A hydrolysis procedure for the analysis of total cocaine residues in wastewater

Fate characteristics, exposure risk, and control strategy of typical antibiotics in Chinese sewerage system: A review

In China, the sewerage system plays an essential role in antibiotic removal; however, the fate profiles of antibiotics in sewers are not well understood, and risk identification throughout the sewerage system is inadequate. Based on the extensive detection results for typical groups of antibiotics in the discharge sources, influent and effluent from wastewater treatment plants (WWTPs), and excess sludge, a comprehensive evaluation was conducted to reveal the elimination profiles of the antibiotics, identify the fate characteristics in both sewers and WWTPs, assess the exposure risk levels, and propose a control strategy. The total concentration (based on the median concentrations of the target antibiotics) in aqueous waters was estimated to decrease from 7383.4 ng/L at the discharge source to 886.6 ng/L in the WWTP effluent, among which 69.6% was reduced by sewers and 18.4% was reduced by WWTPs. Antibiotic reduction in sewers was a combined effect of dilution, physiochemical reactions, sorption, biodegradation, and retransformation, and the A2O-MBR + ozonation process in the WWTPs exhibited superior performance in diminishing antibiotics. Notably, accumulated antibiotics in the excess sludge posed a high risk to natural environments (with a risk quotient of approximately 13.0), and the potential risk during combined sewer overflows (CSOs) was undetermined. Thus, enhanced sludge treatment techniques, accurate risk prediction, and proper precautions at CSOs are required to mitigate potential risk. A novel scheme involving an accurate estimation of discharge loads, preliminary treatment of highly concentrated discharge sources, and synergic control in sewers was proposed to eliminate antibiotics at the front end of pipes.

Transformation of Illicit Drugs and Pharmaceuticals in Sewer Sediments

In-sewer stability of human excreted biomarkers is a critical factor of wastewater-based epidemiology in back-estimating illicit drug and pharmaceutical use in the community. Biomarker stability has been investigated in sewers with the presence of biofilms, but the understanding in sewer sediments is still lacking. This study for the first time employed a laboratory sediment reactor to measure 18 illicit drug and pharmaceutical biomarkers under gravity sewer environments with the presence of sediments. Biomarkers exhibited various stability patterns due to transformation processes occurring in the bulk wastewater and sediments. The attenuation of a biomarker by sediments is driven by complex processes involving biodegradation, diffusion, and sorption, which is directly proportional to the ratio of sediment surface area against wastewater volume. The sediment-driven transformation coefficients of biomarkers are higher than the accordingly biofilm-mediated rates because of stronger microbial activities in sediments. Additionally, the stability of most biomarkers was insensitive to the natural pH variation in sewers, except for a few compounds (e.g., methadone, ketamine, and paracetamol) susceptible to pH changes. In general, this study delineates the stability data of various biomarkers in gravity sewers with sediments, which are novel and long-missing information for wastewater-based epidemiology and improve the reliability of back-estimation in complex sewer networks.

Pharmaceuticals and illicit drugs in wastewater samples in north-eastern Tunisia

Pharmaceutically active substances (PhACs) and drugs of abuse (DAs) are two classes of contaminants of emerging concern that have attracted great concern and interest by the scientific community during the last two decades. Numerous studies have revealed their presence in treated urban wastewaters. This is mainly due to the fact that some compounds are not efficiently removed during wastewater treatment processes, and are thus able to reach the aquatic environment through wastewater discharge and reuse practices. The application of an optimized multi-residue method for the simultaneous confirmation and quantification of licit and illicit drugs has been investigated in influent and effluent wastewater samples from seven wastewater treatment plants (WWTPs) located in north-eastern Tunisia. Analysis was performed through ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Out of 12 pharmaceutical compounds analyzed, 11 of them were detected mainly in effluent wastewaters. In both matrices, antibiotics and β-blockers were the most detected groups. This suggests that these compounds show noticeable resistance against biological treatment in WWTPs. The estimated concentrations of antibiotics in effluents ranged from ca. 35 ng/L to 1.2 μg/L. However, all five studied illicit drugs were detected, mainly in influent wastewaters. Forensic investigation performed on people suspected to be drug abusers covering all Tunisian cities was conducted by monitoring an epidemiological study of human urine samples surveying rate of consumption for illicit drugs. Hence, these preliminary results confirmed the presence of illicit drugs in the influent wastewater samples. For example, quantification ranges for cocaine were found to be 25-450 ng/L in influent wastewater samples. Significant differences for cocaine consumption across the two sampling methods were observed. Consequently, we conclude that the analyses in wastewater are more reflective of the real levels of illicit drug consumption. Moreover, the cost for chromatographic analysis is lower than the screening test methods for human biological specimen, particularly staffing, which are likely to be much lower.

Transformation and Sorption of Illicit Drug Biomarkers in Sewer Biofilms

In-sewer transformation of drug biomarkers (excreted parent drugs and metabolites) can be influenced by the presence of biomass in suspended form as well as attached to sewer walls (biofilms). Biofilms are likely the most abundant and biologically active biomass fraction in sewers. In this study, 16 drug biomarkers were selected, including the parent forms and the major human metabolites of mephedrone, methadone, cocaine, heroin, codeine, and tetrahydrocannabinol (THC). Transformation and sorption of these substances were assessed in targeted batch experiments using laboratory-scale biofilm reactors operated under aerobic and anaerobic conditions. A one-dimensional model was developed to simulate diffusive transport, abiotic and biotic transformation, and partitioning of drug biomarkers. Model calibration to experimental results allowed estimating biotransformation rate constants in sewer biofilms, which were compared to those obtained for suspended biomass. Our results suggest that sewer biofilms can enhance the biotransformation kinetics of most selected compounds. Through scenario simulations, we demonstrated that the estimation of biotransformation rate constants in biofilm can be significantly biased if the boundary layer thickness is not accurately estimated. This study complements our previous investigation on the transformation and sorption of drug biomarkers in the presence of only suspended biomass in untreated sewage. A better understanding of the role of sewer biofilms-also relative to the in-sewer suspended solids-and improved prediction of associated fate processes can result in more accurate estimation of daily drug consumption in urban areas in wastewater-based epidemiological assessments.

Assessing cocaine abuse using LC-MS/MS measurements in biological specimens

Cocaine use is still a problem in today's world, and this has several implications on human activities. Indeed, important problems related to cocaine derive from its use in situations where concentration and focus skills are necessary, namely while driving and/or working. The need of analytical methods for drug analysis in specimens of biological origin for proper documentation of human exposure is increasing. While GC-MS-based procedures represented the state-of-the-art of analytical techniques a few years ago, there is a growing trend for their replacement by LC-MS/MS, which can be justified by the increased sensitivity presented by these new technologies. This paper will review recently published papers on the use of LC-MS/MS-based procedures for cocaine measurement in biological specimens.

Degradability of creatinine under sewer conditions affects its potential to be used as biomarker in sewage epidemiology

Creatinine was proposed to be used as a population normalising factor in sewage epidemiology but its stability in the sewer system has not been assessed. This study thus aimed to evaluate the fate of creatinine under different sewer conditions using laboratory sewer reactors. The results showed that while creatinine was stable in wastewater only, it degraded quickly in reactors with the presence of sewer biofilms. The degradation followed first order kinetics with significantly higher rate in rising main condition than in gravity sewer condition. Additionally, daily loads of creatinine were determined in wastewater samples collected on Census day from 10 wastewater treatment plants around Australia. The measured loads of creatinine from those samples were much lower than expected and did not correlate with the populations across the sampled treatment plants. The results suggested that creatinine may not be a suitable biomarker for population normalisation purpose in sewage epidemiology, especially in sewer catchment with high percentage of rising mains.

Challenges of surveying wastewater drug loads of small populations and generalizable aspects on optimizing monitoring design

AIMS

Quantifying illicit drug loads through wastewater analysis (WWA) is an alternative approach to estimating population drug use. This study investigated the variability of daily drug loads in wastewater and their relationships to environmental factors over an extended period to: (i) explore the suitability of WWA in small populations and (ii) optimize the monitoring design for future studies.

DESIGN, SETTING, PARTICIPANTS

Daily wastewater samples (n = 1369 consecutive days) from a German village with approximately 7160 inhabitants.

MEASUREMENTS

Samples were analysed for cocaine and benzoylecgonine with liquid chromatography-tandem mass spectrometry. Time-series analysis was used to explore the effects of weather and other factors on daily cocaine loads. Subsampling was used to assess monitoring design.

FINDINGS

Cocaine loads [mean = 652 mgCOC /day, standard deviation (SD) = 498 mgCOC /day] increased over the study period, with higher values during winter and spring. Despite high day-to-day variation, loads were significantly higher during weekends [+161 mgCOC /day, 95% confidence interval (CI) = 115-207 mgCOC /day, P < 10(-4) ] and days with frost (+114 mgCOC /day, 95% CI = 6-223 mgCOC /day, P = 0.039) or snow (+150 mgCOC /day, 95% CI = 46-253 mgCOC /day, P = 0.005). Annual means estimated from 1-week periods were subject to approximately 60% relative error. Increasing sample size and changing sampling from consecutive days to stratified random decreased this uncertainty.

CONCLUSIONS

Day-to-day variation and seasonality of drug loads from the few long-term wastewater studies available to date suggest that up to 56 stratified random samples are required to obtain reliable (expected uncertainty around 10%) annual estimates of drug loads. Successfully assessing changes in consumption patterns or relationships to external factors requires larger sample sizes than estimating annual means, which holds true for high-prevalence drugs in small communities and low-prevalence drugs in big cities.

Stability of cocaine and its metabolites in municipal wastewater--the case for using metabolite consolidation to monitor cocaine utilization

Transformations of cocaine and eleven of its metabolites were investigated in untreated municipal sewage at pH ≈ 7 and 9, 23, and 31 °C. Results indicated that hydrolysis-possibly bacterially mediated-was the principal transformation pathway. Residues possessing alkyl esters were particularly susceptible to hydrolysis, with pseudo-first-order rate constants varying from 0.54 to 1.7 day(-1) at 23 °C. Metabolites lacking esters or possessing only a benzoyl ester appeared stable. Residues lacking alkyl esters did accumulate through hydrolysis of precursors, however. As noted previously, this may positively bias cocaine utilization estimates based on benzoylecgonine alone. Reported variability in metabolic excretion was used in conjunction with transformation data to evaluate different approaches for estimating cocaine loading. Results indicate that estimates derived from measurands that capture all major cocaine metabolites, such as COCtot (the sum of all measurable metabolites) and EChyd (the sum of all metabolites that can be hydrolyzed to ecgonine), may reduce uncertainty arising from variability in metabolite transformation and excretion, possibly to ≈ 10 % RSD. This is more than a two-fold reduction relative to estimates derived from benzoylecgonine (>26 % RSD), and roughly equivalent to reported uncertainties from sources that are not metabolite-specific (e.g., sampling frequency, flow variability). They and other composite measurands merit consideration from the sewage epidemiology community, beginning with efforts to evaluate the stability of the total cocaine load under realistic sewer conditions.

Occurrence of organic microcontaminants in the wastewater treatment process. A mini review

A wastewater treatment plant may receive various types of wastewater namely, urban, industrial, agricultural, washout from the streets, wet or/and dry atmospheric deposition. As such, scientists have detected in wastewaters all major categories of pollutants like persistent organic pollutants (POPs), polycyclic aromatic hydrocarbons (PAHs) and pesticides, but also substances that are widely used as pharmaceuticals and cosmetics, classified as "PPCPs" (pharmaceuticals and personal care products). Finally, the latest categories of compounds to be looked upon in these types of matrices are illicit drugs (drugs of abuse, like cocaine, etc.) and doping substances. This review article summarises major categories of organic microcontaminants that have been detected in wastewaters and studies their fate during the wastewater treatment process. Occurrence of these compounds in the influents and effluents are reported, as well as percents of removal, mass balances and phase distributions.

Drugs of abuse in wastewater and suspended particulate matter--further developments in sewage epidemiology

This manuscript reports, for the first time, a monitoring study analysing wastewater and associated suspended particulate matter (SPM) to determine the concentration of drugs of abuse and metabolites in wastewater influent. The monitoring of SPM is crucial for target analytes because, depending on their physico-chemical properties, they may partition to particulates; thus, analysis of wastewater only will result in under-reporting of the concentration of target analytes in the sample. A daily one week monitoring study was carried out at a WWTP serving one of the largest cities in the Czech Republic; representing the first comprehensive application of the sewage epidemiology approach in the Czech Republic. In total, 60 analytes were targeted in the monitoring programme including stimulants, opioid and morphine derivatives, benzodiazepines, antidepressants, dissociative anaesthetics, drug precursors and their metabolites. Analysis of SPM determined that significant proportions of some compounds were present on the solids. For example, 21.0-49.8% of the total concentration of EDDP (2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine) in the sample was determined on SPM and 11.2-19.6% of methadone. The highest proportion on SPM was determined for fluoxetine in the range 68.1-79.6%, norfluoxetine 46.6-61.9% and amitriptyline 21.8-51.2%. In contrast, some compounds presented very little partitioning to SPM. Less than 5% was determined partitioned to SPM over the week period for analytes including cocaine, benzoylecgonine, cocaethylene, amphetamine, methamphetamine, MDMA (3,4-methylenedioxymethamphetamine), codeine, dihydrocodeine, tramadol, nortramadol, oxazepam and ephedrine. Determined concentrations in wastewater influent were subsequently utilised in the sewage epidemiology approach to estimate drug consumption, in the community from which the wastewater was derived. This back-calculation was updated for the first time to include the concentration of analytes present on SPM. The consumption of methamphetamine and MDMA was determined to be especially high in the studied community in relation to other European countries, while cocaine and methadone consumption was relatively low. This manuscript shows that in order to apply the sewage epidemiology approach, SPM analysis is required for some compounds; whereas for others the partitioning is small and one may regard this as negligible.

Normalized diurnal and between-day trends in illicit and legal drug loads that account for changes in population

Drug concentrations in composite municipal wastewater samples and census-based estimates of population are used to derive daily loads of illicit substances that are indexed to population. However, such estimates do not provide information on the diurnal trends of substance excretion nor can they account for changes in population. To address these limitations, a series of 1 h composites created by sampling wastewater influent at 6 min intervals was collected over four consecutive days at a single wastewater treatment plant. Creatinine (a urinary indicator), caffeine, methamphetamine, benzoylecgonine (BZE), and cocaine were analyzed by liquid chromatography/tandem mass spectrometry (LC-MS/MS). Diurnal trends and between-day trends were substance specific and related to the number of estimated doses and excretory half-life. Normalization to creatinine yielded trends in substances that differed significantly from non-normalized trends by accounting for changes in population within the municipality studied. Increases in normalized substance excretion observed during early morning hours originate from individuals among the resident population of the municipality due to the absence of commuters.