Lab-scale assessment of combined biogas production and brewery wastewater treatment with a forward osmosis anaerobic membrane bioreactor

Everyday a vast amount of wastewater is being produced due to various production processes. This, coupled with the shortage of clean or drinkable water, led many researchers to face the problem of recovery of water and energy from industrial and urban wastewaters. The aim of the present work was to perform a preliminary study of the performance of a novel system of anaerobic digestion coupled with forward osmosis (FO), which would theoretically allow the treatment of waste, the production of good quality water, and simultaneously the recovery of energy from biogas obtained by the degradation of the organic matter contained in the wastewater. The first stage of this work consisted in membrane assessment to evaluate the water flux achievable under different conditions: this step would serve as a basis for the subsequent stages of the investigation. Specifically, biomimetic aquaporin membranes, which are highly effective membranes capable of selective transport of a large number of molecular species, were used for this project. The second stage of the study was the set up and startup of the reactors for the anaerobic process using a synthetic wastewater, in order to achieve a better control over the results. During the third and final stage, the anaerobic reactors and the FO membranes were connected, and the main physical, biological and chemical parameters (e.g., water flux, VFAs, pH, temperature) were kept under constant monitoring and were analyzed in order to investigate thoroughly the interactions between the two systems. The results showed a decreasing trend of biogas production and a corresponding accumulation of VFAs (volatile fatty acids). This study highlights the complexity of the coupled system and hints at possible simultaneous advantages and disadvantages of the FO-anaerobic reactor. The interaction between the two systems needs further investigation to understand its feasibility and to pursue process optimization.