Sahar S. Dalahmeh

Assamra wastewater treatment plant (WWTP) is the largest treatment facility in Jordan. Treated wastewater is discharged into the Zarqa River (ZR) and used to irrigate fodder and vegetables. ZR also includes surface runoff, stormwater, and raw wastewater illegally discharged into the river. This study examined pharmaceutically active compounds (PhAC) in water resources in the ZR basin. Samples of WWTP influent and effluent and river water from four sites along ZR were collected. Concentrations of 18 target antibiotics, one stimulant, and 15 other PhACs were determined in the samples. Five antibiotics were detected in WWTP influent (510–860 ng L⁻¹ for ∑Antibiotics) and six in the effluent (2300–2600 ng L⁻¹ for ∑Antibiotics). Concentrations in the effluent of all antibiotics except clarithromycin increased by 2- to 5-fold compared with those in influent, while clarithromycin concentration decreased by around 4- fold (from 308 to 82 ng L⁻¹). WWTP influent and effluent samples contained 14 non-antibiotic PhACs, one simulant, and six antibiotics at detectable concentrations. The dominant PhACs were paracetamol (74% of ∑PhACs) in the influent and carbamazepine (78% of ∑PhACs) in the effluent. At ZR sampling sites, carbamazepine was the dominant PhAC in all cases (800–2700 ng L⁻¹). The antibiotics detected in WWTP effluent were also detected at the ZR sites. In summary, water in ZR is contaminated with PhACs, including antibiotics, and wastewater discharge seems to be the main pathway for this contamination. The occurrence of antibiotics and other PhACs in the irrigated soil requires investigation to assess their fate.

This study evaluated the potential of biochar impregnated with Fe³⁺ or Ca²⁺, or mixed with Polonite^®, as a filter material for removal of phosphate (PO₄-P) from wastewater in onsite wastewater treatment systems (OWTS). Four treatments with biochar were investigated: unimpregnated biochar (UBC), biochar impregnated with iron Fe³⁺ (FBC), biochar impregnated with calcium oxide (CBC), and biochar mixed with Polonite^® (PBC). In a batch experiment using phosphate solution at concentrations 0.5, 3.3, 6.5, 13, and 26 mg PO₄-P L^–1, adsorption of PO₄-P in the different treatments was modeled using Langmuir and Freundlich isotherms. Column filters (5 diameter × 55 cm height) packed with UBC, FBC, CBC, and PBC were then furnished with raw wastewater over 148 weeks. During this experiment, adsorption of PO₄-P was investigated in response to increasing hydraulic loading rate (HLR; 56, 74, and 112 L m^–2 day^–1) and increasing phosphate loading rate (PLR; 195, 324, 653, and 1715 mg PO₄-P m^–2 day^–1). Among the materials, FBC had the highest maximum adsorption capacity (Q_m) based on Langmuir isotherms (3.21 ± 0.01 mg g^–1). FBC and CBC showed robust performance with increasing HLR, while increasing PLR increased the amount of PO₄-P retained in all filters. After 148 weeks of operation, removal of PO₄-P (averaged over the last 18 weeks of operation) was 13 ± 16% for UBC, 40 ± 20% for CBC, 88 ± 12% for FBC, and 30 ± 18% for PBC. The PO₄-P amount retained in filters over the 148 weeks was 84.75, 221.75, 358.38, and 152.36 g m^–2 in UBC, CBC, FBC, and PBC, respectively. The adsorption capacity of the filters after 148 weeks was 1.50, 4.02, 6.41, and 2.75 mg g^–1 for UBC, CBC, FBC, and PBC, respectively. The adsorption capacity values and breakthrough curves showed that low concentrations (i.e., –1) of PO₄-P in wastewater would allow the FBC filter to remain active for 58 months and the CBC filter for 15 months, before PO₄-P removal declined to 4-P from wastewater in OWTS.

The authors wish to make the following corrections to this paper