4. Conclusion and future perspectives
This study significantly advances our understanding of MFC
technology scaling up. The analysis demonstrates that MFC has the
potential of producing reclaimed water for irrigation with simultaneous
electricity generation; both of large economic benefit to
farmers. Another advantage of the application is providing an
affordable method for wastewater discharge. The costs for treating
food processing and beverage wastewater have increased significantly
in the past few years, ranging from $300,000 to $1,000,000
annually for medium to large food and beverage industries. In
addition, incomplete removal of organic and inorganic matter by
MFC is beneficial as MFC effluents may help in improving soil
health without oversupplying the soil with nutrients.
In this study, the net profit from using MFC for the treatment of
fruit wastewater before irrigation for 20 years is $7.1 million in the
San Joaquin Valley of California where water value is $440 per ac-ft
and electricity costs 15.5 cents per kWh. In regions with more
serious drought and where electricity is of higher value, the net
profit would be higher and could reach $50 million. Findings in this
research have given a promising idea for construction of large scale
MFCs and have brought the technology closer to real world applications.
MFC could be more feasible than conventional systems for
wastewater treatment prior irrigation. The technology has significant
potential to empower farmers and enhance water, energy and
food security.
Additional studies on nutrient removal by MFC are needed.
Testing the system on a pilot scale is essential before the application
of a full scale due to the limited number of developed models in the
literature and due to additional challenges such as unstable bacterial
biofilm and low power density when organic matter concentration
is low in wastewater. Techno-economic analysis for fullscale
MFC application is also needed to determine the appropriate
MFC configuration and operation for various wastewater sources.