Performance and microbial community analysis of a full-scale hybrid anaerobic-aerobic membrane system for treating molasses-based bioethanol wastewater

We evaluated the efficacy of a full-scale combined biophysicochemical system for treating molasses-based bioethanol wastewater in terms of organic substances, nutrient, and dark brown color removal. The main organic removal unit, i.e., the upflow anaerobic sludge blanket [UASB] reactor, achieved 80.7% removal and 4.3 Nm3 methane production per cubic meter of wastewater with a hydraulic retention time of 16.7 h. Downflow hanging sponge [DHS] reactors were important in reducing the biochemical oxygen demand [BOD], and the lowest possible organic waste intake prevented excessive biomass formation. The BOD removal efficiency was 71.2-97.9%. The denitrification upflow anaerobic fixed bed [UFB] reactor achieved 99.2% total nitrogen removal. Post-physicochemical membrane treatment reduced the total phosphate, color, and remaining organic matter by 90.4%, 99.1%, and 99.8%, respectively. We analyzed the microbial diversity of the sludge from the UASB reactors. Methanosaeta was the dominant archaeal genus in the system, followed by Methanolinea, Methanomicrospillum, Caldiserica, Bacteroidetes, and Deltaproteobacteria

Rubber and methane recovery from deproteinized natural rubber wastewater by coagulation pre-treatment and anaerobic treatment

A newly developed natural rubber deproteinization process produces deproteinized natural rubber [DPNR] wastewater as an intermediate product containing a high concentration of sodium dodecyl sulfate [SDS] and rubber. In this study, a novel process to recover the residual rubber and energy as methane from DPNR wastewater was developed. As a pretreatment, SDS and residual rubber in DPNR wastewater were coagulated and recovered by addition of CaCl[2] at Ca[2+]/SDS and Ca[2+]/rubber mass ratios of 0.070 and 0.055, respectively. The remaining organic matter in the pre-treated DPNR wastewater was converted to methane by using a mesophilic up-flow anaerobic sludge bed [UASB] reactor. The UASB reactor with the diluted pre-treated DPNR wastewater showed a total chemical oxygen demand [COD] removal efficiency of 92 +/- 2% at a maximum loading rate of 6.8 +/- 1.8 kgCODm[-3]d[-1] at a hydraulic retention time [HRT] of 12 h. Under the condition of effluent recirculation with raw pre-treated DPNR wastewater, the UASB reactor showed a total COD removal efficiency of 84 +/- 8% at the maximum loading rate of 6.4 +/- 1.7 kgCODm[-3]d[-1] at HRT of 39 h. The results suggest that the newly developed resource recovery process for DPNR wastewater could be a promising treatment system