Q2. What is the cause of the concentrations of amphetamine in the urine?
Amphetamine concentrations observed in this study might be due to methamphetamine metabolism in human body, causing it to appear in urine.
Q3. How many minutes of sampling frequency in this study could cause uncertainty?
Fifteen minutes of sampling frequency in this study could also cause uncertainty as short-term variations in drugs’ loads can be easily ignored (Ort et al. 2010).
Q4. What is the way to remove DOAs from wastewater?
Although MBR is considered advanced wastewater treatment and is expected to perform better in terms of removal efficiencies for conventional parameters, activated sludge has also shown to be very efficient process for removal of DOAs (Yadav et al. 2017).
Q5. What was the mean concentration of cotinine in the wastewater effluent?
The mean concentrations of cotinine and methamphetamine were found to be in range of 50-100 ng/L while the mean concentrations of methadone and EDDP ranged between 0-50 ng/L in the effluent.
Q6. What is the effect of the secondary treatment on the removal efficiency of amphetamine?
Negative removal efficiency can be explained by the deconjugation of glucuronides metabolites in the secondary treatment process (Subedi and Kannan 2014).
Q7. Why was the concentration of amphetamine higher in the secondary treatment?
The higher effluent concentration of amphetamine could be because of transformation of methamphetamine to amphetamine during secondary treatment (Heuett et al. 2015).
Q8. Why have DOAs been detected in surface water?
These DOAs and their metabolites have also been detected in surface water ranging from sub-ng level to >100 ng/L, due to their inefficient removal during wastewater treatment (Yadav et al. 2017).
Q9. What was the correction factor used to estimate the daily consumption of pure alcohol?
The correction factor of 3,047 and alcohol density of 789 kg/m3 were used to estimate the daily consumption of pure alcohol on a volume basis (Rodríguez-Álvarez et al. 2015, Yin et al. 2018).ACCEPTED MANUSCRIPTAC
Q10. What is the reason for the discrepancy between estimation of alcohol consumption in this study?
The discrepancy between estimation of alcohol consumption in this study estimated by WBE and by epidemiological surveys could be because of in-sewer degradation of alcohol markers.