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.
Highlights
Increasing attention has recently been paid to the presence of micropollutants in the aquatic environment and wastewater treatment plants [1]
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
Organic matter removal was higher in the moving bed biofilm reactors (MBBR)-membrane bioreactor (MBR) technology for the same hydraulic retention time (HRT) and similar mixed liquor suspended solids (MLSS)
Summary
Increasing attention has recently been paid to the presence of micropollutants in the aquatic environment and wastewater treatment plants [1]. Recent studies have identified the presence of contaminants of emerging concern (CECs) in effluents and in receiving waters, where CECs can potentially affect aquatic organisms [2]. CECs are not completely removed during wastewater treatments, and as a result, they are discharged into the receiving streams and can end up in soils when the sewage sludge. CECs are discharged into the environment throughout effluents from wastewater treatment plants (WWTPs) that are not designed for their removal, and their impact is of particular relevance to wastewater disposal and re-use in agricultural settings due to CEC uptake and the accumulation in food crops and their consequent diffusion into the food-chain [5].
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