Review of Constructed Wetland Microbial Fuel Cells

Based on Liam Doherty at al (2015) review, Constructed Wetland Microbial Fuel Cells (CM-MFC) is a recently emerged technology for treating wastewater and generating electricity. MFC utilize substrate to generate electricity and it can be supported by microorganism that is applied in rhizospere of constructed wetland. Constructed wetland is known as technology which can remove pollutant such as nitrogen (nitrate, nitrite, and ammonia), phosphorus, and even heavy metals. So do MFC, can treat both chemical oxygen demand (COD) and harmful contaminant in wastewater. 

Sediment microbial fuell cell (SMFC) which has been developed before microbial fuel cells use plant (Plant MFC) to get higher voltage, moreover, currently it shows a promising bioenergy because it can generate electricity to power mini fan and biosensor in somewhere lake in US.


There are a lot of studies to improving this technology performance. Many researcher have been made some different design knowing the best configuration to treating the fuel and generating electricity. Present study give an information that combination of Constructed Wetland and Microbial Fuel Cell can work effectively if we use suitable material for each part of microbial fuel cell (anode, cathode, or separator).


Oon et al (2015) in their research showing best voltage of upflow constructed wetland microbial fuel cell (UFCW-MFC) when electrode (anode and cathode) spacing was small (in this research, 15 cm of space required). Maximum power density was 6,12 mW/m2, respectively. Nitrate and ammonium can be removed for about 40% and 91%. Aeration have done to control the aerobic and anaerobic regions of the system. They use carbon felt electrodes which have 280 cm2 of surface area and inoculated in the mixed culture sludge. This sophisticated design give a new paradigm that microbial fuel cells can be applied with upflow constructed wetland.

Different study (Lu et al, 2015) focused on how microbial consortia in anode side can improve the wetland microbial fuel cell performance. Associated with Canna indica, bacterial and archaeal communities can produce maximum current of 106 mA/m2 by utilizing fuel as electron donor and another nutrient contained in rhizospere. That association is called syntrophy which positively give better performance of microbial fuel cells. But there is another syntrophy which can be limit the growth condition of microbial consortia especially oligotrophic bacteria. That is competition between denitrifying bacteria or methanogens which produce an electron acceptor that can decrease the current production.

 

This review proof me something that microbial fuel cells and constructed wetland are suitable to be applied in Indonesia in which many treatment plants applicate wetlands to treat wastewater. Microbial fuel cells is also being developed in lab-scale and is still few research on it. This chance need to be explored, especially to increase pollutant removal effieciency, and further to generate electricity. This field of study still rare to be found in Indonesia. Many renewable energy researcher still focus on biodiesel and another bioconversion of waste. Constructed wetland microbial fuel cell can be a compromising technology which have viable cost, generate electricity, and high efficiency removal. This ‘power plant’ is a green energy that this country needed.


References :
Oon Yoong-Ling, Soon-An Ong, Li-Ngee Ho, Yee-Shian Wong, Yoong-Sin Oon, Harvinder Kaur Lehl, Wei-Eng Thung. 2015. Hybrid system up-flow constructed wetland integrated with microbial fuel cell for simultaneous wastewater treatment and electricity generation. Bioresource Technology 186 (2015) 270–275. Malaysia.
Lu Lu, Defeng Xing, Zhiyong Jason Ren. 2015. Microbial community structure accompanied with electricity production in a constructed wetland plant microbial fuel cell. Bioresource Technology 195 (2015) 115–121. China.
Liam Doherty, Yaqian Zhao, Xiaohong Zhao, Yuansheng Hu, Xiaodi Hao, Lei Xu, Ranbin Liu. 2015. A review of a recently emerged technology: Constructed wetland - Microbial fuel cells. Journal of Water Research 85 (2015) 38-45. University College Dublin : Dublin.