## 7 Discussion
### Efficiency Table Analysis  
Chlorination performed excellently in the inorganic contaminants category, as was expected from the literature. However, it was highly inefficient at removing organic contaminants. While phenol degraded in a minute, the chlorine concentration was high. These high doses could lead to a residual chlorine concentration beyond the maximum allowable limit of 4 mg/L if the contaminant concentration is insufficient. This would then require a declorination step on the plant, which increases the plant's capital and operating expenses. The two EDCs for which information was available was also poorly removed, with PFOS taking 6 h to degrade to only 83 %, and only 40 % of carbamazepine degrading in an hour. This unexpectedly poor performance from such a popular disinfectant highlights the need for advanced oxidation processes. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Contaminant Description**} & \multicolumn{3}{c}{**Non-Thermal Plasma Technology**} & \multicolumn{2}{c}{**Chlorination Technology**} & \multicolumn{2}{c}{**Ozonation Technology**} \\ \cline{3-8}  & **Plasma Type** & **PT (W \(\times\)** & **\%** & **CT (mg/L \(\times\)** & **\%** & **CT (mg/L \(\times\)** & **\%** \\)** & **\%** & **min** & **Removal** & **min** & **Removal** & **min**) & **Removal** \\ \hline Organic & Phenol & DBD 1 & 2430 [81] & 98 & 5570 [90] & 99 & 1200 [91] & \textgreater{}99 \\ Organic: EDC & Carbamazepine & DBD 1 & 36 [82] & 99.99 & 1065 [92] & 40 & 2.2 [93] & \textgreater{}99.9 \\ Organic: EDC & Oestrone & DBD 1 & 60,000 [71] & 83.6 & IDA 1 & IDA 1 & 0.06 [94] & 99.8 \\ Organic: EDC & PFOS & DBD 1 & 19,320 [83] & 93.5 & 1440 [95] & 83 & 840 [96] & 43 \\ \hline Inorganic & Manganese & IDA 2 & & & 1.161 [97; 98] & 99 & 0.792 [99] & 99 \\ Inorganic & Iron & IDA 2 & & & 0.496 [97; 98] & 99 & 0.344 [99] & 99 \\ \hline Pathogen & _E. coli_ & DBD 1 & 1080 [84] & 99.9 & 0.25 [100] & 99.99 & 0.05 [101] & 99.99 \\ Pathogen & _Cryptosporidium_ & AC 3 Gliding & 1647 [85] & \textgreater{}99 & 7200 [102] & 99 & 6.2 [103] & \textgreater{}99 \\ Pathogen & Norovirus & DBD 1 & 24 [106] & 99.99 & 2 [104] & 99.9 & 1.3 [105] & 99.99 \\ \hline Disinfection & Chloroform & DBD 1 & 18 [43; 71] & 80 & + 2 & & + 2  & & & & + 2  & & & & + 2  & & & + 2  & & & + 2  & & & + 2  & & & + 2  & & & + 2  & & & + 2  & & & + 2  & & & + 2  & & & + 2  & & & + 2  & & & + 2  & & & + 2  & & & + 2  & & & + 2  & & & + 2  & & & + 2  & & & + 2  & & & + 2  & & & + 2 [FOOTNOTE:2]Footnote 2: Dielectric barrier discharge reactor. 2 Insufficient data available. E. coli and norovirus were sufficiently degraded, which agreed with the literature. Cryptosporidium degradation was also as expected: reasonably high (99%), but at the expense of a high chlorine concentration and residence time. The chloroform and bromate degradation were not quantified because chlorination is more likely to produce these DBPs than to remove them. Next, ozonation was considered. It displayed a low CT value (0.06) for oestrone, which is generally difficult to remove. It also offered far better performance for carbamazepine removal than chlorine. This agreed with the literature, since ozone is known for its high oxidising abilities. However, chlorine exhibited more efficient phenol degradation (CT of 430 as opposed to 1200) and more effective PFOS removal (83 % versus 43 %), although chlorine did have a greater contact time. Ozone redeemed its superiority when analysing the organics: it had a CT value for iron and manganese that was approximately 30% lower than that of chlorine's. Ozone was also significantly superior to chlorine at pathogen degradation. Reductions of 99.99% were achieved for both _E. coli_ and norovirus, with the CT values being respectively one-fifth and approximately half of the corresponding chlorination CT values. Ozone's oxidative prowess was furthered by its rapid degradation of _Cryptosporidium_, which is considered a resistant pathogen.