scholarly journals Quantifying the Log Reduction of Pathogenic Microorganisms by Constructed Wetlands: A Review

Proceedings ◽  
2019 ◽  
Vol 48 (1) ◽  
pp. 9
Author(s):  
Sotirios Paraskevopoulos ◽  
Patrick Smeets
Keyword(s):  
Wastewater Treatment ◽  
Case Studies ◽  
Constructed Wetlands ◽  
Water Reuse ◽  
Fecal Coliforms ◽  
Operational Parameters ◽  
Pathogen Removal ◽  
Knowledge Gaps ◽  
Climatic Zones ◽  
Conventional Wastewater Treatment

Over the last 30 years, constructed wetlands (CWs) have been used as an alternative, cost-efficient way of treating wastewater, often in combination with conventional wastewater technologies. When CWs are attached at the end of conventional wastewater treatment plants, they treat the effluent and thus provide a polishing step. However, recent studies have shown that when CWs are used as the main wastewater treatment method for the agricultural reuse of effluents, they perform poorly on meeting the accepted limit of microbial contamination. Moreover, CWs are increasingly used within the scope of the circular economy and water reuse applications. Therefore, there is a need for a comprehensive exploration of the performance of CWs on pathogen removal. This paper explores relevant case studies regarding pathogen removal from constructed wetlands to create a comprehensive dataset that provides a complete overview of CWs performance under various conditions. After a systematic literature review, a total of 48 case studies were qualified for both qualitative and quantitative analyses. From the dataset, the general performance, optimal conditions, and knowledge gaps were identified. The review confirmed that constructed wetlands (as a standalone treatment) cannot meet the accepted limits of pathogen removal. However, they can be a credible choice for wastewater polishing when they are combined with conventional wastewater treatment systems. Regarding the most common indicators that were recorded, the removal of Escherichia coli ranged between 0.01–5.6 log; the removal of total and fecal coliforms was 0.2–5.32 log and 0.07–6.08 log, respectively; while the removal of fecal streptococci was 0.2–5.2 log. The great variability of pathogen removal indicates that the complexity of CWs makes it difficult to draw robust conclusions regarding their removal efficiency. Potential correlations were identified between influent and effluent concentrations, as well as between log removal and hydraulic characteristics. Additionally, no correlations between pathogen removal and temperature/climatic zones were found since average pathogen removal per country showed high variation throughout the various climatic zones. The dataset can be used as a benchmark of CWs’ performance as a barrier against the spreading of pathogens in the environment. The knowledge gaps identified in this review can provide direction for further research. Finally, a potential meta-analysis of the dataset using statistical analysis can pave the way for a better understanding of the design and operational parameters of CWs in order to fine-tune and quantify the factors that influence the performance of these systems.

Constructed wetland for water quality improvement: a case study from Taiwan

2010 ◽  
Vol 62 (10) ◽  
pp. 2408-2418 ◽  
Author(s):  
C. Y. Wu ◽  
J. K. Liu ◽  
S. H. Cheng ◽  
D. E. Surampalli ◽  
C. W. Chen ◽  
...  
Keyword(s):  
Water Quality ◽  
Wastewater Treatment ◽  
Constructed Wetlands ◽  
Constructed Wetland ◽  
Water Reuse ◽  
Oxygen Demand ◽  
Sediment Oxygen Demand ◽  
Nucleotide Sequence Analysis ◽  
Sediment Samples ◽  
Wetland System

In Taiwan, more than 20% of the major rivers are mildly to heavily polluted by domestic, industrial, and agricultural wastewaters due to the low percentage of sewers connected to wastewater treatment plants. Thus, constructed or engineered wetlands have been adopted as the major alternatives to clean up polluted rivers. Constructed wetlands are also applied as the tertiary wastewater treatment systems for the wastewater polishment to meet water reuse standards with lower operational costs. The studied Kaoping River Rail Bridge Constructed Wetland (KRRBCW) is the largest constructed wetland in Taiwan. It is a multi-function wetland and is used for polluted creek water purification and secondary wastewater polishment before it is discharged into the Kaoping River. Although constructed wetlands are feasible for contaminated water treatment, wetland sediments are usually the sinks for organics and metals. In this study, water and sediment samples were collected from the major wetland basins in KRRBCW. The investigation results show that more than 97% of total coliforms (TC), 55% of biochemical oxygen demand (BOD), and 30% of nutrients [e.g. total nitrogen (TN), total phosphorus (TP)] were removed via the constructed wetland system. However, results from the sediment analyses show that wetland sediments contained high concentrations of metals (e.g. Cu, Fe, Zn, Cr, and Mn), organic contents (sediment oxygen demand = 1.7 to 7.6 g O2/m2 d), and nutrients (up to 18.7 g/kg of TN and 1.22 g/kg of TN). Thus, sediments should be excavated periodically to prevent the release the pollutants into the wetland system and causing the deterioration of wetland water quality. Results of polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE), and nucleotide sequence analysis reveal that a variation in microbial diversity in the wetland systems was observed. Results from the DGGE analysis indicate that all sediment samples contained significant amounts of microbial ribospecies, which might contribute to the carbon degradation and nitrogen removal. Gradual disappearance of E. coli was also observed along the flow courses through natural attenuation mechanisms.

Experience in non-conventional wastewater treatment techniques used in the Czech Republic

2007 ◽  
Vol 56 (5) ◽  
pp. 149-156
Author(s):  
L. Felberova ◽  
J. Kucera ◽  
E. Mlejnska
Keyword(s):  
Wastewater Treatment ◽  
Czech Republic ◽  
Constructed Wetlands ◽  
Algal Bloom ◽  
Horizontal Flow ◽  
Legal Regulations ◽  
The Czech Republic ◽  
Treatment Techniques ◽  
Removal Efficiencies ◽  
Conventional Wastewater Treatment

Among the most common non-conventional wastewater treatment techniques used in the Czech Republic are waste stabilisation ponds (WSP), subsurface horizontal flow constructed wetlands (CW) and vertical flow groundfilters (GF). These extensive systems can be advantageously used for treatment of waters coming from sewerages where the ballast weighting commonly makes more than half of dry-weather flow. The monitoring was focused at 14 different extensive systems. Organics removal efficiencies were favourable (CW–82%; GF–88%); in the case of WSP only 57% due to the algal bloom. Total nitrogen removal efficiencies were 43 and 47% for WSP and GF; in the case of CW only 32% due to often occurring anaerobic conditions in filter beds. Total phosphorus removal efficiencies were 37, 35 and 22% for WSP, GF and CW, respectively. Often occurring problems are the ice-blockage of surface aerators at WSP during wintertimes, the pond duckweed-cover or the algal bloom at WSP during summers; a gradual colmatage of filter systems; and the oxygen deficiency in beds of subsurface horizontal flow constructed wetlands. Czech legal regulations do not allow treated wastewater disposal into underground waters. There is only an exception for individual family houses. Up to now, knowledge gained by monitoring of a village (which uses the infiltration upon a permission issued according to earlier legal regulations) have not shown an unacceptable groundwater quality deterioration into the infiltration areas.

scholarly journals Disinfection of constructed wetland effluent by in situ electrochemical chlorine production for water reuse

2021 ◽  
Author(s):  
Suanny Sophia Mosquera Romero ◽  
Antonin Prévoteau ◽  
Jan B.A. Arends ◽  
Diederick Rousseau ◽  
Luis Dominguez-Granda ◽  
...  
Keyword(s):  
Constructed Wetlands ◽  
Constructed Wetland ◽  
Water Reuse ◽  
Additional Treatment ◽  
Pathogen Removal

Constructed wetlands (CW) are globally used for the treatment of wastewater. Due to various causes, often the water is not fully treated in terms of pathogen removal requiring additional treatment....

How ‘Green’ Are Aquaculture, Constructed Wetlands and Conventional Wastewater Treatment Systems?

1999 ◽  
Vol 40 (3) ◽  
pp. 45-50 ◽  
Author(s):  
Hans Brix
Keyword(s):  
Water Quality ◽  
Wastewater Treatment ◽  
Constructed Wetlands ◽  
Plant Biomass ◽  
Renewable Energy Sources ◽  
Energy Requirements ◽  
Life Cycle Approach ◽  
Treatment Technologies ◽  
Recycling Potential ◽  
Conventional Wastewater Treatment

The term ‘green’ is nowadays widely used (and misused) in connection with many types of technologies. If a technology is ‘green’ it usually means that the technology requires less non-renewable energy sources than other alternatives. However, other parameters need to be considered as well, such as sustainability, recycling potential, treatment capacity and potential, conservation of ecosystems, etc. In this paper the energy requirements and nutrient recycling potential of constructed wetlands and wastewater aquaculture facilities are compared with that of conventional wastewater treatment technologies. The energy requirements of constructed wetlands are very low, but if significant reuse of nutrients is included (aquaculture), the energy requirements increase significantly and usually beyond the energy equivalent of the biomass produced. This is especially true in cold temperate climates where the aquaculture systems need to be housed in heated greenhouses and artificial light must be provided to secure operation throughout the year. In countries where fresh water itself is a limiting resource and where the economic capability may limit the use of artificial fertilisers, the reuse potential of wastewater may be more important. The potential for sustainable cropping of the plant biomass is excellent in tropical wetlands as the plants have a high productivity and a continuous growing season. In order to evaluate in more detail the ‘greenness’ of the different wastewater treatment technologies, the life-cycle approach might be applied. However, because constructed wetlands, besides the water quality improvement function, perform a multitude of other functions such as biodiversity, habitat, climatic, hydrological and public use functions, methodologies need to be developed to evaluate these functions and to weigh them in relation to the water quality issues.

scholarly journals Potential Use of Constructed Wetland Systems for Rural Sanitation and Wastewater Reuse in Agriculture in the Moroccan Context

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 156
Author(s):  
Meryem Hdidou ◽  
Mohamed Chaker Necibi ◽  
Jérôme Labille ◽  
Souad El Hajjaji ◽  
Driss Dhiba ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Constructed Wetlands ◽  
Rural Areas ◽  
Emerging Contaminants ◽  
Wastewater Reuse ◽  
Cost Effective ◽  
Water Shortage ◽  
Treated Wastewater ◽  
Operational Parameters ◽  
Different Types

Located in a semi-arid to arid region, Morocco is confronting increasing water scarcity challenges. In the circular economy paradigm, the reuse of treated wastewater in agriculture is currently considered a possible solution to mitigate water shortage and pollution problems. In recent years, Morocco has made significative progress in urban wastewater treatment under the National Wastewater Program (PNA). However, rural sanitation has undergone significant delays. Therefore, an alternative technology for wastewater treatment and reuse in rural areas is investigated in this review, considering the region’s economic, social, and regulatory characteristics. Constructed wetlands (CWs) are a simple, sustainable, and cost-effective technology that has yet to be fully explored in Morocco. CWs, indeed, appear to be suitable for the treatment and reuse of wastewater in remote rural areas if they can produce effluent that meets the standards of agricultural irrigation. In this review, 29 studies covering 16 countries and different types of wastewater were collected and studied to assess the treatment efficiency of different types of CWs under different design and operational parameters, as well as their potential application in agricultural reuse. The results demonstrated that the removal efficiency of conventional contamination such as organic matter and suspended solids is generally high. CWs also demonstrated a remarkable capacity to remove heavy metals and emerging contaminants such as pharmaceuticals, care products, etc. The removal of microbial contamination, on the other hand, is challenging, and does not satisfy the standards all the time. However, it can be improved using hybrid constructed wetlands or by adding polishing treatment. In addition, several studies reported that CWs managed to produce effluent that met the requirements of wastewater reuse in agriculture of different countries or organisations including Morocco.

Microbial indicator removal in onsite constructed wetlands for wastewater treatment in the southeastern U.S.

2001 ◽  
Vol 44 (11-12) ◽  
pp. 177-182 ◽  
Author(s):  
E.C. Barrett ◽  
M.D. Sobsey ◽  
C.H. House ◽  
K.D. White
Keyword(s):  
North Carolina ◽  
Wastewater Treatment ◽  
Constructed Wetlands ◽  
Geometric Mean ◽  
Domestic Wastewater ◽  
Fecal Coliforms ◽  
Indicator Organisms ◽  
Somatic Coliphages ◽  
Wastewater Indicator ◽  
Male Specific

Seven onsite constructed wetlands for wastewater treatment in the coastal plains of Alabama and North Carolina were studied from September 1997 to July 1998. Each site was examined for its ability to remove a range of fecal contamination indicators from settled wastewater. Indicator organisms include total and fecal coliforms, enterococci, Clostridium perfringens, and somatic and male-specific (F+) coliphages. Four identical domestic wastewater treatment sites in Alabama were evaluated. In these sites the Log10 geometric mean reductions ranged between 0.5 and 2.6 for total and fecal coliforms, 0.1 and 1.5 for enterococci, 1.2 to 2.7 for C. perfringens, -0.3 and 1.2 for somatic coliphages, and -0.2 and 2.2 for F+ coliphages. Three unique designs were examined in North Carolina. Log10 geometric mean reductions ranged between 0.8 to 4.2 for total and fecal coliforms, 0.3 to 2.9 for enterococci, 1.6 to 2.9 for C. perfringens, -0.2 and 2.8 for somatic coliphages, and -0.1 and 1.5 for F+ coliphages. Somatic and F+ coliphage detection was highly variable from month to month.

scholarly journals Influence of diffuser design on selected operating variables for wastewater flotation systems: a review

2021 ◽  
Author(s):  
M. R. Mukandi ◽  
M. Basitere ◽  
B. I. Okeleye ◽  
B. S. Chidi ◽  
S. K. O. Ntwampe ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Energy Consumption ◽  
Pore Size ◽  
Column Flotation ◽  
System Efficiency ◽  
Operational Parameters ◽  
Separation Processes ◽  
Operating Variables ◽  
Design Factors ◽  
Conventional Wastewater Treatment

Abstract Air diffusers or spargers have since been used in separation processes that include conventional wastewater treatment. Over the years, there has been advancements in diffuser design in terms of shape, pore size, orientation and materials of construction as a way of mitigating challenges such as fouling, clogging, energy consumption and poor system efficiency. Some of the available air diffusers are inadequate to solve most of these challenges due to reduced quality and increased quantity of wastewater being treated. Additionally, there is a paucity of information regarding air diffuser design and their effect on operational parameters in wastewater treatment. This review seeks to address the advancement in diffuser design and also the effects of design factors including parameters of air diffusers with a focus of their use in a column flotation system for wastewater treatment.

scholarly journals Considerations on design and implementation parameters of domestic wastewater treatment by subsurface flow constructed wetlands

2019 ◽  
Vol 24 (4) ◽  
pp. 809-819
Author(s):  
Lis Eveline Athaydes Fadanelli ◽  
Alceu Gomes de Andrade Filho ◽  
Giovana Kátie Wiecheteck ◽  
Maria Magdalena Ribas Döll
Keyword(s):  
Wastewater Treatment ◽  
Constructed Wetlands ◽  
Subsurface Flow ◽  
Domestic Wastewater ◽  
Previous Treatment ◽  
Temperate Climate ◽  
Operational Parameters ◽  
Urban Centers ◽  
Domestic Wastewater Treatment ◽  
Operational Criteria

ABSTRACT Constructed wetlands might be an alternative for communities away from urban centers and not served by a domestic wastewater treatment system. The purpose of this study was to provide instructions for the implementation of subsurface flow constructed wetland systems. To that end, we gathered information regarding the construction aspect, plants, and operational parameters used in systems which already operate in the country and the respective efficiency of these sets after previous treatment. The system in real scale proposed by Oliveira et al. (2005) was prominent among those that presented the highest efficiency. It was preceded by upflow anaerobic reactor built in brick, with macrophyte of the Typha genre, crushed stone at the entry and exit of the system, and sand in its intermediate portion. It required 1.04 m² surface area per inhabitant in humid temperate climate and hot summer, 1.71 m³ d-1 flow, and one-day hydraulic detention. The considerations presented here might help the construction of this kind of system, regarding dimensional and operational criteria.

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