Tags:Adsorption, Biochar, Nature-based solutions and Wastewater treatment
Abstract:
Constructed wetlands (CWs) represent a natural wastewater treatment process, offering economic and environmental advantages. These systems can remove several compounds that may cause negative impacts on the environment while reducing peak flows and enhancing ecosystem services. On the other hand, anaerobic membrane bioreactor (AnMBR) is an innovative technology combining biological treatment and membranes for solid-liquid separation. The AnMBR is effective to transform organic compounds into biogas while creating permeate rich in nutrients (ammonia-N and phosphate-P). The combination of these two technologies can generate a high-quality effluent, meeting superior discharge standards. Thus, the goal of this study is to evaluate the capacity of an AnMBR coupled with CWs to remove contaminants from swine wastewater. The CWs were designed to operate with a 10 cm drainage layer (gravel size ¾” to 1”), a 20 cm main gravel layer (gravel size ½” to ¾”), a 3 cm separation layer (gravel ¼” to 3/8”), a 20 cm layer of soil (silt loam:sand, 2:1 ratio) mixed with eastern redcedar biochar (70% soil and 30 % biochar), and 7 cm top layer (gravel size ½” to ¾”). The systems were planted with cattail, a low cost and low maintenance plant often used for biomass production and is able to tolerate cold weather and occasional flooding. Results indicate that the CWs are effective to remove up to 99.5% of NH4+ and P from the AnMBR effluent. Moreover, sorption tests show that the biochar used in the CW configuration was able to decrease the concentrations of commonly used antibiotics in the swine industry such as tetracycline, oxytetracycline, and chlortetracycline up to 99.93%, 96.23%, and 98.28%, respectively. Thus, our findings highlighted the capacity of this CWs design to be used as a polishing step for AnMBR, while removing antibiotics and generating an effluent with nutrient concentrations below 1 mgL-1.
Constructed Wetlands Systems for Anaerobic Membrane Bioreactor Effluent Polishing