Performance of Constructed Wetland Systems for Anaerobic Membrane Bioreactor Effluent Polishing

Abstract

Pollution from animal wastes is a threat to water resources. Insufficient treatment and disposal of animal manure results in potential runoff and transport of waste into surface and groundwater and ultimately contaminating drinking water in many rural areas. The goal of this research is to assess the efficiency of an innovative configuration of anaerobic membrane bioreactor (AnMBR) and constructed wetlands (CWs) to treat animal waste, providing a sustainable, resilient management system for agricultural wastewaters. Numerical simulations were conducted to assess the capacity of CWs to remove nutrients from AnMBR permeate with varying ammonium (NH4+), phosphorus (P), and chemical oxygen demand (COD) concentrations and temperature conditions (10°C, 20°C, 30°C, and 40°C). The simulations were conducted using HYDRUS software with the Constructed Wetland 2D (CW2D) module. The results supported the assumption that CWs can be an efficient polishing step for AnMBR permeate, removing more than 90% of NH4+ and P, which was further confirmed with experimental measurements. The effectiveness of this design relies on the natural processes for nutrient removal that can be optimized by altering nutrient and COD loading rates from the AnMBR system. When AnMBR systems face unexpected failures or technical issues, the integration of CWs provides a reliable contingency plan, ensuring a practical and resilient wastewater treatment process. The findings from this research offer significant promise for developing cost-effective and environmentally friendly solutions for the treatment and reuse of concentrated animal feeding operations (CAFOs) wastewater through a hybrid treatment configuration, contributing to the broader goals of decentralized wastewater treatment and agricultural practices.