China
Africa
Explore chapters and articles related to this topic
Pathogen Removal in Constructed Wetlands
Published in Donald A. Hammer, Constructed Wetlands for Wastewater Treatment, 2020
Richard M. Gersberg, R. A. Gearheart, Mike Ives
Constructed wetlands can make important contributions as wastewater treatment systems not only through their ability to reduce bacteria and virus levels but also due to their ability to remove suspended solids and ammonia, both of which interfere with efficient disinfection. It appears that at hydraulic residence times of three to six days, constructed wetlands are at least equivalent and, in most cases, more effective than conventional wastewater treatment systems for the removal of disease-causing bacteria and viruses.
Remediation of Heavy Metals by Biota
Published in Abhik Gupta, Heavy Metal and Metalloid Contamination of Surface and Underground Water, 2020
Constructed wetlands have been defined as “engineered systems” that exploit the natural processes occurring in wetlands with the involvement of soils, vegetation, and associated microorganisms for wastewater treatment. These natural processes remove heavy metals and other contaminants within a more controlled environment of constructed wetlands. Such wetlands are also termed as “man-made,” “engineered,” or “artificial” wetlands. Various processes of metal removal are operative in constructed wetlands. These include sedimentation, filtration, adsorption, complexation, precipitation, cation exchange, plant uptake, and microbially mediated reactions like oxidation. These processes can especially remove metals in dissolved form, which is highly bioavailable. Dr. Käthe Seidel did pioneering work in the application of constructed wetlands in wastewater treatment, and showed that contaminants like heavy metals could be removed by plants such as the common bulrush (Schoenoplectus lacustris) planted in constructed wetlands (Seidel 1966—as cited in Brix 1994b).
Subsurface Flow Wetlands at Mesquite, Nevada
Published in Gerald A. Moshiri, Constructed Wetlands for Water Quality Improvement, 2020
C. C. Lekven, R. W. Crites, R. A. Beggs
Constructed wetlands represent a low-cost, low-maintenance form of wastewater treatment suitable for smaller communities which do not have the economic resources required to construct, operate, and maintain a conventional wastewater treatment plant.2 Constructed wetlands are generally designed to operate in one of two different ways.
Domestic wastewater treatment efficiency of the pilot-scale trickling biofilter system with variable flow rates and hydraulic retention times
Published in Environmental Technology, 2021
Abdul Rehman, Haris Ali, Iffat Naz, Devendra P. Saroj, Safia Ahmed
In attached growth treatment systems, microorganisms present in wastewater attached to the suitable packing materials and form a slime layer over the surface of packing materials [19]. Variety of support materials are available nowadays to be used in attached growth system as filter media and it includes stones, plastic cubes, gravels and pebbles [20,21]. These filter media have been considered as heart of the attached growth system as they provide a larger surface area per unit volume for the development of microbial slime layer. Therefore, selection criteria for packing materials must be accurate and precise so that a high active biomass and microbial population is sustained [22]. Examples of attached growth system are trickling filter system, rotating biological contactors, fluidized bed biofilm reactors and sub-surface flow constructed wetlands [22,23]. Constructed wetlands are ecological contrived systems that employ natural processes, however, they require a large amount of land, continuous monitoring of operating units and sludge removal [24]. Although TBF (trickling biofilter) systems are an old and deep-rooted technology for wastewater treatment in developed countries. In developing countries like Pakistan, there is a lack of infrastructure for wastewater treatment. Therefore pilot-scale TBF system using pebbles and gravels filter bed is assumed to be a novel technique for the treatment of wastewater. They have the advantage of comparatively low energy consumption, a long biomass retention time, and low operational and maintenance requirements [25,26].
Strategies to promote the adoption of sustainable drainage by private developers: a case study from Singapore
Published in Urban Water Journal, 2021
J. J. G. Buurman, T. K. Lee, M. S. Iftekhar, S. M. Yu
Shortcomings of traditional stormwater management approaches are forcing a transition in urban stormwater management in many countries, such as the USA, Australia, New Zealand, the UK, China, Singapore and Germany (Radcliffe 2019). Worldwide new approaches appear that move from a narrow focus on flood protection to a broader focus with multiple objectives, such as improving surface water quality, enhancing urban landscaping, providing habitats for wildlife and addressing the urban heat island effect. Rather than quickly evacuating stormwater through pipes and channels, new approaches aim to slow-down and cleanse stormwater on-site, often through vegetation-based, distributed features such as bioswales, retention ponds, green roofs, constructed wetlands and rain gardens (Cettner et al. 2014; Nickel et al. 2014; Keeley et al. 2013; Chui, May, and Ngai 2016). The new approaches for urban stormwater management are known under different names or part of broader paradigms, including Water Sensitive Urban Design (WSUD), Sustainable Urban Drainage Systems (SUDS), Best Management Practices (BMP), Low Impact Development (LID), Green Infrastructure (GI), Landscape Based Stormwater Management (LSM) and Integrated Urban Water Management (IUWM) (Adugna et al. 2019; Fletcher et al. 2014). In this paper, we focus on the Singaporean approach, which is known as the Active, Beautiful, Clean Waters (ABC Waters) Programme (Lim and Lu 2016; PUB 2018a). The ABC Waters Programme takes from other approaches, such as WSUD and LID, but is adapted to the tropical and socioeconomic context in Singapore.
Feasibility of using plastic wastes as constructed wetland substrates and potential for pharmaceuticals and personal care products removal
Published in Journal of Environmental Science and Health, Part A, 2020
Xiaofei Chen, Xiaolong Huang, Kai Zhang, Chenxi Wu
Constructed wetlands are artificial wetland systems that utilize natural processes of sorption, microbial degradation, and plant uptake to treat wastewater contaminants. Constructed wetlands are considered to be a cost-effective approach compared to other wastewater technologies.[16] The ability of constructed wetlands to treat PPCPs has been previously studied. [17–19] Constructed wetlands have shown great potential for the removal of PPCPs. However, removal efficiency can be affected by factors such as wetland design, wetland components, operation conditions, and properties of the treated chemicals.[20] Substrate is one of the most important components affecting the performance of constructed wetlands, and primarily acts as a sorbent to remove contaminants from water via sorption. Additionally, substrate supports the growth of microbes, which are responsible for the biological degradation of contaminants.[21]