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Low-polluted waters treated by traditional constructed wetlands were usually difficult especially because of restricted available land use. A hybrid constructed wetlands (CWs) could be applied to remediate low-polluted rivers, which can realize steps complementary to each other that exploit the specific advantages of the individual systems and achieve higher treatment effects. The hybrid CWs covering a total area of 99647m2, was developed to treat the polluted Bagong River, one of tributary to the Yellow River, have been in operation since the end of 2020. This paper introduced the specific construction method of the hybrid CWs, and the water quality of the river could be improved 1–2 grades after flowing through the CWs (according to the Chinese standard GB3838-2002). The treatment capacity was designed to be 65,000 m3·d−1, and the obtained results showed a satisfactory pollutant removal capacity of the hybrid system, with mean removal rates of 57.00%, 20.00%, 48.00%, and 29.00% for ammonia nitrogen, total nitrogen (TN), total phosphorus (TP), and chemical oxygen demand (COD), respectively. Meanwhile, >12 species of aquatic birds were attracted to inhabited in the hybrid CWs. The results of correlation analysis concluded that temperature and plant growth were the dominant factors affecting the removal of pollutants in the hybrid CWs system, and the porous concrete as substrate also has obvious phosphorus removal effect. The results showed that the system had relatively stable impact resistance and good ecological benefits under different influent loads, and can better improve water quality and biodiversity. Thus, the hybrid CWs would be a promising and feasible treatment method for low-polluted waters, as adapted to the local context. [Display omitted] • A hybrid CWs was developed to treated low polluted waters. • The hybrid CWs granted high pollutants removal as well as ecological benefits when treating polluted Bagong River. • The porous concrete filter bed could effectively improve phosphorus removal efficiency and SS interception. • Recognizing the relationship between the removal efficiency of the system and environmental factors. [ABSTRACT FROM AUTHOR]

Abstract: As environmental legislation has become stricter in recent years, the issue of wastewater treatment in rural areas has become an increasing concern. Choice of the most suitable on-site purification systems is based on the key issues of affordability and appropriateness in Chinese rural areas. This paper describes an integrated household constructed wetland (IHCW) system planted with willow (Salix babylonica) to treat household domestic wastewater in rural villages in northern China. The precast frame structure of IHCW is strong and waterproof. It can be mass-produced and installed per a standard set of specifications. The IHCW has achieved high overall removal efficiencies for BOD5, TSS, NH4-N, and TP: 96.0%, 97.0%, 88.4% and 87.8%, respectively. A 0.4m biomass layer cover on the system provided significant system thermal insulation, maintaining high treatment performance in freezing winter conditions. The system is cost effective and does not need any operational energy inputs, demonstrating its feasibility for single-family use in developing countries. [Copyright &y& Elsevier]

Abstract: Presented in this paper is a low-carbon assessment for wastewater treatment by a constructed wetland as ecological engineering. Systems accounting by combining process and input–output analyses is applied to track both direct and indirect GHG emissions associated with the wastewater treatment. Based on the detailed assessment procedures and the embodied GHG emission intensity database for the Chinese economy in 2007, the GHG emissions embodied in both the construction and operation stages of a pilot constructed wetland in Beijing are investigated in concrete detail, with parallel calculations carried out for a cyclic activated sludge plant as a typical conventional wastewater treatment system for comparison. With the overall embodied GHG emissions taken into account, the constructed wetland is shown to be remarkably less carbon intensive than the conventional wastewater treatment system, and the contrast in GHG emission structure is also revealed and characterized. According to the results, the ecological engineering of the constructed wetland is considered to be favorable for achieving the low-carbon goal. [Copyright &y& Elsevier]

Abstract: An integrated wetland system (IWS) including constructed wetlands (CWs) and modified natural wetlands (NWs) for wastewater treatment to replenish water to wetlands located at the Beijing Wetland School (BWS) in Beijing, China, is presented in this paper. The synergistic effects of CWs and NWs on treated water quality are investigated. The IWS is proved to be an effective wastewater treatment technique and a better alternative to alleviate the water shortage for conservation of wetlands based on the monitoring data obtained from October 2007 to 2008. The results show that CWs and NWs play different roles in removing contaminants from wastewater. The COD removal efficiency in CWs is higher than that in modified NWs, whereas the modified NWs can compensate for the deficiency of CWs where a stable and sufficient rhizosphere is not fully formed in the start-up period. All removal rates of COD, TN, and TP in CWs and modified NWs vary from 50 to 70%, while the total removal rate of COD, TN, and TP in IWS is about 85–90%. The operational results show that the maximum area loading of organic pollutants in modified NWs (65kg/had) is slightly higher than the empirical one (60kg/had) recommended by for free water surface wetlands. [ABSTRACT FROM AUTHOR]

Abstract: Large-scale centralized wastewater treatment systems often prevail in industrial countries and have been regarded as a successful approach during the last century. However, to solve the multifold water-related problems in China with its rapid growth of urbanization and industrialization, complete replication of this centralized, cost- and energy-intensive technology has proved to be extremely limited in scope and success. As one of the most important applications of ecological engineering, constructed wetland (CW) systems for wastewater treatment can offer an optimal alternative and result in beneficial conservation of natural resources with low capital costs and energy consumption, as well as minimal operation and maintenance expenditures. CW technology is particularly suitable for rapidly growing small- and medium-size cities in China. This paper aims at examining the mechanisms of pollutant removal efficiency in these systems and investigating the merits, status and feasibility of using constructed wetland systems to treatment wastewater in China. Additionally, it investigates existing impediments to application and implementation of CWs in China, as well as challenges to future development. [Copyright &y& Elsevier]