Demonstration Study of High-Rate Floatation/Contactor Treatment of Raw Wastewater

Research will be conducted in the following categories: biological wastewater treatment; innovative primary treatment for carbon diversion; thermal hydrolysis pre-treatment of sludges; anaerobic digestion; co-digestion of fats, oils, and grease (FOG); food waste; bioplastics; sludge dewatering; on-site wastewater treatment including passive denitrifying absorption systems and constructed wetlands; water recycling; membrane bioreactors; groundwater infiltration into sewers; stormwater runoff management including green roofs; and biofiltration systems.

Demonstration Study of High-Rate Floatation/Contactor Treatment of Raw Wastewater

R.M. Towill Corporation

03/01/2016 – 06/30/2021

The Honouliuli Wastewater Treatment Plant (WWTP) is the second largest treatment plant in Hawai‘i. At the WWTP, an average of 26 million gallons per day (MGD) of sewage is treated via primary clarifiers—13 MGD is further treated by trickling filter/solids contact (TF/SC) secondary treatment prior to further treatment and recycling at the ‘Ewa Recycling Facility. The remaining 13 MGD of primary effluent is discharged through an ocean outfall. The City is under agreement to upgrade the treatment train to treat all wastewater to secondary level using conventional activated sludge (CAS). Currently being considered as an option is a new process to reduce the amount of organic material passing through the primary treatment process into the secondary process, and thereby reducing the energy used for oxidation of the organics in the secondary processing. In addition, the diversion of raw/primary solids directly to the anaerobic digesters enhances the production of biogas and energy capture via co-generation. The new process replaces primary clarifiers with a two-step process consisting of an aerated contact chamber followed by a dissolved air flotation (DAF) unit. The upgraded facility will also incorporate a thermal hydrolysis process (THP) for sludge pretreatment before anaerobic digestion (AD), a sludge dryer/pelletizer, and combined-heat and power (CHP). This project will conduct bench and pilot scale testing of the high-rate primary diversion/biosorption process, bench testing of THP, THP-AD, and sludge dewatering.