## 3 Results and Discussion
### Automated Column Sorption System  
#### 3.2.1 Sampling Sequence and Flow Rate  
Table 3 provides the timeline of modes in the system set-up sequence. Once the inlet tubing and check valve are primed, the pump starts to fill the inlet connection cavity. At full flow rate in Mode-I, it requires approximately 8:39 mins to travel from the base to the top of column 1 (C1). After approximately 3:40 mins, sample chamber 1 (SC1) is filled, and Mode-II (circulation) is initiated while the first sample (C1-A) is collected. In the continuous flow of Mode-II, and it requires approximately 8:27 mins for the flow to travel from the base to the top of column 2 (C2). The flow is then switched to Mode-III (pulse), which divides the flow to fill both sample chambers SC1 and SC2. Once the 30-mL volumes are filled, Mode-III is switched back to Mode-II and the samples C1-B and C2-B are collected at 42:50 mins. Once the system is set-up, there is an orderly switch between Mode-II (circulation) and Mode-III (pulse). Table 4 summarizes this sampling sequence. Altogether, there are twenty-nine 30-mL samples collected throughout the analysis period. During the system set-up, the collection of the first sample (C1-A) is followed by the second column 1 sample (C1-B) and first column 2 sample (C2-B). The orderly sequence begins at the collection of Cx-1 (48:04 mins), for a total of two samples for each of the thirteen (13) runs. A total waste (TW) sample in the collection basin of the sorption system is also collected half-way through sampling (115:45 mins) and at the end of the analysis period (195:00 mins). The final influent stock and total effluent volumes are approximately 1.45-L and 550-mL, respectively. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**MODE** & **Function** & **Flow Description** & **Time (min:s)** \\ \hline \multirow{4}{*}{I} & \multirow{4}{*}{Fill C1} & Primed Inlet to C1 Base & 2:26 \\ \cline{3-4}  & & C1 Base to C1 Top & 11:05 \\ \cline{3-4}  & & C1 Top to SC1 Drip & 15:10 \\ \cline{2-4}  & \multirow{4}{*}{Fill SC1} & Sample C1-A & 18:50 \\ \cline{3-4}  & & C2 Inlet to C2 Base to C2 Top & 24:08 \\ \cline{3-4}  & & C2 Base to C2 Top & 32:35 \\ \cline{3-4}  & & C2 Top to SC2 Drip & 36:14 \\ \hline \multirow{2}{*}{II} & \multirow{2}{*}{Fill SC1 and SC2} & Sample C1-B and C2-B & 42:50 \\ \cline{3-4}  & & C2 Inlet to C2 Base to C2 Top & 48:04 \\ \cline{3-4}  & & C2 Top to SC2 Drip & 36:14 \\ \hline \multirow{2}{*}{III} & \multirow{2}{*}{Fill SC1 and SC2} & Sample C1-B and C2-B & 42:50 \\ \cline{3-4}  & & C2 Top to SC2 Drip & 48:04 \\ \hline \multirow{2}{*}{III} & \multirow{2}{*}{Fill SC1 and SC2} & Sample C1-1 and C2-1 & 54:27 \\ \cline{3-4}  & & C2 Top to SC2 Drip & 36:14 \\ \hline \multirow{2}{*}{III} & \multirow{2}{*}{Fill SC1 and SC2} & Sample C1-B and C2-B & 42:50 \\ \cline{3-4}  & & C2 Top to SC2 Drip & 48:04 \\ \hline \multirow{2}{*}{III} & \multirow{2}{*}{Fill SC1 and SC2} & Sample C1-B and C2-B & 42:50 \\ \cline{3-4}  & & C2 Top to SC2 Drip & 48:04 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Sorption system set-up sequence. The flow patterns are continuous and methodically kept consistent throughout the analysis period. Once samples C1-B and C2-B are collected, an average time of 6:26 min:s passes to switch from Mode-III to Mode-II, and 5:05 mins:s from Mode-II to Mode-III. When the flow is divided in Mode-III, the average sampling acquisition time of 6:19 mins:s is required to fill the 30-mL chambers, which is then collected for the filtering and dilution of the 25-mL sub-sample. The adjustable bi-stable timer at an approximate 50% duty setting automatically toggles the pulsing in Mode-III, to maintain a relatively consistent division of flow between the two columns, creating partial diversion to the two sampling chambers. This is demonstrated in relation to the start and end times of the sampling sequence. It is important to note that the first sorption column (C1) receives a continuous inlet flow rate, as observed by the Mode-I filling rate of 8.18 mL/min for SC1 sample C1-A.