Effect of the Filling Ratio, MLSS, Hydraulic Retention Time, and Temperature on the Behavior of the Hybrid Biomass in a Hybrid Moving Bed Membrane Bioreactor Plant to Treat Urban Wastewater

Seven cycles of operation in relation to the filling ratio, mixed liquor suspended solids (MLSS), hydraulic retention time (HRT), and temperature were studied in a pilot-scale experimental plant of a hybrid moving bed biofilm reactor-membrane bioreactor (MBBR-MBR). The aim of the present research was to study the influence of the operative variables on the behavior of a hybrid MBBR-MBR in relation to organic matter removal and nitrification activity through the kinetic constants for the autotrophic and heterotrophic biomass. Biofilm density during the present research depended on the operative variables changing from 4,403±188 to 5,844±268 mg/L of the carrier, increasing with the increase in MLSS and with the decrease in the HRT. The removal rate was higher than 87.40±4.90 and 94.88±2.41% for chemical oxygen demand (COD) and biological oxygen demand (BOD) BOD5, respectively, increasing process efficiency with the MLSS, HRT, and temperature. Yield for heterotrophic biomass (YH) was between 0.506±0.004 and 0.714±0.076 mg CODformed/mg CODoxidized, and μH,máx of between 0.0245±0.0006 and 0.056±0.012 h−1. The minimum values of efficiencies obtained for ammonia and total nitrogen were 40.40±20.84 and 8.75±5.09%, respectively, presenting yield for autotrophic biomass (YA) between 0.23±0.01 and 0.51±0.12 mgCODformed/mgNoxidized, and μA,máx varying from 0.0816±0.063 to 0.3083±0.1199 days−1. Considering the results obtained in this research, hybrid MBBR-MBR could be a reliable technology to reduce the energy demands and fouling problems associated with conventional MBR technology.