Microbial fuel cell biosensor for the determination of biochemical oxygen demand of wastewater samples containing readily and slowly biodegradable organics.

OBJECTIVES: Single-chamber air cathode microbial fuel cells (MFCs) were applied as biosensors for biochemical oxygen demand (BOD) measurement of real wastewaters with considerable suspended and/or slowly biodegradable organic content. RESULTS: The measurement method consists of batch sample injection, continuous measurement of cell voltage and calculation of total charge (Q) gained during the biodegradation of organic content. Diverse samples were analyzed: acetate and peptone samples containing only soluble readily biodegradable substrates; corn starch and milk samples with suspended and colloidal organics; real domestic and brewery wastewaters. Linear regression fitted to the Q vs. BOD5 measurement points of the real wastewaters provided high (> 0.985) R2 values. Time requirement of the measurement varied from 1 to 4 days, depending on the composition of the sample. CONCLUSIONS: Relative error of BOD measured in the MFCs comparing with BOD5 was less than 10%, thus the method might be a good basis for the development of on-site automatic BOD sensors for real wastewater samples.

Full-scale use of glycogen-accumulating organisms for excess biological carbon removal.

The purpose of this study has been to verify the efficient full-scale applicability of glycogen-accumulating organisms (GAOs) for excess biological carbon removal, that is, for removing more carbon substrate than the amount of available nutrients would allow in the conventional activated sludge process of microbial growth. This aims to cost-effectively overcome the problem of viscous bulking occurring in a fully aerated system, with nutrient deficiency. Analytical data measured at the wastewater treatment plant of the Balatonboglár (BB) winery in Balatonboglár, Hungary, containing consecutive unaerated and aerated activated sludge basins, reflected a high performance with efficient carbon removal and good sludge settling, without dosing any external nutrient source to the severely nitrogen- and phosphorous-deficient influent. Supplementary laboratory-scale batch experiments and microbiological tests verified the abundance of GAOs in the activated sludge system and elucidated their role in efficient excess biological carbon removal.