Search

Nutrients carried in upstream rivers to lakes are the main cause of eutrophication. Building near-natural estuarine wetlands between rivers and lakes is an effective way to remove pollutants and restore the ecology of estuarine areas. However, for the existing estuarine wetland ecological restoration projects, there is a lack of corresponding evaluation methods and index systems to make a comprehensive assessment of their restoration effects. By summarizing a large amount of literature and doing field research, an index system was constructed by combining the characteristics of the near-natural estuarine wetlands themselves. It covered environmental benefits, technical management and maintenance, and socio-economic functions, and contained 3 systems, 7 criteria, and 16 indicators. The analytical hierarchy process (AHP) was used to determine the weights of each indicator. The top 5 indicators in order of importance were habitat diversity, total phosphorus (TP), coverage of aquatic plants, ammonia nitrogen (NH3-N), and adaptation to the surrounding landscape. The above evaluation system was used for the comprehensive evaluation of the water purification project in the Fuhe estuarine wetland, Hebei Province, as an example. The results showed that the comprehensive score of the Fuhe estuarine wetland at this stage was 4.1492, and the evaluation grade was excellent. The effect of water purification and ecological restoration was good, and the selected technology was suitable and stable in operation. It had a greater positive impact on the surrounding economy and society and can be promoted and applied. The research results were important for clarifying the advantages and defects of the project and developing efficient and advanced restoration technologies.

Microplastics exist widely in water environment. The microplastic distribution in sediments can better reflect the long-term microplastic pollution, especially the vertical distribution. However, the vertical microplastic distribution in sediments is diverse and unclear. This paper is the first study on vertical microplastic distribution in estuary sediment of Fuhe River, the main upstream river flowing to Baiyangdian Wetland in the northern China. The typical feature of Fuhe River is that the effluent of municipal wastewater treatment plants is its main water source. Microplastics in 15 sampling sites and different depths (0–50 cm) were examined. Results showed that the microplastic content decreased with the increase of sediment depth, and the highest content was 1049 ± 462 items/kg in the topmost sediment layer (0–5 cm). The particle size of microplastics was smaller in deeper sediment layers. The proportion of colored microplastics in deeper sediment layers was larger than that in shallower layers. Polyethylene (PE) and polypropylene (PP) were the main plastic polymer types in all sediment samples. The spatial distribution characteristics of microplastics in sediments were closely related to human activities, and the microplastic content was higher in the areas with more intense human activities. This study is helpful to understand the detailed distribution characteristics of microplastics in typical rivers in the northern China, and can provide guidance for reducing microplastic pollution.

The estuarine wetland buffer zone of the Fuhe river plays an important role in terms of improving water quality of Baiyangdian lake. In this study, the water purification effect and microbial community composition of an estuarine wetland buffer zone during a low-temperature period were investigated (March, 2021). The results indicated that the pre-sedimentation ecological pond (Pep), the subsurface flow wetland (Sfw), and the aquatic plant pond (App) exhibited good removal effects on total phosphorus (TP) and NH3-N. In contrast, the removal effects on chemical oxygen demand (COD) and total nitrogen (TN) was unsatisfied. Various phosphorus removal bacteria were detected in the water samples from the Pep and the Sfw, such as Arthrobacter, Flavobacterium, and Planococcus. These findings indicated the water purification performance and the microbial community composition in an estuarine wetland buffer zone during a low-temperature period.

Water shortage severely restricts vegetation restoration of mining area in the northwest China. Moderate treatment of reclaimed water is essential for improving the local ecological environment. In this study, relevant water quality standards issued by the states and research results were comprehensively considered to propose a reclaimed water quality standard suitable for vegetation restoration of mining area. The available domestic sewage and mine water was moderately treated by hybrid biological reactor system and nanofiltration membrane system, respectively. The effluent quality meet the requirement of reclaimed water quality standards in this study. This study provides theoretical support for vegetation restoration of mining area.

As a national key protection and restoration project, ecological restoration of Baiyangdian Wetland has an important significance for environmental management. As the research area in Zaozhadian wetland, the purification effect of warm season and cold season aquatic plants was studied under different overflying water qualities. It provides a theoretical and experimental basis for the ecological environment restoration and management of wetlands. The results showed that the warm season and cold season aquatic plants all played important roles on the nitrogen and phosphorus removal and maintained the stable water environmental from the nutrient release from soil. The warm season plant-mixed Myriophyllum spicatum and Ceratophyllum demersum and the cold season plant-Potamogeton crispus L. can be reasonably configurated for the wetland restoration.

Wetlands play an important role in sustaining ecosystems on the earth, which regulate water resources, adjust local climate and produce food for human beings, etc. However, wetlands are facing huge challenges due to human activities and other natural evolution, such as area shrinkage, function weakening and biodiversity decrease, and so on, therefore, some wetlands need to be urgently restored. In this study, the main technology components of close-to-natural restoration of wetlands were summarized. The ecological water requirement and water resource allocation can be optimized for the water balance between social, economy and ecology, which is a key prerequisite for maintaining wetland ecosystem. The pollution of wetland sediments and soils can be assessed by various indicators to provide the scientific basis for natural restoration of wetland base, and suitable strategies should be taken according to the actual conditions of wetland bases. The hydrological connectivity in wetlands and with related water system can be numerically simulated to make the optimal plan for improvement of hydrological connectivity. The ecological restoration of wetlands with the synergetic function of plants, animals and microorganisms was summarized, to improve the quality of wetland water environment and maintain the ecosystem stability. Based on the wetland close-to-natural restoration strategies, a brief ecological restoration plan for a typical wetland, Zaozhadian Wetland, near Xiong'an New Area in the north China was proposed from water resource guarantee, base pollution management, hydrological connectivity improvement and biological restoration. The close-to-natural restoration shows more effective, sustainable and long-lasting and thus a practical prospect.

Rapid development of livestock industry produces large amount of livestock manure rich in nutrients, organic matters, antibiotics, and heavy metals, thus imposes great harms to human and environment, if the manure is not suitably treated. Biological removal and recovery of nutrients from manure as agriculture fertilizer is attractive due to low cost and simple operation. This review offers an overview of recent development in biological nutrient removal and recovery from livestock manure. Livestock manure is divided into solid manure and liquid manure. Composting and anaerobic digestion of solid manure are fully discussed and important parameters are investigated. Then various processes of nutrient removal and recovery from liquid manure are summarized. Brief economic sustainability and eco-environmental effects are carried out. Finally, current challenges and future prospects in this field are analyzed.

The storage of large amount of power production waste occupies huge land resource; moreover, the stored or discarded waste may pollute the water environment through changing the water pH, releasing the trace and toxic elements even radioactive elements, and so on by leachate. Therefore, the recycling and disposal of power production waste are important and necessary. This paper reviews the research literatures published in 2019 on power generation waste from coal-fired and nuclear power plants, mainly including the recycling of fly ash and flue gas desulfurization gypsum in construction industry and environmental application, the recovery and immobilization of different metals from coal combustion products and selective catalytic reduction catalysts, and the treatment and disposal of radioactive elements from nuclear power plants. Practioner points Coal-fired power plant waste can be applied for material preparation and wastewater purification. Valued and toxic metals are normally recovered or removed from spent selective catalytic reduction catalyst. Recovery and removal of radioactive elements is essential for nuclear power plant wastes disposal.