[0123] Operational results of the pilot test unit may also be better appreciated by reference to FIGS. 5, 6, 7, and 8. FIG. 5 illustrates the relationship between the axial differential pressure (!i.P) versus time, in pounds per square inch, for the reverse osmosis membrane employed in the pilot reverse osmosis test equipment. The differential pressure shown has not been corrected for changes in feedwater flowrate. In comparison to conventional RO, the pilot test results show that a stable normalized permeate flow rate, a stable silica rejection rate, and a stable differential pressure have been achieved. This indicates that fouling/scaling have been essentially eliminated in my new process. FIG. 6 shows the normalized permeate flow, in liters per minute, versus time over a six month period, for the reverse osmosis membrane employed in the pilot reverse osmosis test equipment. 

[0124] FIG. 7 illustrates the silica concentration in the reverse osmosis reject stream over a six month period in pilot reverse osmosis test equipment. FIG. 8 illustrates the rejection percentage of silica, versus time over a six month period, for the reverse osmosis membrane employed in pilot reverse osmosis test equipment. This silica rejection is based on an arithmetical mean silica concentration in the pilot RO unit. 

[0125] After each shutdown of pilot plant operation due to a ten percent (10%) or more decline in normalized permeate flow, the membranes were inspected and cleaned. An impor› tant finding was that cleaning can be simply and effectively accomplished by commodity membrane cleaning chemicals, such as hydrochloric acid solutions, tetrasodium EDTA, and sodium hydroxide. Expensive proprietary chemical cleaning agents were not required. An RO membrane operated with feedwater pretreatment in the manner set forth herein was proven to be completely restored to a flux of essentially one hundred percent (100%) of startup performance values. Substantially all of the cleaning was accomplished with the acidic first step of the cleaning process, thus indicating that calcium carbonate, magnesium hydroxide, magnesium sili› cate, and the like, were the predominant scaling species. Importantly, this revealed that neither silica scaling or bio› fouling were major concerns under the specified process conditions. The enhanced runnability, or increased system availability, with minimal scaling and virtually non-existent bio-fouling, is clearly another important benefit of my novel RO operational method. 

[0126] Biological fouling of thin film composite mem› branes has heretofore tended to be a common problem, and, with certain specific feedwater sources, has been virtually insurmountable. Although it was anticipated that control of biological fouling would be improved due to operation at relatively high pH levels, the degree of is biological fouling control actually achieved far exceeded expectations, with bacteria levels being virtually non-detectable during autopsy of RO membrane elements. This means that instead of accumulating living and dead bacteria against the membrane surface, as is common in conventional RO systems, in my unique method, incoming bacteria are killed and dissolved away from the membrane surface. Thus, this method of RO pretreatment and operation may become useful for treating problematic water sources. This is effective because high pH solutions cause disinfection by cell lysing or rupture of the cell wall. This is a quite potent and quick acting method of anti-bacterial activity, when compared, for example, with chlorination which acts by the much slower method of 

diffusion through the cell wall to cause death by inactivation of the microorganism’s enzymes. Also in contrast to chlorine sanitized systems, at the high pH operation preferred in the present method, viruses and endotoxins (lipopolysaccharide fragments derived from cell walls of Gram-negative bacte› ria) are effectively destroyed by lysis, thus enabling the present method to be employable for the production of pyrogen free or sterile water. In essence, the present method, when operated at a pH in excess of about 10, provides sanitization (3 log reduction in bacteria and destruction of vegetative matter), and may also prove to essentially provide true sterilization (12 log reduction in bacteria and the elimination of biofilm and spores) of the process equipment, as test results showed a zero (0) bacteria count in the permeate. Also, it should be noted that the increased pH of permeate in this method of operation enables similar, helpful results in the post RO treatment equipment. Such a method of operation should be of particular benefit in the production of high purity water for pharmaceutical applications, where the requirements for United States Pharmacopeia 23 ("USP 23") standards, as supplemented, must ultimately be met by the final product water. In this regard, the avoidance of use of raw water polymers, antiscalants, and other proprietary chemicals in RO pretreatment, as described herein with respect to a preferred embodiment, can eliminate undesir› able additives to pharmaceutical grade water, and reduce costs by reducing the necessary tests on RO product water. More concisely, the selection of a pH for RO operating conditions which does not support bacteria growth, and carrying out of hardness and alkalinity removal to a level which avoid use of additives, is a superior method for production of high purity water. 

[0127] A further benefit of high pH operation is with respect increased protection of membranes, particular the thin film composite types, which have limited tolerance for oxidizing agents at neutral, near neutral, and moderate alkaline pH’s (up to roughly pH 9). When chlorine is added to RO feedwater, gaseous chlorine (Cl$_{2}$ ) or sodium hypochlorite (NaOCl) are typically utilized. Because of membrane sensitivity to free chlorine, in conventional RO systems, it is normally removed by sulfite (SO$_{3}$ --) injection. However, above.pH 9, and particularly above pH 10, the effect of chlorine and other similar oxidants on thin film composite membranes is significantly reduced. This is because the concentration of the non-ionized species (such as HOCl, known as hypochlorous acid) is decreased dra› matically, since such acids are relatively weak. Conse› quently, in my HERO(tm) high pH reverse osmosis process, typically operating at a pH of 10 or higher, chlorine removal is not generally necessary, thus reducing system complexity and costs. This may be especially beneficial for those systems which utilize a municipal water source as the feedwater to the water treatment plant. 

[0128] Enhanced membrane life is also another benefit of my novel membrane operation process. In membrane opera› tions, and in particular with respect to RO operations, longer membrane element life may be expected, primarily because scaling and biofouling are avoided, and thus, exposure to harsh cleaning chemicals (for instance, acid chemicals and surfactants) is reduced dramatically. 

[0129] RO membranes are taken out of service when the rejection of critical species, for example silica, boron, or TOC, falls below an acceptable limit. For silica, this usually 

