Table 4.
Information from articles on the efficacy of different wastewater treatment systems to remove microbial agents
| Author/Year/Ref | Sample Size | Type of samples/City | Types of wastewater treatment systems | Microbial agent | Microbial agent removal rate | Compliance with US-EPA Standard (Ref. [26, 27]) |
|---|---|---|---|---|---|---|
| Hashemi et al., 2010 [28] | 17 | Municipal wastewater/Esfahan | UV disinfection system including low pressure (LP) | Total coliforms | 1000 MPN/100 mL | Yes |
| Fecal coliforms | 400 MPN/100 mL | Yes | ||||
| Fecal streptococci | 400 MPN/100 mL | Yes | ||||
| UV disinfection system including medium pressure (MP) | Total coliforms | 1000 MPN/100 mL | Yes | |||
| Fecal coliforms | 400 MPN/100 mL | Yes | ||||
| Fecal streptococci | 400 MPN/100 mL | Yes | ||||
| LP + MP | Total coliforms | 1000 MPN/100 mL | Yes | |||
| Fecal coliforms | 400 MPN/100 mL | Yes | ||||
| Fecal streptococci | 400 MPN/100 mL | Yes | ||||
| Banejad et al., 2010 [29] | 12 | Domestic wastewater/Hamedan | Flocculation and coagulation with moringa peregrina seeds | Total coliforms | 97% | Yes |
| Escherichia coli | 97% | Yes | ||||
| Derayat et al., 2011 [30] | 120 | Municipal wastewater/Kermanshah and Gilangharb | Conventional activated sludge | Cysts | 97.5% | Yes |
| Parasite eggs | 98.3% | Yes | ||||
| Stabilization pond systems | Cysts | 100% | Yes | |||
| Parasite eggs | 100% | Yes | ||||
| Baghapour et al., 2013 [31] | 64 | Municipal wastewater/Shiraz | Activated sludge | Total coliforms | 1291.11 ± 1165.88 MPN/100 mL | No |
| Fecal coliforms | 675.22 ± 1008.21 MPN/100 mL | No | ||||
| Helminth egg | 73.61 ± 96.125 N/L | No | ||||
| Safari et al., 2013 [32] | 7 | Municipal wastewater/Shahrak Gharb Tehran | Two-stage fluidized bed reactor (FBR) | Fecal coliforms (without chlorine addition) | 35–75% | No |
| Fecal coliforms (with the chlorine addition) | 67–97% | No | ||||
| Navidjouy et al., 2014 [33] | 8 | Municipal treatment plants and slaughterhouse treatment plants/Tehran | Activated sludge | Helminth egg | 94.8–95.7% | Yes |
| Protozoa (oo)cyst | 79.3–85.8% | No | ||||
| Karimi et al., 2014 [34] | 100 | Municipal wastewater/Yazd | Wetlands | Fecal coliforms | 1.13 × 1014 MPN/100 | No |
| Escherichia coli | 5.03 × 1012 MPN/100 mL | No | ||||
| Aslani et al., 2014 [35] | 9 | Municipal wastewater/North of Tehran | Activated sludge effluent | Fecal coliforms | 5.5 ± 05 MPN/100 mL | No |
| Jamshidi et al., 2014 [36] | 70 Lit | Domestic wastewater/Tehran | Anaerobic baffled reactor (ABR) followed by Bio-rack wetland planted with Phragmites sp. and Typha sp. | Total coliforms | 99% | Yes |
| Nahavandi et al., 2015 [37] | 8 | Municipal treatment plants and slaughterhouse treatment plants/Tehran | Activated sludge | Helminth egg | 94.8–95.7% | Yes |
| Protozoa (oo)cyst | 79.3–85.8% | No | ||||
| Ghoreishi et al., 2016 [38] | 9 | Municipal wastewater/Azerbaijan Province | Extended aeration activated sludge/Tabriz | Total coliforms | 2.17 × 105 MPN/100 mL | No |
| Extended aeration activated sludge/Marand | Total coliforms | 1.34 × 106 MPN/100 mL | No | |||
| Extended aeration activated sludge/Jolfa | Total coliforms | 1.82 × 106 MPN/100 mL | No | |||
| Activated sludge/Ajabshir | Total coliforms | 4.53 × 105 MPN/100 mL | No | |||
| Extended aeration activated sludge/Ahar | Total coliforms | 2.25 × 103 MPN/100 mL | No | |||
| Extended aeration activated sludge/Mianeh | Total coliforms | 3.93 × 103 MPN/100 mL | No | |||
| Conventional activated sludge/Maragheh | Total coliforms | 3.02 × 104 MPN/100 mL | No | |||
| SBR/Bostanabad | Total coliforms | 1.09 × 106 MPN/100 mL | No | |||
| Extended aeration activated sludge/Sarab | Total coliforms | 2.02 × 103 MPN/100 mL | No | |||
| Mollaie Tavani et al., 2017 [39] | 16 | Hospital wastewater/Behshahr | Conventional activated sludge | Total coliforms | 46 MPN/100 mL | Yes |
| Fecal coliforms | 4.75 MPN/100 mL | Yes | ||||
| Sasani et al., 2017 [40] | 36 | Municipal wastewater/Ahvaz | Conventional activated sludge | Total coliforms | 7.8 × 1012 MPN/100 mL | No |
| Choopan et al., 2018 [41] | 45 | Municipal wastewater/Torbat-heydarieh | Activated sludge | Fecal coliforms | 200 MPN/100 mL | Yes |
*In compliance with the US-EPA standard, the results of studies within the US-EPA standard range were marked with Yes and the results of studies that exceeded the US-EPA standard were marked with No.