A new phosphorous-free antiscalant for membrane desalination

Abstract

ab s t r ac tPhosphorous containing antiscalants, which are commonly used in RO desalination process, have become an environmental concern for RO concentrate disposal. These chemicals are suspected of contributing to algal blooms in the water bodies where RO concentrate is discharged. Therefore, phosphorous-free antiscalants are increasingly being required for both brackish and seawater membrane desalination systems. Nalco recently developed a phosphorous-free antiscalant (PC-1611T) to address this environmental concern. In the laboratory testing, this product performed similar to ATMP (commonly used phosphonate based antiscalant) for CaCO 3 scale inhibition up to 3.0 LSI (Langelier Saturation Index). It also inhibited CaCO 3 scale in presence of up to 1 ppm Fe 3+ and residual levels of poly(DADMAC) based pre-treatment coagulant. It also showed 2-5× lower bio-growth contribution potential than polycarboxylates and is compatible with polyamide RO membranes. Full-scale evaluation of this product is in progress and the results for first 4 weeks show stable RO performance, indicating successful scale-control.