# High Rate Stormwater Treatment for Water Reuse and Conservation--Review
## 5 High-Rate Stormwater Treatment Technologies
### Applications of High-Rate Filter Systems
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Treatment Process** & **Influent (mg/L)** & **Anthracite (mg/L)** & **GAC (mg/L)** \\ \hline GAC filter & 2.3–6.9 (range) & & ND-1.0 (range) \\  & 4.6 (average) & & 0.1 (average) \\ \hline \multirow{2}{*}{Anthracite followed by GAC} & 2.3–6.9 (range) & 2.3–6.4 (range) & ND-1.0 (range) \\  & 4.6 (average) & 4.1 (average) & 0.1 (average) \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Total organic carbon values (modified from [PERSON] et al. [54]). conclusion of each operational day, the filter columns underwent a backwashing process lasting 60 s, which effectively kept the pressure across the columns below 1 bar. Table 8 presents the influent stormwater and effluent concentrations of total organic carbon (TOC). The results are based on seven samples taken daily for a period of three days. The GAC filter column achieved a TOC removal rate ranging from a minimum of 86% (0.95 mg/l) to over 99.9%, effectively adsorbing most organic matter. Additionally, one other treatment configuration was evaluated. It consisted of first an anthracite filter column and then a GAC filter column. However, incorporating the anthracite filter did not enhance the overall TOC removal. The average reduction rate by the anthracite filter for TOC was recorded at 10.8% with the anthracite filter showing a 4.1 mg/l decline in concentration decline. Table 9 presents the turbidity concentrations of influent stormwater. These findings are derived from seven samples collected daily over a period of three consecutive days. The granular activated carbon (GAC) filter alone achieved an average turbidity reduction of 84%. The average turbidity levels for the influent raw water and the effluent from the GAC filter were 29.2 NTU and 4.5 NTU, respectively. When an anthracite filter was incorporated into the treatment setup, the average turbidity removal became 71%, i.e., turbidity reduced from 28.9 NTU to 8.5 NTU. The GAC filter then further reduced the turbidity to 4.2 NTU. Heavy Metals: Table 10 summarizes the concentrations of heavy metals found in the influent stormwater. Typically, the raw stormwater showed low levels of these metals. The granular activated carbon (GAC) filter performed well, achieving notable reductions in most heavy metals. Most of the heavy metals were removed through adsorption, with average removal rates of 85% for aluminum, 94% for iron, 80% for manganese, and 64% for zinc, as indicated in Table 10. Parameters for the batch equilibrium adsorption models fit experimental data for Cu, Pb, and Zn adsorption on GAC are given in Table S1. Organic Characterization: The dissolved organic carbon (DOC) concentration in the canal water was measured at 5.86 mg/L, comprising 66% hydrophobic and 34% hydrophilic components. Various organic fractions were analyzed using LC-OCD (liquid chromatography organic carbon detection). Within the hydrophilic fraction, humic substances represented 52%, building blocks (23%), biopolymers (8%), and lower molecular neutrals and acids (16%). For comparison, Table 11 provides data for raw rainwa \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & \multirow{2}{*}{**Raw Canal (mg/L)**} & \multicolumn{2}{c}{**Treatment**} \\ \cline{3-4}  & & **GAC Filter Alone** & **Anthracite Followed by GAC Filter (mg/L)** \\ \hline Aluminum & 0.25 & 0.038 & ND \\ \hline Copper & 0.025 & NA & 0.019 \\ \hline Iron & 1.277 & 0.082 & NA \\ \hline Manganese & 0.478 & 0.098 & 0.053 \\ \hline Lead & 0.003 & NA & 0.002 \\ \hline Zinc & 0.058 & 0.021 & 0.038 \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Removal of heavy metals using filtration/adsorption columns (modified from [PERSON] et al. [54]).