Patent ID: 7736513
Filing Date: 2010-06-15
Classification: C02F,Y02W,Y10S

Abstract:
1. A process for biological nutrient removal in a raw wastewater feed stream to remove carbon, nitrogen and phosphorus therefrom, comprising the steps of: flowing raw wastewater feed stream into a first fluidized bed and flowing a first fluidizing fluid into the first fluidized bed and passing solid particles having effective immobilized bacteria coated thereon and the first fluidizing fluid through an anoxic zone maintained under anoxic conditions suitable for denitrification of raw wastewater constitutents flowing through the anoxic zone, said first fluidized bed being operated with a liquid velocity of the first fluidizing fluid being lower than a transition velocity from a particulate fluidization regime to a fast fluidization regime; circulating said solid particles and the first fluidizing fluid through an anaerobic zone maintained under anaerobic conditions in said first fluidized bed suitable for the release of stored phosphorus; separating some of said first fluidizing fluid from said solid particles to form a recycle stream and circulating said solid particles and a remaining amount of the first fluidizing fluid into a second fluidized bed, wherein the first fluidizing fluid includes at least the recycle stream which is flowed into the first fluidized bed; circulating the particles transferred to the second fluidized bed with a stream of a second fluidizing fluid through the second fluidized bed, the second fluidized bed having an aerobic zone maintained under aerobic conditions suitable for biodegradation of raw wastewater constitutents forming part of the second fluidizing fluid in the presence of oxygen to carbon dioxide, water, and nitrates by the immobilized bacteria to produce nitrified effluent from the aerobic zone; and circulating solid particles from said second fluidized bed to the first fluidized bed along with a part of the nitrified effluent and separating the remaining nitrified effluent from said solid particles in said second fluidized bed and removing a portion of this separated nitrified effluent from the system as treated effluent and recycling the rest back into an inlet to the second fluidized bed to form the second fluidizing fluid.