Molecular Characterization of Estrogen Receptor Agonists during Sewage Treatment Processes Using Effect-Directed Analysis Combined with High-Resolution Full-Scan Screening.

Endocrine-disrupting potential was evaluated during the sewage treatment process using in vitro bioassays. Aryl hydrocarbon receptor (AhR)-, androgen receptor (AR)-, glucocorticoid receptor (GR)-, and estrogen receptor (ER)-mediated activities were assessed over five steps of the treatment process. Bioassays of organic extracts showed that AhR, AR, and GR potencies tended to decrease through the sewage treatment process, whereas ER potencies did not significantly decrease. Bioassays on reverse-phase high-performance liquid chromatography fractions showed that F5 (log KOW 2.5-3.0) had great ER potencies. Full-scan screening of these fractions detected two novel ER agonists, arenobufagin and loratadine, which are used pharmaceuticals. These compounds accounted for 3.3-25% of the total ER potencies and 4% of the ER potencies in the final effluent. The well-known ER agonists, estrone and 17ß-estradiol, accounted for 60 and 17% of the ER potencies in F5 of the influent and primary treatment, respectively. Fourier transform ion cyclotron resonance mass spectrometry analysis showed that various molecules were generated during the treatment process, especially CHO and CHOS (C: carbon, H: hydrogen, O: oxygen, and S: sulfur). This study documented that widely used pharmaceuticals are introduced into the aquatic environments without being removed during the sewage treatment process.

Design, Operation and Optimization of Constructed Wetland for Removal of Pollutant.

Constructed wetlands (CWs) are affordable and reliable green technologies for the treatment of various types of wastewater. Compared to conventional treatment systems, CWs offer an environmentally friendly approach, are low cost, have fewer operational and maintenance requirements, and have a high potential for being applied in developing countries, particularly in small rural communities. However, the sustainable management and successful application of these systems remain a challenge. Therefore, after briefly providing basic information on wetlands and summarizing the classification and use of current CWs, this study aims to provide and inspire sustainable solutions for the performance and application of CWs by giving a comprehensive review of CWs' application and the recent development of their sustainable design, operation, and optimization for wastewater treatment. To accomplish this objective, thee design and management parameters of CWs, including macrophyte species, media types, water level, hydraulic retention time (HRT), and hydraulic loading rate (HLR), are discussed. Besides these, future research on improving the stability and sustainability of CWs are highlighted. This article provides a tool for researchers and decision-makers for using CWs to treat wastewater in a particular area. This paper presents an aid for informed analysis, decision-making, and communication. The review indicates that major advances in the design, operation, and optimization of CWs have greatly increased contaminant removal efficiencies, and the sustainable application of this treatment system has also been improved.

Quantification, removal and potential ecological risk of emerging contaminants in different organic loads of swine wastewater treated by integrated biological reactors.

This study aims to evaluate the dynamics and their ecological risks for aquatic species of lipid regulator, nervous stimulant, anti-inflammatory and endocrine disrupters in an upflow anaerobic sludge blanket (UASB), submerged aerated biological filters (SABF) and horizontal subsurface flow constructed wetland (HSSF-CW) reactors that treat swine wastewater. Four organic loads of swine wastewater (SW) were used according to changing the chemical oxygen demand. 13 contaminants were quantified, standing out the endocrine disruptors, lipid regulator and anti-inflammatory. In phase III, 8318.4 ng L-1 of 4-ocylphenol was found at the influent of the UASB reactor and removal from 1877.1 to 13.7 ng L-1 in the bisphenol A system. With the maximum organic load, there was a reduction among all the treatment units, with concentrations between 1877.1 and 13.7 ng L-1 of bisphenol A and had naproxen removal of 94.5% and 2,7 ng L-1 after treating phases II and III. It was found that 24.6% of the contaminants presented a high ecological risk, with maximum values of 27.4 (4-nonylphenol, phase II), 24.6 and 5.9 (17ß-estradiol, phase IV and I, respectively), 13.4 (4-ocylphenol, phase III) and 4.4 (estrone, phase IV) in the influent system. The reduction of ecological risk potentials was optimized by SABF and HSSF-CW. The effect oxygen availability and microbiological activities optimized the reduction of ecological risks on zebrafish (Danio rerio) and cnidarian (Hydra attenuata) species, moreover, the reduction of mass flows and ecological risks of the emerging contaminants are associated with the use of biological reactors in series and organic stabilizations.

Biological treatment of coke plant effluents: from a microbiological perspective.

During coke production, large volume of effluent is generated, which has a very complex chemical composition and contains several toxic and carcinogenic substances, mainly aromatic compounds, cyanide, thiocyanate and ammonium. The composition of these high-strength effluents is very diverse and depends on the quality of coals used and the operating and technological parameters of coke ovens. In general, after initial physicochemical treatment, biological purification steps are applied in activated sludge bioreactors. This review summarizes the current knowledge on the anaerobic and aerobic transformation processes and describes key microorganisms, such as phenol- and thiocyanate-degrading, floc-forming, nitrifying and denitrifying bacteria, which contribute to the removal of pollutants from coke plant effluents. Providing the theoretical basis for technical issues (in this case the microbiology of coke plant effluent treatment) aids the optimization of existing technologies and the design of new management techniques.

Sugar beet industry process wastewater treatment using electrochemical methods and optimization of parameters using response surface methodology.

Sugar production is a water intensive process that produces a large amount of wastewaters with high concentration of chemical oxygen demand (COD), mostly consists of organic carbon compounds. Conventional treatment methods are limited to provide the necessary treatment of effluent COD to meet the regulatory limits prior to discharge. The treatment performance of electrooxidation (EO) and electrochemical peroxidation (ECP) for organic removal were investigated in a laboratory scale study. The experimental conditions were optimized for both EO and ECP using Box-Behnken Design (BBD) and the models provided highly significant quadratic models for both treatment methods. The effects of pH, H2O2 dosage, current density, and operation time were investigated using BBD. The results showed that EO could remove 75% of organics at optimum conditions of pH 5.3; current density of 48.5 mA cm-2; and operation time of 393 min. The predicted values were in reasonable agreement with measured values. ECP could remove total and soluble COD and total and dissolved organic carbon by 65, 64, 66, and 63%, respectively at optimum conditions of H2O2 dosage of 21 mL L-1; current density of 48 mA cm-2; and operation time of 361 min. The methods were compared based on removal efficiency and energy consumption during operation.

Comparative study on treatment of methylene blue dye wastewater by different internal electrolysis systems and COD removal kinetics, thermodynamics and mechanism.

In this study, Fe/Cu, Fe/Al/Cu, Fe/Cu/C and Fe/Al/Cu/C internal electrolysis systems (IESs) were constructed and used to treat methylene blue dye (MB) wastewater. The effects of filler mass ratio, filler dosage, solution pH, reaction time and reaction temperature on COD removal were discussed, while the kinetics, thermodynamics and mechanism of COD removal were also investigated. The results showed that when the COD removal rates were basically the same, the reaction times of Fe/Al/Cu, Fe/Cu/C and Fe/Al/Cu/C IESs were shorter, and the filler dosages were lower. For the four systems, the appropriate pH was around 5, while the suitable reaction temperature was in the range of 20-25 °C. The COD removals of these four IESs were generally greater than 90%. The COD removal processes of the four systems could be better described by the improved pseudo-second-kinetic model, and the liquid film diffusion was the rate-controlling step. Moreover, the COD removal was a spontaneous and endothermic process. MB was degraded into inorganic substances in four steps. In addition, the FTIR characterization of the fillers before and after reaction suggests the four IESs have good stability.

Electro-Fenton with peroxi-coagulation as a feasible pre-treatment for high-strength refractory coke plant wastewater: Parameters optimization, removal behavior and kinetics analysis.

Electro-Fenton (EF) with peroxi-coagulation (PC) as an emerging electro-chemical advanced oxidation method has been extensively applied to treat refractory wastewater. However, the studies on the pretreatment of the raw coke plant wastewater by EF process were still lacking. In this study, a lab-scale EF system (Fe as anode and graphite as cathode) achieved the highest COD removal of 69.2% based on the preliminary experiments. The process parameters and corresponding COD removal performance were further optimized using response surface methodology (RSM) combined with Box-Behnken experimental design (BBD). The optimal conditions were obtained as: 3.2 mA cm-2 of current density, 2 h of the reaction time and 2.6 of the initial pH value, with the COD removal reaching 70.0%. Fourier infrared (FTIR), fluorescence excitation-emmission matrix (EEM) and gas chromatography-mass spectrometry (GC-MS) also revealed the degradation behaviors of dissolved organic matters (DOMs) by characterizing their structures and compositions before and after EF pretreatment, thus greatly improving the biodegradability of the wastewater. Moreover, the EF process for COD removal well followed third-order kinetics model. These findings give helpful guidance to design, optimize and control the EF process as a favourable pretreatment for actual refractory coking wastewater in practice.

Recommendations to derive quality standards for chemical pollutants in reclaimed water intended for reuse in agricultural irrigation.

The reuse of treated municipal wastewater (herein referred to as reclaimed water) in agricultural irrigation (RWAI) as a means to alleviate water scarcity is gaining increasing policy attention, particularly in areas where water demand mitigation measures have proved insufficient. However, reclaimed water reuse in practice is lagging behind policy ambition, with <2.5% of it reused in a European context. A key barrier identified as limiting its full valorisation is concern over its impact on human and environmental health. To address this concern, and to meet further objectives including achieving parity between current reclaimed water reuse guidelines operational in various Member States, the European Commission has proposed a regulation which identifies minimum quality requirements (MQR) for a range of microbiological and physico-chemical parameters but the inclusion of compounds of emerging concern (CECs) in terms of the determination of quality standards (QS) is missing. This paper reviews the existing pertinent EU legislation in terms of identifying the need for CEC QS for RWAI, considering the scope and remit of on-going pan-European chemicals prioritisation schemes. It also evaluates opportunities to link in with the existing EQS derivation methodology under the EU WFD to address all protection targets in the environmental compartments exposed via potential pathways of RWAI. Finally, it identifies the main data gaps and research needs for terrestrial ecosystems, the removal efficiency of CECs by WWTPs and transformation products generated during the wastewater reuse cycle.

Specific affinity and relative abundance of methanogens in acclimated anaerobic sludge treating low-strength wastewater.

Kinetic parameters affecting effluent water quality including half saturation constant (Ks), maximum specific growth rate (µmax), and specific affinity ([Formula: see text], defined as µmax/Ks) were investigated using three types of anaerobic sludge (raw anaerobic digestion sludge referred to as unacclimated sludge, unacclimated sludge after endogenous decay, and sludge acclimated to low-strength wastewater in an anaerobic membrane bioreactor (AnMBR) for 360 days). Long-term acclimation to low-strength wastewater resulted in sludge with high specific affinity (1.6 × 10-3 L/mg COD/day for acclimated sludge compared to 4.1 × 10-4 L/mg COD/day for unacclimated sludge). The µmax values for unacclimated sludge and acclimated sludge were 0.08 and 0.07 day-1, respectively. The Ks values for unacclimated sludge and acclimated sludge were 194 ± 81 mg COD/L and 45 ± 13 mg COD/L, respectively. Although the Ks of unacclimated sludge after endogenous decay increased to 772 ± 74 mg COD/L, µmax increased to 0.35 day-1 as well, resulting in no statistically significant difference of [Formula: see text] between the two types of unacclimated sludge. Overall, [Formula: see text] is a better indicator than µmax or Ks alone for determining effluent water quality, as effluent substrate concentration is approximately inversely proportional to the specific affinity. 16S rRNA sequencing data analysis indicated a high abundance (85.8% of total archaea) of Methanosaeta in the microbial community after long-term acclimation. High [Formula: see text] associated with the enrichment of Methanosaeta appears to ensure successful anaerobic treatment of low-strength wastewater.

Nitrate removal performance and diversity of active denitrifying bacteria in denitrification reactors using poly(L-lactic acid) with enhanced chemical hydrolyzability.

Poly(L-lactic acid) (PLLA) can be used as an external electron donor in denitrification reactors to treat drinking water, aquaculture water, and industrial wastewater with an imbalanced carbon/nitrogen ratio. However, for PLLA to function in these applications, its chemical hydrolyzability requires improvement. Although the adjustment of the crystallinity (Xc) is effective in improving the hydrolyzability of PLLA, the condition for the Xc of PLLA, in which a sufficient amount of lactic acid is released for denitrification, must be clarified. Therefore, this study investigated the effective Xc range and optimal PLLA content as an electron donor for continuous nitrate removal in denitrification reactors. This study also explored the abundance, succession, and diversity of active denitrifying bacteria in denitrification reactors. The nitrate removal activity of activated sludge using the highly crystalline PLLA (Xc = 39.4%) was 1.8 mg NO3- -N g MLSS-1 h-1, which is 2.4 times higher than that using the nearly amorphous PLLA (Xc = 0.9%). During the 57 days of operation, the denitrification reactor with 3% (w/v) highly crystalline PLLA continued to completely remove nitrate, with a maximum nitrate removal activity of 22.8 mg NO3- -N g MLSS-1 h-1. The 16S rRNA amplicon sequencing and clone library analyses are using transcripts of two nitrite reductase genes, encoding cytochrome cd1 nitrite reductase, and copper-containing nitrite reductase revealed that bacteria belonging to the families Comamonadaceae, Rhodocyclaceae, and Alcaligenaceae were active denitrifying bacteria in the denitrification reactor using PLLA.

Spatial Patterns of Urban Wastewater Discharge and Treatment Plants Efficiency in China.

With the rapid economic development, water pollution has become a major concern in China. Understanding the spatial variation of urban wastewater discharge and measuring the efficiency of wastewater treatment plants are prerequisites for rationally designing schemes and infrastructures to control water pollution. Based on the input and output urban wastewater treatment data of the 31 provinces of mainland China for the period 2011⁻2015, the spatial variation of urban water pollution and the efficiency of wastewater treatment plants were measured and mapped. The exploratory spatial data analysis (ESDA) model and super-efficiency data envelopment analysis (DEA) combined Malmquist index were used to achieve this goal. The following insight was obtained from the results. (1) The intensity of urban wastewater discharge increased, and the urban wastewater discharge showed a spatial agglomeration trend for the period 2011 to 2015. (2) The average inefficiency of wastewater treatment plants (WWTPs) for the study period was 39.2%. The plants' efficiencies worsened from the eastern to western parts of the country. (3) The main reasons for the low efficiency were the lack of technological upgrade and scale-up. The technological upgrade rate was -4.8%, while the scale efficiency increases as a result of scaling up was -0.2%. Therefore, to improve the wastewater treatment efficiency of the country, the provinces should work together to increase capital investment and technological advancement.

Quantitative Microbial Risk Assessment for Workers Exposed to Bioaerosol in Wastewater Treatment Plants Aimed at the Choice and Setup of Safety Measures.

Biological risk assessment in occupational settings currently is based on either qualitative or semiquantitative analysis. In this study, a quantitative microbial risk assessment (QMRA) has been applied to estimate the human adenovirus (HAdV) health risk due to bioaerosol exposure in a wastewater treatment plant (WWTP). A stochastic QMRA model was developed considering HAdV as the index pathogen, using its concentrations in different areas and published dose⁻response relationship for inhalation. A sensitivity analysis was employed to examine the impact of input parameters on health risk. The QMRA estimated a higher average risk in sewage influent and biological oxidation tanks (15.64% and 12.73% for an exposure of 3 min). Sensitivity analysis indicated HAdV concentration as a predominant factor in the estimated risk. QMRA results were used to calculate the exposure limits considering four different risk levels (one illness case per 100, 1.000, 10.000, and 100.000 workers): for 3 min exposures, we obtained 565, 170, 54, and 6 GC/m³ of HAdV. We also calculated the maximum time of exposure for each level for different areas. Our findings can be useful to better define the effectiveness of control measures, which would thus reduce the virus concentration or the exposure time.

Occurrence of parent and substituted polycyclic aromatic hydrocarbons in typical wastewater treatment plants and effluent receiving rivers of Beijing, and risk assessment.

Sixteen polycyclic aromatic hydrocarbons (PAHs) and some typical substituted polycyclic aromatic hydrocarbons (SPAHs) were investigated in wastewater treatment plants (WWTPs) and effluent effluent-receiving rivers in order to indentify the elimination of these compounds in WWTPs, as well as the potantial potential risk in the effluent-receiving rivers. The concentrations of ΣPAHs in the total phase (combined dissolved and adsorbed phases) in influent were between 944.1 and 1246.5 ng·L-1, and ΣSPAHs, including methyl PAHs (MPAHs) and oxygenated PAHs (OPAHs), between 684.9 and 844.9 ng·L-1. Regarding the SPAHs, the concentrations of ΣOPAHs (312.3 ng·L-1) were higher than those of ΣMPAHs (271.8 ng·L-1). The total removal efficiencies of PAHs in the biological treatment processes were between 59% and 68%, and those of SPAHs were a little lower (58-65%). The removal efficiency in the adsorbed phase was higher than in the dissolved phase. The concentrations of PAHs and SPAHs in the effluent were a little higher than in the receiving river. According to a PAH risk assessment of the effluent, 7 carcinogenic PAHs accounted for a relatively high proportion. Benzo[a]pyrene (BaP) and Dibenz[a,h]anthracene (DBA) were major contributors to the TEQs in the effluent of WWTPs, which should be taken into consideration.

A framework for good biofilm reactor modeling practice (GBRMP).

A researcher or practitioner can employ a biofilm model to gain insight into what controls the performance of a biofilm process and for optimizing its performance. While a wide range of biofilm-modeling platforms is available, a good strategy is to choose the simplest model that includes sufficient components and processes to address the modeling goal. In most cases, a one-dimensional biofilm model provides the best balance, and good choices can range from hand-calculation analytical solutions, simple spreadsheets, and numerical-method platforms. What is missing today is clear guidance on how to apply a biofilm model to obtain accurate and meaningful results. Here, we present a five-step framework for good biofilm reactor modeling practice (GBRMP). The first four steps are (1) obtain information on the biofilm reactor system, (2) characterize the influent, (3) choose the plant and biofilm model, and (4) define the conversion processes. Each step demands that the model user understands the important components and processes in the system, one of the main benefits of doing biofilm modeling. The fifth step is to calibrate and validate the model: System-specific model parameters are adjusted within reasonable ranges so that model outputs match actual system performance. Calibration is not a simple 'by the numbers' process, and it requires that the modeler follows a logical hierarchy of steps. Calibration requires that the adjusted parameters remain within realistic ranges and that the calibration process be carried out in an iterative manner. Once each of steps 1 through 5 is completed satisfactorily, the calibrated model can be used for its intended purpose, such as optimizing performance, trouble-shooting poor performance, or gaining deeper understanding of what controls process performance.

Model based evaluation of plant improvement at a large wastewater treatment plant (WWTP).

In this work, the effect of the improvement carried out at a large-scale wastewater treatment plant (WWTP) was evaluated, by means of modelling works, with the aim to determine the influence of the modernization over the process performance. After modernization, the energy consumption due to the aeration decreased about a 20% maintaining the effluent quality. In order to double-check the good effluent quality, modelling works were carried out at the full-scale plant. After calibration, the model was applied to the upgraded full-scale plant obtaining deviations lower than 10%. Then, the performance of the main biochemical processes was evaluated in terms of oxygen uptake rate (OUR), ammonia uptake rate (AUR), and chemical oxygen demand (COD) consumption. The rate of the main processes depending on the aeration, that is OUR and AUR, were about 22 gO2/(kg VSS·h) and 2.9 gN/(kg VSS·h), respectively.

Heavy metals in handloom-dyeing effluents and their biosorption by agricultural byproducts.

The Madhabdi municipality in the Narsingdi district of Bangladesh is a well-known area for textile, handloom weaving, and dyeing industries. These textile industries produce a considerable amount of effluents, sewage sludge, and solid waste materials every day that they directly discharge into surrounding water bodies and agricultural fields. This disposal poses a serious threat to the overall epidemic and socio-economic pattern of the locality. This research entailed the collection of 34 handloom-dyeing effluent samples from different handloom-dyeing industries of Madhabdi, which were then analyzed to determine the contents of the heavy metals iron (Fe), zinc (Zn), copper (Cu), chromium (Cr), manganese (Mn), lead (Pb), and cadmium (Cd). Average concentrations of Fe, Cr, Cu, Pb, Mn, and Zn were 3.81, 1.35, 1.70, 0.17, 0.75, and 0.73 mg L-1, respectively, whereas Cd content was below the detectable limit of the atomic adsorption spectrophotometer. The concentrations of Fe, Cr, Cu, Pb, and Mn exceed the industrial effluent discharge standards (IEDS) for inland surface water and irrigation water guideline values. A biosorption experiment of the heavy metals (Fe, Cr, Cu, Mn, and Zn) was conducted without controlling for any experimental parameters (e.g., pH, temperature, or other compounds present in the effluent samples) by using four agricultural wastes or byproducts, namely rice husk, sawdust, lemon peel, and eggshell. Twenty grams of each biosorbent was added to 1 L of effluent samples and stored for 7 days. The biosorption capacity of each biosorbent is ranked as follows: eggshell, sawdust, rice husk, and lemon peel. Furthermore, the biosorption affinity of each metal ion was found in the following order: Cu and Cr (both had similar biosorption affinity), Zn, Fe, Mn. The effluents should not be discharged before treatment, and efficient treatment of effluents is possible with eggshell powder or sawdust at a rate of 20 g of biosorbent per liter of effluents.

Performance and microbial characteristics of biomass in a full-scale aerobic granular sludge wastewater treatment plant.

By modification of the operational conditions of batch reactors, a municipal wastewater treatment plant was upgraded from activated sludge to aerobic granular sludge (AGS) technology. After upgrading, the volume of the biological reactors was reduced by 30%, but the quality of the effluent substantially improved. The concentration of biomass in the reactors increased twofold; the average biomass yield was 0.6 g MLVSS/g COD, and excess granular sludge was efficiently stabilized in aerobic conditions. Canonical correspondence analysis based on the results of next-generation sequencing showed that the time of adaptation significantly influenced the microbial composition of the granules. In mature granules, the abundance of ammonium-oxidizing bacteria was very low, while the abundance of the nitrite-oxidizing bacteria Nitrospira sp. was 0.5 ± 0.1%. The core genera were Tetrasphaera, Sphingopyxis, Dechloromonas, Flavobacterium, and Ohtaekwangia. Bacteria belonging to these genera produce extracellular polymeric substances, which stabilize granule structure and accumulate phosphorus. The results of this study will be useful for designers of AGS wastewater treatment plants, and molecular data given here provide insight into the ecology of mature aerobic granules from a full-scale facility.

Technical and natural conditions and operating efficiency of a municipal stormwater treatment plant.

A decade of observations provided grounds for assessing the operation of one of the few stormwater treatment plants in Poland (system: screens-grit chambers-settler-retention pond) which collects effluents from 471 ha of the city. Among other aspects, the following were evaluated: treatment efficiency, relationship between the quality of treated stormwater and that of waters in the receiving body (the ox-bow lake of the Vistula river), operating stability of key units, significance of the facility for nature. During the assessment, the plant had a positive effect on the quality of stormwater effluents-the content of the analysed pollutants was reduced (more than 80% average efficiency for mineral forms of nitrogen and suspension matter) and oxygen ratios improved (23% increase in the average concentration of dissolved oxygen and more than 50% decrease in 5-day biochemical oxygen demand and chemical oxygen demand). Although the overall assessment of the facility's operation was good, some omissions and operating errors were noted (method of removing retained pollutants, stormwater flow control). Eliminating them is a prerequisite for maintaining the expected reliability of the system. An effect of stormwater ponds on the increase in biodiversity in the poor urbanised landscape has also been observed. The structures, forming a uniform system along with urban green areas, constitute specific enclaves which attract living organisms.

Too Big, Too Small, or Just Right? Cost-Efficiency of Environmental Inspection Services in Connecticut.

OBJECTIVE: To assess optimal activity size/mix of Connecticut local public health jurisdictions, through estimating economies of scale/scope/specialization for environmental inspections/services. DATA SOURCES/STUDY SETTING: Connecticut's 74 local health jurisdictions (LHJs) must provide environmental health services, but their efficiency or reasons for wide cost variation are unknown. The public health system is decentralized, with variation in organizational structure/size. We develop/compile a longitudinal dataset covering all 74 LHJs, annually from 2005 to 2012. STUDY DESIGN: We estimate a public health services/inspections cost function, where inputs are translated into outputs. We consider separate estimates of economies of scale/scope/specialization for four mandated inspection types. DATA COLLECTION/EXTRACTION METHODS: We obtain data from Connecticut Department of Public Health databases, reports, and other publicly available sources. There has been no known previous utilization of this combined dataset. PRINCIPAL FINDINGS: On average, regional districts, municipal departments, and part-time LHJs are performing fewer than the efficient number of inspections. The full-time municipal departments and regional districts are more efficient but still not at the minimum efficient scale. The regional districts' elasticities of scale are larger, implying they are more efficient than municipal health departments. CONCLUSIONS: Local health jurisdictions may enhance efficiency by increasing inspections and/or sharing some services.

Residual volume in vials of antibiotics used in pediatrics.

OBJECTIVE: Quantifying residual volume contained in vials of antibiotics used in pediatrics. METHOD: This is an experiment involving samples from vials of antibiotics used in a pediatric hospital. Residual volume was identified by calculating the difference in weight measurement before and after the vials were washed. Evaluation of the residual volume difference in the vials was determined by the Wilcoxon non-parametric test for a sample and established at a significance level of 5%. RESULTS: 105 samples of antibiotics were selected. The correct use of the antibiotics oxacillin (88.57%) and ceftriaxone (94.28%) predominated with low residual values. The same did not occur for procaine benzylpenicillin + potassium benzylpenicillin, since a greater residual volume was discarded in 74.28% of the vials. CONCLUSION: We highlight the need for improvements in managing antibiotics in the institution under study, so that the excess volume of the antibiotics in the vials is used within the acceptable stable time. It is also necessary that the disposal of the residual volume be adequately disposed, since it presents a risk to public health and the environment. OBJETIVO: Quantificar o volume residual contido em frascos-ampola de antibióticos utilizados na pediatria. MÉTODO: Trata-se de um experimento com amostras de frascos-ampola de antibióticos utilizados em hospital pediátrico. O volume residual foi identificado calculando-se a diferença da aferição do peso antes e após a lavagem do frasco-ampola. A avaliação da diferença dos volumes residuais nos frascos-ampola foi determinada pelo teste não paramétrico de Wilcoxon para uma amostra e estabelecido o nível de significância de 5%. RESULTADOS: Foram selecionadas 105 amostras de antibióticos. Predominou o correto aproveitamento dos antibióticos oxacilina (88,57%) e ceftriaxona (94,28%), com baixos valores residuais. O mesmo não ocorreu com a benzilpenicilina procaína + potássica, pois em 74,28% dos frascos houve descarte de volume residual superior. CONCLUSÃO: Destaca-se a necessidade de melhorias na gestão dos antibióticos na instituição em estudo, para que o volume excedente do antibiótico em frasco-ampola seja aproveitado até o tempo de estabilidade permitido, assim como é necessário que haja a adequação da forma de descarte do volume residual, que apresenta risco à saúde pública e ao meio ambiente.