Water. Desalination + reuse
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Water. desalination + reuse September 2017 SPONSORED ARTICLE 15 Sustainability for Post Treatment / Rem- ineralization Processes The need to develop and improve sustain- able desalination processes includes also post treatment respectively remineralization of the desalinated water (permeate/distil- late). From a first glance, calcium carbon- ate based processes are the obvious choice for the remineralization and stabilization of desalinated water. This is since calcium carbonate is itself a source of both hardness and carbonate alkalinity - the two funda- mental water qualities that desal-permeate is lacking. Calcium carbonate is one of the most abun- dant and naturally occurring raw materi- als, making up just under 4% of the earth's crust. Furthermore, calcium carbonate is regenerated through the carbonate cycle and precipitation from water bodies mak- ing it a truly sustainable alternative for post- treatment processes. Omya Advanced Remineralization Pro- cess (OARP) in a nutshell Over the course of the past few years, Omya has been working on processes that use Omyaqua ® a micronized calcium carbonate for the remineralization of desalinated water and thereby exploit the technical and eco- nomic advantages that calcium carbonate has over lime, but at the same time address the drawbacks of calcite contactors, includ- ing its slow reactivity and large footprint required. The result is a new and innovative water stabilization process known as Omya Advanced Remineralization Process (OARP). A flow diagram of the process is shown above in Figure 1. At the heart of the process is the Membrane The use of Omyaqua ® micronized calcium carbonate with its specially engineered prop- erties for rapid dissolution, in combination with the Membrane Calcite Reactor (MCR) allows for the generation of higher concen- trations, and much decreased contact times with increased carbon dioxide efficiencies in comparison to calcite contactors. Short contact times also ensures the plant can respond very rapidly to changes in plant flow rate. Furthermore, a major advantage of the OARP process is the absence of generation of any backwash waste water since membrane backwash is made into the Membrane Cal- cite Reactor. This removes the requirement for backwash waste water treatment and sedimentation systems and thus allows for a zero-waste generating and handling process. Omyaqua ® micronized calcium carbonate products used within the Omya Advanced Remineralization Process is characterized by very high purity ensuring compliance to European Norm EN-1018 for Chemicals Used for Treatment of Water Intended for Human Consumption and the requirements of the American Standard NSF-60: Drinking Water Treatment Chemicals. Being a hazardous free micronized calcium carbonate product, it can be easily transported in various packag- ing, stored in a silo and fed from a hopper, all without caking and clogging, simplifying the delivery and dosage process. Interested in learning more about our Omya Advanced Remineralization Process? Join our webinar in collaboration with Water. desalination + reuse visit http://webinars.de- salination.biz/list to register Omya Advanced Remineralization Process THE BIG IDEA SPONSORED ARTICLE By JOchen KAllenBeRg & nichOlAs nelsOn Calcite Reactor (MCR) – a reactor contain- ing a submerged microfiltration membrane immersed in a suspension of micronized calcium carbonate. The use of modular com- ponents provides redundancy in the system, makes the process flexible in operation and allows for easy capacity expansions. Car- bon dioxide is added to the calcium car- bonate suspension, which in turns reacts to form a calcium bi-carbonate solution. The membrane acts as a barrier between the dissolved and undissolved calcium carbon- ate enabling a perfectly clear solution to be extracted from the reactor, and therefore ensuring a pristine water quality. This con- centrated calcium bi-carbonate solution is then dosed into the desalination permeate to increase both the hardness and alkalinity of the mineral-deficient water. The use of submerged membranes prohibits the introduction of turbidity as seen in the current techniques, whether due to the pre- cipitation of calcium carbonate within lime processes or from the loading of new prod- uct into the calcite contactors. Desalinated Water Permeate/Distillate CO 2 Membrane Calcite Reactor Calcium Bicarbonate Solution Omyalime pH adjustment pH/Alk/Turb Omyaqua® Micronized Calcium Carbonate Omya Advanced Remineralization Process (OARP) MF/UF Filtration H 2 O CaCO 3 CO 2 HCO 3 - Ca 2 + Omyaqua® Suspension Figure 1: Omya Advanced Remineralization Process