Problems treating sewage in rural areas in China have attracted increasing attention in recent years. However, only 6% of rural areas had spray drainage and wastewater treatment systems by the end of 2010. It is neces...Problems treating sewage in rural areas in China have attracted increasing attention in recent years. However, only 6% of rural areas had spray drainage and wastewater treatment systems by the end of 2010. It is necessary to assess the technologies currently used so that sewage treatment in rural areas can be developed appropriately, to provide reliable and affordable waste- water treatment, in these areas. We evaluated the sewage treatment technologies currently used in rural areas by conducting case studies on 62 facilities that had each been operating for at least one year. Our study was carried out between 2009 and 2011, and the aim was to assess the situation during that period and assess any problems involved in decentralized sewage treatment in villages. We found that decentralized sewage treatment is the most popular wastewater treatment method in villages, and that the most common primary treatment technology used in rural areas is the septic tank. Our investigation highlights the need to establish standards for assessing effluent quality, including a range of target pollutants. Our results also show that effluents should be reused to meet the local environmental requirements in different areas, especially in ecologically sensitive areas.展开更多
In Saint-Louis, Senegal, a constructed wetland with horizontal flow reed beds (FHa and FHb) has demonstrated significant efficacy in treating municipal wastewater. Analyzing various treatment stages, the system showed...In Saint-Louis, Senegal, a constructed wetland with horizontal flow reed beds (FHa and FHb) has demonstrated significant efficacy in treating municipal wastewater. Analyzing various treatment stages, the system showed only a slight temperature variation, from an influent average of 26.3°C to an effluent of 24.7°C. Electrical conductivity decreased from 1331 mS/cm to 974.5 mS/cm post-primary treatment, with suspended solids (SS) dramatically reduced from 718.9 mg/L to 5.7 mg/L in the final effluent. Biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) saw a notable decrease, from initial levels of 655.6 mg/L and 1240 mg/L to 2.3 mg/L and 71.3 mg/L, respectively. Nitrogenous compounds (N-TN) and phosphates () also decreased significantly, indicating the system’s nutrient removal capacity. Microbiological analysis revealed a reduction in fecal coliforms from 7.5 Ulog/100ml to 1.8 Ulog/100ml and a complete elimination of helminth eggs. The presence of Phragmites and Typha was instrumental in enhancing these reductions. The system’s compliance with the Senegalese standards for disposal into natural environments, WHO recommendations for unrestricted water reuse in irrigation, and the European legislation for water reuse was established. The effluent quality met the stringent criteria for various classes of agricultural reuse, illustrating the system’s potential for sustainable water management. This wetland model presents a robust solution for water-stressed regions, ensuring environmental protection while supporting agricultural needs. The study calls for ongoing research to further refine the system for optimal, reliable wastewater treatment and water resource sustainability.展开更多
基金Acknowledgements This research was financial supported by the National Natural Science Foundation of China （Grant No. 20077085）, Key Project of the National Natural Science Foundation of China （Grant No. 51138009）, and Key Project of the Chinese Academy of Science （No. KZZD-EW-09）.
文摘Problems treating sewage in rural areas in China have attracted increasing attention in recent years. However, only 6% of rural areas had spray drainage and wastewater treatment systems by the end of 2010. It is necessary to assess the technologies currently used so that sewage treatment in rural areas can be developed appropriately, to provide reliable and affordable waste- water treatment, in these areas. We evaluated the sewage treatment technologies currently used in rural areas by conducting case studies on 62 facilities that had each been operating for at least one year. Our study was carried out between 2009 and 2011, and the aim was to assess the situation during that period and assess any problems involved in decentralized sewage treatment in villages. We found that decentralized sewage treatment is the most popular wastewater treatment method in villages, and that the most common primary treatment technology used in rural areas is the septic tank. Our investigation highlights the need to establish standards for assessing effluent quality, including a range of target pollutants. Our results also show that effluents should be reused to meet the local environmental requirements in different areas, especially in ecologically sensitive areas.
文摘In Saint-Louis, Senegal, a constructed wetland with horizontal flow reed beds (FHa and FHb) has demonstrated significant efficacy in treating municipal wastewater. Analyzing various treatment stages, the system showed only a slight temperature variation, from an influent average of 26.3°C to an effluent of 24.7°C. Electrical conductivity decreased from 1331 mS/cm to 974.5 mS/cm post-primary treatment, with suspended solids (SS) dramatically reduced from 718.9 mg/L to 5.7 mg/L in the final effluent. Biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) saw a notable decrease, from initial levels of 655.6 mg/L and 1240 mg/L to 2.3 mg/L and 71.3 mg/L, respectively. Nitrogenous compounds (N-TN) and phosphates () also decreased significantly, indicating the system’s nutrient removal capacity. Microbiological analysis revealed a reduction in fecal coliforms from 7.5 Ulog/100ml to 1.8 Ulog/100ml and a complete elimination of helminth eggs. The presence of Phragmites and Typha was instrumental in enhancing these reductions. The system’s compliance with the Senegalese standards for disposal into natural environments, WHO recommendations for unrestricted water reuse in irrigation, and the European legislation for water reuse was established. The effluent quality met the stringent criteria for various classes of agricultural reuse, illustrating the system’s potential for sustainable water management. This wetland model presents a robust solution for water-stressed regions, ensuring environmental protection while supporting agricultural needs. The study calls for ongoing research to further refine the system for optimal, reliable wastewater treatment and water resource sustainability.
