Reclamation feed water

Another good example is the NEWater project in Singapore shown in Fig. 11 (36). The advanced water reclamation demonstration plant has been operated for 4 yr to produce 10,000 mVd of high-grade water. The source water (feed), which is the effluent from a conventional biological treatment plant, is first treated by microfiltration (MF) and reverse osmosis (RO), and then disinfected by UV radiation, and subsequently adjusted by acid, base, and carbonate in order to have a sufficient alkalinity. The source... 

The superior flux and rejection capabilities of the thin film composite membrane has been demonstrated at the municipal wastewater reclamation facility of the Orange County Water District in California. Both asymmetric cellulose acetate and thin film composite membranes were tested on lime clarified secondary effluent. The pilot plants were operated at 85% recovery and the rejections reported in Table 4.5 are the percent rejection of the constituents in the feed-water and not the rejection of the average concentration of the specific constituents in the feed/reject stream. Use of the average concentration would give a higher rejection in both cases. 

Water reclamation Backwashing enables the MF/UF systems to run on feed water with turbidity up to 500 NTU. 

TABLE 7.1 Comparison of Feed Water Quality for Reclamation and Desalination... 

Reverse osmosis continues to be dominated by desalination, that is, by removing salt from water. The substantial range of applications includes seawater, brackish water, and reclamation of municipal waste water. Similar membranes can be used to pretreat boiler feed water, desirable because pretreated water forms scale in boilers more slowly. There... 

For relatively low solids content feeds, it is feasible to operate without continuous cross flow or surface shear, and this can reduce energy costs. Such applications include water treatment and pretreatment for RO desalination and reclamation. This mode of operation is called dead-end filtration or frontal filtration, and the key feature is that the deposition of retained species is allowed to grow. A t5q)ical cycle commences with a clean membrane (after backwash), and at constant flux the TMP rises according to Eq. (10.4). After a specified period (Q, or at a predetermined AP iax. the flux is stopped and the deposit is removed by backwashing and (usually) vigorous aeration. The contents of the membrane... 

Because of its ability to remove minute particles such as fats, protein and pathogens [29,216], membrane filtration is another widely used technology of choice for superior water and large-scale reclamation of waste-water. The factors such as pressure, chemical composition, temperature, feed flow and interactions between components in the feed flow and the membrane surface influence the separation performance of membranes [116]. Conventional techniques have their own inherent limitations such as less efficiency, sensitive operating conditions, production of secondary sludge and further the disposal is a costly affair [4, 41, 199]. Another powerful technology is adsorption of heavy metals from industrial waste-water [77, 79]. 

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