Fate of Pharmaceuticals in a Submerged Membrane Bioreactor Treating Hospital Wastewater

The fate of 12 pharmaceutical pollutants was investigated to understand their removal mechanism during hospital wastewater (HWW) treatment in submerged membrane bioreactor (SMBR). High concentrations of anti-depressant (venlafaxine and desvenlafaxine), analgesic (ibuprofen and hydroxy-ibuprofen), and caffeine were detected in the HWW during the entire study period. The SMBR showed high removal >70% of antibiotics (sulfamethoxazole and clarithromycin), beta-blocker (acebutolol), hormone (estrone), and caffeine via biodegradation. The partial degradation of diclofenac, venlafaxine, and desvenlafaxine in SMBR indicates the growth promoter or agent requirement, which could facilitate the metabolism and co-metabolism of these pharmaceuticals by microorganisms. The study demonstrated that the major removal mechanism of pharmaceuticals in SMBR at optimized treatment conditions was biodegradation for the majority of examined pharmaceuticals. The assessment of SMBR performance at the low temperature of 15 and 10°C resulted in the drop of biodegradation efficiency of SMBR, affecting overall pharmaceuticals removal.

Effect of the Oxidative Phosphorylation Uncoupler Para-Nitrophenol on the Activated Sludge Community Structure and Performance of a Submerged Membrane Bioreactor

In this work, the metabolic uncoupler para-nitrophenol (pNP) was applied to suppress excess sludge production and to investigate its effects on the system’s performance and activated sludge community structure. The COD removal efficiency decreased from 99.0% to 89.5% prior to and after pNP addition, respectively. Application of pNP transiently reduced NH4+-N, NO3−-N and NO2−-N removal efficiencies, suggesting partial inhibition of both nitrifying and denitrifying activity. However, no changes in the relative abundance of the nitrifying bacteria occurred. Phosphorus removal efficiency was sharply reduced after pNP addition, as the consequence of hydrolysis of stored cell reserves. Tetrasphaera, a key polyphosphate accumulating organism, was also affected by the addition of pNP, a fact that highly influenced system’s ability to remove phosphorus. A drastic drop in Soluble Microbial Products (SMP) and Extracellular Polymeric Substances (EPS) was also detected shortly after the introduction of the uncoupler. On the other hand, MBR’s physicochemical parameters were restored to initial values a week after the addition of pNP. Moreover, remarkable changes in beta-diversity were noted after pNP addition. An increase of Bacteroidetes, Gammaproteobacteria and Firmicutes over Actinobacteria and Alphaproteobacteria was also observed after pNP addition.

Determination of modeled costs at sewage treatment plants in the case of different sequences of treatment

Introduction. The article considers the definition of the key components of operating costs at wastewater treatment plants with a capacity of 1 to 100 thousand cubic meters per day by modeling using specialized software. Materials and methods. In the study, two technological cleaning schemes were investigated — the conventional line-up with biological aeration reactor and secondary clarifier and the scheme of biological aeration reactor with submerged membrane bioreactor for sludge separation. The other structures for the two facilities were identical. Since it was important to obtain results that could be used at real facilities, the values of concentrations of major pollutants typical for urban wastewater before treatment, as well as technological parameters of operation, were used as initial data for calculations. Results. As the results of calculations, the values of concentrations of pollutants in wastewater after treatment using both technological schemes and the values of the required volumes for the arrangement of biological treatment facilities and the area occupied by them were obtained and analyzed. Operating costs were considered in terms of electricity costs for the operation of biological treatment facilities and treatment facilities in General, as well as the specific cost of electricity for treatment 1 m3 of wastewater. In addition, the cost of purchasing membrane modules was calculated, which can be classified as operational due their replacement frequency of approximately every 7–10 years. Conclusions. The results of the study showed that application of membrane technologies at the stage of secondary treatment could have a significant potential for the reconstruction of wastewater treatment plants in conditions of increased productivity and limited opportunities for expanding the area.

Study on the Removal of Fluorescent Whitening Agent from Paper-Mill Wastewater Using the Submerged Membrane Bioreactor (SMBR) with Ozone Oxidation Process

In this study, paper-mill wastewater was treated using the Submerged Membrane Bioreactor (SMBR) process. In particular, the ozone oxidation treatment process is applied after SMBR to remove the fluorescent whitening agent, which is a trace pollutant and non-biodegradable. Fluorescent whitening agent concentration was indirectly measured by UV scanning and COD concentration. The concentration of COD before SMBR and ozone oxidation was 449.3 mg/L, and the concentration of treated water was 100.3 mg/ℓ. The COD removal efficiency of paper-mill wastewater through SMBR and the ozone oxidation process was about 77.68%. The optimized amount of ozone was required for the removal of the fluorescent whitening agent after SMBR was 95 mg·O3/ℓ calculated by UV scan results. Additionally, the optimized amount of required ozone to remove COD was calculated to 0.126 mg·COD/mg·O3.