Microbial fuel cells and constructed wetlands as a sustainable alternative for the treatment of hospital laundry wastewaters: Assessment of load parameters and genotoxicity

This research investigated the sequential use of microbial fuel cells (MFC) and constructed wetlands (CW) for the treatment of wastewaters generated at a hospital laundry. The MFC was vegetated with Chrysopogon zizanioides whereas Hymenachne grumosa was planted in the CW unit. The hydraulic retention time in each unit was of 7 days, totaling 14 days of treatment. The evaluation of the efficiency of the integrated system considered the analysis of load parameters and the genotoxicity potential before and after the treatments. Regarding the raw wastewaters, the results revealed mean values of some of the analyzed parameters above the maximum emission limits established by Brazilian and international guidelines. Furthermore, the untreated effluents presented a strong genotoxic effect (p < 000.1) against D. magna. On the other hand, the results of the treated wastewaters showed reductions of 79.8 %,78.6 %, 81.6 %, 53.1 %, 81.5 % and 99.9 % for COD, BOD5, Total N, TDC, DOC and Turbidity. Also, the treated wastewaters presented significant reductions (p < 0.05) of the genotoxicity. Therefore, the use of the integrated system showed that both units had complimentary effect and presented satisfactory results regarding the removal of the organic load, complying with national and international standards and significantly reduced the genotoxicity. The maximum open circuit voltages reached values of 148 mV using the graphite electrodes, whereas for the granular activated carbon electrode the bioenergy generated attained 268 mV. So, besides been effective, the integrated system can be sustainable from both environmental and economic aspects, especially for developing countries, where there is limited or insufficient wastewater treatment infrastructure.