Pretreatment 7 Water Quality Guidelines

Pretreatment At sea, evaporator condensate in port, evaporator condensate or water from shore facilities meeting feedwater quality guidelines. 

The federal guidelines [13] for state and local pretreatment programs reported the raw wastewater characteristics (Table 1) in mg/L concentration and the flows and water quality parameters (Table 2) based on the production or 1 ton of product manufactured for the subcategories of the industry. Most soap and detergent manufacturing plants contain two or more of the subcategories shown in Table 3, and their wastewaters are a composite of these individual unit processes. 

Clean Water Act (CWA 33 U.S. Code 1251 et seq.). Under the CWA, the U.S. EPA establishes water quality criteria used to develop water quality standards, technology-based effluent limitation guidelines, and pretreatment standards... 

Table 3.4 provides guidelines for a combination of treatment processes recommended for the effective pretreatment of the source seawater as a function of seawater turbidity and SDI levels. The pretreatment configurations shown in this table have to be used as a guideline only. Thorough water quality analysis and pilot testing are recommended to define an optimum pretreatment system for the site-specific source water quality of a given project. 

Membrane performance tends to naturally deteriorate over time due to a combination of material wear-and-tear and irreversible fouling of the membrane elements. Typically, membrane elements have to be replaced every 5-7 years to maintain their performance in terms of water quality and power demand for salt separation. Improvements of membrane element polymer chemistry and production process have made the membranes more durable and have extended their useful life. Use of elaborate granular media pretreatment technologies and ultra and microfiltration (UF and MF) membrane pretreatment systems prior to RO desalination is expected to allow extending the membrane useful life to 7 years and beyond, thereby reducing the costs for their replacement and the overall cost of water. Detailed guidelines for designing SWRO plants are provided elsewhere (AWWA, 2007). 

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