Operation of an Anaerobic Membrane Bioreactor at low temperatures

Abstract

The growing concern in the development of new intensive technologies, is due to increasingly stringent regulations regarding waste disposal and to reduce energy needs. During vintage, the high organic load of wastewater from the production of wine, favors the application of mesophilic anaerobic processes to convert organic matter into biogas. However, when loads are low during the winter season, anaerobic digestion has been carried out at room temperature. The main objective of this project is to run an anaerobic membrane bioreactor (AnMBR) fed with synthetic wastewater wine at low temperatures (15ºC and 25ºC) and assess the activity of methanogenic biomass. During the experiment conducted, the AnMBR shows a good performance for the treatment of these waters, getting a good elimination of organic matter with a low requirement of nutrients. COD removal efficiency was not sufficient to meet the current regulations established. The operation at 25ºC had a better removal of COD than at 15 ºC, 80% and 71%, respectively. A higher acid value was detected when operated at 15ºC. It was obtained of the VFA accumulation on average 132±135 mg VFA/L and 183±135 mg VFA/L at 25ºC and 15ºC, respectively. The flux decline was 2.14 and 3.63 LMH d-1 at 25°C and 15°C, respectively, this coincides with the increased removal of organic matter at 25°C. The biogas production at 25ºC was 0.007±0.002 m3 biogas/m3reactord and at 15ºC was not possible to determinate experimentally. At 25ºC were favored the methanosaetas spp and methanosarcinas. Instead, only the methanosarcinas were developed at 15ºC.