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.

A survey has been carried out involving 55 Hungarian wastewater treatment plants in order to evaluate the wastewater quality, the applied technologies and the resultant problems.Characteristically the treatment temperature is very wide-ranging from less than 10 W C to higher than 26 W C. Influent quality proved to be very variable regarding both the organic matter (typical COD concentration range 600-1,200 mg l À1 ) and the nitrogen content (typical NH 4 -N concentration range 40-80 mg l À1 ). As a consequence, significant differences have been found in the carbon availability for denitrification from site to site. Forty two percent of the influents proved to lack an appropriate carbon source. As a consequence of carbon deficiency as well as technologies designed and/or operated with non-efficient denitrification, rising sludge in the secondary clarifiers typically occurs especially in summer. In case studies, application of intermittent aeration, low DO reactors, biofilters and anammox processes have been evaluated, as different biological nitrogen removal technologies.With low carbon source availability, favoring denitrification over enhanced biological phosphorus removal has led to an improved nitrogen 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. Water Environ. Res., 83, 855 (2011).

The pharmaceutical industry produces carbon-rich liquid wastes which have been generally qualified as hazardous. A significant proportion of these carbon-rich wastes are currently sent for incineration, although they could be utilised. It was found that the majority of the liquid wastes investigated in this study could be used in biological N-removal as carbon sources for denitrification in domestic wastewater treatment, or for anaerobic biogas production. The volatile content could be separated and the solvents re-utilised, the residual toxic organic compounds could be decomposed by wet oxidation and subsequently sent for biological treatment.

Wet oxidation was carried out for treating different industrial process wastewaters (PWW's) of pharmaceutical production, with oxygen in a stainless steel autoclave at 230 and 250°C and total pressure of 50 bar. Beside non-catalytic, a catalytic reaction was also carried out. The catalyst applied was Ti mesh covered with Ru and Ir oxide. PWW samples were analyzed with respect to their TOC, COD (BOD) content. The tested PWW's could be oxidized but with rather different conversions. Some effluents were converted with remarkable rate due in some cases to their Fe or Cu ion content, in other cases to the Ti based precious metal oxide catalyst.