397
magnitude) has been observed for some ECs where chlorine and acetaminophen were
found within influent wastewater at mean concentrations ranging from 6924 to
492,340 ng/L [11, 12]. This indicates spatial and/or temporal variations in their usage.
However, dilution from industrial inputs, degradation within the upstream sewer, and
rainfall and sampling mode will all contribute to this variability. The use of inappropriate sampling strategies is considered the greatest weakness of reported occurrence
data. Ort et al. gave an excellent account of uncertainties associated with different
sampling modes. Current approaches tend to use sampling of low inter-day frequency
and often no intraday repetition. This approach has limitations as it only yields a
snapshot of EC concentration for a specific point of time. Time- and volume/flowproportional composite samplers are also reported, but to a lesser extent [13, 14]. The
latter are preferred as it accounts for fluctuations in flow. The relatively high cost and
logistical issues associated with this sampling mode have resulted in very few studies
applying flow-proportional sampling report. Also, a major uncertainty of 24-h composite sampling is chemical stability. This is not often investigated but is known to be
significant for some chemicals [15, 16]. Due to uncertainties of existing sampling
methods, there is lack of understanding on spatial and temporal variations in EC concentrations. Consequently, on the other hand, studies have been able to tentatively
assess spatial distribution of microorganisms within the water catchment [17, 18].
Such studies must rely heavily on sampling due to the large number of sites which are
monitored at approximately the same time. Despite the uncertainties associated with
sampling report, information attained from such studies is extremely valuable. It was
used as a primary indicator of sites within the catchment that require more detailed
study. These can then be subject to more robust sampling protocols to facilitate greater
understanding of EC fate and occurrence during wastewater treatment and in the environment at these predetermined sites of interest.
Results and Discussion
It is anticipated that concentrations of ECs in receiving wastewater vary throughout
the day. The collected hourly composite samples (i.e., one sample every 15 min to
create an hourly composite) for influent wastewater over 24-h sampling periods
were used to investigate within-day variability of chlorine and acetaminophen concentrations. Samples were chilled upon collection but their stability at 4 °C was not
investigated or referenced to. However, significant degradation (>15%) has been
observed for some ECs stored at 4 °C for only 12 h. Despite this uncertainty, due to
the presence of chlorine and acetaminophen in the water the microbial contaminants
showed variation in concentration throughout the day [19, 20]. A peak in receiving
load was observed between 07:00 and 9:00 h [7, 17, 21]. Therefore, the response of
wastewater treatment process (WwTP) to this daily spike in receiving concentration
and volumetric load has been analyzed to get the influence of microorganism on
water contamination in different concentrations of microorganism and time
(Fig. 19.1).
Results and Discussion
magnitude) has been observed for some ECs where chlorine and acetaminophen were
found within influent wastewater at mean concentrations ranging from 6924 to
492,340 ng/L [11, 12]. This indicates spatial and/or temporal variations in their usage.
However, dilution from industrial inputs, degradation within the upstream sewer, and
rainfall and sampling mode will all contribute to this variability. The use of inappropriate sampling strategies is considered the greatest weakness of reported occurrence
data. Ort et al. gave an excellent account of uncertainties associated with different
sampling modes. Current approaches tend to use sampling of low inter-day frequency
and often no intraday repetition. This approach has limitations as it only yields a
snapshot of EC concentration for a specific point of time. Time- and volume/flowproportional composite samplers are also reported, but to a lesser extent [13, 14]. The
latter are preferred as it accounts for fluctuations in flow. The relatively high cost and
logistical issues associated with this sampling mode have resulted in very few studies
applying flow-proportional sampling report. Also, a major uncertainty of 24-h composite sampling is chemical stability. This is not often investigated but is known to be
significant for some chemicals [15, 16]. Due to uncertainties of existing sampling
methods, there is lack of understanding on spatial and temporal variations in EC concentrations. Consequently, on the other hand, studies have been able to tentatively
assess spatial distribution of microorganisms within the water catchment [17, 18].
Such studies must rely heavily on sampling due to the large number of sites which are
monitored at approximately the same time. Despite the uncertainties associated with
sampling report, information attained from such studies is extremely valuable. It was
used as a primary indicator of sites within the catchment that require more detailed
study. These can then be subject to more robust sampling protocols to facilitate greater
understanding of EC fate and occurrence during wastewater treatment and in the environment at these predetermined sites of interest.
Results and Discussion
It is anticipated that concentrations of ECs in receiving wastewater vary throughout
the day. The collected hourly composite samples (i.e., one sample every 15 min to
create an hourly composite) for influent wastewater over 24-h sampling periods
were used to investigate within-day variability of chlorine and acetaminophen concentrations. Samples were chilled upon collection but their stability at 4 °C was not
investigated or referenced to. However, significant degradation (>15%) has been
observed for some ECs stored at 4 °C for only 12 h. Despite this uncertainty, due to
the presence of chlorine and acetaminophen in the water the microbial contaminants
showed variation in concentration throughout the day [19, 20]. A peak in receiving
load was observed between 07:00 and 9:00 h [7, 17, 21]. Therefore, the response of
wastewater treatment process (WwTP) to this daily spike in receiving concentration
and volumetric load has been analyzed to get the influence of microorganism on
water contamination in different concentrations of microorganism and time
(Fig. 19.1).
Results and Discussion