For safe water reuse, there are wide concerns regarding the health and ecological risk of exposure to trace pollutants that may not be easily removed by treatment processes commonly applied for water reclamation, compared with conventional pollutants such as bulk organic matter, nutrients, etc. Table 1 summarizes the occurrence of a series of trace pollutants in the wastewater, reclaimed water, and the lake water (Ma et al. 2016).
Occurrence of typical trace pollutants at different locations
| Category . | Number of chemicals detected . | Detected concentration (ng/L in total) . | ||
|---|---|---|---|---|
| Wastewater . | Reclaimed water . | Lake water . | ||
| PPCPs | 26 | 1.0–2.4 × 103 | 0.1–1.0 × 103 | 0.3–1.3 × 102 |
| Phenols | 16 | 3.3–6.5 × 103 | 0.1–1.8 × 102 | 0.6–1.6 × 102 |
| Pesticides | 3 | 0.8–8.7 × 101 | 0.4–1.2 × 101 | 2.4–2.7 × 100 |
| PAHs | 13 | 1.3–3.2 × 101 | 1.6–2.7 × 101 | 2.6–4.6 × 101 |
| Category . | Number of chemicals detected . | Detected concentration (ng/L in total) . | ||
|---|---|---|---|---|
| Wastewater . | Reclaimed water . | Lake water . | ||
| PPCPs | 26 | 1.0–2.4 × 103 | 0.1–1.0 × 103 | 0.3–1.3 × 102 |
| Phenols | 16 | 3.3–6.5 × 103 | 0.1–1.8 × 102 | 0.6–1.6 × 102 |
| Pesticides | 3 | 0.8–8.7 × 101 | 0.4–1.2 × 101 | 2.4–2.7 × 100 |
| PAHs | 13 | 1.3–3.2 × 101 | 1.6–2.7 × 101 | 2.6–4.6 × 101 |
Notes: (1) The lake mainly for landscaping is operated under a condition shown in Figure 3, where water quality is maintained by continuous replenishment using reclaimed water (average hydraulic retention time as about 5 days). (2) Samples were collected during a 7-month period after the whole system had been put into continuous operation for 5 years. (3) PPCPs detected mainly include tetracycline, sulfapyridine, sulfamethoxazole, sulfadiazine, roxithromycin, oxytetracycline, ofloxacin, norfloxacin, lamotrigine, cotinine, cimetidine, etc. (4) Phenols detected mainly include o-phenylphenol, 2-Nitrophenol, 4-methylphenol, 3-methylphenol, 2,4-dimethylplhenol, 4-chloro-3-methylphenol, 4-chloro-3,5-dimethylphenol, bisphenol A, etc. (5) Pesticides detected include dichlorphos, chlorpyrifos, and atrazine. (6) PAHs detected include pyrene, phenanthrene, fluorene, fluoranthene, chrysene, anthracene, acenaphthylene, acenaphthene, etc.