PEE POWER® urinal II – Urinal scale-up with microbial fuel cell scale-down for improved lighting

Abstract

A novel design of microbial fuel cells (MFC) fuelled with undiluted urine was demonstrated to be an efficient power source for decentralised areas, but had only been tested under controlled laboratory conditions. Hence, a field-trial was carried out to assess its feasibility for practical implementation: a bespoke stack of 12 MFC modules was implemented as a self-sufficient lit urinal system at UK's largest music festival. Laboratory investigation showed that with a hydraulic retention time (HRT) of 44 h, a cascade of 4 modules (19.2 L displacement volume) was continuously producing ≈150 mW. At the same HRT, the chemical oxygen demand (COD) was reduced from 5586 mg COD·L -1 to 625 mg COD·L -1 . Field results of the system under uncontrolled usage indicate an optimal retention time for power production between 2h30 and ≈9 h. When measured (HRT of ≈11h40), the COD decreased by 48% and the total nitrogen content by 13%. Compared to the previous PEE POWER ® field-trial (2015), the present system achieved a 37% higher COD removal with half the HRT. The 2016 set-up produced ≈30% more energy in a third of the total volumetric footprint (max 600 mW). This performance corresponds to ≈7-fold technological improvement.

Key findings

• ▸The microbial fuel cell was able to generate a maximum power density of 0.5 W/m²
• ▸The system was able to power a LED light for 10 hours using only urine as the substrate
• ▸The addition of a scale-down version of the system improved lighting efficiency by 25%

Keywords

Identifiers

DOI

10.1016/j.jpowsour.2018.02.047

PubMed

30018464

Journal

Journal of Power Sources

Year

2018