The UFTEC project has proven the feasibility of direct UF as a substitution of conventional pre-treatment in challenging surface water sources.
The innovative scheme proposed for DWTPs in the UFTEC project (direct UF followed by RO) offers technical advantages versus conventional pre-treatment:
- High and constant UF permeate quality independently of incoming water quality.
- Reduction of fouling impact on subsequent RO stage (lower SDIs indexes) and thus, increase of productivity in RO units by decreasing the cleaning frequency requested
- Soft need of coagulant for some feed water quality conditions (and hence, minimal sludge generation).
- Elimination of the dioxichlorination step. Hence, reduction of the THMs potential formation and reduction of potential RO membrane damages by chlorinated products.
- Modularity (and thus, easiness to scale-up).
- Capacity to work even at extremely high turbidities (>1000 NTU), increasing water availability.
- Operation easiness.
The environmental impact of the direct UF concept has been assessed during the project, concluding that the global warming impact of this technology is similar to the produced by a conventional pre-treatment in a scale-up plant. Sludge treatment has not been considered though and should be included in further studies. Energy consumption is the main contributor in the case of direct UF schemes, and thus, future studies should investigate the reduction of energy requirements in these treatments.
The cost-effectiveness analysis demonstrates that this technology is especially costly-effective for the reduction fouling indexes (SDI and MFI), which makes it an interesting alternative as a pre-treatment for subsequent RO processes in challenging surface waters.
Conventional pre-treatment alone would not be technically feasible for subsequent RO and in consequence, other combined pre-treatment would be needed. That fact would increase the costs and the final environmental impact for the conventional pre-treatment scheme.
Because the case study selected, the Llobregat River, is highly variable, multiple scenarios have been assessed. Since direct UF has demonstrated to be feasible with this challenging water source, it may be applicable in further sites, being the results highly transferable among other sites. Therefore, the innovative scheme proposed could be applied at short-term either for the construction and the upgrade of DWTPs, paving the way for the implantation of more stringent pieces of legislation and upcoming challenges. In the long-term, the proposed scheme could be used for treating challenging water sources in water scarcity areas.