scholarly journals Bacterial Biomass Effect on Performance Improving of Vertical Flow Constructed Wetlands for Domestic Wastewater Treatment

2021 ◽  
Author(s):  
Franck Michael ZAHUI ◽  
Jean-Marie Pétémanagnan Ouattara ◽  
Mahamadou Kamagaté ◽  
Lacina Coulibaly
Keyword(s):  
Constructed Wetlands ◽  
Anaerobic Bacteria ◽  
Bacterial Biomass ◽  
Domestic Wastewater ◽  
Pennisetum Purpureum ◽  
Aerobic Bacteria ◽  
Vertical Flow ◽  
Distribution Profile ◽  
Andropogon Gayanus ◽  
Total Bacteria

Abstract Bacteria are frequently studied in constructed wetlands (CWs) due to their effective involvement in pollutants purification processes. In this study, aerobic, anaerobic and total bacteria densities and their vertical distribution profile within pilot-scale vertical flow CWs planted with different plant species were investigated. Five beds were planted in monoculture with Andropogon gayanus, Chrysopogon zizanioides, Echinochloa pyramidalis, Pennisetum purpureum and Tripsacum laxum, and one unplanted bed was used as control. At the end of the treatment trial, bacteria were collected by taking cores of sediment samples at the corners and the center of each bed following six layers in the vertical profile. In fact, the presence of plants on CWs improved the bacterial density and removal efficiencies in the system, with yields from 5.9 to 24.1% regardless the pollutant. However, few anaerobic bacteria were obtained in the different wetlands, and unable to reduce NO3−, excluding for beds planted with T. laxum and P. purpureum. Besides, the number of aerobic bacteria determined decreased (i.e., 17.4 106 to 0.1 106 CFU.g− 1), while that of anaerobic bacteria increased (i.e., 0.1 106 to 2.1 106 CFU.g− 1) from the upper to the bottom layers in the planted beds. Otherwise, anaerobic bacteria were more abundant in the control than in planted beds. Then, total bacteria were dominated by aerobic bacteria, and decreased from surface toward the bottom. As P purpureum promotes the best performance, CWs with this type of plant could be a cost-effective alternative method of treating wastewater.

scholarly journals Effect of Plant Species on the Performance and Bacteria Density Profile in Vertical Flow Constructed Wetlands for Domestic Wastewater Treatment in a Tropical Climate

Water ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 3485
Author(s):  
Franck Michaël Zahui ◽  
Jean-Marie Pétémanagnan Ouattara ◽  
Mahamadou Kamagaté ◽  
Lacina Coulibaly ◽  
Alexandros I. Stefanakis
Keyword(s):  
Wastewater Treatment ◽  
Plant Species ◽  
Constructed Wetlands ◽  
Anaerobic Bacteria ◽  
Tropical Climate ◽  
Pennisetum Purpureum ◽  
Aerobic Bacteria ◽  
Vertical Flow ◽  
Vertical Flow Constructed Wetlands ◽  
Andropogon Gayanus

Bacteria are frequently studied due to their involvement in pollutants transformation processes during wastewater treatment. In this study, the treatment efficiency, bacteria densities and their vertical profile were investigated in pilot-scale vertical flow constructed wetlands (VFCW) planted with different plant species under a tropical climate in west Africa. Five beds were planted with local plant species, i.e., Andropogon gayanus, Chrysopogon zizanioides, Echinochloa pyramidalis, Pennisetum purpureum and Tripsacum laxum, while one bed remained unplanted. These species have been rarely used in CWs while some (e.g., T. laxum) are tested for the first time. After a 7-month trial, bacteria densities were measured in substrate samples separated into six layers along the bed depth. Plants presence enhanced the bacterial density and VFCW efficiency; the removal rates of organic matter (90.9–95.9%; COD and 95.2–98.5%; BOD5), nitrogen (74.3–84%; TN and 76–84%; NH4-N) and phosphorus (77.4–96.9%; PO4-P) were higher by 5.9–24.1% compared to the control bed, providing an overall excellent treatment performance for a single-stage VFCW system. Small numbers of anaerobic bacteria were obtained in the VFCWs, explaining the low-to-zero NO3-N removal, except for the VFCWs with T. laxum and P. purpureum. Aerobic bacteria decreased from the upper to bottom layers from 17.4 to 0.1 × 106 CFU/g in the planted beds, while anaerobic bacteria increased from 0.1 to 2.1 × 106 CFU/g. Anaerobic bacteria were more abundant in the unplanted than in the planted beds. The total bacteria count was dominated by aerobic bacteria, and decreased from the surface towards the bottom. Overall, the VFCW with P. purpureum demonstrated the highest efficiency, indicating that this design is an effective and sustainable nature-based solution for wastewater treatment in a tropical climate.

scholarly journals XỬ LÝ NƯỚC THẢI SINH HOẠT BẰNG ĐẤT NGẬP NƯỚC NHÂN TẠO NỀN XỈ THAN TỔ ONG KẾT HỢP TRỒNG CỎ VOI

2021 ◽  
Vol 5 (3) ◽  
pp. 2596-2605
Author(s):  
Kim Lavane ◽  
Nguyễn Thị Hoàng Hạnh ◽  
Phạm Văn Toàn
Keyword(s):  
Constructed Wetlands ◽  
Subsurface Flow ◽  
Domestic Wastewater ◽  
Pollutant Removal ◽  
Napier Grass ◽  
National Standard ◽  
Pennisetum Purpureum ◽  
Good Growth ◽  
Standard Type ◽  
Experimental Systems

Nghiên cứu này nhằm đánh giá hiệu suất của đất ngập nước (ĐNN) nhân tạo dòng chảy ngầm theo phương ngang (HSSF) và phương đứng (VF) có vật liệu nền là xỉ than tổ ong và trồng cỏ voi. Thí nghiệm được tiến hành trên mô hình phòng thí nghiệm với lưu lượng nạp của nước thải sinh họat là 85 lít/ngày. Tải lượng nạp BOD5, COD, TN, TP vào mô hình lần lượt là 7,47 g/m2.ngày, 3,17 g/m2.ngày, 1,43 g/m2.ngày, 0,12 g/m2.ngày. Kết quả nghiên cứu cho thấy nồng độ các chỉ tiêu ô nhiễm sau xử lý giảm đáng kể và đạt loại A theo QCVN 14:2008/BTNMT trong cả hai mô hình HSSFCW và VFCW. Hiệu suất xử lý của HSSFCW và VFCW đối với các chỉ tiêu lần lượt là SS: 88,7% và 92,4%; BOD5: 95,3% và 92,6%; COD: 94,3% và 92,6%; TN: 54,1% và 47,5%; N-NO3-: 38,4% và 33,6%; TP: 73,5% và 63,2%; P-PO43-: 87,6% và 59,7%. Nhìn chung, mô hình HSSFCW có hiệu suất loại bỏ các chất ô nhiễm tương đối cao hơn mô hình VFCW, ngoại trừ chỉ tiêu SS. Cỏ voi phát triển tốt và cho sinh khối cao trong thí nghiệm. Từ kết quả nghiên cứu cho thấy xỉ than tổ ong có thể tái sử dụng làm chất nền trong ĐNN nhân tạo dòng chảy ngầm. Bên cạnh đó, cỏ voi có thể trồng trong hệ thống ĐNN dòng chảy ngầm xử lý nước thải sinh hoạt. ABSTRACT This study aimed to evaluate the performances of horizontal subsurface flow (HSSF) and vertical flow (VF) constructed wetlands (CW) using combusted beehive charcoal residues as filtration bed media and planted with Napier grass (Pennisetum purpureum). The experimental systems were fed with a flow rate of 85 m3/day. The loading rates of BOD5, COD, TN, TP into the system were 7.47 g/m2.day, 3.17 g/m2.day, 1.43 g/m2.day, 0.12 g/m2.day, respectively. The results showed that the concentration of pollutants in effluents is significantly reduced and meet the national standard type A of QCVN 14:2008/BTNMT in both HSSFCW and VFCW models. The removal efficiencies in HSSFCW and SVFCW for SS: 88.7% and 92.4%; BOD5: 95.3% and 92.6%; COD: 94.3% and 92.6%; TN: 54.1% and 47.5%; N-NO3-: 38.4% and 33.6%; TP: 73.5% and 63.2%; P-PO43-: 87.6% and 59.7%, respectively. In general, the HSSFCW model has a relatively higher pollutant removal efficiency than the VFCW model, except for the SS. good growth and high biomass yield of Napier grass had been observed in the experimental systems. This study suggested that combusted beehive charcoal residues could be reused as bed substrate in constructed wetlands. Besides, Napier grass might also be a potential plant associated with subsurface flow constructed wetlands to treat domestic wastewater.

Two strategies for advanced nitrogen elimination in vertical flow constructed wetlands

1997 ◽  
Vol 35 (5) ◽  
pp. 71-77 ◽  
Author(s):  
Johannes Laber ◽  
Reinhard Perfler ◽  
Raimund Haberl
Keyword(s):  
Constructed Wetlands ◽  
Settling Tank ◽  
Domestic Wastewater ◽  
Experimental Period ◽  
Vertical Flow ◽  
One Stage ◽  
Upper Austria ◽  
System A ◽  
Vertical Flow Constructed Wetlands ◽  
Stage System

Since 1991 the institute for water provision has run two vertical flow constructed wetlands for domestic wastewater treatment at two farm houses (8 p.e.) in Upper Austria. The systems are designed for elimination of organic compounds and for nitrification which was no problem even under winter conditions. In 1995 two methods were tested to achieve denitrification also in both systems. System A is a one-stage system, system B has two stages operated in series. The approach to the one-stage system consisted in pumping a part of the nitrified effluent from the soil filter back to the settling tank of the influent, where the raw wastewater mixes with the nitrified effluent-water. The approach to the two-stage system B consisted in adding an external carbon source (methanol) into the second, water saturated stage. The research was undertaken during several experimental stages to test the influence of the recirculation ratio (system A) respectively of the feeding (system B; intermittent, continuous, batch). The highest elimination rates could be achieved with system B (dosage of methanol) during experimental stage 1 (intermittent loading four times a day). The mean elimination rates were 82% for Ninorg and 78% for TN. The TN elimination performance of system A was only a little lower (72%). The elimination of COD, BOD5 and TOC was no problem throughout the whole experimental period (effluent concentrations of both systems were well below the Austrian standards).

Comprehensive evaluation of substrates in vertical-flow constructed wetlands for domestic wastewater treatment

2015 ◽  
Vol 10 (3) ◽  
pp. 625-632 ◽  
Author(s):  
Junmei Wu ◽  
Dong Xu ◽  
Feng He ◽  
Jie He ◽  
Zhenbin Wu
Keyword(s):  
Constructed Wetlands ◽  
Nitrogen Removal ◽  
Phosphorus Removal ◽  
Evaluation System ◽  
Comprehensive Evaluation ◽  
Steel Slag ◽  
Domestic Wastewater ◽  
Vertical Flow ◽  
Substrate Selection ◽  
Comprehensive Evaluation System

Substrates are the important component of constructed wetlands (CWs), which have an effect on construction cost, purification capability and stable operation, so that substrate optimization is the key part of CWs design. The comprehensive evaluation system, including four layers, eleven indicators and nine schemes, for substrates in vertical-flow CWs treating domestic wastewater was established based on analytic hierarchy process. Then combined with Delphi method and fuzzy synthetic evaluation approach, zeolite, anthracite, shale, vermiculite, ceramic filter material, gravel, steel slag, bio-ceramic and combination substrate (isopyknic layered anthracite, bio-ceramic and zeolite) were evaluated from the viewpoints of purification effect, practical performance and economic analysis. The results showed that phosphorus removal, nitrogen removal, chemical stability were the main factors of substrate selection. Combination substrate was the best scheme among nine substrates. Zeolite was ideal substrate for nitrogen removal and biocompatibility, while anthracite and steel slag were ideal substrates for phosphorus removal. The comprehensive evaluation system of substrates was beneficial to comprehensive compare all aspects of performance for different substrates, and could be improved according to the actual situation of engineering applications, so as to provide guidance of substrate selection for CWs design.

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