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.

Biochar is a promising material for wastewater treatment. This study assessed multi-module biochar filters (MmBFs) as onsite wastewater treatment systems (OWTSs), comprising movable modules filled with biochar to remove chemical oxygen demand (COD), nitrogen, phosphorus, and Escherichia coli (E. coli) in wastewater. The MmBF treats wastewater sequentially through six modules: three aerobic modules (M1-M3) for organic matter oxidation and nitrification, two anoxic modules (M4-M5) for denitrification, and an additional module (M6) for the removal of faecal bacteria using biochar and bark. The experiments ran for 381 days using three identical MmBF pilots with two distinct sampling periods, conducted under conditions relevant to OWTSs using municipal wastewater as influent. Water samples were taken from the influent, final effluent, and effluent of each module to evaluate the removal efficiency of organic matter, nitrogen, phosphorus, and E. coli. During the second sampling period, the results showed a 95 ± 2.1% removal of COD, along with a substantial removal of total inorganic nitrogen (71 ± 6.6%). However, phosphate removal was limited (3.4 ± 30.4%). E. coli removal decreased from 2.63 ± 0.93 log₁₀ removal in the first sampling period to 1.8 ± 0.73 log₁₀ removal in the second sampling period. In summary, the MmBFs showed promising potential in treating organic matter, nitrogen, and E. coli, making it an alternative option for OWTS. However, further exploration is needed to assess long-term performance, micropollutant removal, and biological activities. Design enhancements, especially for phosphorus removal are necessary.

Pharmaceutically active compounds (PhACs) in wastewater pose significant environmental risks due to their persistence and potential to disrupt aquatic ecosystems. Onsite wastewater treatment systems (OWTS) often fail to adequately remove PhACs. This study investigated the efficiency of a multi-module biochar filter (MmBF) system as secondary treatment in OWTS for removing PhACs. Two parallel MmBF systems, each comprising six sequential modules filled with biochar, were evaluated for their removal of 25 detected PhACs across multiple pharmaceutical classes. The MmBFs were operated with municipal wastewater as influent for over one year, after which wastewater samples were collected and analysed from the influent and effluent of each module. The MmBFs showed consistent reduction in the aggregated PhACs concentrations by >99% over several sampling occasions, with only six PhACs having less than 95% removal. The first aerobic module M1 contributed to more than 92% of the total removal. The subsequent aerobic modules (M2–M3) provided additional reduction, resulting in over 98% of PhACs removal in the aerobic modules. In contrast, the anoxic modules (M4–M5) had a lower overall contribution, but the removal of specific compounds was observed, suggesting potential anaerobic degradation. This study demonstrates the potential of biochar-based systems as a sustainable option for OWTSs.

A high level of nutrient removal in onsite wastewater treatment systems is critical for avoiding eutrophication and groundwater contamination, especially in phosphorus- and nitrogen-sensitive areas. This study evaluates modifications to a pilot-scale Multi-module Biochar Filter (MmBF) system aimed at enhancing nitrogen and phosphorus removal through material amendments. A preliminary column experiment identified sawdust as an efficient carbon source for supporting denitrification, motivating its use in anoxic modules containing biochar and 10 wt% and 30 wt% sawdust. Polonite, a calcium-silicate material, was also tested at the same dosages in the final aerobic module for phosphate removal. The results showed that biochar with 30 wt% sawdust significantly enhanced nitrate removal (up to 83%) during the initial three weeks of operation, while biochar with 30% polonite addition achieved an average phosphate removal of 38%, with a peak of 95%. However, these improvements were not sustained over the full sampling period (199 days), suggesting the need for periodic media replacement. The MmBF system maintained high COD and nitrogen removal efficiencies even under doubled hydraulic loading (100 L m−2 day−1), though phosphate removal declined under these conditions. These findings support the potential of MmBF systems with targeted media amendments as a flexible and modular onsite wastewater treatment.