Performance and design considerations for an anaerobic moving bed biofilm reactor treating brewery wastewater: Impact of surface area loading rate and temperature.

Three 4 L anaerobic moving bed biofilm reactors (AMBBR) treated brewery wastewater with AC920 media providing 680 m2 protected surface area per m3 of media. Different hydraulic retention times (HRT; 24, 18, 12, 10, 8 and 6 h) at 40% media fill and 35 °C, as well as different temperatures (15, 25 and 35 °C) at 50% media fill and 18 h HRT were examined. Best performance at 35 °C and 40% media fill was observed when HRT was 18 h, which corresponded with 92% removal of soluble COD (sCOD). Organic loading rates (OLR) above 24 kg-COD m-3d-1 decreased performance below 80% sCOD removal at 35 °C and 40% media fill. The reason was confirmed to be that surface area loading rates (SALR) above 50 g-sCOD m-2d-1 caused excessive biofilm thickness that filled up internal channels of the media, leading to mass transfer limitations. Temperature had a very significant impact on process performance with 50% media fill and 18 h HRT. Biomass concentrations were significantly higher at lower temperatures. At 15 °C the mass of volatile solids (VS) was more than three times higher than at 35 °C for the same OLR. Biofilms acclimated to 25 °C and 15 °C achieved removal of 80% sCOD at SALR of 10 g-sCOD m-2d-1 and 1.0 g-sCOD m-2d-1, respectively. Even though biomass concentrations were higher at lower temperature, biofilm acclimated to 25 °C and 15 °C performed significantly slower than that acclimated to 35 °C.

Removal of Soluble Phosphorus from Surface Water Using Iron (Fe-Fe) and Aluminum (Al-Al) Electrodes.

The removal of soluble phosphorus using iron and aluminum electrodes was studied in water samples from the Red River, a hyper-eutrophic stream in Winnipeg, Canada. Four trials were conducted: (I) mixed batch with 150-900 mA applied for 1 min to 1 L, (II) stagnant batch with 600-900 mA applied for 1 min to 1 L, and (III and IV) continuously stirred-tank reactor with 6.25-10 min hydraulic retention times and constant 900 mA. Maximum soluble phosphorus removals of 70-80% were observed in mixed batch, and there was no significant difference between aluminum and iron electrodes (P value of 0.0526-0.9487). Aluminum electrodes performed significantly worse than iron electrodes under higher hydraulic loads, with iron removing >70% soluble phosphorus and aluminum <40% (P values of 0.0035-0.0143). The estimated cost of consumables, reported per million liters of water treated, to remove 70% soluble phosphorus from eutrophic waters with 0.35 g m-3 soluble phosphorus would include 5-17.5 USD electricity costs and material costs of 5.3-12.2 USD for iron and 39.2 USD for aluminum.

Granulation of activated sludge under low hydrodynamic shear and different wastewater characteristics.

Five reactors were operated with low upflow superficial air velocities (0.41cmmin-1) in order to observe granulation on synthetic wastewaters with different characteristics: 1) 340mg-CODL-1; 2) 630mg-CODL-1; and 3) 1300mg-CODL-1. Stable granulation was only observed under low hydrodynamic shear for low-strength wastewater. 55-70% of soluble chemical oxygen demand (COD) was utilized before aeration and 91% COD, 62% total nitrogen (TN), and 96% total phosphorus (TP) were removed from the low-strength wastewater. Although medium-strength wastewater did generate granules they rapidly acquired a filamentous surface layer that resulted in decreased performance and loss of nitrification. 94% COD, 30% TN, and 85% TP were removed from the medium-strength wastewater. The high-strength wastewater did not develop granules and 85% COD was removed. Results demonstrated that high shear force was not required for granulation. Rather, granulation depended on multiple parameters to out-select rapidly growing aerobic microorganisms.