Modeling of micropollutant removal in full-scale membrane bioreactors: calibration and operations to limit the emissions

A Mechanistic Model to Assess the Fate of Naphthalene and Benzo(a)pyrene in a Chilean WWTP

Polycyclic aromatic hydrocarbons (PAHs) are a family of organic compounds of widespread presence in the environment. They are recalcitrant, ubiquitous, prone to bioaccumulation, and potentially carcinogenic. Effluent from wastewater treatment plants (WWTPs) constitutes a major source of PAHs into water bodies, and their presence should be closely monitored, especially considering the increasing applications of potable and non-potable reuse of treated wastewater worldwide. Modeling the fate and distribution of PAHs in WWTPs is a valuable tool to overcome the complexity and cost of monitoring and quantifying PAHs. A mechanistic model was built to evaluate the fate of PAHs in both water and sludge lines of a Chilean WWTP. Naphthalene and benzo(a)pyrene were used as models of low-MW and high-MW PAHs. As there were no reported experimental data available for the case study, the influent load was determined through a statistical approach based on reported values worldwide. For both naphthalene and benzo(a)pyrene, the predominant mechanism in the water line was sorption to sludge, while that in the sludge line was desorption. Compared to other studies in the literature, the model satisfactorily describes the mechanisms involved in the fate and distribution of PAHs in a conventional activated sludge WWTP. Even though there is evidence of the presence of PAHs in urban centers in Chile, local regulatory standards do not consider PAHs in the disposal of WWTP effluents. Monitoring of PAHs in both treated effluents and biosolids is imperative, especially when considering de facto reuse and soil amendment in agricultural activities are currently practiced downstream of the studied WWTP.

Capabilities and mechanisms of microalgae on removing micropollutants from wastewater: A review

Micropollutants in wastewater are a set of compounds receiving a growing concern to the environment and human health. As a green and low-cost process, microalgae-based systems (MBSs) have already been demonstrated the ability of micropollutant removal. In the present review, 114 micropollutants and 16 microalgae species in total are summarized and analyzed to present an overview capability of the MBSs. The analysis shows that MBSs can eradicate most of the included micropollutants with 94 compounds (82% of total) being removed by ≥ 50%. Regarding the reliability of removal efficiency, those from hormone active substances, macrolides, and cephalosporins are consistently removed at a high level (≥80%). Herein, biodegradation is the predominant removal pathway for most micropollutants, particularly, bearing electron-donating groups. Besides, the large family of microalgae species and unique phototrophic ability enables broad ecological niches and extra abilities over activated sludge systems to remove some recalcitrant micropollutants, e.g. pesticides. In the future study, optimization on the reactor configuration and operation parameters is expected to improve the stability of MBSs before extrapolating to full-scale deployment.