Catalytic Partial Desalination of Saline Water

Abstract

More than 1 billion ha of land is adversely affected by salinization, including about 54 million ha of irrigated cropland. This study trials a batch flow, bubble column, static bed, catalytic, pressure swing adsorption−desorption, zero valent iron, and diffusion reactor train, which is designed to partially desalinate water, for use as either livestock feed water or partially desalinated irrigation water. ZVI desalination produces a partially desalinated water product, without producing a waste brine product. The trial demonstrates sequential batch processing of 50 (0.86 m3) batches of saline water (43 m3 total), using a single ZVI charge, without loss of activity. The trialed feed water contained between 1 and 9 g NaCl L−1. The average desalination was 41.84% (standard deviation was 15.61%). The optimum batch processing time is determined as being between 12 and 24 h. For each batch, the first-order forward rate constants, for both Cl− and Na+ ion removal, decline with time. The study considers the irrigation application of the product water on crop yield for 70 crop varieties; the application of the technology to desalinate a saline aquifer; applications of the technology to improve the environmental efficiency of conventional desalination plants.

Desalination of Irrigation Water Using Metal Polymers

“…The observed ion decline patterns (Supplementary Information, Figures S1-S24), could be interpreted as a function of Equations ( 18) and (19).…”

“…Using Fe n+ ions to manufacture SiO 2 supported polymers of the form SiO 2 @Fe(a,b,c) and SiO 2 @Fe(a,b,c)@urea, where the pH increase is effected by bubbling air through the water [19]. Cyclic pressure fluctuations in the water are used to promote adsorption and desorption from the polymer.…”

“…Catalyst regeneration is achieved by replacing the partially desalinated water with a fresh saline water charge. A single polymer charge containing 10 g Fe was demonstrated to process 50 batches of water (43 m 3 ) without loss of activity [19]. It was proposed that the polymer catalyses the formation of entrained polymer particles in the water using metal cations present in the feed water [19].…”

“…A single polymer charge containing 10 g Fe was demonstrated to process 50 batches of water (43 m 3 ) without loss of activity [19]. It was proposed that the polymer catalyses the formation of entrained polymer particles in the water using metal cations present in the feed water [19]. The water contained Fe, Ca, Mg and Al ions.…”

“…The associated anions considered are SO 4 2− , R-COO − , CO 3 2− , OH − , and O 2− . A detailed screening methodology, which will allow the expected impact of partial desalination on crop yield, for 70 different crop types, to be quickly assessed, is provided in references [18,19].…”