Enhancing Biochemical Methane Potential and Enrichment of Specific Electroactive Communities from Nixtamalization Wastewater using Granular Activated Carbon as a Conductive Material

Abstract

Nejayote (corn step liquor) production in Mexico is approximately 1.4 × 1010 m3 per year and anaerobic digestion is an effective process to transform this waste into green energy. The biochemical methane potential (BMP) test is one of the most important tests for evaluating the biodegradability and methane production capacity of any organic waste. Previous research confirms that the addition of conductive materials significantly enhances the methane production yield. This study concludes that the addition of granular activated carbon (GAC) increases methane yield by 34% in the first instance. Furthermore, results show that methane production is increased by 54% when a GAC biofilm is developed 10 days before undertaking the BMP test. In addition, the electroactive population was 30% higher when attached to the GAC than in control reactors. Moreover, results show that electroactive communities attached to the GAC increased by 38% when a GAC biofilm is developed 10 days before undertaking the BMP test, additionally only in these reactors Geobacter was identified. GAC has two main effects in anaerobic digestion; it promotes direct interspecies electron transfer (DIET) by developing an electro-active biofilm and simultaneously it reduces redox potential from −223 mV to −470 mV. These results suggest that the addition of GAC to biodigesters, improves the anaerobic digestion performance in industrial processed food waste.

In Situ Electrochemical Characterization of a Microbial Fuel Cell Biocathode Running on Wastewater

“…It should be noted that the number of electroactive microorganisms is in constant expansion, such as the case of Methanobacteriales or Methanosarcinales (also found in abundance in the biocathode chamber), as recently described [27][28][29]. In addition, the results are in agreement with the observations that some microorganisms, in particular Methanosarcina, were enriched on carbon-based materials such as carbon felt [30] and recent reports point to the ability of this strain to direct exchange electrons with electrified surfaces [28].…”

Improvement in Methane Production from Pelagic Sargassum Using Combined Pretreatments

“…Although the use of different conductive materials (GAC, biochar, nano-magnetite, and minerals) in the production of methane has been evaluated [ 31 , 32 ], this work has focused on GAC, mainly due to its high conductivity of 3,600 µS·cm −1 ; this conductivity is higher than magnetite (160 µS·cm −1 ) and biochar (5 µS·cm −1 ) [ 75 ]. GAC is the ideal conductive material due to its surface area, high conductivity, and economically favorable low cost [ 76 , 77 ].…”

Sulfur, Phosphorus and Metals in the Stoichiometric Estimation of Biomethane and Biohydrogen Yields

“…. +100 mV if no oxygen is present, with some exceptions [48][49][50][51]) define the following species of dissociation that should be in the solution: HS − , H 2 PO 4 − , NH 4 + ;, and a mixture of CO 2 and HCO 3 − . In such forms, they should be consumed for building anaerobic microbial biomass, with a composition usually expressed as C 5 H 7 O 2 NP 0.06 S 0.1 according to [52][53][54][55].…”