Influence of biofilm on removal of surrogate faecal microbes in a constructed wetland and maturation pond

2005 ◽  
Vol 51 (9) ◽  
pp. 315-322 ◽  
Author(s):  
R. Stott ◽  
C.C. Tanner
Keyword(s):  
Particle Size ◽  
Removal Efficiency ◽  
Constructed Wetland ◽  
Open Water ◽  
Water Systems ◽  
Surface Flow ◽  
Particle Sizes ◽  
Pathogen Removal ◽  
Biofilm Thickness ◽  
Autotrophic Biofilms

The effect of biofilm on the attenuation of pathogen-sized particles from wastewater was compared for biofilms cultivated in a surface flow constructed wetland (SFW) and maturation pond (MP) The fate of fluorescently labelled microspheres (FLM) as surrogates for viruses (0.1 μm), bacteria (1 μm) and parasitic protozoa (4.5 μm dia) was investigated in microcosms in the presence or absence of biofilms. Rates of FLM removal from suspension were higher in the presence of biofilms for all particle sizes (kd 0.02–0.11 h−1) in MP and SFW microcosms with removal efficiency related to particle size and biofilm thickness and structure. Greater removal of 0.1 μm (79–81%), 1 μm FLM (92–96%) and 4.5 μm FLM (up to 98%) from suspension were found for microcosms containing thicker (autotrophic) biofilms grown in the MP or open water zone of the SFW. Lower removal of 43% (0.1 μm), 59% (1 μm) and 84% (4.5 μm) occurred in microcosms containing thinner heterotrophic biofilms from SFW vegetated zones. Providing surfaces for attachment of photosynthetic biofilms offers potential to enhance pathogen removal in open water systems. In vegetated systems, linkage to more oxic openwater zones may allow thicker and ‘stickier’ epiphytic biofilms to develop, improving pathogen interception and removal.

Influence of substrate depth and particle size on phosphorus removal in a surface flow constructed wetland

2017 ◽  
Vol 75 (10) ◽  
pp. 2291-2298 ◽  
Author(s):  
Cui Lijuan ◽  
Li Wei ◽  
Zhou Jian ◽  
Zhang Yan ◽  
Zhang Manyin ◽  
...  
Keyword(s):  
Particle Size ◽  
Constructed Wetlands ◽  
Total Phosphorus ◽  
Constructed Wetland ◽  
Organic Phosphorus ◽  
Subsurface Layer ◽  
Iron Phosphate ◽  
Inorganic Phosphorus ◽  
Surface Flow ◽  
Phosphorus Adsorption

Substrate adsorption is one of the main processes by which redundant phosphorus is removed from wastewater in surface flow constructed wetlands (SFCWs). The physical properties of the substrate, such as depth and particle size, will influence the amount of phosphorus adsorption. This study was carried out in a long-running intermittent inflow constructed wetland that covered a total area of 940.4 m2 in the Shunyi District of Beijing, China. We investigated how the concentrations of four phosphorus fractions, namely calcium phosphate (CaP), iron phosphate (FeP), adsorbed phosphorus (AdsP), and organic phosphorus (OP), varied between the surface (0–10 cm) and subsurface (10–20 cm) substrate and among the different substrate particle sizes. The total phosphorus concentrations in the substrate ranged from 154.97 to 194.69 mg/kg; CaP accounted for more than 80% of the total phosphorus content. The concentrations of OP were significantly higher in the surface layer than in the subsurface layer, but the concentrations of inorganic phosphorus were not significantly different between the two layers. The CaP, AdsP, and OP adsorption capacities were greater for small-sized substrate particles than for large-sized substrate particles. The results from this study provide a theoretical basis for the construction of constructed wetlands.

Treatment of laboratory wastewater in a tropical constructed wetland comparing surface and subsurface flow

2001 ◽  
Vol 44 (11-12) ◽  
pp. 499-506 ◽  
Author(s):  
A.A. Meutia
Keyword(s):  
Removal Efficiency ◽  
Constructed Wetland ◽  
Rainy Season ◽  
Transition Period ◽  
Subsurface Flow ◽  
Dry Season ◽  
Surface Flow ◽  
Cod Removal ◽  
N Removal ◽  
Removal Efficiencies

Wastewater treatment by constructed wetland is an appropriate technology for tropical developing countries like Indonesia because it is inexpensive, easily maintained, and has environmentally friendly and sustainable characteristics. The aim of the research is to examine the capability of constructed wetlands for treating laboratory wastewater at our Center, to investigate the suitable flow for treatment, namely vertical subsurface or horizontal surface flow, and to study the effect of the seasons. The constructed wetland is composed of three chambered unplanted sedimentation tanks followed by the first and second beds, containing gravel and sand, planted with Typha sp.; the third bed planted with floating plant Lemna sp.; and a clarifier with two chambers. The results showed that the subsurface flow in the dry season removed 95% organic carbon (COD) and total phosphorus (T-P) respectively, and 82% total nitrogen (T-N). In the transition period from the dry season to the rainy season, COD removal efficiency decreased to 73%, T-N increased to 89%, and T-P was almost the same as that in the dry season. In the rainy season COD and T-N removal efficiencies increased again to 95% respectively, while T-P remained unchanged. In the dry season, COD and T-P concentrations in the surface flow showed that the removal efficiencies were a bit lower than those in the subsurface flow. Moreover, T-N removal efficiency was only half as much as that in the subsurface flow. However, in the transition period, COD removal efficiency decreased to 29%, while T-N increased to 74% and T-P was still constant, around 93%. In the rainy season, COD and T-N removal efficiencies increased again to almost 95%. On the other hand, T-P decreased to 76%. The results show that the constructed wetland is capable of treating the laboratory wastewater. The subsurface flow is more suitable for treatment than the surface flow, and the seasonal changes have effects on the removal efficiency.

scholarly journals Nitrogen removal from summer to winter in a field pilot-scale multistage constructed wetland-pond system

2020 ◽  
Author(s):  
Liping Xiao ◽  
Tao Wang ◽  
Hongbin Lu ◽  
Shaoyong Lu ◽  
Jiaxin Li ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Total Nitrogen ◽  
Nitrogen Removal ◽  
Constructed Wetland ◽  
Pilot Scale ◽  
Surface Flow ◽  
Treatment Unit ◽  
Pond System ◽  
Load Rate ◽  
Plant Harvesting

Abstract Background Single-stage constructed wetlands (CWs) has a single ecological service function and is greatly affected by temperature, which are general in removal of total nitrogen. Multistage hybrid CWs were proven to capable of enhancing removal of nitrogen. Therefore, this study aimed to explore the variation in nitrogen removal in the combined CWs-pond process from summer to winter and the contribution of plant harvesting and the functions of bacteria to nitrogen removal. Methods A pilot-scale multistage constructed wetland-pond system (MCWP) with the process of "the pre-ecological oxidation pond + the two-level horizontal subsurface flow constructed wetland (HSCW) + the surface flow constructed wetland (SFCW) and the submerged plant pond (SPP)" was used to treat actual polluted river water in the field. During the 124 days of operation, the nitrogen concentrations in the units influent and effluent of the system were measured every two days, and the plant height in HSCWs and SFCW was measured once per month. When the system operated stably to the 72nd day, the substrates in the CWs were sampled to analyze the bacterial community structure and composition. Results The concentration of total nitrogen (TN) in the MCWP gradually decreased from 3.46 mg/L to 2.04 mg/L, and the average removal efficiency of TN was approximately 40.74%. The SPP performed the best among all units, and the TN removal efficiency was as high as 16.08%. The TN removal efficiency was significantly positively affected by the daily highest temperature. A formula between the total TN removal efficiency and the highest temperature was obtained by nonlinear fitting. The TN removal load rate in the HSCWs was 2.7–3.7 times that of the SFCW. Furthermore, the TN transformed by Iris pseudacorus L. accounted for 54.53% in the SFCW. Conclusion We found that the significant positive correlation between the daily highest temperature and the total TN removal rate a field MCWP system. The SFCW, as an advanced treatment unit, increased the proportion of nitrogen removed by plant harvesting. The bacteria completed the nitrogen cycle in the SFCW, which had high-density planting, through a variety of nitrogen removal pathways.

Potential of constructed wetland systems for treating tannery industrial wastewater

2010 ◽  
Vol 61 (4) ◽  
pp. 1043-1052 ◽  
Author(s):  
Mengiseny E. Kaseva ◽  
Stephen E. Mbuligwe
Keyword(s):  
Removal Efficiency ◽  
Flow Rate ◽  
Constructed Wetland ◽  
Volumetric Flow Rate ◽  
Control Unit ◽  
Surface Flow ◽  
Chromium Removal ◽  
Mean Flow ◽  
Tannery Effluents ◽  
The Mean

This paper reports on findings of a study on the performance of two units of a Horizontal Sub-Surface Flow Constructed Wetland (HSSFCW) units in treating wastewater effluent from a tannery industry. One of the HSSFCW units was planted with macrophytes, while the other was used as a control (without plants). Wastewater was fed into the wetland units at the mean flow rate of 0.045±0.005 m3/day. The studied parameters were chromium, turbidity, salinity, Total Dissolved Solids (TDS), Electric Conductivity (EC), pH and temperature. The mean Hydraulic Retention Time (HRT) was 1.60 days (in the control) and 1.80 days (in the vegetated) units, obtained as a ratio of the volume of the wastewater and the volumetric flow rate of wastewater through the units while taking into consideration the porosity of the media. The vegetated HSSFCW exhibited higher chromium removal efficiency (99.83%), than the control unit with the removal efficiency of 92.53%. High chromium removal was associated with both high temperature as well as high pH values in the HSSFCW units. The reduction in turbidity was found to be 71% in the vegetated wetland unit while the corresponding value for the control unit was 66%. Results obtained indicated low reduction efficiencies of both EC (0.3% in the vegetated unit and 1.6% in the control unit) and salinity (11% in the vegetated unit and 22% in the control unit) in the two mesocosms. Generally, however, the study demonstrated that constructed wetlands can be used as an option for improving the quality of tannery effluents especially in the removal of chromium. Chromium removal might have been effected by, among others, gravitational settling of solids and formation of co-precipitation with insoluble compounds as well as adsorption on the substrates and plant surfaces.

Field Synergy Analysis for Inclusion Removal in the Continuous Casting Tundish

2011 ◽  
Vol 704-705 ◽  
pp. 16-22
Author(s):  
Mei Jie Zhang ◽  
Xiao Long Lin ◽  
Hua Zhi Gu ◽  
Hong Xi Zhu ◽  
Cheng Ji Deng ◽  
...  
Keyword(s):  
Particle Size ◽  
Flow Field ◽  
Removal Efficiency ◽  
Optimization Design ◽  
Particle Sizes ◽  
Field Synergy ◽  
Concentration Gradients ◽  
Inclusion Removal ◽  
Inclusion Concentration ◽  
Steel Flow

The field synergy principle has been successfully used for optimization design of heat transfer exchanger. In this subject, the field synergy between the molten steel flow field and the inclusion concentration distribution is analyzed based on the mass transfer equations and removal mechanisms of inclusions. Then, inclusions removals of different particle sizes are numerically calculated for a two-strand tundish. The results show the large particle size inclusions are removed mainly by Stokes floatation and the removal efficiency has no obvious relationship on flow field. The small size inclusions removal efficiency is influenced by the synergy between the velocity vectors and the inclusion concentration gradients. So, changing the flow field mainly promotes the removal efficiency of small size inclusions. For the selected two-strand tundish, flow controls should be set for removing those inclusions which particle sizes are less than 100μm,. When the inclusion particle size is less than 10μm, the overall maximum removal efficiency is no more than 25%. So some new metallurgy techniques should be developed to improve the removal efficiency of small size inclusions. Keywords: Continuous tundish; Inclusion removal; Field synergy

scholarly journals Removal of pollutants from abattoir wastewater using a pilot-scale bamboo constructed wetland system

2020 ◽  
Vol 7 (2) ◽  
pp. 70-74
Author(s):  
Fidelis C. Nkeshita ◽  
A. A. Adekunle ◽  
R. B. Onaneye ◽  
O. Yusuf
Keyword(s):  
Removal Efficiency ◽  
Constructed Wetland ◽  
Urban Areas ◽  
Low Cost ◽  
Oxygen Demand ◽  
Pilot Scale ◽  
Surface Flow ◽  
Green Technology ◽  
Bambusa Vulgaris ◽  
Wetland System

Wastewater from abattoir sources in urban areas can adversely affect the environment and cause health problems. This research investigated the ability of a bamboo constructed wetland system (BCWS) using Bambusa vulgaris, to treat wastewater from abattoir by removing nutrients and organics. This study adopted pilot scale reactors with bed dimension of 1 m length x 1 m width x 1 m depth to simulate a horizontal sub-surface flow constructed wetland and planted with six strands of bamboo plants. Parameters analyzed include the nutrients (in the form of phosphate and nitrate) and the organics (in the form of Chemical oxygen demand, COD and Biochemical oxygen demand, BOD). The effluent analysis that were carried out within a 28-day retention period showed that there was a very good decrease in the nutrient pollutant parameters; phosphate (99.6 %), nitrate (98.5 %). The organics showed a lesser performance with a 39.3 % removal efficiency for COD and 49.9 % removal efficiency for BOD. Bamboo can be used in a BCWS for low cost green technology in urban areas and can be improved upon by increasing the number of bamboo shoot in order to have a larger root system.

Surface energy of cellulosic materials: The effect of particle morphology, particle size, and hydroxyl number

TAPPI Journal ◽  
2015 ◽  
Vol 14 (9) ◽  
pp. 565-576 ◽  
Author(s):  
YUCHENG PENG ◽  
DOUGLAS J. GARDNER
Keyword(s):  
Particle Size ◽  
Surface Energy ◽  
Particle Morphology ◽  
Nanofibrillated Cellulose ◽  
Particle Sizes ◽  
Hydroxyl Number ◽  
Small Individual ◽  
Dispersion Component ◽  
Commercial Applications ◽  
Lower Temperature

Understanding the surface properties of cellulose materials is important for proper commercial applications. The effect of particle size, particle morphology, and hydroxyl number on the surface energy of three microcrystalline cellulose (MCC) preparations and one nanofibrillated cellulose (NFC) preparation were investigated using inverse gas chromatography at column temperatures ranging from 30ºC to 60ºC. The mean particle sizes for the three MCC samples and the NFC sample were 120.1, 62.3, 13.9, and 9.3 μm. The corresponding dispersion components of surface energy at 30°C were 55.7 ± 0.1, 59.7 ± 1.3, 71.7 ± 1.0, and 57.4 ± 0.3 mJ/m2. MCC samples are agglomerates of small individual cellulose particles. The different particle sizes and morphologies of the three MCC samples resulted in various hydroxyl numbers, which in turn affected their dispersion component of surface energy. Cellulose samples exhibiting a higher hydroxyl number have a higher dispersion component of surface energy. The dispersion component of surface energy of all the cellulose samples decreased linearly with increasing temperature. MCC samples with larger agglomerates had a lower temperature coefficient of dispersion component of surface energy.

scholarly journals Effect of particle size on phytochemical composition and antioxidant properties of Sargassum cristaefolium ethanol extract

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
E. S. Prasedya ◽  
A. Frediansyah ◽  
N. W. R. Martyasari ◽  
B. K. Ilhami ◽  
A. S. Abidin ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Particle Size ◽  
Antioxidant Activities ◽  
Antioxidant Properties ◽  
Ethanol Extract ◽  
Total Phenolic ◽  
Particle Sizes ◽  
Epicatechin Gallate ◽  
Particle Size Reduction ◽  
Phytochemical Composition

AbstractSample particle size is an important parameter in the solid–liquid extraction system of natural products for obtaining their bioactive compounds. This study evaluates the effect of sample particle size on the phytochemical composition and antioxidant activity of brown macroalgae Sargassum cristaefolium. The crude ethanol extract was extracted from dried powders of S.cristeafolium with various particle sizes (> 4000 µm, > 250 µm, > 125 µm, > 45 µm, and < 45 µm). The ethanolic extracts of S.cristaefolium were analysed for Total Phenolic Content (TPC), Total Flavonoid Content (TFC), phenolic compound concentration and antioxidant activities. The extract yield and phytochemical composition were more abundant in smaller particle sizes. Furthermore, the TPC (14.19 ± 2.08 mg GAE/g extract to 43.27 ± 2.56 mg GAE/g extract) and TFC (9.6 ± 1.8 mg QE/g extract to 70.27 ± 3.59 mg QE/g extract) values also significantly increased as particle sizes decreased. In addition, phenolic compounds epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC), and Epigallocatechin gallate (EGCG) concentration were frequently increased in samples of smaller particle sizes based on two-way ANOVA and Tukey’s multiple comparison analysis. These results correlate with the significantly stronger antioxidant activity in samples with smaller particle sizes. The smallest particle size (< 45 µm) demonstrated the strongest antioxidant activity based on DPPH, ABTS, hydroxyl assay and FRAP. In addition, ramp function graph evaluates the desired particle size for maximum phytochemical composition and antioxidant activity is 44 µm. In conclusion, current results show the importance of particle size reduction of macroalgae samples to increase the effectivity of its biological activity.

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