In this study, which aimed to evaluate wastewater treatment and provide data to support improved wastewater treatment plant (WWTP) design, operation and ongoing monitoring strategies, mixed liquor, return activated sludge, primary effluent and secondary effluents of two WWTPs (n = 15) and five of the industries they service (n = 15) in Emfuleni municipality, Gauteng Province, South Africa, were characterised following a 5-month monitoring study. Following physical and chemical analysis, the parameters, including the Chemical Oxygen Demand (COD), were higher than local limits (75 mg/L) for both WWTPs and extremely high for the abattoir industry (13400 mg/L). In particular, high ammonia levels were recorded in both WWTPs. Following Illumina high-throughput sequencing and analysis using the Whole Metagenome Sequencing Assembly-based (WGSA2) pipeline on the Nephele platform, Bacteria was the dominant domain in the WWTPs. The dominant phyla were Proteobacteria (87.7%), followed by Firmicutes (8.25%), Actinobacteria (2.71%) and Bacteroidetes (0.68%). Aeromonas (39.86%) was the most dominant genus, with Acinetobacter (9.29%), Pseudomonas (6.78%), Bacillus (5.99%), and Thauera following (4.78%). Total Suspended Solids (TSS), pH, Total Dissolved Solids (TDS), and DO have influenced the diversity and distribution of the microbiome. Krona charts elucidated the xenobiotics degradation and metabolism distribution potential of the microbiome of each sampled site. This study reiterates the need for constant monitoring of WWTPs due to the high pollution parameters recorded from the WWTP effluent. The metagenomic data generated in this study provides insight into the diversity and functionality of the microbiome present in WWTPs of different process configurations which can inform existing WWTP configurations and future designs.
Maharaj et al. (Sat,) studied this question.