Truck-Wash Wastewater in Three-Stage Sedimentation Basins on Construction Sites: Wastewater Characteristics, Bacterial Communities, and Pathogenic Bacteria Distribution

Truck-wash facilities have become popularized globally on construction sites, and the wastewater was frequently treated by three-stage sedimentation basins. The wastewater and bacterial characteristics in three-stage sedimentation basins need to be studied, which might affect the treatment cost and reuse security. In this study, the wastewater characteristics, bacterial communities, and pathogenic bacteria distribution of three-stage sedimentation basins on four construction sites were investigated. Results indicated that truck-wash wastewater contained a high concentration of suspended solids ($29–211\mathrm{mg}/\mathrm{L}$) and bacteria ($4.2\times {10}^3$ to $2.7\times {10}^4$ colony forming $\mathrm{units}/\mathrm{mL}$). Proteobacteria (mean at 72.3%), Firmicutes (mean at 11.3%), and Bacteroidetes (mean at 10.6%) were the predominant bacterial phyla and Acinetobacter (mean at 18.4%), Chryseomicrobium (mean at 6.3%), and Paracoccus (mean at 6.1%) were the predominant bacterial genera. Truck-wash wastewater contained pathogenic bacteria, identified by the Illumina sequencing method. Acinetobacter, Shigella, or Escherichia (about 0.2%) and Legionella (about 0.2%) were the main pathogenic bacteria and Legionella should be a concern due to the wastewater reuse method. Traditional three-stage sedimentation basins should be simplified and further improved because of the lower suspended solids or pathogenic bacteria removal effect. The practical technology for suspended solids and pathogenic bacteria control in truck-wash wastewater should be further studied, and disinfection facilities should be applied to protect construction workers.