphthenic acid mixture using principle component analysis. We demonstrate the direct analysis of a synthetic oil sands process-affected water for classical naphthenic acids (CnH2n+zO2) as they are attenuated through constructed wetlands containing sedge (Carex aquatilis), cattail (Typha latifolia), or bulrush (Schoenoplectus acutus). Quantitative results for on-line membrane sampling compare favourably to those obtained by solid-phase extraction high-resolution mass spectrometry. Additionally, chemometric analysis of the mass spectra indicates a clear discrimination between naphthenic acid-influenced and natural background waters. Furthermore, the compositional changes within complex naphthenic acid mixtures track closely with the degree of attenuation. Overall, the technique is successful in following changes in both the concentration and composition of naphthenic acids from synthetic oil sands process-affected waters, with the potential for high throughput screening and environmental forensics.
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•Oil sands process-affected waters (OSPWs) contain naphthenic acids (NAs) that have been associated with aquatic toxicity•On-line membrane sampling used for direct mass spectrometry analysis of NAs in constructed wetland treatment system (CWTS)•A simple workflow for rapid in situ sample screening provides quantitative and qualitative results•An analysis of water samples fortified with synthetic OSPW that have undergone biological treatment in CWTS
Water quality degradation poses a global threat, with surface water resources bearing the brunt of pollution from various sources, including inadequately treated wastewater discharged from industrial ...and commercial processes. This discharge introduces a wide range of pollutants, compromising surface water quality and potentially contaminating groundwater. Floating Wetland Treatment (FWT) systems, particularly utilizing affordable and easy-to-construct bamboo rafts, emerge as a promising eco-technology offering a sustainable solution for rehabilitating water bodies polluted with inadequately treated domestic sewage. Research exploring the combined remediation potential of different plant combinations remains limited, although several studies demonstrate the efficacy of individual plant species in FWT systems. This study addresses this gap by evaluating the effectiveness of three terrestrial plant combinations (Canna indica, Chrysopogon zizanioides, and Hibiscus rosa-sinensis) supported by bamboo rafts in treating domestic wastewater. Among FWT methods, systems utilizing bamboo as floating rafts stand out due to their affordability, ease of construction, and adaptability to diverse plant species. FWT systems were meticulously designed with three plant combinations, utilizing soil and coco peat as growth media. Different FWT systems exhibited variations in their ability to remove several key water quality indicators. These variations were influenced by operational conditions, system design, plant selection, and growth media. Notably, the peat-based FWT system (FWT-BPCV) combining Canna indica and Chrysopogon zizanioides consistently demonstrated outstanding performance in reducing various pollutants, including total nitrogen (78.9 %), ammonia (90.2 %), total phosphorus (86.9 %), COD (92.8 %), BOD5 (94.8 %), TDS (70.7 %), TSS (93.6 %), turbidity (93.3 %), phosphate (73.2 %), electrical conductivity (62.5 %), and E. coli (78 %). This research suggests that FWT-BPCV is an eco-friendly wastewater treatment solution and an effective option for domestic wastewater treatment practices.
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•Evaluated the FWT using terrestrial plant combinations supported by a bamboo raft.•FWTs were found to enhance dissolved oxygen levels and reduce turbidity.•The FWT-BPCV demonstrates remarkable efficiency in removing most pollutants.•The FWT-BPVH showed a promising removal rate for total nitrogen, potassium, and sodium.
Abstract
Several developing countries have limited infrastructure and finance to treat domestic and industrial wastewater. Discharging untreated sewage pollutes the surface and groundwater. Floating ...wetlands are an alternate method for treating polluted surface water bodies. This study's objective is to investigate the remediation of domestic wastewater using natural buoyant bamboo as a floating raft and terrestrial plants such as Ocimum tenuiflorum, Hibiscus, Chrysopogon zizanioides, and Canna in the floating wetland treatment (FWT) system. Floating rafts with a healthy terrestrial plant were planted and made to float in four plastic tanks with domestic wastewater. The water quality analysis was carried out periodically after 0, 3, 5, 10, 15, 20, and 25 days intervals. The experimental results of FWT using C. indica showed the highest removal efficiency of the pollutants such as TSS (96%), TP (98%), ammonia (95%), and DO (45%). In contrast, Ch. zizanioides showed its maximum removal efficiencies for turbidity (90%), TDS (48%), TN (85%), sodium (53%), potassium (74%), TP (92%), EC (27%), COD (93%), BOD (95%), and E. coli (47%). This study finding showed that the best terrestrial plants for removing various nutrients and other contaminants from municipal sewage were C. indica and Ch. zizanioides. However, further research is required to utilize these terrestrial plants with substrates under long-term study.
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