Colloid and silt fouling are the major causes of loss in performance of membrane separation systems. For this reason, many system designs include upstream multimedia filtration which involves a variety of mechanisms to achieve particle removal. When added to the feedwater, RoQuest® coagulants neutralize the negative electrostatic charges on both particles and filter media surfaces. Elimination of these charges makes collisions and attachments between particles and media grain surfaces possible.
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Avista Technologies formulates a variety of liquid coagulant/flocculant chemicals under the RoQuest® name. RoQuest® 3000 is an organic polymer while the RoQuest® 4000, 5000, and 6000 are a blend of organic coagulants and ferric sulfate.
RoQuest® formulations change the behavior of particles and colloids which normally exhibit negative charges in naturally occurring feed waters. Because like charges repel each other and unlike charges attract each other, the addition of the positively charged RoQuest® polymer allows the negatively charged particles to clump together. This creates larger particles which are more readily retained in the multimedia filter (MMF), resulting in improved MMF filtration.
Studies have proven that MMF performance without coagulant addition will remove approximately 35% - 50% of the feedwater particulates. A nominal dosage of a RoQuest® coagulant may allow the MMF to remove up to 98% of the particulates, resulting in improved effluent turbidity and reduced SDI values. The resulting improvement in filtrate quality positively effects the downstream filtration equipment including reduced cleaning frequencies and longer system run times of membrane systems.
RoQuest® is available in 45-pound pails, 500-pound drums, and 2500-pound totebins. Bulk deliveries are also available.
