Raw Wastewater Samples Research Articles

Monitoring population exposure to pesticides based on liquid chromatography-tandem mass spectrometry measurement of their urinary metabolites in urban wastewater: A novel biomonitoring approach

Biomonitoring studies have documented the high exposure of the population to pesticides which are widely used for crop protection, industrial and household purposes. This is the first study which has measured human urinary metabolites of pesticides in urban wastewater as biomarkers of population exposure. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to measure fifteen urinary metabolites selected from the major classes of pesticides. Raw wastewater samples were processed by solid phase extraction (SPE) or direct injection into the LC-MS/MS system. Recoveries ranged from 75 to 115% and the limits of quantification were 1–15ng/L for the SPE method and 40–800ng/L for direct injection. The method was employed for the analysis of 44 composite 24-h wastewater samples collected in seven Italian cities. Most of the target substances were detected at concentrations ranging from 1.1ng/L to 1.6μg/L. The highest concentrations were for some common metabolites of alkyl phosphates and pyrethroids and the specific metabolite of chlorpyrifos and chlorpyrifos-methyl (3,5,6-trichloro-2-pyridinol). The frequency of detection and abundance of most of the measured metabolites were in line with the profiles reported in urine biomonitoring studies. This method is therefore proposed as a novel “biomonitoring approach” for obtaining objective, direct information on the levels of exposure of a specific population to pesticides, and current research is addressed to validate the method identifying the most reliable biomarkers.

Quantitative detection of viable helminth ova from raw wastewater, human feces, and environmental soil samples using novel PMA-qPCR methods.

In this study, we have evaluated the efficacy of propidium monoazidequantitative polymerase chain reaction (PMA-qPCR) to differentiate between viable and non-viable Ancylostoma caninum ova. The newly developed method was validated using raw wastewater seeded with known numbers of A. caninum ova. Results of this study confirmed that PMA-qPCR has resulted in average of 88% reduction (P<0.05) in gene copy numbers for 50% viable +50% non-viable when compared with 100% viable ova. A reduction of 100% in gene copies was observed for 100% non-viable ova when compared with 100% viable ova. Similar reductions (79-80%) in gene copies were observed for A. caninum ova-seeded raw wastewater samples (n=18) collected from wastewater treatment plants (WWTPs) A and B. The newly developed PMA-qPCR method was applied to determine the viable ova of different helminths (A. caninum, A. duodenale, Necator americanus and Ascaris lumbricoides) in raw wastewater, human fecal and soil samples. None of the unseeded wastewater samples were positive for the above-mentioned helminths. N. americanus and A. lumbricoides ova were found in unseeded human fecal and soil samples. For the unseeded human fecal samples (1g), an average gene copy concentration obtained from qPCR and PMA-qPCR was found to be similar (6.8×10(5)±6.4×10(5) and 6.3×10(5)±4.7×10(5)) indicating the presence of viable N. americanus ova. Among the 24 unseeded soil samples tested, only one was positive for A. lumbricoides. The mean gene copy concentration in the positively identified soil sample was 1.0×10(5)±1.5×10(4) (determined by qPCR) compared to 4.9×10(4)±3.7×10(3) (determined by PMA-qPCR). The newly developed PMA-qPCR methods were able to detect viable helminth ova from wastewater and soil samples and could be adapted for health risk assessment.

Rapid screening of testosterone in the aquatic environment using direct analysis in real-time (DART) mass spectrometry

Testosterone (TES) in the aquatic environment was analyzed for the first time using direct analysis in real-time mass spectrometry (DART MS) without any sample pre-treatment. TES with the addition of 2H and its dehydration products was observed. The instrument parameters were studied systematically and optimized concerning the specific analyte. Limits of detection for the pure compound were 2.5 ng for TES spiked in raw wastewater samples and 500 pg in TES standards. The whole analysis time was within 1 min. A simple derivatization of TES by hydroxylamine and introducing ammonia as dopant gas for the sensitivity and intensity enhancement were also investigated. Both methods improved the intensity of the TES signal by about twofold. The results of this study illustrate that DART MS is capable to detect TES in complicated matrixes and could realize the rapid and direct screening of TES in the aquatic environment at a low nanogram range for pure compound without coupling with any pre-treatment tools.

Comparative measurement and quantitative risk assessment of alcohol consumption through wastewater-based epidemiology: An international study in 20 cities

Quantitative measurement of drug consumption biomarkers in wastewater can provide objective information on community drug use patterns and trends. This study presents the measurement of alcohol consumption in 20 cities across 11 countries through the use of wastewater-based epidemiology (WBE), and reports the application of these data for the risk assessment of alcohol on a population scale using the margin of exposure (MOE) approach. Raw 24-h composite wastewater samples were collected over a one-week period from 20 cities following a common protocol. For each sample a specific and stable alcohol consumption biomarker, ethyl sulfate (EtS) was determined by liquid chromatography coupled to tandem mass spectrometry. The EtS concentrations were used for estimation of per capita alcohol consumption in each city, which was further compared with international reports and applied for risk assessment by MOE. The average per capita consumption in 20 cities ranged between 6.4 and 44.3L/day/1000 inhabitants. An increase in alcohol consumption during the weekend occurred in all cities, however the level of this increase was found to differ. In contrast to conventional data (sales statistics and interviews), WBE revealed geographical differences in the level and pattern of actual alcohol consumption at an inter-city level. All the sampled cities were in the “high risk” category (MOE<10) and the average MOE for the whole population studied was 2.5. These results allowed direct comparisons of alcohol consumption levels, patterns and risks among the cities. This study shows that WBE can provide timely and complementary information on alcohol use and alcohol associated risks in terms of exposure at the community level.

Survivability, Partitioning, and Recovery of Enveloped Viruses in Untreated Municipal Wastewater.

Many of the devastating pandemics and outbreaks of the 20th and 21st centuries have involved enveloped viruses, including influenza, HIV, SARS, MERS, and Ebola. However, little is known about the presence and fate of enveloped viruses in municipal wastewater. Here, we compared the survival and partitioning behavior of two model enveloped viruses (MHV and ϕ6) and two nonenveloped bacteriophages (MS2 and T3) in raw wastewater samples. We showed that MHV and ϕ6 remained infective on the time scale of days. Up to 26% of the two enveloped viruses adsorbed to the solid fraction of wastewater compared to 6% of the two nonenveloped viruses. Based on this partitioning behavior, we assessed and optimized methods for recovering enveloped viruses from wastewater. Our optimized ultrafiltration method resulted in mean recoveries (±SD) of 25.1% (±3.6%) and 18.2% (±9.5%) for the enveloped MHV and ϕ6, respectively, and mean recoveries of 55.6% (±16.7%) and 85.5% (±24.5%) for the nonenveloped MS2 and T3, respectively. A maximum of 3.7% of MHV and 2% of MS2 could be recovered from the solids. These results shed light on the environmental fate of an important group of viruses and the presented methods will enable future research on enveloped viruses in water environments.

Subtype analysis of Giardia duodenalis isolates from municipal and domestic raw wastewaters in Iran.

A total of 54 raw wastewater samples collected from three urban treatment plants and two slaughterhouses in Tehran, Iran, were assessed for the presence of the Giardia cysts using immunofluorescence with monoclonal antibodies. To characterize the cysts at the molecular level, the three genetic loci were amplified and sequenced. The assemblages A (37.5%) and E (58.3%) were detected in livestock wastewater samples. Assemblage A, which is composed of only G. duodenalis genotype, was detected in 100% of urban wastewater samples. The subassemblages A2, A3, A-I, A-II, and E3 were identified with β-giardin, triose phosphate isomerase, and glutamate dehydrogenase genes. This study is the first to report on G. duodenalis genotypes in aquatic environmental samples in Iran.

Occurrence and removal of polycyclic aromatic hydrocarbons in real textile dyeing wastewater treatment process

In this work, the occurrence and removal of polycyclic aromatic hydrocarbons (PAHs) were investigated in a combination process of anoxic baffled reactor (ABR)-hybrid coagulation/membrane bioreactor (HCMBR) for real textile dyeing wastewater treatment. It was found that the target compounds except for the chrysene, benzo(b)fluoranthene, dibenzo(a,h)anthracene, and benzo(g,hi)perylene occurred widely in raw textile dyeing wastewater, treated effluent and sludge samples. In the raw wastewater, two-ring naphthalene was the dominant compound, while three-ring PAHs predominated in the final effluent. The dominant compounds in the raw sludge samples were phenanthrene, while they were pyrene and indeno(1,2,3-cd)pyrene for final discharge sludge. The combination process achieved over 88% removal for all the PAHs. Low molecular weight (LMW) PAHs might be mainly removed by volatilization, adsorption, and sedimentation in the ABR treatment unit. High molecular weight (HMW) PAHs might be mainly removed by adsorption and sedimentation processes after coagulation and solid–liquid separation in the HCMBR treatment unit. The final discharge of treated textile dyeing wastewater and sludge was biologically safe based on the toxicity evaluation test.

Simultaneous reduction of copper and toxicity in semiconductor wastewater using protonated alginate beads

Using protonated alginate (HA) beads, copper (Cu2+) levels and toxicity were concurrently reduced in semiconductor wastewater produced from the chemical mechanical planarization process. The beneficial effect of protonation could be explained by a reduction in the release of Ca2+, which is a competitive cation during sorption of Cu2+, leading to an increased in the sorption capacity from 107 to 189mg/g. Monitoring of the acute toxicity of two different types of semiconductor wastewater toward Daphnia magna suggested that Cu2+ was the cause of toxicity. The toxicity identification evaluation using D. magna indicated that Cu2+ was a major toxicant in the raw wastewater with concentrations of 1.97 and 3.37mg/L for two different raw wastewater samples with initial toxicities of 14.2 and 23.6 toxic unit (TU), respectively. This relationship was verified by the correlation coefficients between Cu2+ concentration and acute toxicity (r2=0.829 at P<0.05 and 0.894 at P<0.05 for two types of semiconductor wastewater) in mass balance tests. The laboratory continuous column test using HA beads showed that the Cu2+ concentration in effluent was proportional to the acute toxicity. In particular, the TU values increased sharply when the residual concentration of Cu2+ exceeded 0.1mg/L. The test battery results indicated that D. magna was more sensitive than other aquatic species, i.e., algae and bacteria, to Cu2+ in semiconductor wastewater.

Comparison of concentration methods for rapid detection of hookworm ova in wastewater matrices using quantitative PCR

Hookworm infection contributes around 700 million infections worldwide especially in developing nations due to increased use of wastewater for crop production. The effective recovery of hookworm ova from wastewater matrices is difficult due to their low concentrations and heterogeneous distribution. In this study, we compared the recovery rates of (i) four rapid hookworm ova concentration methods from municipal wastewater, and (ii) two concentration methods from sludge samples. Ancylostoma caninum ova were used as surrogate for human hookworm (Ancylostoma duodenale and Necator americanus). Known concentration of A. caninum hookworm ova were seeded into wastewater (treated and raw) and sludge samples collected from two wastewater treatment plants (WWTPs) in Brisbane and Perth, Australia. The A. caninum ova were concentrated from treated and raw wastewater samples using centrifugation (Method A), hollow fiber ultrafiltration (HFUF) (Method B), filtration (Method C) and flotation (Method D) methods. For sludge samples, flotation (Method E) and direct DNA extraction (Method F) methods were used. Among the four methods tested, filtration (Method C) method was able to recover higher concentrations of A. caninum ova consistently from treated wastewater (39–50%) and raw wastewater (7.1–12%) samples collected from both WWTPs. The remaining methods (Methods A, B and D) yielded variable recovery rate ranging from 0.2 to 40% for treated and raw wastewater samples. The recovery rates for sludge samples were poor (0.02–4.7), although, Method F (direct DNA extraction) provided 1–2 orders of magnitude higher recovery rate than Method E (flotation). Based on our results it can be concluded that the recovery rates of hookworm ova from wastewater matrices, especially sludge samples, can be poor and highly variable. Therefore, choice of concentration method is vital for the sensitive detection of hookworm ova in wastewater matrices.

Rapid concentration and sensitive detection of hookworm ova from wastewater matrices using a real-time PCR method

The risk of human hookworm infections from land application of wastewater matrices could be high in regions with high hookworm prevalence. A rapid, sensitive and specific hookworm detection method from wastewater matrices is required in order to assess human health risks. Currently available methods used to identify hookworm ova to the species level are time consuming and lack accuracy. In this study, a real-time PCR method was developed for the rapid, sensitive and specific detection of canine hookworm (Ancylostoma caninum) ova from wastewater matrices. A. caninum was chosen because of its morphological similarity to the human hookworm (Ancylostoma duodenale and Necator americanus). The newly developed PCR method has high detection sensitivity with the ability to detect less than one A. caninum ova from 1 L of secondary treated wastewater at the mean threshold cycle (CT) values ranging from 30.1 to 34.3. The method is also able to detect four A. caninum ova from 1 L of raw wastewater and from ∼4 g of treated sludge with mean CT values ranging from 35.6 to 39.8 and 39.8 to 39.9, respectively. The better detection sensitivity obtained for secondary treated wastewater compared to raw wastewater and sludge samples could be attributed to sample turbidity. The proposed method appears to be rapid, sensitive and specific compared to traditional methods and has potential to aid in the public health risk assessment associated with land application of wastewater matrices. Furthermore, the method can be adapted to detect other helminth ova of interest from wastewater matrices.

Evidence of viral dissemination and seasonality in a Mediterranean river catchment: Implications for water pollution management

Conventional wastewater treatment does not completely remove and/or inactive viruses; consequently, viruses excreted by the population can be detected in the environment. This study was undertaken to investigate the distribution and seasonality of human viruses and faecal indicator bacteria (FIB) in a river catchment located in a typical Mediterranean climate region and to discuss future trends in relation to climate change. Sample matrices included river water, untreated and treated wastewater from a wastewater treatment plant within the catchment area, and seawater from potentially impacted bathing water. Five viruses were analysed in the study. Human adenovirus (HAdV) and JC polyomavirus (JCPyV) were analysed as indicators of human faecal contamination of human pathogens; both were reported in urban wastewater (mean values of 106 and 105 GC/L, respectively), river water (103 and 102 GC/L) and seawater (102 and 101 GC/L). Human Merkel Cell polyomavirus (MCPyV), which is associated with Merkel Cell carcinoma, was detected in 75% of the raw wastewater samples (31/37) and quantified by a newly developed quantitative polymerase chain reaction (qPCR) assay with mean concentrations of 104 GC/L. This virus is related to skin cancer in susceptible individuals and was found in 29% and 18% of river water and seawater samples, respectively. Seasonality was only observed for norovirus genogroup II (NoV GGII), which was more abundant in cold months with levels up to 104 GC/L in river water. Human hepatitis E virus (HEV) was detected in 13.5% of the wastewater samples when analysed by nested PCR (nPCR). Secondary biological treatment (i.e., activated sludge) and tertiary sewage disinfection including chlorination, flocculation and UV radiation removed between 2.22 and 4.52 log10 of the viral concentrations. Climate projections for the Mediterranean climate areas and the selected river catchment estimate general warming and changes in precipitation distribution. Persistent decreases in precipitation during summer can lead to a higher presence of human viruses because river and sea water present the highest viral concentrations during warmer months. In a global context, wastewater management will be the key to preventing environmental dispersion of human faecal pathogens in future climate change scenarios.

Wastewater analysis to monitor spatial and temporal patterns of use of two synthetic recreational drugs, ketamine and mephedrone, in Italy.

Wastewater analysis was applied in a four-year monitoring study to assess temporal and spatial patterns of ketamine and mephedrone use in the general population in Italy. Composite raw wastewater samples were collected from sewage treatment plants (STPs) in 17 cities. Target analytes were measured using a validated method based on solid phase extraction and liquid chromatography coupled to tandem mass spectrometry analysis. Mass loads were use to assess ketamine and mephedrone use and were normalized to the population served by the plants. Ketamine was detected in wastewater in all except one (Palermo) of the cities investigated, while mephedrone was detected only in Bologna and Florence. Ketamine mass loads progressively increased from 2010 to 2013, and in Milan rose from 1 to 1.5 g/day in 2008-2010 to 3.4-3.6 g/day in 2013-2014. Mass loads were higher in north and central Italy than in the south, and in larger rather than small cities. Wastewater analysis was suitable to provide objective and up-to-date information on the use of ketamine in Italy, to identify ketamine spatial and temporal changes, and to confirm the low use of mephedrone. These results can complement information from population surveys which often provide only scant and incomplete figures for these substances.

Determination of Some Heavy Metals in Raw Petroleum Wastewater Samples Before and After Passing on &amp;lt;i&amp;gt;Australis Phragmites&amp;lt;/i&amp;gt; Plant

The main objective of this project was determining of lead, cadmium, nickel and chromium in raw petroleum wastewater (RPWW) samples. The samples were taken before and after passage the RPWW on Australis Phragmites Plant (APP). Atomic absorption spectrophotometer was used to determine the heavy metals in RPWW samples before and after passing, The concentration of lead, cadmium, nickel and chromium before passing on APP was found to be 0.25, 0.9, 0.52 & 0.012 ppm respectively, but after passing on APP was fond to be 0.123, 0.75,0.45 & 0.01 ppm, respectively. The obtained results after passage were found within the range assigned by American Society for Testing and Materials ASTM, except the concentration of nickel.

Quinolone resistance genes (qnrA and qnrS) in bacteriophage particles from wastewater samples and the effect of inducing agents on packaged antibiotic resistance genes

This study quantifies quinolone antibiotic resistance genes (qnrA and qnrS) in DNA of phage particles isolated from faecally polluted waters and evaluates the influence of phage inducers on the abundance of antibiotic resistance genes in packaged DNA. qnrA and qnrS were quantified by qPCR in DNA of phage particles isolated from 18 raw urban wastewater samples, 18 river samples and 28 archived samples of animal wastewater. The bacterial fraction of the samples was treated with mitomycin C, ciprofloxacin, EDTA or sodium citrate under different conditions, and the number of resistance genes in DNA of phage particles was compared with the non-induced samples. qnrA was more prevalent than qnrS, with 100% of positive samples in urban wastewater and river and 71.4% of positive samples in animal wastewater. Densities of qnrA ranged from 2.3 × 10(2) gene copies (GC)/mL in urban wastewater to 7.4 × 10(1) GC/mL in animal wastewater. qnrS was detected in 38.9% of urban wastewater samples, in 22.2% of river samples and only in one animal wastewater sample (3.6%). Despite the lower prevalence, qnrS densities reached values of 10(3) GC/mL. Both qnr genes and other resistance genes assayed (blaTEM and blaCTX-M) showed a significant increase in DNA of phage particles when treated with EDTA or sodium citrate, while mitomycin C and ciprofloxacin showed no effect under the different conditions assayed. This study confirms the contribution of phages to the mobilization of resistance genes and the role of the environment and certain inducers in the spread of antibiotic resistance genes by means of phages.

Occurrence and suitability of pharmaceuticals and personal care products as molecular markers for raw wastewater contamination in surface water and groundwater

This study aimed to provide the first and comprehensive data on the occurrence of 17 target pharmaceuticals and personal care products (PPCPs) in urban water environment in Singapore. Meanwhile, this study also verified the suitability of these PPCPs as specific markers of raw wastewater contamination in receiving water bodies in highly urbanized areas where both surface water and groundwater are not impacted by the discharge of treated wastewater effluents. Analytical results of wastewater showed that among 17 target PPCPs examined, only 5 PPCPs were detected in 100 % of raw wastewater samples, including acetaminophen (ACT), carbamazepine (CBZ), caffeine (CF), diethyltoluamide (DEET), and salicylic acid (SA). Similarly, these PPCPs were found in most surface water and groundwater. Interestingly, the three PPCPs (ACT, CBZ, and SA) were only detected in surface water and groundwater in the sampling sites close to relatively older sewer systems, while they were absent in background samples that were collected from the catchment with no known wastewater sources. This suggests that ACT, CBZ, and SA can be used as specific molecular markers of raw wastewater in surface water and groundwater. This study also confirmed that CF and DEET were not really associated with wastewater sources, thus cannot serve well as specific molecular markers of wastewater contamination in receiving water bodies. To the best knowledge of the authors, the use of ACT and SA as specific molecular markers of raw wastewater contamination in urban surface waters and groundwater was first reported. Further studies on the use of ACT, CBZ, and SA along with other chemical/microbial markers are recommended to identify and differentiate contamination sources of surface waters/groundwater.

Toxicity evolution of alum-coagulated municipal wastewater to sea urchin embryogenesis and fertilization

The alum-based coagulation process is a worldwide treatment method in industrial and municipal wastewater (MW) management. In the present study, alum-coagulation was performed on wastewater from the MW plant located south of Naples, Italy, to evaluate any negative impact of MW on marine biota by means of sea urchin bioassays. A series of Jar test experiments (100 rpm for 1 min, 30 rpm for 20 min, and 30 min for settling) was performed using 150 and 450 mg/L of alum concentrations at pH ranging from 5 to 7 and room temperature (20° ± 2°C). Raw and alum-coagulated wastewater samples were analyzed for their COD and TSS, and residual aluminum (RA) concentrations. Toxicity testing of samples (diluted to 1%) by Sphaerechinus granularis sea urchin bioassays (collected in Naples bay) was evaluated to meet the following specifications: (a) acute and/or developmental toxicity, (b) changes in fertilization success, and (c) cytogenetic abnormalities. The results provided the following evidences: (i) the coagulation process at a 150 mg/L alum level in the SG plant was sufficient to meet the discharge standards; (ii) RA was found significantly related to alum dose used in coagulation process and raw wastewater alum concentration; (iii) sea urchin bioassays provided evidence for both embryo toxicity in raw wastewater to a lesser extent, and in alum-coagulated Jar test supernatants, at elevated extent, at a 1% concentration; and (iv) no statistically significant spermiotoxic or cytogenetic effect was observed. Altogether, the results highlighted the influence of wastewater characteristics on developmental toxicity, such as pH-related Al(III) speciation and alum complex formation in wastewater.

Distribution of polycyclic aromatic hydrocarbons in coke plant wastewater

The subject of examinations presented in this paper is the distribution of polycyclic aromatic hydrocarbons (PAHs) between solid and liquid phases in samples of raw wastewater and wastewater after treatment. The content of 16 PAHs according to the US EPA was determined in the samples of coke plant wastewater from the Zdzieszowice Coke Plant, Poland. The samples contained raw wastewater, wastewater after physico-chemical treatment as well as after biological treatment. The ΣPHA16 content varied between 255.050 μg L(-1) and 311.907 μg L(-1) in raw wastewater and between 0.940 and 4.465 μg L(-1) in wastewater after full treatment. Investigation of the distribution of PAHs showed that 71-84% of these compounds is adsorbed on the surface of suspended solids and 16-29% is dissolved in water. Distribution of individual PAHs and ΣPHA16 between solid phase and liquid phase was described with the use of statistically significant, linear equations. The calculated values of the partitioning coefficient Kp changed from 0.99 to 7.90 for naphthalene in samples containing mineral-organic suspension and acenaphthylene in samples with biological activated sludge, respectively.

Suitability of artificial sweeteners as indicators of raw wastewater contamination in surface water and groundwater

There is no quantitative data on the occurrence of artificial sweeteners in the aquatic environment in Southeast Asian countries, particularly no information on their suitability as indicators of raw wastewater contamination on surface water and groundwater. This study provided the first quantitative information on the occurrence of artificial sweeteners in raw wastewater, surface water and groundwater in the urban catchment area in Singapore. Acesulfame, cyclamate, saccharin, and sucralose were ubiquitous in raw wastewater samples at concentrations in the range of ng/L–μg/L, while other sweeteners were not found or found only in a few of the raw wastewater samples. Residential and commercial effluents were demonstrated to be the two main sources of artificial sweeteners entering the municipal sewer systems. Relatively higher concentrations of the detected sweeteners were frequently found in surface waters at the sampling sites located in the residential/commercial areas. No significant difference in the concentrations of the detected sweeteners in surface water or groundwater was noted between wet and dry weather conditions (unpaired T-test, p> 0.05). Relatively higher concentrations and detection frequencies of acesulfame, cyclamate and saccharin in surface water samples were observed at the potentially impacted sampling sites, while these sweeteners were absent in most of the background surface water samples. Similarly, acesulfame, cyclamate, and saccharin were found in most groundwater samples at the monitoring well (GW6), which is located close to known leaking sewer segment; whereas these were absent in the background monitoring well, which is located in the catchment with no known wastewater sources. Taken together, the results suggest that acesulfame, cyclamate, and saccharin can be used as potential indicators of raw wastewater contamination in surface water and groundwater.

Estimating daily and diurnal variations of illicit drug use in Hong Kong: A pilot study of using wastewater analysis in an Asian metropolitan city

The measurement of illicit drug metabolites in raw wastewater is increasingly being adopted as an approach to objectively monitor population-level drug use, and is an effective complement to traditional epidemiological methods. As such, it has been widely applied in western countries. In this study, we utilised this approach to assess drug use patterns over nine days during April 2011 in Hong Kong. Raw wastewater samples were collected from the largest wastewater treatment plant serving a community of approximately 3.5 million people and analysed for excreted drug residues including cocaine, ketamine, methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA) and key metabolites using liquid chromatography coupled with tandem mass spectrometry. The overall drug use pattern determined by wastewater analysis was consistent with that have seen amongst people coming into contact with services in relation to substance use; among our target drugs, ketamine (estimated consumption: 1400–1600mg/day/1000 people) was the predominant drug followed by methamphetamine (180–200mg/day/1000 people), cocaine (160–180mg/day/1000 people) and MDMA (not detected). The levels of these drugs were relatively steady throughout the monitoring period. Analysing samples at higher temporal resolution provided data on diurnal variations of drug residue loads. Elevated ratios of cocaine to benzoylecgonine were identified unexpectedly in three samples during the evening and night, providing evidence for potential dumping events of cocaine. This study provides the first application of wastewater analysis to quantitatively evaluate daily drug use in an Asian metropolitan community. Our data reinforces the benefit of wastewater monitoring to health and law enforcement authorities for strategic planning and evaluation of drug intervention strategies.

Spent green tea leaves for decolourisation of raw textile industry wastewater

True colour measurements of wastewater samples, in terms of American Dye Manufacturers' Institute values, were used to evaluate the effectiveness of decolourisation of textile wastewater using spent green tea leaf powder waste. Raw wastewater samples with a true colour of 868 ADMI were used in the batch adsorption experiments. Results revealed that the true colour removal efficiency of the raw textile wastewater was high in acidic solution and at high temperature, indicating an endothermic nature of the system. The major functional groups of the green tea leaf powder waste involved in adsorption were identified by Fourier Transform‐infrared spectroscopy analysis. Adsorption kinetic data were modelled using the modified Freundlich and intraparticle diffusion kinetics equations. Fitting results of the Langmuir adsorption isotherm showed that the adsorption capacity of the green tea leaf powder waste was 775 ADMI g−1, which is higher than that of powder activated carbon (526 ADMI g−1). The low activation energy values (13.9 kJ mol−1) suggested that adsorption was governed by a diffusion process and the reaction involved a physisorption mechanism. From the perspectives of waste utilisation, remarkable colour adsorption capacity and inexpensive and abundant availability, green tea leaf waste is an attractive alternative for decolourisaton of textile wastewater. Because high temperature favours colour removal, green tea leaf powder can be directly applied in raw textile wastewater treatment.