Fate of selected pharmaceutically active compounds in the integrated fixed film activated sludge process.

The potential for integrated fixed film activated sludge (IFAS) processes to achieve enhanced transformation of pharmaceuticals relative to conventional activated sludge (CAS) processes was assessed. Previous studies have focused on direct comparisons of parallel reactors with and without fixed film carriers and little information is available on the impacts of how varying operating parameters impact the differences in observed pharmaceutical compound (PC) transformation capabilities between CAS reactors and those equipped with both an activated sludge (AS) and fixed film carriers. The testing was carried out using bench scale sequencing batch reactors fed with authentic municipal wastewater and operated at selected combinations of temperature and solids retention time (SRT). PC transformation efficiencies were assessed in a 22 factorial design that employed the IFAS and CAS processes, operated in parallel under identical process conditions. Nitrification rate testing that was conducted to obtain insight into the biomass activity demonstrated that IFAS consistently had improved nitrification kinetics despite lower mixed liquor volatile suspended solids levels thereby demonstrating the contribution of the biofilm to nitrification. Increased transformation of atenolol (ATEN; ranging from 10-60%) and trimethoprim (TRIM; ranging from 30-50%) in the IFAS equipped reactors relative to their respective activated sludge (AS) controls was observed under all experimental conditions. Negligible transformation of carbamazepine was observed in both reactors under all conditions investigated. More than 99% of acetaminophen was transformed in both configurations under all conditions. There was no correspondence between nitrification activity and TRIM removal in the control AS while conditions that stimulated nitrification in the control AS also resulted in enhanced removal of ATEN. The results of this study indicate that the integration of biofilms in AS processes enhances transformation of some PCs.

Impact of activated sludge process configuration on removal of micropollutants and estrogenicity.

The efficacy of three different wastewater treatment configurations, conventional activated sludge (CAS), nitrifying activated sludge (NAS) and biological nutrient removal (BNR) for removal of selected micropollutants from authentic wastewater was investigated. The processes were also characterized based on their proficiency to reduce the estrogenic activity of the influent wastewater using the in vitro recombinant yeast assay. The removal efficiency of trimethoprim improved with the complexity of the three treatment process configurations. Ibuprofen, androstendione, sulfamethoxazole, nonyl-phenol, estrone and bisphenol-A had moderate to high removals (>65%) while carbamazepine and meprobamate remained recalcitrant in the three treatment process configurations. The removal of gemfibrozil was better in the NAS than in BNR and CAS treatment configurations. The yeast estrogen screen (YES) assay analyses showed an improvement in estrogenicity removal in the BNR and NAS treatment configurations as compared to the CAS treatment configuration. Comparing the estrogenic responses from the three treatment configurations, the removal efficiencies followed the order of BNR=NAS>CAS and all were greater than 81%.

Modifying ADM1 to include formation and emission of odourants.

A mathematical model that is based upon the ADM1 structure has been developed to describe the formation and emission of odourous compounds in anaerobic sludge digestion. Special emphasis is given to the general mechanisms for the formation of common odorous sulfur compounds that are found in anaerobic digesters: methyl mercaptan, dimethyl sulfide and hydrogen sulfide, as well as volatile fatty acids and ammonia. The model includes multiple-reaction stoichiometry, microbial growth kinetics and conventional material balances for an ideally mixed reactor. Simulations that were performed with the model revealed that changes in common operational parameters such as temperature, HRT and sludge metal content can dramatically impact upon the gas phase concentrations of odourants. Additional research is required to reduce uncertainty in the model formulation.

Effect of bubble-induced surface turbulence on gas-liquid mass transfer in diffused aeration systems.

Models that predict volatilization of organic compounds from wastewater treatment basins may underestimate emission rates if the surfaces are considered as quiescent. In reality, the water surface may be agitated by subsurface aeration, increasing mass transfer across the tank surface air-water interface. This study investigated the effect of turbulence, induced by diffused bubble aeration, on mass transfer at the water surface of a pilot aeration basin. The mass transfer of ammonia from an enclosed headspace over the basin to acidified water was measured when different diffuser types and airflow rates were applied. Oxygen-transfer tests were conducted immediately following each ammonia-transfer test. Increasing airflow rates through fine- and coarse-bubble diffusers had a significant effect on the ammonia mass-transfer rate. Experimental mass-transfer parameters (K(L)a's) for surface volatilization derived with aeration present were up to 48% higher than the K(L)a values for quiescent conditions over the range of conditions tested. No effect of diffuser type on ammonia transfer could be determined. The study results infer an effect on oxygen transfer into the water at the surface and potential transfer of volatile organic compounds, if present, from the water. The results of the ammonia mass-transfer experiments suggest that adjustments to the existing mass transfer correlations for surface volatilization from aeration basins may be in order. Such adjustments will have the greatest effect on predictions for the less volatile compounds, under conditions of low airflow rates.

Assessment of the removal of estrogenicity in biological nutrient removal wastewater treatment processes.

The removal of estrogenicity in a University of Cape Town-biological nutrient removal (UCT-BNR) wastewater treatment process was investigated using pilot and bench scale systems, batch experiments and mathematical modeling. In the pilot BNR process, 96 ± 5% of the estrogenicity exerted by the influent wastewater was removed by the treatment process. The degradation efficiencies in the anaerobic, anoxic and aerobic zones of the pilot BNR bioreactor were 11 ± 9%, 18 ± 2% and 93 ± 10%, respectively. In order to further understand the performance of the BNR process in the removal of estrogenicity from wastewater, a bench scale BNR process was operated with synthetic wastewater dosed with E1 and E2. The removal of estrogenicity in the bench scale system (95 ± 5%) was comparable to the pilot BNR process and the degradation efficiencies were estimated to be 8 ± 0.8%, 38 ± 4% and 85 ± 22% in the anaerobic, anoxic and aerobic zones, respectively. A biotransformation model developed to predict the fate of E1 and E2 in batch tests using the sludge from the BNR process was calibrated using the data from the experiments. The biotransformation rate constants for the transformation of E2 to E1 were estimated as 71 ± 1.5, 31 ± 3.3 and 1 ± 0.9 Lg COD(-1)d(-1) for the aerobic, anoxic and anaerobic batch tests, respectively, while the corresponding biotransformation rate constants for the transformation of E1 were estimated to be 7.3 ± 1.0, 3 ± 2.0, and 0.85 ± 0.6 L·g COD(-1)d(-1). A steady state mass balance model formulated to describe the interactions between E2 and E1 in BNR activated sludge reasonably described the fate of E1 and E2 in the BNR process.

Distribution of selected antiandrogens and pharmaceuticals in a highly impacted watershed.

Endocrine disruption and high occurrences of intersex have been observed in wild fish associated with municipal wastewater treatment plant (WWTP) effluents in urbanized reaches of rivers around the globe. These reproductive effects have often been attributed to the presence of estrogen receptor agonists in effluents. However, recent studies have isolated a number of androgen receptor antagonists (antiandrogens) that may also contribute to the endocrine disruption observed at sites that are influenced by WWTP outfalls. This study aimed to characterize the spatial and temporal distribution of antiandrogenic personal care products (triclosan, chlorophene, dichlorophene, oxybenzone, 1-naphthol, and 2-naphthol), along with a herbicide (atrazine) and representative pharmaceuticals (carbamazepine, ibuprofen, naproxen, and venlafaxine) in the Grand River watershed in southern Ontario. Surface water sampling of 30 sites associated with six municipal WWTP outfalls was conducted during a summer low flow. Monthly samples were also collected immediately upstream and downstream of a major WWTP from August to November 2012. Atrazine was consistently found in all surface water sampling locations. Many of the target pharmaceuticals and triclosan were detected in WWTP effluents, especially those that did not nitrify. Under low flow conditions, the concentrations of triclosan and several pharmaceuticals increased directly downstream of the WWTPs then decreased rapidly with distance downstream. Chlorophene was either found at trace levels or below detection limits in the effluents while dichlorophene, oxybenzone, 1-naphthol, and 2-naphthol were not detected in any samples. Chlorophene was detected in surface water during the low flow summer period and once during the monthly sampling from August to November. However, the primary source of chlorophene did not appear to be associated with WWTP effluent. This study documents the spatial and temporal occurrence of several antiandrogens and pharmaceuticals in a highly impacted Canadian watershed. It supports previous observations that there is a diversity of contaminants in wastewater effluents and other sources that have the potential to alter endocrine function in wild fish.

Spontaneous pneumoventriculogram following radiation of a pituitary adenoma.

Three years after radiation therapy for an intrasellar tumor, a 42-year-old housewife presented with headache, lethargy, and remarkable plain skull roentgenograms, in which dilated lateral and third ventricles were filled with air. Air apparently had entered the cranium through the sphenoid sinus and eroded sellar floor, extending directly through intrasellar remnants of the chromophobe adenoma and into the floor of the third ventricle. Frontal exploration showed an empty sella turcica and no residual tumor. She made an excellent recovery and has done well for 5 years after operative closure of the defect.

An evaluation of solid phase microextraction for analysis of odorant emissions from stored biosolids cake.

Odors are a common occurrence at wastewater treatment plants, biosolids processing facilities and biosolids recycling locations. Accurate, objective measurement techniques are needed to monitor emissions, to develop new waste handling procedures and to reduce the production of the volatile gases. The objective of this study was to evaluate the use of solid phase microextraction for measuring common odorants that are found in biosolids facilities. The odorants were collected and concentrated by solid phase microextraction (SPME) and then quantified by gas chromatography with detection by mass spectrometry. A 75-microm Carboxen-Polydimethylsiloxane coating was used for the analysis of trimethylamine, dimethyl sulfide, dimethyl disulfide and methyl mercaptan. Gaseous standards were generated for individual compounds and for dry and wet mixture from permeation apparatus. The differences in sensitivity between fibers, the competition between analytes and water vapor for the active sites on the fiber and the lack of production of artifacts make SPME suited for qualitative analysis and enables quick screening for the identification of compounds with adverse organoleptic characteristics.

A tracer study of headspace ventilation in a collector sewer.

A field-scale tracer test was conducted to evaluate in-situ ventilation rates in a major collector sewer. The sewer under study was approximately 11 km long and ranged from 0.61 to 2.1 m in diameter. For the purposes of the tracer testing, the collector was divided into four reaches, each of which was tested individually. The tracer test involved injecting a measured volume of CO gas into a manhole over a short time period. CO concentrations were then measured in the collector headspace at selected manholes along the length of the reach. The technique employed successfully measured average headspace velocities over extended lengths of the collector. In a section that had a relatively stagnant headspace, approximately 1.1 km of sewer could be evaluated, with substantial tracer loss attributed to losses to manholes. In a section of the sewer with elevated headspace velocities, a section approximately 7.0 km long was successfully tested with one injection of tracer gas. The velocities observed in the collector varied substantially with time and location in the collector. The lowest velocities measured were in the upstream sections, with a minimum observed value of 3.8 m/min. The highest velocities were observed in the downstream sections, with a maximum value of 31.5 m/min. The presence of a substantial drop structure appeared to reduce the headspace velocity in the upstream reach. In general, there was an increasing trend in gas-phase flows with distance along the length of the collector. Flows at the discharge end of the collector were almost 2 orders of magnitude greater than those at the beginning.

Simulation of the fate of selected pharmaceuticals and personal care products in a highly impacted reach of a Canadian watershed.

Municipal wastewater treatment plants (WWTPs) dispose of numerous trace organic contaminants in the receiving waters that can impact biological function in aquatic organisms. However, the complex nature of WWTP effluent mixtures and a wide variety of potential mechanisms that can alter physiological and reproductive development of aquatic organisms make it difficult to assess the linkages and severity of the effects associated with trace organic contaminants. This paper describes a surface water quality modeling exercise that was performed to understand the relevant contaminant fate and transport processes necessary to accurately predict the concentrations of trace organic compounds present in the aquatic environment. The target compounds modeled include a known antiandrogenic personal care product (triclosan) and selected pharmaceuticals (venlafaxine, naproxen, and carbamazepine). The WASP 7.5 model was adapted and calibrated to reflect approximately ten kilometers of reach of the Grand River watershed that is highly influenced by a major urban WWTP. Simulation of the fate and transport of the target compounds revealed that flow-driven transport processes (advection and dispersion) greatly influenced the behavior of the target contaminants in the aquatic environment. However, fate mechanisms such as photolysis and biodegradation can play an important role in the attenuation of some compounds. The exception was carbamazepine where it was shown to act as a conservative tracer compound for wastewater specific contaminants in the water phase. The calibrated water quality model can now be employed in a number of future applications. Prediction of fate and transport of other trace organic contaminants across the watershed and assessment of the performance of WWTP infrastructure upgrades in the removal of these compounds are just a few examples.

Impact of activated sludge configuration and operating conditions on in vitro and in vivo responses and trace organic compound removal.

This study tested municipal sewage effluents generated at the pilot scale using conventional activated sludge (CAS), nitrifying activated sludge (CAS-N) and biological nutrient removal (BNR) in terms of the removal of trace organic compounds (TrOCs) and final effluent quality as indicated by yeast estrogenicity screening (YES), short term zebrafish reproduction and fathead minnow life-cycle tests. Under cold weather conditions (extended SRTs), the BNR configuration reduced the concentrations of the largest number of TrOCs while under warm weather conditions (reduced SRTs) the CAS-N was most effective. By comparison, YES test results indicated statistically lower responses in the BNR effluent in the warm weather tests and no difference between the effluents of CAS-N and BNR in the cold weather tests. Short term tests with adult zebrafish revealed no impact of the BNR and CAS-N effluents on egg production. By contrast egg production and gene expression in the CAS-exposed zebrafish were substantially less than that of control exposures and were similar to that of exposures to ammonia at similar concentrations as the CAS exposures. In fathead minnow life-cycle tests, exposures to CAS effluent (70-50% v/v) resulted in considerable mortality, reduced growth and reduced egg production that was likely due to the elevated ammonia concentrations. The CAS-N effluent (100% v/v) also resulted in some mortality and reduced growth and egg production in the fathead minnows. By contrast, the BNR effluent (100% v/v) had no effect on mortality, growth or egg production. The results suggest that enhancements to wastewater treatment plants that are associated with improved nitrogen removal can result in enhanced removal of TrOCs and can reduce the harmful effects of the effluents on aquatic biota.

Impact of concentration, temperature, and pH on inactivation of Salmonella spp. by volatile fatty acids in anaerobic digestion.

It is known that the presence of volatile fatty acids may play a role in the inactivation of pathogens for systems that employ an acid phase reactor. This study was conducted to investigate the influence of volatile fatty acids on the inactivation of Salmonella spp. over a range of digestion temperatures. In this study, digesters that were treating municipal wastewater treatment plant sludges were operated at temperatures that ranged from 35 to 49 degrees C and had a solids residence time of 15 days. Samples collected from the effluent of the digesters were dosed with solutions containing acetic, propionic, and butyric acids alone and in mixtures, and the dosed effluents were analyzed for Salmonella spp. over time. In the first round of testing, the digester effluents were dosed with individual organic acids and also a mixture containing all three volatile fatty acids over a range of concentrations from 750 to 6000 mg/L, and the pH of the samples was fixed at a value of 5.5. In the second round of testing, the sample sludges were spiked with a fixed amount of organic acid mixture, and the pH was varied from 4.5 to 7.5. The reduction of Salmonella spp. in digester effluents, when dosed with volatile organic acids, was found to depend on pH, temperature, the chain length of the acids, and the concentration and composition of the acids present. Increases in temperature appeared to increase the inhibitory effects of the volatile organic acids. At mesophilic temperatures, acidic pHs resulted in a greater inhibition of Salmonella spp.; whereas at higher temperatures neutral pHs were found to be more inhibitory. The results suggest that acid phase digesters that operate at elevated temperatures and low pH can achieve substantial reduction of Salmonella spp.

A proposed transient model for cometabolism in biofilm systems.

A dynamic model was developed to describe the behaviour of primary and secondary substrates in a biofilm reactor. The model incorporates structured kinetics to describe the generation and consumption of reducing power in the catabolic and respiratory subsystems, respectively. Secondary substrate transformation through oxygenolytic or reductive mechanisms can be modelled under either single or dual limitation of the electron donor and electron acceptor substrates. An example simulation of a theoretical biofilm system was performed.