Applications of antiscalants to control calcium sulfate scaling in reverse osmosis systems

Kinetic and morphological investigation of calcium sulfate dihydrate (gypsum) scale formation on heat exchanger surfaces in the presence of inhibitors

“…As illustrated these polymers vary significantly both in terms of ionic charge of the functional groups present in monomer(s) and the MW. It has been previously reported [4] that influence of polymeric and non-polymeric additives as gypsum growth inhibitors falls into two categories: those additives that affect the induction period and those that show no significant effect on the induction period preceding the gypsum crystal growth. The calcium-time profiles for the first type were observed for the better additive while profiles for the second type were obtained for less effective additives.…”

“…Amjad [4] in a study using the seeded growth method, reported that trace amounts of low molecular weight poly(acrylic acid), PAA, can stabilize supersaturated solutions and lengthen the induction time before the onset of crystallization. The duration of induction times observed in the presence of polymers was found to be greatly influenced by the polymer concentration, solution temperature, pH, and the amount of gypsum seed crystals added.…”

Pilot-scale study on the reverse osmosis treatment of oil sands tailings pond water: Impact of pretreatment on process performance

“…The primary obstacles in operating the RO system were the mineral scaling and organic fouling [14]. Scaling was mitigated through the use of antiscalants (Hydrex 4102; Veolia Water Technologies), pH control, and chemical cleaning [15,16], while organic fouling was mitigated by the occasional application of biocide (Nalco Permaclean PC-11) to prevent biological growth and by chemical cleaning [17]. The treatment train 1 tests were carried out from November 2nd to December 12th, 2012.…”

Synthesis and evaluation of phosphate-free antiscalants to control CaSO 4 ·2H 2 O scale formation in reverse osmosis desalination plants

“…Harris [4] discussed the effect of various additives in inhibiting the precipitation of alkaline scale (e.g., calcium carbonate, magnesium hydroxide) and sulfate scale (e.g., calcium sulfate, strontium sulfate) in desalination plants. Amjad [5] presented the influence of various antiscalants such as polyphosphates, phosphonates, polystyrene sulfonate, polyacrylamide, polyacrylate and formulated polyelectrolytes on crystallization and crystal modification process of gypsum scale at 25°C. It is reported [6] that some correlation exists between the structure of the inhibitors and the inorganic scale.…”