Unpacking the effects of adverse regulatory events: Evidence from pharmaceutical relabeling.

We provide causal evidence that regulation induced product shocks significantly impact aggregate demand and firm performance in pharmaceutical markets. Event study results suggest an average loss between $569 million and $882 million. Affected products lose, on average, $186 million over their remaining effective patent life. This leaves a loss of between $383 million and $696 million attributable to declines in future innovation. Our findings complement research that shows drugs receiving expedited review are more likely to suffer from regulation induced product shocks. Thus, it appears we may be trading off quicker access to drugs today for less innovation tomorrow. Results remain robust to variation across types of relabeling, market sizes, and levels of competition.

Impacts of feed dilution and lower solids retention time on performance of thermal hydrolysis/anaerobic digestion.

The goal of this study was to evaluate using feed dilution/solids retention time (SRT) control to manage potential ammonia inhibition in highly loaded anaerobic digesters after thermal hydrolysis. The study compared three digesters operated at the same target volatile solids (VS) loading rate of 5.5 kg VS/d-m3 , but at different feed concentrations resulting in SRTs of 10, 15, and 18 days. Lowering the feed concentration decreased the digester total ammonia nitrogen concentrations which averaged 1,580, 2,610, and 3,080 mg NH 4 + -N/L for the 10-, 15-, and 18-day digesters. The VS reduction and methane yields were equivalent for the 15- and 18-day digesters and about 4% lower for the 10-day digester. Ammonia inhibition of the 18-day digester occurred early in the study, but the system acclimated over time. Feed dilution reduced the viscosity and the potential for volume expansion due to gas holdup and foaming. PRACTIONER POINTS: Feed dilution reduces digester ammonia concentrations and inhibition potential without sacrificing digester performance at lower SRTs. Feed dilution greatly reduces digester viscosity and associated issues with digester volume expansion due to gas holdup and foaming. Operating at the lower SRT does not impact cake solids after dewatering and substantially decreases polymer demand for conditioning.

Effects of post anaerobic digestion thermal hydrolysis on dewaterability and moisture distribution in digestates.

Organic waste fractions such as sewage sludge, food waste and manure can be stabilized by anaerobic digestion (AD) to produce renewable energy in the form of biogas. Following AD, the digested solid fraction (digestate) is usually dewatered to reduce the volume before transportation. Post-AD treatments such as the Post-AD thermal hydrolysis process (Post-AD THP) have been developed to improve the dewatering, but the mode of action is not well understood. In this study, samples from 32 commercial full-scale plants were used to assess the impact of Post-AD THP on a broad range of raw materials. Maximum dewatered cake solids after Post-AD THP was predicted by thermogravimetric analysis (TGA). Post-AD THP changed the moisture distribution of the samples by increasing the free water fraction. A consistent improvement in predicted dewatered cake solids was achieved across the 32 samples tested, on average increasing the dry solids concentration by 87%. A full-scale trial showed that dewatering Post-AD THP digestate at 80 °C improved dewatered cake solids above the predictions by TGA at 35 °C. In conclusion, dewatered cake solids were significantly improved by Post-AD THP, reducing the volume of dewatered cake for disposal.

Regulation of human cytidine triphosphate synthetase 2 by phosphorylation.

Cytidine triphosphate synthetase (CTPS) is the rate-limiting enzyme in de novo CTP synthesis and is required for the formation of RNA, DNA, and phospholipids. This study determined the kinetic properties of the individual human CTPS isozymes (hCTPS1 and hCTPS2) and regulation through substrate concentration, oligomerization, and phosphorylation. Kinetic analysis demonstrated that both hCTPS1 and hCTPS2 were maximally active at physiological concentrations of ATP, GTP, and glutamine, whereas the K(m) and IC(50) values for the substrate UTP and the product CTP, respectively, were close to their physiological concentrations, indicating that the intracellular concentrations of UTP and CTP may precisely regulate hCTPS activity. Low serum treatment increased hCTPS2 phosphorylation, and five probable phosphorylation sites were identified in the hCTPS2 C-terminal domain. Metabolic labeling of hCTPS2 with [(32)P]H(3)PO(4) demonstrated that Ser(568) and Ser(571) were two major phosphorylation sites, and additional studies demonstrated that Ser(568) was phosphorylated by casein kinase 1 both in vitro and in vivo. Interestingly, mutation of Ser(568) (S568A) but not Ser(571) significantly increased hCTPS2 activity, demonstrating that Ser(568) is a major inhibitory phosphorylation site. The S568A mutation had a greater effect on the glutamine than ammonia-dependent activity, indicating that phosphorylation of this site may influence the glutaminase domain of hCTPS2. Deletion of the C-terminal regulatory domain of hCTPS1 also greatly increased the V(max) of this enzyme. In summary, this is the first study to characterize the kinetic properties of hCTPS1 and hCTPS2 and to identify Ser(568) as a major site of CTPS2 regulation by phosphorylation.

Effect of feeding patterns on the performance of activated sludge systems.

Excessive amounts of monovalent cations are known to cause deterioration in settling and dewatering properties of activated sludge. In this study, variations in the feeding pattern to a sequencing batch reactor (SBR) were evaluated to determine if the feed pattern could influence effluent quality and sludge characteristics under high monovalent cation concentrations. Data showed that deflocculation caused by high concentrations of sodium could be mitigated by using a feed cycle where the influent to the SBR was provided over a period of 1 minute. In contrast, when the feed was provided over 4 hours, deterioration in settling and effluent water quality was observed, as reflected by an increase in effluent suspended solids, effluent chemical oxygen demand, and capillary suction time.

Do alternate bacterial indicators and pathogens increase after centrifuge dewatering of anaerobically digested biosolids?

The objectives of this research were to evaluate the potential for sudden increase and/or regrowth of alternative bacteria as either indicators or pathogens after dewatering of thermophilic and mesophilically digested biosolids. The results showed that, in general, for thermophilic processes, even when a statistically significant (p < 0.05) sudden increase and regrowth occurred for fecal coliforms, Escherichia coli, and Enterococci, it did not occur for Salmonella or Aeromonas. For the mesophilic process evaluated, sudden increase did not occur, but regrowth occurred for fecal coliforms, E. coli, Enterococci, and Salmonella. The results have implications for Class A and B biosolids regulations, as both fecal coliform and Salmonella are part of the regulatory limits. The results also suggest that the public health risks are minimal, as a result of the potential sudden increase and regrowth that may occur.

The effect of digestion and dewatering on sudden increases and regrowth of indicator bacteria after dewatering.

Several investigators have reported higher densities of indicator bacteria after dewatering of anaerobically digested biosolids. The increases appear to occur at two points in the biosolids process: the first, referred to as "sudden increase", occurs immediately after dewatering; the second, "regrowth", occurs during storage over longer periods. The objectives of this study were to examine the effect of digestion and dewatering processes on sudden increase and regrowth of fecal coliform and E. coli. Samples were collected from five thermophilic and five mesophilic digestion processes, with either centrifuge or belt filter press dewatering. Sudden increase typically was observed in the thermophilic processes with centrifuge dewatering and was not observed in the mesophilic processes with either centrifuge or belt filter press dewatering. Regrowth was observed in both thermophilic and mesophilic processes with centrifuge dewatering but not belt filter press dewatering.

Exploring the impact of bulk and substrate physics on hydrolysis rates and biogas yields of anaerobic digesters pretreated with thermal hydrolysis.

This study evaluated the role of bulk and substrate physics on hydrolysis rates and biogas yields in anaerobic digestion (AD) pretreated by thermal hydrolysis (THP). Although THP decreases sludge viscosity, no evidence was found that bulk viscosity impacted the biogas yield or hydrolysis kinetics. In addition, no significant difference between the biogas yields for different total solids concentrations nor floc sizes was detected. However, increased mixing speeds did increase biogas yields. As a result of thermal treatment, the model protein, bovine serum albumin, was harder to degrade in terms of both overall biodegradability and hydrolysis rates when their macrostructures were changed from liquid to gel and to solid structures; the opposite was true for the model polysaccharide, amylopectin. These results demonstrated that hydrolysis in THP-AD systems was impacted mostly by the physical properties of the substrate (gelation) rather than the bulk physical properties within the digester. PRACTITIONER POINTS: Bulk viscosity does not significantly impact hydrolysis efficiency (biogas yield). However, mixing speed impacts hydrolysis beyond biogas holdup effect. Increasing the amount of substrate-microbe collisions through increasing biomass concentration does not have an impact on hydrolysis efficiency or biogas yield. Proteins are harder to degrade when macrostructure changes from liquid to gel/solid as a result of heat treatment. Polysaccharides are easier to degrade when macrostructure changes from liquid to gel/solid as a result of heat treatment. The time required for digesters to reach peak biogas production rates increased with decreasing specific surface available on gel and solid structures.

Impact of anaerobically digested biosolids characteristics and handling conditions on dewatering performance at multiple facilities.

Anaerobically digested biosolids (ABD) characteristics that affect dewatering were assessed at three water resource recovery facilities (WRRF) with different handling practices. Dewatering performance at the three sites corresponded to different levels of soluble chemical oxygen demand (COD), ammonia (NH4 -N), and mono- and divalent cation concentrations in ADB. Capillary suction time (CST) and a modified centrifugal technique were used to determine optimum polymer doses and to assess the impact of handling conditions on dewatering performance. Both techniques indicated that polymer dosing between 15 and 20 kg/dry tonne was optimal for all facilities and that biosolids mixing and pumping did not significantly impact dewaterability. The CST values of anaerobically digested biosolids decreased as temperature increased, but no significant difference was found for either temperature or location of dewatering facilities. Sludge viscosity and rheological properties that vary with temperature appeared to have influenced CST values. Modified centrifugal technique results indicated cake solids were not affected by polymer make-up water or ADB temperature when emulsion polymer was used. This study shows the value of laboratory testing of biosolids under controlled conditions to identify and correct potential problems in full-scale operations. PRACTITIONER POINTS: Capillary suction time and a modified centrifugal technique were used to assess the impact of different process-related and environmental factors on dewatering. Higher concentrations of soluble COD (potentially extracellular polymeric substances - EPS) and low calcium (Ca) in anaerobically digested biosolids align with reduced dewaterability. Cell disruption and break down of floc structures due to storage/mixing and pumping of biosolids did not appear to negatively impact dewatering. Modified centrifugal test results did not provide conclusive evidence of whether dewatering of anaerobically digested biosolids could be significantly impacted by temperature over the range 15-30°C, especially when emulsion polymer is used. This study shows the value of laboratory testing of biosolids under controlled conditions to identify potential problems in the full-scale operations.

Oxide rupture-induced conductivity in liquid metal nanoparticles by laser and thermal sintering.

Metallic inks with superior conductivity and printability are necessary for high-throughput manufacturing of printed electronics. In particular, gallium-based liquid metal inks have shown great potential in creating soft, flexible and stretchable electronics. Despite their metallic composition, as-printed liquid metal nanoparticle films are non-conductive due to the surrounding metal oxide shells which are primarily Ga2O3, a wide-bandgap semiconductor. Hence, these films require a sintering process to recover their conductivity. For conventional solid metallic nanoparticles, thermal and laser processing are two commonly used sintering methods, and the sintering mechanism is well understood. Nevertheless, laser sintering of liquid metal nanoparticles was only recently demonstrated, and to date, the effect of thermal sintering has rarely been investigated. Here, eutectic gallium-indium nanoparticle films are processed separately by laser or thermal sintering in an ambient environment. Laser and thermally sintered films are compared with respect to electrical conductivity, surface morphology and elemental composition, crystallinity and surface composition. Both methods impart thermal energy to the films and generate thermal stress in the particles, resulting in rupture of the gallium oxide shells and achieving electrical conductivity across the film. For laser sintering, extensive oxide rupture allows liquid metal cores to flow out and coalesce into conductive pathways. For thermal sintering, due to less thermal stress and more oxidation, the oxide shells only rupture locally and extensive phase segregation occurs, leading to non-liquid particle films at room temperature. Electrical conductivity is instead attributed to segregated metal layers and gallium oxide which becomes crystalline and conductive at high temperatures. This comprehensive comparison confirms the necessity of oxidation suppression and significant thermal stress via instantaneous laser irradiation to achieve conductive patterns in liquid form.

Role of protein, amino acids, and enzyme activity on odor production from anaerobically digested and dewatered biosolids.

The main objective of this research was to test the hypothesis that bioavailable protein and, more specifically, the sulfur-containing amino acids within the protein, can be degraded by proteolytic enzymes to produce odor-causing compounds--mainly volatile sulfur compounds (VSCs)--during biosolids storage. To achieve these objectives, samples of digester effluent and cake solids were collected at 11 different wastewater treatment plants in North America, and the samples were analyzed for protein and amino acid content and general protein-degrading enzyme activity. At the same time, cake samples were stored using headspace bottles, the concentration of VSCs were measured using gas chromatography, and olfactometry measurements were made by a trained odor panel. The results showed that the bound cake protein content and methionine content was well-correlated with VSC production and the detection threshold measured by the odor panel.

Post-anaerobic digestion thermal hydrolysis of sewage sludge and food waste: Effect on methane yields, dewaterability and solids reduction.

Post-anaerobic digestion (PAD) treatment technologies have been suggested for anaerobic digestion (AD) to improve process efficiency and assure hygenization of organic waste. Because AD reduces the amount of organic waste, PAD can be applied to a much smaller volume of waste compared to pre-digestion treatment, thereby improving efficiency. In this study, dewatered digestate cakes from two different AD plants were thermally hydrolyzed and dewatered, and the liquid fraction was recirculated to a semi-continuous AD reactor. The thermal hydrolysis was more efficient in relation to methane yields and extent of dewaterability for the cake from a plant treating waste activated sludge, than the cake from a plant treating source separated food waste (SSFW). Temperatures above 165 °C yielded the best results. Post-treatment improved volumetric methane yields by 7% and the COD-reduction increased from 68% to 74% in a mesophilic (37 °C) semi-continuous system despite lowering the solid retention time (from 17 to 14 days) compared to a conventional system with pre-treatment of feed substrates at 70 °C. Results from thermogravimetric analysis showed an expected increase in maximum TS content of dewatered digestate cake from 34% up to 46% for the SSFW digestate cake, and from 17% up to 43% in the sludge digestate cake, after the PAD thermal hydrolysis process (PAD-THP). The increased dewatering alone accounts for a reduction in wet mass of cake leaving the plant of 60% in the case of sludge digestate cake. Additionaly, the increased VS-reduction will contribute to further reduce the mass of wet cake.

Reactivation and growth of non-culturable indicator bacteria in anaerobically digested biosolids after centrifuge dewatering.

Recent literature has reported that high concentrations of indicator bacteria such as fecal coliforms (FCs) were measured in anaerobically digested sludges immediately after dewatering even though low concentrations were measured prior to dewatering. This research hypothesized that the indicator bacteria can enter a non-culturable state during digestion, and are reactivated during centrifuge dewatering. Reactivation is defined as restoration of culturability. To examine this hypothesis, a quantitative polymerase chain reaction (qPCR) method was developed to enumerate Escherichia coli, a member of the FC group, during different phases of digestion and dewatering. For thermophilic digestion, the density of E. coli measured by qPCR could be five orders of magnitude greater than the density measured by standard culturing methods (SCMs), which is indicative of non-culturable bacteria. For mesophilic digestion, qPCR enumerated up to about one order of magnitude more E. coli than the SCMs. After centrifuge dewatering, the non-culturable organisms could be reactivated such that they are enumerated by SCMs, and the conditions in the cake allowed rapid growth of FCs and E. coli during cake storage.

Pretreatment of a primary and secondary sludge blend at different thermal hydrolysis temperatures: Impacts on anaerobic digestion, dewatering and filtrate characteristics.

A study was performed to evaluate the effect of thermal hydrolysis pretreatment (THP) temperature on subsequent digestion performance and operation, as well as downstream parameters such as dewatering and cake quality. A blend of primary and secondary solids from the Blue Plains treatment plant in Washington, DC was dewatered to about 16% total solids (TS), and thermally hydrolyzed at five different temperatures 130, 140, 150, 160, 170 °C. The thermally hydrolyzed solids were then fed to five separate, 10 L laboratory digesters using the same feed concentration, 10.5% TS and a solids retention time (SRT) of 15 days. The digesters were operated over a six month period to achieve steady state conditions. The higher thermal hydrolysis temperatures generally improved the solids reduction and methane yields by about 5-6% over the temperature range. The increased temperature reduced viscosity of the solids and increased the cake solids after dewatering. The dissolved organic nitrogen and UV absorbance generally increased at the higher THP temperatures. Overall, operating at a higher temperature improved performance with a tradeoff of higher dissolved organic nitrogen and UV adsorbing materials in the return liquor.

DNA extraction and Escherichia coli quantification of anaerobically digested biosolids using the competitive touchdown PCR method.

Accurate enumeration of indicator organisms such as Escherichia coli is important for assessing the safety of water and wastewater samples. Recent research has shown that E. coli can enter a viable but non-culturable state; therefore, traditional cultivation methods could potentially underestimate the quantities of the organisms. The goals of the research were to develop and verify a DNA extraction protocol and a quantitative polymerase chained reaction (PCR) method for E. coli enumeration in digested biosolids. A solvent-based DNA extraction protocol with extensive cell lysis recovered approximately 78-84% of spiked DNA. In comparison, a commercial kit only recovered 28-42% of DNA, likely from inefficient cell lysis. The developed competitive touchdown PCR (cPCR) method for E. coli enumeration was comparable to both real-time PCR (rt-PCR) and cultivation methods with sensitivity of approximately 50,000-500,000 E. coli per gram dry solids (DS), which is suitable for Class B biosolids monitoring in the US and "conventional" biosolids in the European Union. The cPCR protocol provides a less expensive alternative than the rt-PCR as a culturing independent method for enumerating E. coli.

Cycling of volatile organic sulfur compounds in anaerobically digested biosolids and its implications for odors.

The objectives of this research were to elucidate the mechanisms for production and degradation of volatile organic sulfur compounds (VOSCs), key odor causing compounds produced by biosolids. These compounds included methanethiol (MT), dimethyl sulfide (DMS), and dimethyl disulfide (DMDS). A series of experiments were used to probe various pathways hypothesized to produce and degrade these VOSCs. The production of MT was found to mainly occur from degradation of methionine and the methylation of hydrogen sulfide. DMS was formed through the methylation of MT. DMDS was formed by MT oxidation. All three of the VOSCs were readily degraded by methanogens and a cyclic pathway was proposed to describe the production and degradation of VOSCs. The research demonstrated that the main source of VOSCs was the biodegradation of protein within the biosolids and the results provided a framework for understanding the production of odor from anaerobically digested sludges before and after dewatering.

Generation pattern of sulfur containing gases from anaerobically digested sludge cakes.

Eleven dewatered sludge cakes collected from anaerobic digesters at different treatment plants were evaluated for the amount, type, and pattern of odorous gas production. All but one of the sludge cakes were from mesophilic anaerobic digesters. One was from a thermophilic digester. The pattern and quantities of sulfur gases were found to be unique for each of the samples with regard to the products produced, magnitude, and subsequent decline. The main odor-causing chemicals were volatile sulfur compounds, which included hydrogen sulfide, methanethiol, and dimethyl sulfide. Volatile sulfur compound production peaked in 3 to 8 days and then declined. The decline was a result of conversion of organic sulfur compounds to sulfide. In one side-by-side test, a high-solids centrifuge cake generated more odorous compounds than the low-solids centrifuge cake. The data show that anaerobic digestion does not eliminate the odor potential of anaerobically digested dewatered cakes.

Examination of three theories for mechanisms of cation-induced bioflocculation.

Research from different studies has been used to support three different theories pertaining to the role of cations in bioflocculation. These theories are the alginate theory. Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory, and divalent cation bridging (DCB) theory. The objectives of this research were to examine the role of cations in bioflocculation to determine which theory, if any, best describes cation induced bioflocculation. Experiments were performed using laboratory scale activated sludge systems with bactopeptone as a feed. The feed was supplemented with either calcium, magnesium, or sodium at increasing concentrations. Floc properties were analyzed in each reactor during steady state periods. The addition of calcium or magnesium to the feed individually resulted in improvements in SVI, CST, SRF, cake solids and floc strength and each of these divalent cations produced similar results. The addition of sodium to the feed resulted in a deterioration in floc properties relative to a control reactor. Analysis of these results suggest that the DCB theory best explains the role of cations. The discrepancies between different studies were examined and are thought to be a result of different experimental procedures in different studies and in particular the use of short-term batch tests versus continuous flow reactor studies. In addition, the implications of DCB theory suggests that activated sludge systems should attempt to lower the ratio of monovalent to divalent cations to improve floc properties and treatment performance.

Case study I: application of the divalent cation bridging theory to improve biofloc properties and industrial activated sludge system performance-direct addition of divalent cations.

The objectives of this study were to examine the application of the divalent cation bridging theory (DCBT) to improve settling, dewatering, and effluent quality in pilot-scale reactors and a full-scale system treating an industrial wastewater. This was accomplished by lowering the monovalent-to-divalent (M/D) cation ratio by direct divalent cation addition. Research has shown that the M/D ratio is a potential indicator for settling and dewatering problems at wastewater treatment plants, and M/D ratios above 2 have been associated with poor settling, dewatering, and effluent quality. The M/D ratio of the wastewater in this study ranged from 6 to 20. The cations studied were calcium and magnesium. Results showed that the addition of calcium improved floc properties compared to control reactors with no calcium addition. The reductions in sludge volume index, effluent chemical oxygen demand (COD), and effluent total suspended solids (TSS) were approximately 35, 34, and 55%, respectively, when the M/D ratio was decreased to approximately 2:1. In addition, the cake solids from a belt filter press simulator increased by 72% and the optimum polymer dose required for conditioning was reduced by 70% in the reactor fed the highest calcium concentration when compared to control reactors with no calcium addition. The addition of calcium also decreased the negative effect of high filamentous organism numbers. In general, the addition of magnesium (Mg2+) had similar effects on effluent quality and dewatering properties, although some differences were measured. A full-scale test using calcium addition was performed. Measurements of effluent quality and floc properties were performed before, during, and after the calcium (Ca2+) addition period. The average M/D ratio during these periods was 6.2, 4.6, and 14.0, respectively. The addition of Ca2+ decreased the effluent five-day biochemical oxygen demand, effluent TSS, and effluent COD. The increased Ca2+ concentration also improved dewatering measured by a decrease in specific resistance to filtration and capillary suction time. Overall, the addition of divalent cations to the pilot- and full-scale activated sludge systems improved floc properties and the data fit well with the DCBT.

Case study II: application of the divalent cation bridging theory to improve biofloc properties and industrial activated sludge system performance-using alternatives to sodium-based chemicals.

The objective of this study was to investigate the application of the divalent cation bridging theory (DCBT) as a tool in the chemical selection process at an activated sludge plant to improve settling, dewatering, and effluent quality. According to the DCBT, to achieve improvements, the goal of chemical selection should be to reduce the ratio of monovalent-to-divalent (M/D) cations. A study was conducted to determine the effect of using magnesium hydroxide [Mg(OH)2] as an alternative to sodium hydroxide (NaOH) at a full-scale industrial wastewater treatment plant. Floc properties and treatment plant performance were measured for approximately one year during two periods of NaOH addition and Mg(OH)2 addition. A cost analysis of plant operation during NaOH and Mg(OH)2 use was also performed. During NaOH addition, the M/D ratio was 48, while, during Mg(OH)2 addition, this ratio was reduced to an average of approximately 0.1. During the Mg(OH)2 addition period, the sludge volume index, effluent total suspended solids, and effluent chemical oxygen demand were reduced by approximately 63, 31, and 50%, respectively, compared to the NaOH addition period. The alum and polymer dose used for clarification was reduced by approximately 50 and 60%, respectively, during Mg(OH)2 addition. The dewatering properties of the activated sludge improved dewatering as measured by decreased capillary suction time and specific resistance to filtration (SRF), along with an increase in cake solids from the SRF test. This corresponded to a reduction in the volume of solids thickened by centrifuges at the treatment plant, which reduced the disposal costs of solids. Considering the costs for chemicals and solids disposal, the annual cost of using Mg(OH)2 was approximately 30,000 dollars to 115,000 dollars less than using NaOH, depending on the pricing of NaOH. The results of this study confirm that the DCBT is a useful tool for assessing chemical-addition strategies and their potential effect on activated sludge performance.