US 11,851,352 B2
Biomass selection and control for continuous flow granular/flocculent activated sludge processes
Hiren Trivedi, Cedar Park, TX (US); John Vorwaller, Salt Lake City, UT (US); Tyson Beaman, Murray, UT (US); Sophia Baker, Ogden, UT (US); Sergio Pino-Jelcic, Salt Lake City, UT (US); and David Stensel, Mercer Island, WA (US)
Assigned to Ovivo Inc., Montreal (CA)
Filed by Ovivo Inc., Montreal (CA)
Filed on Aug. 20, 2021, as Appl. No. 17/445,558.
Application 17/445,558 is a division of application No. 17/027,528, filed on Sep. 21, 2020, granted, now 11,161,760.
Application 17/027,528 is a continuation in part of application No. 16/537,379, filed on Aug. 9, 2019, granted, now 10,781,125, issued on Sep. 22, 2020.
Claims priority of provisional application 62/718,313, filed on Aug. 13, 2018.
Prior Publication US 2021/0380443 A1, Dec. 9, 2021
Int. Cl. C02F 1/52 (2023.01); C02F 3/02 (2023.01); C02F 1/00 (2023.01)
CPC C02F 1/52 (2013.01) [C02F 3/02 (2013.01); C02F 2001/007 (2013.01); C02F 2301/046 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A wastewater treatment process with a series of process zones including biological process zones, with continuous flow of influent wastewater through the series of zones, a first of the biological process zones being an anaerobic zone for encouraging selective growth of granular biomass, comprising:
providing at least two successive stages in the anaerobic zone, including a first stage and a second stage,
into the continuous flow of influent wastewater, introducing a first portion of a recycled activated sludge (RAS) stream from a downstream process zone of the series of process zones to produce a continuous combined raw influent/RAS flow into the first stage,
the first stage being of preselected volume, and dwell time in the first stage being no greater than 30 minutes, promoting contact between the influent wastewater, with food, and the RAS, with biological activity, such that granular biomass present in the RAS is exposed to the food of the influent wastewater for consumption and storage leading to growth of granules in further process zones,
operating a mixer in the first stage to mix the RAS and incoming wastewater to provide a mixed liquor,
moving the mixed liquor in continuous flow to the second stage,
introducing to a bottom region of the second stage a second, remaining portion of the RAS to mix with the mixed liquor in the second stage,
in the second stage, operating a mixer intermittently such that mixing of the incoming RAS and sludge from the first stage occurs for a time, then the mixer is shut off for a selected period of time whereby heavier granular biomass tends to settle deeper than floc biomass in the second stage, so that said remaining portion of RAS entering the second stage comes into intimate contact with the settled granular biomass and particulate BOD, and
the proportions of incoming wastewater and RAS in the first stage being such as to create a food to mass ratio (F/M) of at least 5.