This study assesses the impact of hydraulic retention time (HRT) on the performance of an anaerobic dynamic membrane bioreactor (AnDMBR) system using a carbon fabric membrane for treating high-strength wastewater. The evaluation of AnDMBR performance encompasses the removal of soluble chemical oxygen demand (sCOD), biogas/methane production, and membrane fouling. The average influent sCOD concentration was 11,814 ± 1064 mg/L, with two HRT applications at 8 and 5 days and high biomass concentration (MLVSS 14,600 ± 500 mg/L). An impressive sCOD removal efficiency exceeding 98% was achieved throughout the operation period. The AnDMBR system exhibited the highest biogas production, reaching 4.33 ± 0.51 L/day, with a methane content of approximately 67.77 ± 2.9% during the 5-day HRT stage. Transmembrane pressure (TMP) increased gradually at the 8-day HRT stage, leading to membrane fouling, whereas fouling occurred more rapidly at the 5-day HRT stage. Biomass analysis showed minimal variations in MLVSS, extracellular polymeric substance (EPS), and soluble microbial product (SMP) concentrations (protein and carbohydrate) across both HRT application stages. This study suggests that the AnDMBR system can be adopted effectively for treating high-strength wastewater, maintaining high COD removal efficiency and biogas production with 5-day HRT.

In this study, anaerobic treatability of diluted chicken manure (with an influent feed ratio of 1 kg of fresh chicken manure to 6 L of tap water) was investigated in a lab-scale anaerobic sludge bed (ASB) reactor inoculated with granular seed sludge. The ASB reactor was operated at ambient temperature (17–25°C) in order to avoid the need of external heating up to higher operating temperatures (e.g., up to 35°C for mesophilic digestion). Since heat requirement for raising the temperature of incoming feed for digestion is eliminated, energy recovery from anaerobic treatment of chicken manure could be realized with less operating costs. Average biogas production rates were calculated ca. 210 and 242 L per kg of organic matter removed from the ASB reactor at average hydraulic retention times (HRTs) of 13 and 8.6 days, respectively. Moreover, average chemical oxygen demand (COD) removal of ca. 89% was observed with suspended solids removal more than 97% from the effluent of the ASB reactor. Influent ammonia, on the other hand, did not indicate any free ammonia inhibition due to dilution of the raw manure while pH and alkalinity results showed stability during the study. Microbial quantification results indicated that as the number of bacterial community decreased, the amount of Archaea increased through the effective digestion volume of the ASB reactor. Moreover, the number of methanogens displayed an uptrend like archaeal community and a strong correlation (−0.645) was found between methanogenic community and volatile fatty acid (VFA) concentration especially acetate.