Municipal waste liquor treatment via bioelectrochemical and fermentation (H2 + CH4) processes: Assessment of various technological sequences

Abstract

In this paper, the anaerobic treatment of a high organic-strength wastewater-type feedstock, referred as the liquid fraction of pressed municipal solid waste (LPW) was studied for energy recovery and organic matter removal. The processes investigated were (i) dark fermentation to produce biohydrogen, (ii) anaerobic digestion for biogas formation and (iii) microbial fuel cells for electrical energy generation. To find a feasible alternative for LPW treatment (meeting the two-fold aims given above), various one- as well as multi-stage processes were tested. The applications were evaluated based on their (i) COD removal efficiencies and (ii) specific energy gain. As a result, considering the former aspect, the single-stage processes could be ranked as: microbial fuel cell (92.4%)> anaerobic digestion (50.2%)> hydrogen fermentation (8.8%). From the latter standpoint, an order of hydrogen fermentation (2277 J g COD d)> anaerobic digestion (205 J g COD d)> microbial fuel cell (0.43 J g COD d) was attained. The assessment showed that combined, multi-step treatment was necessary to simultaneously achieve efficient organic matter removal and energy recovery from LPW. Therefore, a three-stage system (hydrogen fermentation-biomethanation-bioelectrochemical cell in sequence) was suggested. The different approaches were characterized via the estimation of COD balance, as well.

Overview of porous media/metal foam application in fuel cells and solar power systems

“…Many advantages are associated with the MFC, such as high conversion efficiency by direct conversion of substrate energy to electricity, does not require further gas treatment of by-products, and does not require energy input for aeration given that the cathode is passively aerated and the MFC can operate at ambient or low temperatures efficiently [51]. The energy recovery rate from municipal liquid waste fraction can be improved through three stages of treatment but still requires further studies for better performance [52]. However, the MFC is limited by cost, high activation loss [53] and limited power density [54].…”

Anaerobic digestion and electromethanogenic microbial electrolysis cell integrated system: Increased stability and recovery of ammonia and methane

“…The combination of anaerobic digestion (AD) and bioelectrochemical systems (BES) is an integrated strategy that can be implemented with different objectives and configurations [4,5] and can attain the goals of the biorefinery concept [6,7]. On the one hand, nutrients can be recovered from ammonium-rich wastewater such as pig slurry or digested pig slurry thanks to cation or anion transport through exchange membranes that takes places in BES [8].…”

“…On the second hand, BES can operate with low organic loading rates and may be used to polish the effluent of the AD [16][17][18] or even to absorb higher organic concentrations in the digestates due to AD destabilisation or inhibition [18,19]. Previous work has shown that integrated or multi-step systems can increase the energy production from complex substrates [4]. The combination of AD and BES for effluent polishing has been studied mainly using energy recovering MFC, to treat the effluent of a two-stage biogas process [20], digested landfill leachate [21], digested swine wastewater [22], a digested mixture of swine manure and rice bran [23] or digested wastewater from processing potato industries [17].…”

On the efficiency of dual-chamber biocatalytic electrochemical cells applying membrane separators prepared with imidazolium-type ionic liquids containing [NTf 2 ] − and [PF 6 ] − anions

“…Until recently, a variety of (i) real i.e. landfill-derived waste liquor [3] as well as (ii) synthetic wastewaters containing relatively simple compounds i.e. glucose, acetate, alcohols, volatile fatty acids, etc.…”