Wastewater Treatment Performance of Aerated Lagoons, Activated Sludge and Constructed Wetlands under an Arid Algerian Climate

Abstract

Water pollution reduces the availability of fresh water, especially in arid areas suffering from water stress, and also adversely affects soil, vegetation and environmental processes. Wastewater treatment processes aim to reduce environmental degradation and increase water availability by improving the quality of wastewater to a standard suitable for irrigation. This paper compares the performance of three wastewater treatment processes: (i) aerated lagoon (AL), (ii) activated sludge (AS), and (iii) constructed wetland (plant beds, PB) under the arid climate of Algeria. The statistical analysis focused on the comparison between the removal rates of the physical (SS) and biological pollution (BOD5 and COD) parameters in the three stations during 8 years of operation. Obtained results show that the maximum removal rates were observed in the AS process and the minimum were in the AL process. The comparison between the removal rates for a given parameter has shown that there is a significant difference between the AL process on the one hand and the AS and PB processes on the other hand. For the last two processes, AS and PB, there is a difference, but it is not statistically significant. For the values of the parameters of wastewater leaving the three systems, results showed that there is a seasonal variation in the average values of the parameters (temperature effect) and that with the exception of orthophosphate, the values recorded are, for the most part, below the values of Algerian discharge standards, WHO standards and FAO standards.