Treatment of canal water with ultrafiltration to produce industrial and household water

Pretreatment in Reverse Osmosis Seawater Desalination: A Short Review

“…At oxidant doses practical for pretreatment, previous studies of conventional water treatment have demonstrated that chlorine and permanganate can be added to the feed water to suppress the growth of microorganisms and maintain oxidative conditions in the water; ozone can partially oxidize natural organic matter (NOM) and increase the assimilable organic carbon that may be removed by downstream biological filters [70]. A previous study found that the concentration of manganese in the permeate of a pilot-scale UF system decreased from 0.16-0.19 mg/L to below the targeted 0.05 mg/L with the addition of KMnO 4 as a result of oxidation and precipitation of soluble Mn species [71]. The presence of low levels of ozone may also improve the removal of organic or organic-coated particles by coagulation and filtration, which indicates a change to the stability or reactivity of…”

Micro‐coagulation effects on direct ultrafiltration of challenging raw river water

“…In drinking water treatment plants (DWTPs) dealing with surface water, ultrafiltration (UF) is typically implemented after a preliminary pre‐treatment consisting of coagulation/flocculation, settling and granular media filtration, sometimes assisted by an initial disinfection. However, some studies have addressed the possibility of raw river water direct UF as an alternative to conventional pre‐treatment for DWTPs . The associated envisaged advantages would be a decrease in reagents dosage and thus in solid waste generation, low footprint, ease of implementation due to its modularity as well as a decrease in the capital and operational expenses of a subsequent reverse osmosis (RO) stage …”

“…On the other hand, other studies reported successful results, confirming the feasibility of UF as an alternative to coagulation, sedimentation/flotation and rapid sand filtration, 10 being feasible especially for those waters with high variability in quality. 6 For example, Rojas et al 6 worked with reservoir water (4)(5)(6)(7)(8)(9)(10)(11)(12)(13) for 180 days at 54 L m −2 h −1 of filtration flux and 93% of water yield (ratio between net permeate produced and intaken water), Hofman et al 4 with canal water (12-40 NTU) for almost 1 year, at filtration flows of 70-100 L m −2 h −1 , Vos et al 7 with canal water (20-70 NTU) for 11-30 days at 50 L m −2 h −1 , only achievable after optimizing the backwash and chemical cleaning operations, and Oosterom et al 10 with surface water of unreported quality, for 800 h, obtained a large decrease in permeability (from > 400 L m −2 h −1 bar −1 to < 50 L m −2 h −1 bar −1 ) after 200 h of filtration. The reported water yields for UF of surface water without extensive pre-treatment were generally low; Schlichter et al 11 quantified them at 70-90%.…”

“…As can be seen, the initial experiences reported with successful results were performed for a few days/months 6,7 and/or with raw water of relatively stable quality. 4,6,7 As a consequence, their results cannot be extrapolated to full scale plants, which need to operate continuously, often with variable feed water. Due to the discrepancies in the conclusions drawn, together with the different conditions tested which make comparison of the results difficult, more research is needed to determine the feasibility of direct UF, to optimize its performance under different scenarios and finally to compare it with conventional pre-treatment.…”

“…The reported water yields for UF of surface water without extensive pre‐treatment were generally low; Schlichter et al quantified them at 70–90%. As can be seen, the initial experiences reported with successful results were performed for a few days/months and/or with raw water of relatively stable quality . As a consequence, their results cannot be extrapolated to full scale plants, which need to operate continuously, often with variable feed water.…”