Abstract:This study aims to assess the environmental impact of wastewater discharges from FERMENCAM. Effluent and wastewater samples were collected respectively at the plant outlet and in the receiving environment, and physico-chemical analyses carried out revealed an organic pollution with a high pollution load that can be observed by phosphate levels in water at the plant outlet. Biochemical oxygen demand (BOD 5 ) is high at the plant outlet (20300 mg of O 2 / L) and 16200 mg of O 2 / L are found in the receiving environment. The BOD 5 /COD (chemical oxygen demand) ratio of effluents discharged by FERMENCAM and that of the receiving environment is 0.90. This value is higher than 0.5, meaning that the organic matter of both effluents is highly biodegradable. The results show that the increase in conductivity and decrease in total dissolved salts are due to an excessive mineralization of organic matters. The results show that the chlorophyll synthesis in Amaranthus viridis leaves is linked to the quality of the environment, and that is why such leaves can easily adapt to the polluted environment. In short, the wastewater impact on water quality of the receiving environment is evident, and these data will allow better environmental protection, thus promoting the development of various waterfront activities. In addition, the need for sustainable wastewater management (wastewater treatment plants, pre-treatment of industrial waters and sensitization) in the study area proves to be vital and urgent in order to improve wastewater quality and contribute to improving the state of the environment.

Human activities are causing wetland degradation. Macrophytes play an important role in the management of hydrosystems. They can therefore be used to restore a polluted environment. The aim of the study is to contribute to the phytorestoration of sewage sludge in nitrates, phosphates, cadmium, iron and lead from the Mangrove landfill of "Bois des singes" by planted filters of Pennisetum purpureum. A planted filter of P. purpureum was constructed. Sewages sludges samples were introduced into the device. Nitrates (NO 3 ), phosphates (PO 4 ), cadmium (Cd), iron (Fe) and lead (Pb) assays were carried out in water and plants at different levels of the filter (Settling basin B1, basin B2, basin B3, negative control and positive control) by absorption spectrophotometry flame atomic. The bioaccumulation and translocation factors as well as the bioaccumulation coefficient have been determined. The high contents of PO 4 (4000 mg/l), NO 3 (89 mg/l), Fe (5000 mg/l), Pb (20 mg/l) and Cd (0.08 mg/l) are greatly reduced by the filters at values below the tolerance threshold in B3 of 0.01 mg/l, 0.14 mg/l, 0.0002 mg/l, 0.0003 mg/l and 0.0003 mg/l respectively. The bioaccumulation factor shows that P. purpureum contained in barrels where the parameters are high is lead accumulator with a value of 1.305 (B2), hyperaccumulator of Fe and Cd with values of 10.05 (B2) and 13, 23 (B3). The leaf translocation is greater than 1 with Fe and Pb in the leaves of the boles. P. purpureum transfers Fe and Pb to the leaves. The planted filter of P. purpureum allows a restoration of this sewage sludge. This macrophyte extracts NO 3 , PO 4 , Cd, Fe and Pb and accumulates them in its vegetative system. P. purpureum cant be use to to restore the environment stressed by faecal sludge in the city of Douala.