scholarly journals Multistage Horizontal Subsurface Flow vs. Hybrid Constructed Wetlands for the Treatment of Raw Urban Wastewater

2020 ◽  
Vol 12 (12) ◽  
pp. 5102
Author(s):  
José Alberto Herrera-Melián ◽  
Mónica Mendoza-Aguiar ◽  
Rayco Guedes-Alonso ◽  
Pilar García-Jiménez ◽  
Marina Carrasco-Acosta ◽  
...  
Keyword(s):  
Constructed Wetlands ◽  
Subsurface Flow ◽  
Oxygen Demand ◽  
Pollutant Removal ◽  
Urban Wastewater ◽  
Total Coliforms ◽  
E Coli ◽  
Effect Of Water ◽  
Horizontal Subsurface Flow ◽  
Water Height

In this study, pilot-scale hybrid constructed wetlands (CWs) and multistage horizontal subsurface flow CWs (HF CWs) have been studied and compared for the treatment of raw urban wastewater. In the hybrid CWs, the first stage was a mulch-based horizontal subsurface flow CW and the second stage was a vertical subsurface flow CW (VF CW). The VF CWs were used to determine if sand could improve the performance of the hybrid CW with respect to the mulch. In the multistage HFs, mulch, gravel and sand were used as substrates. The effect of water height (HF10: 10 cm vs. HF40: 40 cm) and surface loading rate (SLR: 12 vs. 24 g Chemical Oxygen Demand (COD)/m2d) has been studied. The results show that the use of sand in the vertical flow stage of the hybrid CW did not improve the average performance. Additionally, the sand became clogged, while the mulch did not. The effect of water height on average pollutant removal was not determined but HF10 performed better regarding compliance with legal regulations. With a SLR of 12 g COD/m2d, removals of HF10 were: 79% for COD, 75% for NH4+-N, 53% for dissolved molybdate-reactive phosphate-P (DRP), 99% for turbidity and 99.998% for E. coli and total coliforms. When SLR was doubled, removals decreased for NH4+-N: 49%, DRP: −20%, E coli and total coliforms: 99.5–99.9%, but not for COD (85%) and turbidity (99%). Considering the obtained results and the simplicity of the construction and operation of HFs, HF10 would be the most suitable choice for the treatment of raw urban wastewater without clogging problems.

scholarly journals Efficiency of horizontal subsurface flow constructed wetlands cultivated with grasses of different root systems

2020 ◽  
Vol 20 (8) ◽  
pp. 3318-3329
Author(s):  
Fernanda Lamede Ferreira de Jesus ◽  
Antonio Teixeira de Matos ◽  
Mateus Pimentel de Matos
Keyword(s):  
Constructed Wetlands ◽  
Subsurface Flow ◽  
Oxygen Demand ◽  
Root Systems ◽  
Sodium Concentration ◽  
Pollutant Removal ◽  
Organic Loading Rate ◽  
Vetiver Grass ◽  
Horizontal Subsurface Flow ◽  
Subsurface Flow Constructed Wetlands

Abstract The objective of this study was to evaluate the influence of stoloniferous and fasciculated root systems, of Tifton 85 and vetiver grass respectively, on pollutant removal for primary treatment of sewage in horizontal subsurface flow constructed wetlands (HSSF-CWs). For this, three HSSF-CWs measuring 4 m × 1 m × 0.25 m, filling with gneiss gravel # 0 (D60 of 7.0 mm and 48.4% porosity) as substrate, were used. One unit was cultivated with Tifton 85 grass (HSSFT-CW), one with vetiver grass (HSSFV-CW) and one remained uncultivated (HSSFC-CW) as a control. Sewage was applied at a flow rate of 0.53–0.80 m3 d−1, corresponding to an organic loading rate of approximately 350 kg ha−1 d−1 (biochemical oxygen demand – BOD), which resulted in a hydraulic retention time of 0.6–0.9 day. The HSSFV-CW was more efficient than the HSSFC-CW in removing dissolved solids (measured as electrical conductivity) and reducing the total suspended solids (TSS), BOD5, turbidity and sodium concentration, while the HSSFT-CW was not superior in any way. The results indicate that cultivation of vetiver grass provided increased efficiency for removing pollutants from sewage when compared with Tifton 85-grass, in the HSSF-CW.

Mass transfer approach and the designing of horizontal subsurface flow constructed wetland systems treating waste stabilisation pond effluent

2018 ◽  
Vol 78 (12) ◽  
pp. 2639-2646 ◽  
Author(s):  
Anita M. Rugaika ◽  
Damian Kajunguri ◽  
Rob Van Deun ◽  
Bart Van der Bruggen ◽  
Karoli N. Njau
Keyword(s):  
Mass Transfer ◽  
Constructed Wetlands ◽  
Rate Constants ◽  
Removal Rate ◽  
Subsurface Flow ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Organic Load ◽  
Mass Transfer Effect ◽  
Horizontal Subsurface Flow

Abstract Pilot-scale constructed wetlands (CWs) that allowed wastewater to flow with high interstitial velocities in a controlled environment were used to evaluate the possibility of using mass transfer approach to design horizontal subsurface flow constructed wetlands (HSSF-CWs) treating waste stabilisation ponds (WSPs) effluent. Since CW design considers temperature which is irrelevant in tropics, mass transfer approach could improve the design. HSSF-CWs were operated in batch recycle mode as continuous stirred tank reactors (CSTR) at different interstitial velocities. The overall removal rate constants of chemical oxygen demand (COD) at various interstitial velocities were evaluated in mesocosms that received pretreated domestic wastewater. The mean overall removal rate constants were 0.43, 0.69, 0.74 and 0.73 d−1 corresponding to interstitial velocities of 15.43, 36, 56.57 and 72 md−1, respectively. Results showed that the interstitial velocities up to 36 md−1 represented a range where mass transfer effect was significant and, above it, insignificant to the COD removal process. Since WSPs effluent has high flow rates and low organic load, it is possible to induce high interstitial velocities in a HSSF-CW treating this effluent, without clogging and overflow. The performance of these HSSF for tertiary treatment in tropical areas could be improved by considering flow velocity when designing.

Removal of bacteria in subsurface flow wetlands

1997 ◽  
Vol 35 (5) ◽  
pp. 109-116 ◽  
Author(s):  
M. B. Green ◽  
P. Griffin ◽  
J. K. Seabridge ◽  
D. Dhobie
Keyword(s):  
Constructed Wetlands ◽  
Subsurface Flow ◽  
Diurnal Pattern ◽  
Flow Rates ◽  
Field Surveys ◽  
Total Coliforms ◽  
E Coli ◽  
Secondary Effluents ◽  
Wet Weather ◽  
Reed Bed

Removal of E. coli and total coliforms in subsurface flow constructed wetlands is investigated in field surveys and pilot experiments. Both systems use reed beds with 5-10 mm gravel medium receiving secondary effluents. A diurnal pattern of numbers was indicated in the survey of an operational tertiary reed bed at Leek Wootton. Removals of E. coli and total coliforms were compared in dry and wet periods in surveys on two successive years. Removals of about 1.5 to 2.1 log were found in dry weather. Removals fell in wet weather although no change was detected in removal of BOD5, TSS and amm N. The effect of different flow rates was compared using a pilot reed bed. A trend of increasing removal was seen between retention times of 12, 24, 48 and 120 hrs but variation between samples implied caution. All effluent samples from the pilot had less than 1000 cfu E. coli/100 ml at retention times of 24 hrs or more.

scholarly journals Efficiency of horizontal subsurface flow-constructed wetlands considering different support materials and the cultivation positions of plant species

2020 ◽  
Vol 15 (2) ◽  
pp. 1 ◽  
Author(s):  
Suymara Toledo Miranda ◽  
Antonio Teixeira de Matos ◽  
Mateus Pimentel Matos ◽  
Claudéty Saraiva
Keyword(s):  
Plant Species ◽  
Constructed Wetlands ◽  
Subsurface Flow ◽  
Pollutant Removal ◽  
Pennisetum Purpureum ◽  
Pet Bottles ◽  
Removal Efficiencies ◽  
Horizontal Subsurface Flow ◽  
Subsurface Flow Constructed Wetlands ◽  
One Year

 The present work evaluated the influence of filling substrate material (crushed PET bottles or fine gravel) on the efficiency of pollutant removal in horizontal subsurface flow constructed wetlands (HSSF-CWs). They were cultivated with a consortium of elephant grass cv. Napier (Pennisetum purpureum Schum) and Tifton 85 (Cynodon spp.) to treat wastewater from a common milk cooling tank (WWMT). For this, six HSSF-CWs were used which had dimensions of 0.6 m tall x 1.0 m wide x 2.5 m long. In order to investigate possible efficiency loss in the removal of pollutants from the system, operation was divided into two periods: Period I (from April to December 2015) and Period II (April to December 2016). Thus, the removal efficiencies of BOD5, solids and total nitrogen (TN), total phosphorus (TP), potassium (K) and sodium (Na) from WWMT were statistically compared. Results indicated that the efficiency of the HSSF-CWs for removing pollutants increased or remained similar after one year and nine months of their operation; and PET bottles were a viable alternative substrate in HSSF-CWs based on the efficient removal of pollutants from WWMT during the one year and nine months of monitoring. Crushed PET bottles constitute a viable substrate for filling HSSF-CWs. Altering the cultivation positions of the plant species did not change pollutant removal efficiencies, but indicates the importance of species arrangement to maximize system performance.

Performance evaluation of wastewater treatment using horizontal subsurface flow constructed wetlands optimized by micro-aeration and substrate selection

2015 ◽  
Vol 71 (9) ◽  
pp. 1317-1324 ◽  
Author(s):  
Fei Zhong ◽  
Juan Wu ◽  
Yanran Dai ◽  
Dongfang Xiang ◽  
Shuiping Cheng ◽  
...  
Keyword(s):  
Constructed Wetlands ◽  
Sewage Treatment ◽  
Subsurface Flow ◽  
Oxygen Demand ◽  
Ammonium Nitrogen ◽  
Domestic Sewage ◽  
Substrate Selection ◽  
N Removal ◽  
Horizontal Subsurface Flow ◽  
The Individual

The effects of micro-aeration and substrate selection on domestic sewage treatment performance were explored using three pairs (with or without micro-aeration) of horizontal subsurface flow (HSSF) constructed wetlands (CWs) filled with zeolite, ceramsite or quartz granules. The individual and combined effects of micro-aeration and substrate selection on the purification performance of the experimental-scale HSSF CWs were evaluated. The results showed that micro-aeration significantly increased the treatment efficiencies for chemical oxygen demand, total nitrogen, total phosphorus (TP), ortho-phosphate (PO43−-P) and ammonium nitrogen (NH4+-N) using HSSF CWs, while the substrate selection significantly affected the TP, PO43−-P and NH4+-N removal efficiencies (p < 0.05). A two-way analysis of variance (ANOVA) indicated that there was a significant interaction term (i.e. micro-aeration × substrate selection) for NH4+-N removal (p < 0.05). Among the three substrates, ceramsite was the best substrate for the treatment of domestic sewage using HSSF CWs. Therefore, the results of this study suggest that a ceramsite-filled HSSF CW with micro-aeration could be the optimal configuration for decentralized domestic sewage treatment.

scholarly journals Effect of Aeration Modes and COD/N Ratios on Organic Matter and Nitrogen Removal in Horizontal Subsurface Flow Constructed Wetland Mesocosms

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1530 ◽  
Author(s):  
Xin Chen ◽  
Hui Zhu ◽  
Yingying Xu ◽  
Brian Shutes ◽  
Baixing Yan ◽  
...  
Keyword(s):  
Nitrogen Removal ◽  
Subsurface Flow ◽  
Oxygen Demand ◽  
Ammonia Nitrogen ◽  
Pollutant Removal ◽  
Artificial Aeration ◽  
Influent Water ◽  
Horizontal Subsurface Flow ◽  
Aerobic And Anaerobic ◽  
Wetland Mesocosms

A series of mesocosm-scale horizontal subsurface flow constructed wetlands (HSSF-CWs) were established. In Experiment 1, four artificial aeration (AA) modes, including pre-aeration at 24 h before the input of influent water (PA), aeration at 6 h (6AA) and 12 h (12AA) after the input of influent water and non-aeration (NA), were tested to obtain an optimal aeration mode for chemical oxygen demand (CODCr) and nitrogen removal. The results showed that aeration after the input of influent water could improve the removal efficiencies of CODCr and ammonia-nitrogen (NH4⁺-N), but lead to an accumulation of nitrate-nitrogen (NO3−-N). The above observation demonstrated that a single aeration cannot create an ideal alternation of aerobic and anaerobic conditions for simultaneous nitrification and denitrification. Therefore, HSSF-CWs with intermittent aeration (IA), after the input of influent water and NA were established to evaluate the combined effects of IA and influent COD/N ratios on pollutant removal in Experiment 2. The HSSF-CW with IA exhibited a better performance in CODCr and nitrogen removal compared to HSSF-CW with NA. The highest removal percentages of CODCr (90.1%), NH4+-N (99.8%) and total nitrogen (TN, 99.5%) were achieved at a COD/N ratio of 9.3 in HSSF-CW with IA.

Sign in / Sign up

Export Citation Format

Share Document