scholarly journals Evaluation of Bed Depth Reduction, Media Change, and Partial Saturation as Combined Strategies to Modify in Vertical Treatment Wetlands

2021 ◽  
Vol 18 (9) ◽  
pp. 4842
Author(s):  
Ismael Vera-Puerto ◽  
Hugo Valdés ◽  
Christian Correa ◽  
Valeria Perez ◽  
Roberto Gomez ◽  
...  
Keyword(s):  
Natural Zeolite ◽  
Domestic Wastewater ◽  
Bottom Layer ◽  
Treatment Wetlands ◽  
Positive Development ◽  
Experimental Plant ◽  
Partial Saturation ◽  
Treatment Wetland ◽  
Media Change ◽  
Depth Reduction

The aim of this work was to evaluate the performance of vertical subsurface flow treatment wetlands (VSSF TWs) for treating rural domestic wastewater when strategies such as bed depth reduction and media change are used in combination with bottom saturation. Two treatment wetland systems were implemented: normal (VF-N), with a bed depth of 1.0 m, and modified (VF-M), with a bed depth of 0.5 m and a bottom layer of natural zeolite. Schoenoplectus californicus was used as experimental plant. These two treatment systems were operated at a hydraulic loading rate of 120 mm/d in two phases. Phase I did not use bottom saturation, while Phase II involved a bottom saturation of the zeolite layer of the VF-M system. The results show that bed depth reduction did not have a significant effect (p > 0.05) in terms of organic matter, solids, and ammonium removal. Conversely, it had a significant influence (p < 0.05) on phosphate as well as a negative effect on pathogen removal. This influence could be explained by initial media capacity for phosphorus removal and filtration importance in the case of pathogens. Partial saturation only had a positive influence on total nitrogen removal. The addition of a bottom layer of natural zeolite showed no positive effect on nutrient removal. The plant showed adaptation and positive development in both VF-N and VF-M. The water balance showed that water loss was not influenced by bed depth reduction. Therefore, according to the previous results, a combination of the proposal modifications to VSSF TWs can be introduced for treating rural domestic wastewater.

scholarly journals Floating treatment wetlands for domestic wastewater treatment

2011 ◽  
Vol 64 (10) ◽  
pp. 2089-2095 ◽  
Author(s):  
J. L. Faulwetter ◽  
M. D. Burr ◽  
A. B. Cunningham ◽  
F. M. Stewart ◽  
A. K. Camper ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Inorganic Nitrogen ◽  
Domestic Wastewater ◽  
Treatment Wetlands ◽  
Synthetic Wastewater ◽  
Treatment Wetland ◽  
Mineral Salts ◽  
Domestic Wastewater Treatment ◽  
Floating Treatment Wetlands

Floating islands are a form of treatment wetland characterized by a mat of synthetic matrix at the water surface into which macrophytes can be planted and through which water passes. We evaluated two matrix materials for treating domestic wastewater, recycled plastic and recycled carpet fibers, for chemical oxygen demand (COD) and nitrogen removal. These materials were compared to pea gravel or open water (control). Experiments were conducted in laboratory scale columns fed with synthetic wastewater containing COD, organic and inorganic nitrogen, and mineral salts. Columns were unplanted, naturally inoculated, and operated in batch mode with continuous recirculation and aeration. COD was efficiently removed in all systems examined (&gt;90% removal). Ammonia was efficiently removed by nitrification. Removal of total dissolved N was ∼50% by day 28, by which time most remaining nitrogen was present as NO3-N. Complete removal of NO3-N by denitrification was accomplished by dosing columns with molasses. Microbial communities of interest were visualized with denaturing gradient gel electrophoresis (DGGE) by targeting specific functional genes. Shifts in the denitrifying community were observed post-molasses addition, when nitrate levels decreased. The conditioning time for reliable nitrification was determined to be approximately three months. These results suggest that floating treatment wetlands are a viable alternative for domestic wastewater treatment.

scholarly journals Structural Changes in French VF Treatment Wetland Porous Media during the Rest Period: An Ex Situ Study Using X-ray Tomography

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 389
Author(s):  
German Dario Martinez-Carvajal ◽  
Laurent Oxarango ◽  
Jérôme Adrien ◽  
Pascal Molle ◽  
Nicolas Forquet
Keyword(s):  
Porous Media ◽  
Structural Changes ◽  
Rest Period ◽  
Treatment Wetlands ◽  
Ex Situ ◽  
Initial Value ◽  
Treatment Wetland ◽  
X Ray ◽  
The Impact ◽  
Deposit Layer

Clogging constitutes a major operational issue for treatment wetlands. The rest period is a key feature of French Vertical Flow (VF) treatment wetlands and serves to mitigate clogging. An ex-situ drying experiment was performed to mimic the rest period and record structural changes in the porous media using X-ray Computed Tomography (CT). Samples containing the deposit and gravel layers of a first stage French VF treatment wetland were extracted and left to dry in a control environment. Based on CT scans, three phases were identified (voids, biosolids, and gravels). The impact of the rest period was assessed by means of different pore-scale variables. Ultimately, the volume of biosolids had reduced to 58% of its initial value, the deposit layer thickness dropped to 68% of its initial value, and the void/biosolid specific surface area ratio increased from a minimum value of 1.1 to a maximum of 4.2. Cracks greater than 3 mm developed at the uppermost part of the deposit layer, while, in the gravel layer, the rise in void volume corresponds to pores smaller than 2 mm in diameter. Lastly, the air-filled microporosity is estimated to have increased by 0.11 v/v.

Advanced Treatment of Domestic Wastewater Using Sequencing Batch Reactor Activated Sludge Process

1993 ◽  
Vol 28 (10) ◽  
pp. 267-274 ◽  
Author(s):  
M. Imura ◽  
E. Suzuki ◽  
T. Kitao ◽  
S. Iwai
Keyword(s):  
Activated Sludge ◽  
Sequencing Batch Reactor ◽  
Batch Reactor ◽  
Domestic Wastewater ◽  
Experimental Period ◽  
Small Scale ◽  
Experimental Plant ◽  
Activated Sludge Process ◽  
Nitrogen And Phosphorus ◽  
Experimental Apparatus

In order to apply a sequencing batch reactor activated sludge process to small scale treatment facilities, various experiments were conducted by manufacturing an experimental apparatus made of a factory-produced FRP cylinder transverse tank (Ø 2,500mm). Results of the verification test conducted for one year by leading the wastewater discharged from apartment houses into the experimental apparatus were as follows. Excellent performance was achieved without any addition of carbon source, irrespective of the organic compound concentration and the temperature of raw wastewater. Organic substances, nitrogen and phosphorus were removed simultaneously. Due to the automated operation format, stable performance was obtained with only periodic maintenance. Though water depth of the experimental plant was shallow, effective sedimentation of activated sludge was continued during the experimental period. Regarding the aerobic and anaerobic process, nitrification and denitrification occurred smoothly.

Design of the treatment wetland determines nitrous oxide emission

2021 ◽  
Author(s):  
Kuno Kasak ◽  
Keit Kill ◽  
Evelyn Uuemaa ◽  
Ülo Mander
Keyword(s):  
Nitrous Oxide ◽  
Water Treatment ◽  
Water Table ◽  
Water Table Depth ◽  
Treatment Wetlands ◽  
Phosphorus Compounds ◽  
Nitrogen And Phosphorus ◽  
Treatment Wetland ◽  
Vegetation Growth ◽  
Sampling Campaign

&lt;p&gt;Treatment wetlands are widespread measures to reduce agricultural diffuse pollution. Systems that are often planted with emergent macrophytes such as Typha spp. and Phragmites spp. are efficient to reduce nutrients, particularly nitrogen and phosphorus compounds. While many experiments have been conducted to study the emission of carbon dioxide (CO&lt;sub&gt;2&lt;/sub&gt;) and methane (CH&lt;sub&gt;4&lt;/sub&gt;), little attention has been paid for the emission of nitrous oxide (N&lt;sub&gt;2&lt;/sub&gt;O). Few studies have been shown that usually N&lt;sub&gt;2&lt;/sub&gt;O emission from water saturated ecosystems such as wetlands is low to negligible. In V&amp;#228;nda in-stream treatment wetland that was built in 2015 and located in southern Estonia, we carried out first long term N&lt;sub&gt;2&lt;/sub&gt;O measurements using floating chambers. The total area of the wetland is roughly .5 ha; 12 boardwalks, each equipped with two sampling spots, were created. Samples were collected biweekly from March 2019 through January 2021. In each sampling campaign water table depth, water and air temperature, O&lt;sub&gt;2&lt;/sub&gt; concentration, oxygen reduction potential, pH and electrical conductivity were registered. Water samples for TN, NO&lt;sub&gt;3&lt;/sub&gt;-N, NO&lt;sub&gt;2&lt;/sub&gt;-N, TOC, TIC and TC were collected from inflow and outflow of the system in each sampling session and the average concentrations were 5.1 mg/L, 3.68 mg/L, &lt;0.1 mg/L, 41.2 mg/L and 28.7, respectively. Our results showed a very high variability of N&lt;sub&gt;2&lt;/sub&gt;O emission: the fluxes ranged from -4.5 ug m&lt;sup&gt;-2&lt;/sup&gt; h&lt;sup&gt;-1&lt;/sup&gt; to 2674.2 ug m&lt;sup&gt;-2&lt;/sup&gt; h&lt;sup&gt;-1&lt;/sup&gt; with mean emission of 97.3 ug m&lt;sup&gt;-2&lt;/sup&gt; h&lt;sup&gt;-1&lt;/sup&gt;. Based on gas samples (n=687) we saw a strong correlation (R&lt;sup&gt;2&lt;/sup&gt; = -0.38, p&lt;0.0001) between N&lt;sub&gt;2&lt;/sub&gt;O emission and water depth. The average N&lt;sub&gt;2&lt;/sub&gt;O emission from sections with the water table depth &gt;15 cm was 45.9 ug m&lt;sup&gt;-2&lt;/sup&gt; h&lt;sup&gt;-1&lt;/sup&gt; while sections with water table depth &lt;15 cm showed average emission of 648.3 ug m&lt;sup&gt;-2&lt;/sup&gt; h&lt;sup&gt;-1&lt;/sup&gt;. The difference between these areas was more than 10 times. Water temperature that is often considered as the main driver had less effect to the N&lt;sub&gt;2&lt;/sub&gt;O emission. For instance, at lower temperatures, when the emissions from deeper zones decreased, there was no temperature effect on emissions from shallow zones. We also saw that over the years the overall N&lt;sub&gt;2&lt;/sub&gt;O emission followed clear seasonal dynamics and has a slight trend towards lower emissions. This can be related to the more intensive vegetation growth that has been increased from ~40% in 2019 to approximately 90% in 2020. Our study demonstrates that the design of the wetland is not only important for the water treatment, but it can also determine the magnitude of greenhouse gas emissions. We saw that even slight changes in water table depth can have a significant effect on the annual N&lt;sub&gt;2&lt;/sub&gt;O emission. Thus, in-stream treatment wetlands that have water table depth at least 15 cm likely have remarkably lower N&lt;sub&gt;2&lt;/sub&gt;O emissions without losing water treatment efficiency.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

Tech-IA floating system introduced in urban wastewater treatment plants in the Veneto region – Italy

2013 ◽  
Vol 68 (5) ◽  
pp. 1144-1150 ◽  
Author(s):  
Anna Mietto ◽  
Maurizio Borin ◽  
Michela Salvato ◽  
Paolo Ronco ◽  
Nicola Tadiello
Keyword(s):  
Wastewater Treatment Plants ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Alnus Glutinosa ◽  
Primary Treatment ◽  
Ammonia Nitrogen ◽  
Surface Flow ◽  
Treatment Wetland ◽  
N Removal ◽  
Floating System

The performance of three integrated wetland treatment plants (horizontal sub-surface flow (h-SSF) and floating treatment wetland (FTW) with differentiated primary treatments) designed for treating domestic wastewater was investigated, monitoring total (TN), nitrate (NO3-N), nitrite (NO2-N) and ammonia nitrogen (NH4-N), total (TP) and phosphate phosphorus (PO4-P), chemical (COD) and biological oxygen demand (BOD5), and dissolved oxygen (DO) at the inlet and outlet of each wetland section from February 2011 to June 2012. Sediments settled in the FTW were collected and analyzed. The growth of plants in each system was also monitored, observing their general conditions. The chemical–physical characteristics of the pretreated domestic wastewater depended on the primary treatment installed. During the monitoring period we observed different reduction performance of the wetland sector in the three sites. In general, the wetland systems demonstrated the capacity to reduce TN, COD, BOD5 and Escherichia coli, whereas NO3-N and NH4-N removal was strictly influenced by the chemical conditions, in particular DO concentration, in the h-SSF and FTW. Vegetation (Phragmites australis, Alnus glutinosa and Salix eleagnos) was well established in the h-SSF as well as in the floating elements (Iris pseudacorus), although there were some signs of predation. FTW is a relatively novel wetland system, so the results obtained from this study can pave the way for the application of this technology.

Performance of a Multipurpose Filter for Simultaneous Removal of Ammonium and Suspended Solids as a Polishing Stage for a Domestic Wastewater Plant Effluent

2010 ◽  
Vol 5 (1) ◽  
Author(s):  
Deniz Alkas ◽  
Bilsen Beler Baykal ◽  
Cumali Kinaci
Keyword(s):  
Natural Zeolite ◽  
Suspended Solids ◽  
Size Range ◽  
Domestic Wastewater ◽  
Filter Material ◽  
Wastewater Effluent ◽  
Ammonium Concentration ◽  
Simultaneous Removal ◽  
Filter Unit ◽  
Solids Removal

A multipurpose filter column was studied as a polishing stage for the simultaneous removal of ammonium and suspended solids from a secondary domestic wastewater effluent. The multipurpose filter consisted of sand as the regular filter material, primarily for the purpose of suspended solids removal, and an ammonium selective natural zeolite, clinoptilolite, for the removal of ammonium. A Turkish clinoptilolite from the Bigadic region was used in the experiments. The capacity of the clinoptilolite was determined by isotherm analysis to be 10.4 mg/g for 20 mg/lt initial wastewater ammonium concentration at pH 7.3 with 0.5-1 mm diameter. In the continuous runs, the multipurpose filter unit was operated down flow with 50% of the unit consisting of clinoptilolite in the upper layer, and 50% sand in the lower both with a grain size range of 0.5-1 mm. The results have revealed that simultaneous removal of 100% of the ammonium and 75% of the suspended solids removal be achieved in the multipurpose filter unit for a working period of 38 hours. The success of this proposal could lend an alternative both for the upgrading of existing treatment plants and for polishing for ammonium and suspended solids rate by using one compact unit.

scholarly journals Potential Application of Chilean Natural Zeolite as a Support Medium in Treatment Wetlands for Removing Ammonium and Phosphate from Wastewater

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1156 ◽  
Author(s):  
Ismael Vera-Puerto ◽  
Matias Saravia ◽  
Jorge Olave ◽  
Carlos Arias ◽  
Erica Alarcon ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Rural Areas ◽  
Potential Application ◽  
Natural Zeolite ◽  
Theoretical Models ◽  
Treatment Wetlands ◽  
Maximum Adsorption Capacity ◽  
Initial Concentration ◽  
Support Medium ◽  
New Material

This study aims to evaluate the sorption characteristics of NH 4 + -N and PO 4 3 − -P onto the surface of natural zeolites coming from Chile and their potential application in the subsurface-flow treatment wetlands for wastewater treatment in rural areas. For this purpose, adsorption experiments onto the zeolite were developed in batch assays. The effects of the adsorbent quantity (20 g and 50 g) and particle size (0.2–1.0 mm; 1.5–3.0 mm, and 5.0–8.0 mm) were evaluated in terms of adsorption capacity at different NH4+-N and PO4−3-P concentrations. Then, the obtained laboratory results were adjusted to theoretical models: Saturation-growth-rate and Langmuir. The saturation adsorption of NH4+-N on the zeolite increases at the same time that the initial concentration increases for the same zeolite quantity; however, the saturation values were similar between the different zeolite sizes tested. For PO4−3-P, the adsorption did not have a direct relationship with the initial concentration nor zeolite quantity and better results were only achieved for zeolite sizes of 1.5–3.0 mm. Regarding the Langmuir model, sizes of 1.5–3.0 mm had the best adsorption characteristics, with the maximum adsorption capacity of up to 1.58 mg/g for NH4+-N and up to 0.08 mg/g for PO4−3-P. Therefore, a new material—a natural zeolite from the Maule Region of Chile—is described as a potential support medium for treatment wetlands.

scholarly journals Performance Evaluation of Baffled and Floating Hybrid Constructed Wetland Operated Under Field Conditions

2020 ◽  
Vol 170 ◽  
pp. 06015
Author(s):  
Shrutee Dasare ◽  
Guru Munavalli
Keyword(s):  
Constructed Wetland ◽  
Loading Rate ◽  
Domestic Wastewater ◽  
Cost Effective ◽  
Cod Removal ◽  
Organic Loading Rate ◽  
Flow Conditions ◽  
Treatment Wetland ◽  
Efficient Treatment ◽  
Controlled Flow

Baffled and Floating Hybrid Constructed Wetland (BFHCW) consisting of constructed wetland with brickbat medium and Floating Treatment Wetland (FTW) was developed and operated under actual field flow conditions. BFHCW was vegetated with dual-species (Typha angustifolia L. and Canna indica). The performance of continuously operated system was evaluated for varied Hydraulic Loading Rate (HLR) and Organic Loading Rate (OLR) for a longer period. The system was also assessed for controlled flow rate resulting more uniform OLR and HLR. The results showed that COD removal efficiency was enhanced by 5 to 15% with controlled flow than uncontrolled highly fluctuating flow conditions. HLR has more impact on COD removal than OLR. BFHCW is effective to an extent of 25 to 40% for COD removal. BFHCW is found to be cost effective and reasonably efficient treatment for pretreated domestic wastewater.

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