Photosynthetic microbial desalination cells (PMDCs) for clean energy, water and biomass production

Abstract

Current microbial desalination cell (MDC) performances are evaluated with chemical catalysts such as ferricyanide, platinum catalyzed air-cathodes or aerated cathodes. All of these methods improve power generation potential in MDCs, however, they are not preferable for large scale applications due to cost, energy and environmental toxicity issues. In this study, performance of microbial desalination cells with an air cathode and an algae biocathode (Photosynthetic MDC - PMDC) were evaluated, both under passive conditions (no mechanical aeration or mixing). The results indicate that passive algae biocathodes perform better than air cathodes and enhance COD removal and utilize treated wastewater as the growth medium to obtain valuable biomass for high value bioproducts. Maximum power densities of 84 mW m(-3) (anode volume) or 151 mW m(-3) (biocathode volume) and a desalination rate of 40% were measured with 0.9 : 1 : 0.5 volumetric ratios of anode, desalination and algae biocathode chambers respectively. This first proof-of-concept study proves that the passive mechanisms can be beneficial in enhancing the sustainability of microbial desalination cells.

Bioelectrochemical Systems (BES) for Microbial Electroremediation: An Advanced Wastewater Treatment Technology

“…External nitrification was beneficial to the current generation and nitrate removal rate, but was not affecting total nitrogen removal (Zhang and Angelidaki 2013). Photosynthetic MDC was designed and operated using algae as catalyst in cathode (biocathode) which enhanced the COD removal and utilized treated wastewater as the growth medium to obtain valuable biomass for high value bioproducts (Kokabian and Gude 2013). The increase in salinity concentrations in anode chamber provide more favourable conditions for certain types of microbes than others resulting in enrichment of selective bacteria with simultaneous elimination of the bacteria that can withstand saline conditions (Mehanna et al 2010).…”

Biodesalination—On harnessing the potential of nature’s desalination processes

“…Although desalination by MFC is an emerging approach, its low fresh water production rate has limited its wider applications. For example the desalination rate of a 200 ml NaCl solution with 10000 mg L -1 NaCl solution is about 6.7 mg h -1 [37] and this value reduces to 2.8 mg h -1 when NaCl concentration increased to 35000 mg L -1 [104].…”

“…Amezaga et al [3] and Minas et al [62] referred to biodesalination as the production of fresh water using bacteria whereas biodesalination was described elsewhere as removing sulfate from highly polluted mine water in a bioreactor [106]. Biologically based fresh water production has also been addressed under different terms such as photosynthetic microbial desalination [37] or microbial desalination cell technology [9]. The large amount of publications and unclear definitions indicate the "biodesalination" has now reached the stage where a comprehensive review is required to cover the latest progress, understand knowledge gaps and most importantly define the term of biodesalination.…”

“…This provided enough motivation for biologists and engineers to conduct a significant amount of research to identify robust new methods of water desalination with lower energy consumption, reduced cost and minimized adverse environmental impacts. As presented in Table 1, the innovative biodesalination approaches such as the photosynthetic microbial desalination cells (PMDCs) can not only desalinate saline water but also are able to generate electricity without compromising ambient environment [37]. The new interdisciplinary field of biodesalination has resulted in several research papers introducing new potential desalinating approaches and also addressing different aspects of this field.…”

Fabrication of Nanofiber Filtration Membranes Using Polyethylene Terephthalate (PET): A Review

“…[15]. Today, other different water treatment and purification methods for the cleaning of water have been developed with the most common ones being i) Chemical methods such as coagulation, flocculation, flotation, chlorination, filtration, chemical precipitation and ion exchange [16][17][18][19][20][21][22], ii) Biological treatments and Biodegradation methods such as microbial biomass adsorption [23], microbial degradation [24] and biodesalination [25], and iii) Adsorption techniques involving solid sorbents such as Carbon Nanotubes (CNTs), activated carbon and carbon fiber [26][27][28][29]. Amongst all above mentioned classic techniques, adsorption with solid adsorbents is a simpler and cheaper method for water pre-treatment and cleaning.…”