A wetland is a unique and distinct ecosystem that is flooded by water, either permanently or seasonally, where oxygen-free processes prevail, and the primary distinctive factor of wetlands from other landforms or water bodies is the occurrence of adaptive vegetation of aquatic plants, characteristic to the unique hydric soil. A constructed wetland is an artificial shallow basin filled with substrate, usually soil or gravel, and planted with vegetation that has tolerance to saturated conditions. As much as the use of constructed wetland has been recommended in the treatment of various forms of wastewater, the system efficiency is a factor of very many natural and artificial factors, with the emerging pollutants and contaminants such as resistant genes being the most complicated contaminants to eliminate through the system. Indeed, the emerging pollutants in forms of antibiotic resistant genes (ARGs) have remained prevalent in aquatic environments such as wetlands that receive ARG-loaded sewage. Therefore, this chapter covers a discussion on constructed wetlands in wastewater treatment and challenges of emerging contaminants, such as resistant genes filtration and reloading mechanisms, and provides recommendation for the proper handling and removal of such pollutants from the wetlands' functional system.
Water is an essential commodity whose quantity and quality needs to be secured for easier accessibility at both the industrial, public and household levels. However, its availability in adequate quality and quantity has continued to decline worldwide. Indeed, rise in human population coupled with the climate change phenomena have greatly impacted on the quality of water resources through increased organic and inorganic pollution. Rhodamine B (RhB) dye is a common organic pollutant majorly in industrial wastewater and with numerous environmental and human health effects. The application of graphitic carbon nitride (G-C3N4) in the purification of industrial wastewater to enhance the removal of RhB is a technology of interest to most environmental quality regulators and agencies. The study was therefore aimed at investigating the performance of graphitic carbon nitride doped with tungsten chloride in the degradation of organic dye pollutant rhodamine B dye from industrial wastewater. The study showed that the as-prepared hybrid photo catalyst exhibits an improved photo degradation performance because of its synergetic effect. Indeed, the photo excited electrons from g-C3N4 were able to efficiently separate and are injected to the conductive band of WO3. The optimum photo activity occurred at the optimum ratio of 0.25WO3/g- C3N4. There was also stability and efficiency within the hybrid catalyst within the photo degradation process. Indeed, the composite indicates a high activity for degradation of RhB under visible light irradiation. The presence of g-C3N4 proved to be beneficial for enhancement in photo catalytic activity of the g-C3N4-WO3 composite and proved to be one of the best alternative modes of n the degrading organic dye pollutant Rhodamine B dye from wastewater.
The sanitation control of pathogens in the tropical effluents needs much more attention to ensure ecosystem health integrity and the safety of human health. The common use of chemicals in achieving this in wastewater treatment has remained unsustainable due to much health concern. Indeed, based on the numerous challenges associated with faecal pathogenic bacteria in wastewaters, the focus is now on achieving higher purification efficiencies in the elimination of the human pathogens from wastewater through eco-sustainable systems such as constructed wetlands (CWs). Hence, the need to explore the application of constructed wetlands in wastewater treatment under specific local environmental conditions for accurate understanding and improved treatment efficiency. This study therefore aimed at monitoring constructed wetlands faecal bacteria purification efficiency through integrated non-molecular membrane filtration technique and molecular quantitative polymerase chain reaction (MFT-qPCR) technique. The results showed some shortfall in the treatment system and also proved that integrating MFT-qPCR in faecal bacterial purification monitoring within a constructed wetland system provides a more accurate and reliable outcome. Additionally, the wetland purification efficiency was low (<80%) with the dissolved oxygen posing the strongest influence on faecal pathogenic bacterial purification trend across the wetland. Hence, the need to regularly carry out dredging and macrophyte harvesting as well as the use of holistic and more integrative approaches such as MFT-qPCR in managing and monitoring the performance of CWs in faecal pathogen eradication for improved CWs purification efficiency.
As in other parts of Africa, and in other developing nations, the rise in the human population and anthropogenic activities within the Lake Naivasha basin is causing an increase in human health risks due to faecal contamination of domestic water sources. This study investigated faecal pollution of community water sources within the Lake Naivasha basin by measuring the densities of total coliforms, Escherichia coli, intestinal enterococci, Clostridium perfringens and heterotrophic bacteria in Lake Naivasha, the Malewa and Gilgil Rivers, and boreholes using membrane filtration techniques and heterotrophic plate count procedures. Selected physico-chemical parameters were also measured in situ from all the water sources sampled. Lakes and rivers had significantly higher microbial abundances than boreholes. Unlike boreholes, surface sources (rivers and lake) showed significant variation with respect to sampling sites for all the microbiological parameters (P < 0.05). The use of solar radiation in water disinfection with temperatures of 75 °C after 30 minutes from pasteurization point (time zero) fully eradicated E. coli and total coliforms from all the water sources. In conclusion, there is faecal pollution in water sources used by communities within the Lake Naivasha basin. The use of solar radiation is therefore recommended for water purification to reduce likely incidences of waterborne diseases.
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