## 3 Decentralized Treatment Systems
### Aquaculture Effluent Treatment
\begin{table}
\begin{tabular}{c c} \hline \hline
**Process and Methods** & **Notes** & **Ref.** \\ \hline MBR; vertical CW & The PCP removal capacity of the two systems was compared during 1 year. In both cases, water met reclaimed water reuse standards, but MBR gave better results. Temperature affected more seriously CW than MBR. & [127] \\  & After coagulation-sedimentation, GW was treated to obtain water to reuse in agriculture. HRT 2 days, removal COD 90.8\%, BOD 89.8\%, TSS 91\%. Effluent discharged in sewerage networks or for restricted use in irrigation & [128] \\  & In various scenarios, VCW, sand and pumice filtration and various adsorbent materials were combined. Incinerator bottom ash and dried stem of _P. australis_ were the best adsorbents. W.Q.: irrigation in rural areas (Iran). & [129] \\  & Different number and kind of filtration units (containing carbon or zeolite) were employed to treat GW at rural schools. After 80 min, turbidity-0. Treated water compiled with Chile guidelines for irrigation of recreational areas, or omamentals, or urban uses. Cost of the system: USD 2050-4450. & [130] \\  & Shower GW treated for 6 months by commercial UF and RO filters. After RO, COD, BOD, surfactants, TOC and _E. coli_ were under the DLs, 14 of 17 micropollutants were removed. W.Q. complied with the most stringent reuse requirements in USA. & [131] \\  & In a modular water reuse system, GW was treated sequentially, then two UV contact lamps provided at least 5.5-log removal for viruses. Water in storage tank was disinfected by UV generated O\({}_{3}\), for domestic uses. & [132] \\  & Kitchen GW treated by prefilter (MF), MBR using microbial consortia from the same GW, NF membrane synthesized using hydrophilized polyamide, UV disinfection, 500 L h\({}^{-1}\). W.Q.: irrigation, groundwater recharge, indirect use for humans, 82\% recovered. Cost: 0.0013 USD/L\({}^{-1}\). & [133] \\  & MBR effluent (HRT 2 d), BOD 0.4 mg L\({}^{-1}\), COD 13 mg L\({}^{-1}\). TC and _E. coli_-99\%, & \\  & NO UV disinfection. Water for crop irrigation, contained biofilm-forming bacteria: their identification helps in choosing appropriate disinfection and avoids possible RO membrane fouling. & [134] \\  & Wastewater & \\  & Full-scale pottable water system. Vertical flow CW, 60 m\({}^{2}\), 6-month activity, produced water for toilet flushing; then filtered on activated carbon, UF-RO, mixed-bed ion exchange, remineralized, UV disinfection. & [136] \\  & Reused as pottable water. & \\  & WTP secondary effluent treated by pre-ozonation, flocculation and DAF, sand filtration, main ozonation, BAC, GAC, UF. pH value adjusted and chlorinated obtaining pottable water. ARB and ARGs were under DL. & [137] \\  & In pilot plant (3 m\({}^{2}\)/person), during 2.5 years, domestic WW collected in septic tank, passed on compost bed, then on denitrification, phosphorous elimination and active carbon beds. HRT 6 days. Water used for toilet flushing and landscape. 50\% of water supply saved. & [138] \\  & Surface flow tank, vertical flow tank and horizontal flow tank, filled with gravel and sand, planted with _Scripus grosus_, treated successively 86.5 L d\({}^{-1}\) & [139] \\  & domestic WW. HRT 3 d. NH\({}_{4}\)+N \(-\)84.7\%; PO\({}_{4}\)-P \(-\)71\%. & \\  & Solar powered, high strong black and yellow WW treatment system: NEWgenerator\({}^{\text{TM}}\), operated one year and half in Africa. The Nutrient Capture System included 3 tanks, 360 L each, 2 filled with zeolite, 1 with GAC. Effluent free from _E. coli_ and helminits owa. W.Q.: except for TP, it met ISO 30500 standards [140] (Cat. A/B). & \\  & Photocatalytic treatment of domestic sewage (dark color, intense odor) by 100 mg L\({}^{-1}\) SrSnO\({}_{3}\)-C\({}_{3}\)N\({}_{4}\) (synthesized; 50\% mineralization obtained after 240 min, no coliforms or heterotrophic bacteria. W.Q.: Class 1 (domestic supply, water balance, agriculture) according to Brazilian standards. 1 & \\  & At 1 mM PMS, the treatment of UWW obtained: bacteria contaminants below DL after 15 min, CECs reduced by 80\% after 27 min, complete removal of ARGs after 120 min. Water reused in agriculture. Cost: 0.96 EUR/m\({}^{-3}\). & \\  & Aerobic granular sludge- and gravity-driven microfiltration system treated domestic WW (about 100 L d\({}^{-1}\)) for 1 year, HRT 8 h, producing effective removal of nutrients, \(>\)90\%, TSS of 60\%. W.Q: better than water produced by full-scale AeMBR, consuming less energy: 0.35 kWh m\({}^{-3}\) vs. 0.8. & \\ \hline \hline \end{tabular}
\end{table}