Coupling electrochemical energy generation with leachate bioremediation in sediment microbial fuel cell reactors

Abstract

The fundamental objective of this investigation is to explore the utilization of sediment and leachate waste as substrates within the framework of a sediment microbial fuel cell (SMFC) reactor. This study's sediment and leachate materials were sourced from the Aceh regional landfill in Blang Bintang, Aceh Besar, Indonesia. The experiment entailed the operation of a trio of reactors in batch mode, manipulating electrode counts. Daily electrochemical measurements employed an Arduino-based open-source microcontroller, while bioremediation assessment of the leachate was performed bi-daily using a UV–Vis spectrophotometer. Morphological transformations of the anode surface pre- and post-experimentation were elucidated through scanning electron microscopy (SEM), and the bacterial consortium forming the anode biofilm was scrutinised using 16S rRNA amplicon sequencing. Consequently, escalating electrode counts exhibited favourable implications for electricity generation. Peak voltages recorded for the SMFC-LL1, SMFC-LL2, and SMFC-LL3 reactors reached 503 mV, 541 mV, and 583 mV, respectively. Conversely, the presence of multiple electrodes yielded no statistically significant disparity in leachate bioremediation efficiency. After a 35-day experimental period, COD concentrations for SMFC-LL1, SMFC-LL2, and SMFC-LL3 samples were measured at 961 mg/L, 888 mg/L, and 895 mg/L, respectively, down from the initial 1368 mg/L. The initial leachate ammonia concentration of 353.6 mg/L underwent reduction to 0.1 mg/L, 0.13 mg/L, and 0.25 mg/L. Nitrate levels dropped from 2.7 mg/L to 1.1 mg/L, 1 mg/L, and 0.95 mg/L, while nitrite concentrations diminished from 17.1 mg/L to 1.15 mg/L, 1.2 mg/L, and 1.15 mg/L for SMFC-LL1, SMFC-LL2, and SMFC-LL3 reactors, respectively. Additionally, robust biofilm formation was observed on the anode surface, predominantly comprised of Proteobacteria phylum members. The 16S rRNA gene analysis of hypervariable regions V1–V9 revealed prevailing bacterial taxa as Thiobacillus, Zeimonas, Thioalkalivibrio, Syntrophobacterium, Luteimonas, Capillibacterium, Acetivibrio, and Steroidobacter.