Heterotrophic Kinetic Study and Nitrogen Removal of a Membrane Bioreactor System Treating Real Urban Wastewater under a Pharmaceutical Compounds Shock: Effect of the Operative Variables

Abstract

Numerous studies have analyzed the viability of the biodegradation and removal of different compounds of emerging concern in biological systems for wastewater treatment. However, the effect on the heterotrophic biomass of organic matter removal is sometimes missed. The aim of the present research was to study the effect of the addition of a mix of three pharmaceuticals (carbamazepine, ciprofloxacin, and ibuprofen) on the behavior of the biomass in two different membrane-based biological systems treating urban wastewater. The present research studied a membrane bioreactor (MBR) pilot plant operating at a similar mixed liquor suspended solids (MLSS) concentration (about 5.5 g/L). This system works as an MBR and is combined with a moving bed biofilm reactor (MBBR-MBR) to treat real urban wastewater at 6 and 10 h of hydraulic retention time (HRT) under three different shocks of pharmaceuticals with increasing concentrations. In all cases, the organic matter removal was, in average terms, higher than about 92% of biochemical oxygen demand on the fifth day (BOD5), 79% of chemical oxygen demand (COD), and 85% of total organic carbon (TOC). Nevertheless, the removal is higher in the MBBR-MBR technology under the same HRT and the MLSS is similar. Moreover, the removal increased during the shock of pharmaceutical compounds, especially in the MBR technology. From a kinetic perspective, MBBR-MBR is more suitable for low HRT (6 h) and MBR is more effective for high HRT (10 h). This could be due to the fact that biofilm systems are less sensitive to hostile environments than the MBR systems. The removal of N-NH4+ decreased considerably when the pharmaceutical compounds mix was introduced into the system until no removal was detected in cycle 1, even when biofilm was present.

Kinetic Effects of Ciprofloxacin, Carbamazepine, and Bisphenol on Biomass in Membrane Bioreactor System at Low Temperatures to Treat Urban Wastewater

“…In this study, the r su,H values varied from 18.6876 to 45.9095 mgO 2 /(L•h), and r' x,H ranged from 4.0965 to 14.5019 mgVSS/(L•h), which highlights a higher effect of very low temperatures on heterotrophic bacteria [35,36]. In light of this, [38] obtained that the presence of a mix of carbamazepine, ciprofloxacin, and ibuprofen almost doubled the r su,H of the control experiment in a membrane bioreactor, with values fluctuating from 183.97 to 192.88 mgO 2 /(L•h) at temperatures varying from 18.9 to 21.4 • C, and the same trend was obtained by [41] in a membrane bioreactor at 12.6 and 21.5 • C. The authors of [29] did not observe any inhibition of COD removal under exogenous respiration in the presence of carbamazepine at 20 • C and similar MLSS and HRT conditions. This strengthens the higher influence of very low temperatures on the kinetic behaviour of heterotrophic bacteria, which could hinder the acclimatization of bacterial populations to the presence of micropollutants.…”

Impacts of Organic Emerging Contaminants (Erythromycin, Ibuprofen, and Diclofenac) on the Performance of a Membrane Bioreactor Treating Urban Wastewater: A Heterotrophic Kinetic Investigation

“…This finding suggests a more favourable adaptation of the biomass to the conditions in Phase 1. Other authors studied the effects of ibuprofen and other compounds, one of an antibiotic nature, such as erythromycin, on the heterotrophic biomass of an MBR, also obtaining decreasing r su,H values in the presence of these compounds [ 41 ].…”