The Efficiency of Constructed Wetlands and Algae Tanks for the Removal of Pharmaceuticals and Personal Care Products (PPCPs): a Systematic Review

Constructed wetlands (CWs) and algae tanks are regarded as promising polishing steps to treat wastewaters for the removal of persistent organic pollutants, such as pharmaceuticals and personal care products (PPCPs). In this systematic review, we provide a synthesis of the relationship between the presence of the most widely studied PPCPs in domestic wastewater and the conformation of the CWs and algae tanks constructed to treat them. The six drugs most commonly found in the reviewed articles were caffeine, carbamazepine, diclofenac, ibuprofen, ketoprofen, and naproxen. Removal efficiency of the PPCPs was evaluated by means of the following selected parameters: hydraulic retention time (HRT), system flow rate, temperature, inflow concentration, and average removal rate. The average removal rate of PPCPs in CWs showed a positive and moderate relationship with the HRT (r = 0.346). A different flow configuration and plant species acted better for different target compounds. The average concentration reduction ranged from 80% for caffeine to zero reduction levels in some conformations for carbamazepine, diclofenac, and ketoprofen. There was a wide variation in the concentration reduction of different plant genera or unplanted tanks, ranging from 81% (caffeine using Phragmites sp.) to no reduction in an unplanted tank for diclofenac. The algae tanks were more efficient in removing most of the six target compounds than the wetlands. Removal rates ranged from 50% for ketoprofen to 16% for naproxen. According to our results, a combination of CW systems and algae tanks might be an effective alternative for the removal of PPCPs from domestic wastewater.