Pathogens Removal in a Sustainable and Economic High-Rate Algal Pond Wastewater Treatment System

Abstract

This study evaluates the efficiency of a sustainable technology represented in an integrated pilot-scale system, which includes a facultative pond (FP), a high-rate algal pond (HRAP), and a rock filter (RF) for wastewater treatment to produce water that complies with the Egyptian standards for treated wastewater reuse. Still, limited data are available on pathogen removal through HRAP systems. Thus, in this study, the performance of the integrated system was investigated for the removal of Escherichia coli (E. coli), coliform bacteria, eukaryotic pathogens (Cryptosporidium spp., Giardia intestinalis, and helminth ova), somatic coliphages (SOMCPH), and human adenovirus (HAdV). Furthermore, physicochemical parameters were determined in order to evaluate the performance of the integrated system. The principal component analysis and non-metric multidimensional scaling analysis showed a strong significant effect of the integrated system on changing the physicochemical and microbial parameters from inlet to outlet. The mean log10 removal values for total coliform, fecal coliform, and E. coli were 5.67, 5.62, and 5.69, respectively, while 0.88 log10 and 1.65 log10 reductions were observed for HAdV and SOMCPH, respectively. The mean removal of Cryptosporidium spp. and Giardia intestinalis was 0.52 and 2.42 log10, respectively. The integrated system achieved 100% removal of helminth ova. The results demonstrated that the system was able to improve the chemical and microbial characteristics of the outlet to acceptable levels for non-food crops irrigation. Such findings together with low operation and construction costs of HRAPs should facilitate wider implementation of these nature-based systems in remote and rural communities. Overall, this study provides a novel insight into the performance of such systems to eliminate multiple microbial pathogens from wastewater.